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Histamine H3 receptor-mediated depression of synaptic transmission in the dentate gyrus of the rat in vitro.

1. The effects of histamine on excitatory synaptic transmission in the dentate gyrus region of rat hippocampal slices were examined using extracellular and whole-cell patch-clamp recording techniques. The GABAA receptor antagonist picrotoxin (50 microM) was present in the bath in all experiments. 2. Histamine (0.7-70 microM) reversibly depressed field excitatory postsynaptic potentials (fEPSPs) or excitatory postsynaptic currents (EPSCs) recorded intracellularly by up to 30%. The presynaptic fibre volley and EPSC reversal potential were unaffected by histamine, as were responses following pressure ejection of the glutamate receptor agonist S-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (S-AMPA) into the slice. 3. Histamine (7 microM) depressed equally the AMPA and N-methyl-D-aspartate (NMDA) components of the dual-component EPSC, recorded at -40 mV. 4. In addition to depressing synaptic transmission, histamine also reduced the magnitude of paired-pulse depression (PPD; 40 ms interpulse interval) of the medial perforant path EPSC. 5. Histamine depressed medial perforant path EPSCs more strongly than lateral perforant path EPSCs. Paired-pulse facilitation (PPF; 40 ms interpulse interval) in the lateral perforant path was enhanced by histamine. 6. The effects of histamine on synaptic transmission and PPD were mimicked by the selective H3 receptor agonist R-alpha-methylhistamine (0.1-10 microM) but not by the selective H2 receptor agonist dimaprit (10 microM). Similarly, the H3 receptor antagonist thioperamide (10 microM) blocked the effect of histamine whereas the H1 antagonist mepyramine (1 microM) and the H2 receptor antagonist cimetidine (50 microM) were ineffective. 7. Histamine actions on synaptic transmission and PPD were not occluded by application of the metabotropic glutamate agonist L-2-amino-4-phosphonobutyrate (AP4). 8. The results indicate that histamine depresses synaptic transmission in the dentate gyrus by binding to histamine H3 receptors located on perforant path terminals. The mechanism by which histamine depresses transmission is independent of that used by class III metabotropic glutamate receptors.

Animals↗

A quantitative analysis of histamine H2-receptor-mediated relaxation of rabbit trachea.

The histamine-induced relaxation of bethanechol-contracted rabbit trachea was analyzed pharmacologically in experiments designed to determine whether this tissue contains relaxant histamine H2-receptors or an atypical histamine receptor. Relaxation to histamine was potentiated by inhibition of histamine H1-receptors with chlorpheniramine. A cimetidine-resistant relaxant effect of high concentrations of histamine was observed which correlated with concomitant decreases in organ bath pH upon addition of histamine. Neutralization of the histamine solution eliminated the cimetidine-resistant effects of histamine. Cimetidine, metiamide and burimamide were competitive antagonists of histamine-responses with pKB values of 6.6, 6.1 and 5.4, respectively. These estimates are not significantly different from literature values for antagonism of H2-receptors by these drugs in guinea-pig right atria. The potency ratio of histamine and 4-methylhistamine (a selective H2-receptor agonist) was not significantly different from that obtained in rabbit right atria, an H2-receptor-containing tissue. These data from studies with antagonists and agonists indicated that histamine produced relaxation of rabbit trachea by activation of histamine H2-receptors.

Animals↗

Production and characterization of rabbit antibodies against histamine.

Antisera were raised in rabbits against histamine conjugated to human serum albumin (HSA) by the carbodiimide (ECDI) method. The specificity of the antisera was studied in a radioimmunoassay using 125I-protein A for detection of IgG binding. The HIS-HSA antisera reacted with histamine-HSA conjugates prepared by either the carbodiimide or diisocyanate coupling procedure, as well as with carbodiimide-prepared histamine-ferritin and histamine-ovalbumin conjugates. On the contrary, the antisera were unreactive with unconjugated HSA, ECDI-reacted HSA, or HSA conjugated to ethanolamine or pentylamine. Free unconjugated histamine significantly inhibited antibody binding to histamine-HSA and 50% inhibition of antibody binding (IC50) was recorded at 3 mM histamine concn. On a histamine molar concn basis a much lower inhibitory potency of free histamine was recorded, as compared to histamine-protein conjugates (IC50 = 3 X 10(-6) mM). This probably reflected amplification of antibody binding to the multivalent ligand, but possibly also that the protein carrier adds some common features to the antigenic determinant. Histidine, ornithine, glutamine, asparagine, sterylamine and several other amino acids lacked inhibitory effects. Histamine H1 and H2 receptor antagonists inhibited histamine binding to the histamine antibodies. The antagonists varied in their affinity for the histamine antibodies and 50% inhibition of antibody binding was recorded in the range of 1-50 mM concn of the antagonists. Comparing one H1 and one H2 antagonist (diphenhydramine and cimetidine, respectively) two of the sera were preferentially inhibited by cimetidine whereas the third serum seemed to be more prone to inhibition by diphenhydramine.

