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Biomedical subjects

D E Cochrane

Publications and source records attributed to D E Cochrane.

At least 37 records · Page 2Linked to original sources
PubMed1988

Replenishment of the cellular calcium required for non-immunologic stimulation of mast cell histamine secretion: temperature sensitivity and inhibition by manganese and sodium-free conditions.

Mast cells depleted of cellular calcium (Ca) by a 3 hr exposure to Ca-free conditions and then bathed in Ca-free Locke failed to release histamine when stimulated by compound 48/80 or peptides. The cellular Ca required for histamine release could be replenished by a 5 sec exposure to extracellular Ca at 37 degrees C. To inhibit this replenished cellular Ca dependent histamine secretion required an additional 3 hr exposure to Ca-free conditions. When cellular Ca was replenished at 4 degrees C, an additional 2 min incubation at 37 degrees C was required to restore stimulated secretion to a maximum. During this 2 min incubation period the replenished cellular Ca is suggested to be "processed" so that it can be used for secretion. Manganese (Mn) or cobalt added during (but not after) this 2 min incubation period prevented the restoration of histamine release. Preincubation of cellular Ca depleted mast cells in Mn (0.1-1 mM) blocked the effect of subsequent Ca replenishment at 37 degrees C while cobalt and barium were less inhibitory. Neither magnesium nor strontium were inhibitory. Extracellular sodium (Na) was required for the restoration of cellular Ca dependent histamine secretion. Lithium could substitute for Na but rubidium and potassium were ineffective.

Animals↗
PubMed1988

Xenopsin-related peptide generated in avian gastric extracts.

Two avian counterparts to amphibian xenopsin have been identified as H-Phe-His-Pro-Lys-Arg-Pro-Trp-Ile-Leu-OH (XP-2) and its partial sequence H-His-Pro-Lys-Arg-Pro-Trp-Ile-Leu-OH (XP-1) isolated from extracts of turkey proventriculus and skin. Both peptides were shown to be present within these and other tissues primarily (99%) in precursor form(s), from which they were liberated by the action of endogenous enzyme(s) during extraction. Synthetic and native preparations of XP-2 increased vascular permeability in rats and released histamine from isolated rat mast cells at submicromolar concentrations. The ubiquitous distribution of this XP-related sequence and its pharmacologic capabilities suggest potential roles in the general regulation of tissue blood flow and fluid exchange.

Amino Acid Sequence↗
PubMed1988

Effect of disodium cromoglycate (DSCG) and antihistamines on postirradiation cerebral blood flow and plasma levels of histamine and neurotensin.

In an attempt to elucidate mechanisms underlying the irradiation-induced decrease in regional cerebral blood flow (rCBF) in primates, hippocampal and visual cortical blood flows of rhesus monkeys were measured by hydrogen clearance, before and after exposure to 100 Gy, whole-body, gamma irradiation. Systemic blood pressures were monitored simultaneously. Systemic arterial plasma histamine and neurotensin levels were determined preirradiation and postirradiation. Compared to control animals, the irradiated monkeys exhibited an abrupt decline in systemic blood pressure to 23% of the preirradiation level within 10 min postirradiation, falling to 12