Animals↗

Hypertonicity of the challenge solution may increase the diagnostic accuracy of histamine challenge.

There is significant overlap in the responsiveness to direct airway challenges, such as the histamine challenge, between asthmatic and non-asthmatic subjects, which decreases their accuracy in the diagnosis of asthma. To minimise this overlap, a new test, hypertonic histamine challenge, was developed. Fifteen healthy subjects, 16 subjects with steroid-naive asthma, and 16 asthmatic subjects undergoing inhaled corticosteroid treatment underwent inhalation challenges with hypertonic saline, isotonic histamine, and hypertonic histamine, using an ultrasonic nebuliser and 2-min tidal breathing method. The increase in histamine solution tonicity decreased the histamine PC20 values only in the steroid-naive asthmatic subjects (1.1 (0.5-2.7) vs. 0.5 (0.2-1.2) mg/ml, P = 0.047). Using 1mg/ml as the cut-off value, the sensitivity, specificity, and accuracy of the hypertonic histamine challenge to detect steroid-naive asthma was 81%, 100%, and 90%. The respective values for the isotonic histamine challenge were 56%, 100%, and 77%. Furthermore, there was a statistically significant difference in the hypertonic histamine PC20 between steroid-naive and steroid-treated asthmatic subjects, which could not be detected in the isotonic histamine PC20. The hypertonic histamine PC20 was highly repeatable, with a single determination 95% range of +/-1.35 doubling concentrations. The hypertonic histamine challenge was safe but provoked more cough and throat irritation than the other two challenges. In conclusion, compared with a conventional, isotonic histamine challenge, hypertonic histamine challenge may be more accurate in the diagnosis of asthma and also, more capable to detect the effects of inhaled corticosteroid treatment.

Adult↗

Structural and functional characterization of gastric mucosa and central nervous system in histamine H2 receptor-null mice.

To examine the physiological role of the histamine H(2) receptor, histamine H(2) receptor-null mice were generated by homologous recombination. Histamine H(2) receptor-null mice, which developed normally and were fertile and healthy into adulthood, exhibited markedly enlarged stomachs and marked hypergastrinemia. The former was due to hyperplasia of gastric gland cells (small-sized parietal cells, enterochromaffin-like cells and mucous neck cells which were rich in mucin), but not of gastric surface mucous cells, which were not increased in number as compared with those in wild-type mice despite the marked hypergastrinemia. Basal gastric pH was slightly but significantly higher in histamine H(2) receptor-null mice. Although carbachol but not gastrin induced in vivo gastric acid production in histamine H(2) receptor-null mice, gastric pH was elevated by both muscarinic M(3) and gastrin antagonists. Thus, both gastrin and muscarinic receptors appear to be directly involved in maintaining gastric pH in histamine H(2) receptor-null mice. Interestingly, gastric glands from wild-type mice treated with an extremely high dose of subcutaneous lansoprazole (10 mg/kg body weight) for 3 months were very similar to those from histamine H(2) receptor-null mice. Except for hyperplasia of gastric surface mucous cells, the findings for gastric glands from lansoprazole-treated wild-type mice were almost identical to those from gastric glands from histamine H(2) receptor-null mice. Therefore, it is possible that the abnormal gastric glands in histamine H(2) receptor-null mice are secondary to the severe impairment of gastric acid production, induced by the histamine H(2) receptor disruption causing marked hypergastrinemia. Analyses of the central nervous system (CNS) of histamine H(2) receptor-null mice revealed these mice to be different from wild-type mice in terms of spontaneous locomotor activity and higher thresholds for electrically induced convulsions. Taken together, these results suggest that (1) gastrin receptors are functional in parietal cells in histamine H(2) receptor-null mice, (2) abnormal gastric glands in histamine H(2) receptor-null mice may be secondary to severe impairment of gastric acid production and secretion and (3) histamine H(2) receptors are functional in the central nervous system.

2-Pyridinylmethylsulfinylbenzimidazoles↗

Histamine fish poisoning revisited.

Histamine (or scombroid) fish poisoning (HFP) is reviewed in a risk-assessment framework in an attempt to arrive at an informed characterisation of risk. Histamine is the main toxin involved in HFP, but the disease is not uncomplicated histamine poisoning. Although it is generally associated with high levels of histamine (> or =50 mg/100 g) in bacterially contaminated fish of particular species, the pathogenesis of HFP has not been clearly elucidated. Various hypotheses have been put forward to explain why histamine consumed in spoiled fish is more toxic than pure histamine taken orally, but none has proved totally satisfactory. Urocanic acid, like histamine, an imidazole compound derived from histidine in spoiling fish, may be the "missing factor" in HFP. cis-Urocanic acid has recently been recognised as a mast cell degranulator, and endogenous histamine from mast cell degranulation may augment the exogenous histamine consumed in spoiled fish. HFP is a mild disease, but is important in relation to food safety and international trade. Consumers are becoming more demanding, and litigation following food poisoning incidents is becoming more common. Producers, distributors and restaurants are increasingly held liable for the quality of the products they handle and sell. Many countries have set guidelines for maximum permitted levels of histamine in fish. However, histamine concentrations within a spoiled fish are extremely variable, as is the threshold toxic dose. Until the identity, levels and potency of possible potentiators and/or mast-cell-degranulating factors are elucidated, it is difficult to establish regulatory limits for histamine in foods on the basis of potential health hazard. Histidine decarboxylating bacteria produce histamine from free histidine in spoiling fish. Although some are present in the normal microbial flora of live fish, most seem to be derived from post-catching contamination on board fishing vessels, at the processing plant or in the distribution system, or in restaurants or homes. The key to keeping bacterial numbers and histamine levels low is the rapid cooling of fish after catching and the maintenance of adequate refrigeration during handling and storage. Despite the huge expansion in trade in recent years, great progress has been made in ensuring the quality and safety of fish products. This is largely the result of the introduction of international standards of food hygiene and the application of risk analysis and hazard analysis and critical control point (HACCP) principles.

Disease Outbreaks↗

Purification of histamine receptor proteins from detergent-solubilized human peripheral blood mononuclear cells.

Histamine is released from mast cells and basophils by either immunological or nonimmunological mechanisms. Histamine, which is the most potent short acting mediator released from these cells, exerts its diverse biological actions by binding to cell surface histamine receptors. We report the affinity purification of histamine receptor proteins from Triton X-100 solubilized peripheral human blood mononuclear cells which include lymphocytes and monocytes. Three different designs of histamine affinity columns were constructed; all three resulted in the same material being eluted. This consisted of bands which on SDS-PAGE after boiling and reduction had the following molecular weights: 193K, 84K, 58K, 48K, 37K, and 16K. The most abundant bands were of molecular weights 193K, 48K, and 16K, and these were disulfide bonded together to form a high molecular weight complex. (The 58K band was present in lower amounts than the others, and in only a few fractions. It had the same molecular weight as the dimeric form of histamine methyltransferase which is present in small amounts in mononuclear cells and may therefore have copurified.) The histamine binding proteins described in this report were purified by conventional affinity chromatography, rather than by an expression cloning approach which obviates the use of any protein chemistry. Consequently, we had the advantage of being able to verify the histamine binding specificity of our purified proteins directly and with several independent assays as follows. The histamine binding specificity of all three columns was established by specific elution with histamine, by preabsorption of crude cell extract with excess free histamine prior to column application, and by comparison with control columns. Independent determination of the binding specificity, using a radioreceptor dot blot assay, of the eluate containing only the 193K, 48K, and 16K disulfide-linked subunits confirmed that the purified material bound specifically to [3H]histamine and that a 300-500-fold degree of purification from tissue extract had been obtained. Following cell surface radioreceptor cross-linking of radiolabeled histamine to intact mononuclear cells, the 16K band was detected, indicating it to be the ligand-binding subunit for histamine. These same three proteins were purified from T lymphocyte and monocytoid cell lines, indicating that both lymphocyte and monocyte subsets of mononuclear cells express these proteins.(ABSTRACT TRUNCATED AT 400 WORDS)

Blood Proteins↗

Proton nuclear magnetic resonance studies of mast cell histamine.

The state of histamine in mast cells was studied by 1H NMR spectroscopy. Spectra were measured for histamine in situ in intact mast cells, for histamine in suspensions of mast cell granule matrices that had been stripped of their membranes, and for histamine in solutions of heparin. The 1H NMR spectrum of intact mast cells is relatively simple, consisting predominantly of resonances for intracellular histamine superimposed on a weaker background of resonances from heparin and proteins of the cells. All of the intracellular histamine contributes to the NMR signals, indicating it must be relatively mobile and not rigidly associated with the negatively charged granule matrix. Spectra for intracellular histamine and for histamine in granule matrices are similar, indicating the latter to be a reasonable model for the in situ situation. The dynamics of binding of histamine by granule matrices and by heparin are considerably different; exchange of histamine between the bulk water and the granule matrices is slow on the 1H NMR time scale, whereas exchange between the free and bound forms in heparin solution is fast. The chemical shifts of resonances for histamine in mast cells are pH dependent, decreasing as the intragranule pH increases without splitting or broadening. The results are interpreted to indicate that histamine in mast cells is relatively labile, with rapid exchange between bound histamine and pools of free histamine in water compartments confined in the granule matrix.

Animals↗

Granulocyte-macrophage colony-stimulating factor and interleukin-3 cause basophil histamine release by a common pathway: downregulation by sodium.

Granulocyte-macrophage colony-stimulating factor (GM-CSF) and interleukin-3 (IL-3) are recognized as enhancers, but not as inducers, of histamine release from normal human basophils. However, when extracellular Na+ is removed IL-3 acquires the capacity to induce histamine release. The aim of this study was to evaluate whether GM-CSF can induce basophil histamine release using the same pathway of IL-3. Leucocyte suspensions from normal human subjects were stimulated with GM-CSF, IL-3 and anti-IgE, and histamine release was evaluated by an automated fluorometric method. In a physiological medium, GM-CSF (10 ng/ml) and IL-3 (10 ng/ml) did not provoke histamine release, in spite of an efficient response to anti-IgE (10 micrograms/ml). However, when extracellular Na+ was substituted iso-osmotically with N-methyl-d-glucamine+ or with choline+, GM-CSF and IL-3 were able to trigger histamine release from either mixed leucocyte suspensions or purified human basophils. The effect of GM-CSF on basophil histamine release was dose dependent, with optimal release at a dose of 1 ng/ml after incubation at 37 degrees for 60-120 min. The kinetics of IL-3-induced histamine release were similar, whereas anti-IgE-induced histamine release was more rapid, being almost maximal after incubation for 30 min. A good correlation was found between GM-CSF-induced and IL-3-induced histamine release; furthermore, the combined effects of the two cytokines were less than additive, suggesting that they share the same pathways leading to histamine release. When extracellular Na+ concentration was increased from 0 to 140 mm, histamine release induced by GM-CSF, IL-3 and anti-IgE was reduced progressively. In contrast, histamine release induced by these stimuli was upregulated when the concentration of extracellular Ca2+ was increased. These results provide indirect evidence that GM-CSF and IL-3 can induce basophil histamine release by a common pathway that is downregulated by Na+.

Adult↗

Disposition of histamine, its metabolites, and pros-methylimidazoleacetic acid in brain regions of rats chronically infused with alpha-fluoromethylhistidine.

In mammalian brain, histamine is known to be metabolized solely by histamine methyltransferase (HMT), forming tele-methylhistamine (t-MH), then tele-methylimidazoleacetic acid (t-MIAA). We previously showed that imidazoleacetic acid (IAA), a GABA agonist, and histamine's metabolite in the periphery, is present in brain where its concentration increased after inhibition of HMT. Also, when [3H]histamine was given intracerebro-ventricularly to rats, a portion was converted to IAA, a process increased by inhibition of HMT. These results indicated that brain has the capacity to oxidize histamine but did not show whether this pathway is operative under physiological conditions. To address this question, rats were infused for > 4 weeks with alpha-fluoromethylhistidine (alpha-FMHis), an irreversible inhibitor of histamine's synthetic enzyme, L-histidine decarboxylase. Compared with controls (untreated and saline-treated rats), brain levels of histamine, t-MH, and t-MIAA in all regions were markedly reduced in treated rats. As a percentage of controls, depletion of t-MIAA > t-MH > histamine in all regions, and regional depletions of histamine co-responded to its turnover rates in regions of rat brain. In contrast, levels of IAA were unchanged as were levels of pros-methylimidazoleacetic acid, an isomer of t-MIAA unrelated to histamine metabolism. Results suggest that in brains of rats, unlike in the periphery, most IAA may not normally derive from histamine. Because histamine in brain can be converted to IAA under certain conditions, direct oxidation of histamine may be a conditional phenomenon. Our results also support the existence of a very slow turnover pool of brain histamine and use of chronic alpha-FMHis infusion as a model to probe the histaminergic system in brain.

Animals↗

Histamine and tryptase levels in patients with acute allergic reactions: An emergency department-based study.

BACKGROUND: Emergency department visits for acute allergic reactions are common. Although the diagnosis and classification of these allergic reactions is primarily empiric, it is not always clear whether certain signs and symptoms constitute systemic mediator release syndromes, such as anaphylaxis, and thus may warrant more aggressive therapy or follow-up. OBJECTIVE: We sought to determine associations between various clinical signs and symptoms with both plasma histamine levels and serum tryptase levels in adult patients presenting to an emergency department with acute allergic syndromes. The clinical correlates of raised beta-tryptase levels were also investigated. METHODS: Ninety-seven adult emergency department patients were prospectively studied by using a questionnaire, physical examination, and serum-plasma sampling. Plasma histamine and serum total and beta-tryptase levels were determined. Clinical groupings were compared for mediator levels by using simple and multivariate analysis. RESULTS: Elevated levels of plasma histamine (>10 nmol/L) and serum total tryptase (>15 ng/mL) were observed in 42 and 20 patients, respectively. Detectable beta-tryptase (>/=1 ng/mL) was observed in 23 patients, including 15 of the patients with elevated total tryptase levels. Suspected food allergy incidences and the duration of reaction were similar in patients with increased histamine levels and in patients with increased tryptase levels. Increased total tryptase levels, histamine levels, or both were observed in some patients who did not have airway, cardiovascular, or abdominal signs. Histamine levels correlated better with clinical signs than tryptase levels. Histamine elevations (>10 nmol/L) were observed more frequently in patients characterized by the following clinical signs in univariate analysis: the presence of urticaria, more extensive erythema, abnormal abdominal findings, and wheezing. Total tryptase increases were observed more frequently only in patients with urticaria. Histamine levels correlated with initial heart rates. In multivariate analysis the extent of urticaria was the best single predictor of plasma histamine levels and of either an elevated histamine or tryptase level. Detectable beta-tryptase levels were observed in some patients who had neither elevated total tryptase nor elevated histamine levels. Unlike patients without detectable beta-tryptase levels, patients who had detectable beta-tryptase levels had a significant correlation between total tryptase and histamine levels (P <.05). CONCLUSIONS: Raised histamine and, less commonly, raised tryptase levels are observed in almost 50% of patients presenting to emergency departments with acute allergic reactions. Some cases associated with systemic mediator release do not have classical features of severe anaphylaxis, such as hypotension or tachycardia. The lack of total tryptase elevations in many patients with elevated plasma histamine levels suggests basophil involvement. The clinical utility of beta-tryptase determinations in the evaluation of acute allergic reactions needs further study.

Adult↗

No correlation between wine intolerance and histamine content of wine.

BACKGROUND: Histamine is thought to be the main cause of adverse reactions to wines. OBJECTIVE: The purpose of this study was to test the hypothesis that the level of histamine in wine affects the tolerance to wine in 16 subjects with wine intolerance. METHODS: We performed a study to examine the effects of wine histamine content in 16 adults with wine intolerance. Each subject underwent 2 double-blind provocation tests with wine: 1 with a wine poor in histamine (0.4 mg/L), and 1 with a wine rich in histamine (13.8 mg/L). Blood was collected for histamine and methylhistamine RIAs at 0, 10, 30, and 45 minutes after ingestion of the wine. Methylhistamine and methylimidazolacetic acid (gas chromatography and mass spectrometry) were measured in urine 5 hours before and 5 hours after ingestion. RESULTS: No significant differences in the occurrence of adverse reactions were noted after ingestion of either of the wines (McNemar test). At 10 minutes, a significant increase was observed in plasma histamine with histamine-poor wine. No significant changes (Wilcoxon test) were observed in the methylhistamine and methylimidazolacetic acid levels after ingestion of either histamine-poor or histamine-rich wine. CONCLUSION: This study demonstrates that there is no correlation between the histamine content of wine and wine intolerance. The increase of plasma histamine levels at 10 minutes with histamine-poor wine suggested the role of a histamine-releasing substance. The role of acetaldehyde is discussed.

Adult↗

Metabolism and distribution of exogenous histamine in cats.

1 The metabolism and disposition in blood and tissues of exogenous [(14)C]-histamine was examined in cats.2 The principal metabolites in blood of histamine instilled into the small intestine (directly or by transfer from the stomach) and colon were imidazoleacetic acid and t-methylimidazoleacetic acid, being present in approximately equal amounts although in individual cats one or other acid could predominate. Only small amounts of histamine entered the circulation although in two of four cats given the largest dose (82 mumol/kg) large amounts were recovered. The amount of (14)C radioactivity absorbed varied directly with the dose instilled. The chief metabolite in kidney and urine, whether histamine was instilled into the intestine or infused parenterally, was t-methylimidazoleacetic acid. Histamine was not absorbed from the stomach and its metabolism there was negligible.3 In contrast, when histamine was infused into blood leaving the intestine (portal vein) the main metabolite in blood and tissues was t-methylimidazoleacetic acid being found in approximately 5-fold the concentration of imidazoleacetic acid. The small amount of histamine which eluded inactivation/uptake by liver, lungs, heart during the infusion was halved on circulation through the intestine. When histamine was infused into blood supplying the intestine, (cranial mesenteric artery) t-methylimidazoleacetic acid while still the major metabolite in blood was now only 1.4 times the concentration of imidazoleacetic acid. Additionally, the blood concentration of histamine during the infusion exceeded that of the metabolites.4t-Methylimidazoleacetic acid was also the principal metabolite in blood and tissues following histamine infusion into a cannula carrying a replacement venous blood supply to the liver of abdominally eviscerated cats. Imidazoleacetic acid and t-methylhistamine were present in equal concentrations and in one-quarter to one-third that of the methylated acid. The latter was also the principal metabolite following intra-arterial histamine infusion to abdominally eviscerated cats without a hepatic blood supply, although initially t-methylhistamine predominated: a large peak of histamine was present during the infusion period. When additionally the renal vessels were ligated, t-methylhistamine predominated throughout the experiment.5 In conclusion, intraduodenally instilled histamine was metabolized equally by diamine oxidase and imidazole N-methyltransferase (followed by deamination by monoamine oxidase). In contrast, imidazole N-methyltransferase was the principal inactivator of parenterally infused histamine, deamination of t-methylhistamine by monoamine oxidase becoming progressively less efficient with the cumulative exclusion of the intestines, liver and kidney from the circulation.

Abdominal Muscles↗

All-or-nothing Ca2+ mobilization from the intracellular stores of single histamine-stimulated HeLa cells.

1. Histamine-stimulated mobilization of intracellular Ca2+ stores was monitored in intact and permeabilized populations of HeLa cells using both the fluorescent Ca2+ indicator Fura-2 and 45Ca2+ measurements. Digital video imaging of Fura-2-loaded cells was used to measure the intracellular calcium concentration ([Ca2+]i) of single cells. 2. In populations of HeLa cells, histamine caused a concentration-dependent increase in cytoplasmic [Ca2+]. The initial transient increase was independent of extracellular Ca2+ (Ca2+o) and was followed by a sustained increase that was abolished by removal of Ca2+o. 3. In Ca(2+)-free medium ([Ca2+]o < 1 microM), a maximal histamine concentration (25 microM) caused a transient increase in [Ca2+]i, and a subsequent challenge with histamine failed to evoke a further response indicating that the inositol 1,4,5-trisphosphate (InsP3)-sensitive Ca2+ stores had been completely emptied. Lower concentrations of histamine (0.5-10 microM) caused smaller, concentration-dependent increases in [Ca2+]i that were also transient. After exposure to these low histamine concentrations, where [Ca2+]i returned to baseline within 2 min, addition of a higher histamine concentration evoked a further increase in [Ca2+]i. The second increase in [Ca2+]i was inversely proportional to the increase caused by the first exposure to histamine, indicating that Ca2+ released in the initial response was not substantially resequestered into histamine-sensitive stores. 4. Single HeLa cells challenged with low concentrations of histamine in Ca(2+)-free medium responded with transient increases in [Ca2+]i, but individual cells differed in their sensitivity with 51% of cells responding to 1 microM, and 98% responding to 25 microM-histamine. 5. When single cells in Ca(2+)-free medium were challenged with stepwise increases in histamine concentration, they responded to each step with a transient [Ca2+]i increase after which [Ca2+]i returned to baseline within 1 min. Prolonging the interval between histamine additions by up to 25 min did not affect the [Ca2+]i increase evoked by a subsequent histamine addition. 6. Unidirectional 45Ca2+ efflux from saponin-permeabilized HeLa cells showed that, under conditions that prevented Ca2+ resequestration, submaximal concentrations of InsP3 rapidly emptied only a fraction of the InsP3-sensitive Ca2+ stores. The failure of low InsP3 concentrations to fully mobilize the InsP3-sensitive Ca2+ stores was not a consequence of InsP3 degradation. 7. We conclude that within single HeLa cells, intracellular Ca2+ stores are heterogeneous in their sensitivity to InsP3, and the fraction of Ca2+ stores mobilized by InsP3 increases as the InsP3 concentration increases.

Biological Transport↗

The interaction of histamine with gastrin and carbamylcholine on oxygen uptake by isolated mammalian parietal cells.

Using oxygen uptake as an index of the physiological response of isolated parietal cells, the interactions between histamine and gastrin and between histamine and carbamylcholine and the effects of atropine and metiamide on these interactions have been studied. Parietal cells were isolated from canine fundic mucosa by sequential exposure of separated mucosa to collagenase and EDTA. In previous studies carbamylcholine, isobutyl methyl xanthine, gastrin, and histamine have each been shown to increase oxygen uptake by these cells. Isobutyl methyl xanthine greatly enhanced the histamine effect. Carbamylcholine was inhibited by atropine but not by metiamide, histamine was inhibited by metiamide but not by atropine, and gastrin was inhibited by neither, suggesting that each of these agents has a direct action on the parietal cell. In the present studies, potentiating interactions between histamine and carbamylcholine and between histamine and gastrin have been demonstrated. Against a histamine (0.1 and 1 muM) plus isobutyl methyl xanthine (0.1 mM) background, the dose for 50% response for gastrin was approximately 1 nM, and the maximal response was obtained at 0.1 muM. When added to these combinations of stimulants, metiamide and atropine retained their respective specificities against stimulation by histamine and carbamylcholine, in that responses were inhibited to the level that was seen when the component of the pair that was not inhibited was given alone. The observation that histamine plus gastrin and histamine plus carbamylcholine produced maximal responses that were greater than the maximal response to histamine alone further supports the hypothesis that these agents each have direct actions on parietal cells. These observations are not consistent with the hypothesis that histamine is the sole mediator for the effects of other secretagogues. Furthermore, the inhibitory effects of atropine and metiamide on the specific cholinergic and histaminic components of the interactions that occur between secretagogues provide a possible explanation for the apparent lack of specificity of these agents on in vivo acid secretion.

Animals↗

Effect of radiographic contrast media on histamine release from human mast cells and basophils.

Radiographic contrast media (RCM) cause histamine-dependent allergic-like reactions. The direct effects of diatrizoate (high osmolar ionic monomer), ioxaglate (low osmolar ionic dimer), iopromide (low osmolar non ionic monomer) and iotrolan (iso-osmolar non ionic dimer) at the concentration of 200 mgI ml-1 (60 min exposure) on the release of histamine from human basophils, human lung mast cells (HLMC), and human skin mast cells (HSMC) were investigated. Diatrizoate induced 48 +/- 4% histamine release in basophils, 15 +/- 3% in HLMC and 25 +/- 6% in HSMC. The remaining RCM were relatively ineffective activators of histamine release in both HLMC and HSMC (ioxaglate 4 +/- 1% and 4 +/- 1%, iopromide 5 +/- 1% and 7 +/- 2%, iotrolan 7 +/- 2% and 10 +/- 3%, respectively). Both iotrolan and ioxaglate were effective in basophils inducing 21 +/- 3% and 24 +/- 6% histamine release, respectively, whereas iopromide was relatively ineffective (7 +/- 4%). Diatrizoate induced histamine release from all three cell types with optimal levels of histamine release after a 2-4 h incubation although significant levels occurred within 15 min. Dose-dependent histamine release from HLMC occurred in all four types of RCM, the largest response (37 +/- 3%) being produced by diatrizoate. The effect of osmolality on histamine release was investigated using different concentrations of mannitol solutions (0.25, 0.5 and 1 M). Histamine release from HLMC, HSMC and basophils after 90 min exposure to mannitol (1 M) was 24 +/- 2% (p < 0.05), 9 +/- 3% (p = 0.06) and 49 +/- 1% (p < 0.05), respectively, suggesting that hyperosmolality per se can induce histamine release from basophils and mast cells. Diatrizoate-induced histamine release in all three cell types was significantly reduced by lowering the temperature to 0 degree C and partially attenuated by the metabolic inhibitors antimycin A (1 microM) and 2-deoxyglucose (5 mM), and by the omission of glucose from the buffer solution. Diatrizoate-induced histamine release was not dependent on extracellular calcium. These data suggest that diatrizoate induces histamine release at least in part by non-cytotoxic mechanisms.

Basophils↗

Histamine food poisoning: toxicology and clinical aspects.

Histamine poisoning can result from the ingestion of food containing unusually high levels of histamine. Fish are most commonly involved in incidents of histamine poisoning, although cheese has also been implicated on occasion. The historic involvement of tuna and mackerel in histamine poisoning led to the longtime usage of the term, scombroid fish poisoning, to describe this food-borne illness. Histamine poisoning is characterized by a short incubation period, a short duration, and symptoms resembling those associated with allergic reactions. The evidence supporting the role of histamine as the causative agent is compelling. The efficacy of antihistamine therapy, the allergic-like symptomology, and the finding of high levels of histamine in the implicated food suggest strongly that histamine is the causative agent. However, histamine ingested with spoiled fish appears to be much more toxic than histamine ingested in an aqueous solution. The presence of potentiators of histamine toxicity in the spoiled fish may account for this difference in toxicity. Several potentiators including other putrefactive amines such as putrescine and cadaverine have been identified. Pharmacologic potentiators may also exist; aminoguanidine and isoniazid are examples. The mechanism of action of these potentiators appears to be the inhibition of intestinal histamine-metabolizing enzymes. This enzyme inhibition causes a decrease in histamine detoxification in the intestinal mucosa and results in increased intestinal uptake and urinary excretion of unmetabolized histamine.

Animals↗

[Histamine release during induction of combination anesthesia using nalbuphine or fentanyl. Modulation of the reaction by premedication with promethazine/pethidine].

In a controlled clinical trial in patients admitted for general surgery (mainly abdominal and thyroid), histamine release following nalbuphine 1 mg/kg i.v. versus fentanyl 5 micrograms/kg i.v. was studied in the course of an otherwise routine induction with promethazine/pethidine as premedication 30 min before the opioids and alcuronium-flunitrazepam-thiopental 5 min later. Succinylcholine was given before intubation and further analgesia was obtained by repeated administration of either nalbuphine or fentanyl. Plasma histamine levels were measured by a specific fluorometric assay, heart rate and blood pressure were measured for assessing hemodynamics, and clinical signs of anaphylactoid reactions such as skin eruptions and arrhythmias were registered. RESULTS. Nalbuphine and fentanyl both released histamine with an incidence of more than 40%. In addition, nalbuphine potentiated the histamine release evoked by the sequential administration of alcuronium-flunitrazepam-thiopental in one complex of application. The incidence of histamine release in the nalbuphine group was 6/13 = 46%, in the fentanyl group only 1/11 = 9% (chi2 test, P less than 0.05). Furthermore, this study showed high histamine levels after succinylcholine and intubation in a relation to time of administration that suggested histamine release as a stress response to intubation. Finally, the incidence of histamine release after a second injection of the opioids was still 30%. A direct correlation between plasma histamine levels, hemodynamic changes, and skin reactions could not be shown. A detailed causality analysis with histamine release as a contributory determinant showed histamine release less detrimental to hemodynamic stability than the opposite, which had been expected. However, the promethazine administered 30 min before induction of anaesthesia had strong H1- and H2-receptor antagonistic activity and was given with optimum timing for H1- and H2-prophylaxis. CONCLUSION. The study demonstrated that histamine release during anaesthesia and surgery depends strongly on the time sequence of drugs and measures used. Histamine release is not predictable from studies in human volunteers alone; studies in patients have to be added. Histamine release is not always detrimental. H3-receptor-mediated effects after H1- and H2-prophylaxis may help patients to counteract the effects of a series of vasoactive drugs given during induction of anaesthesia.

Adult↗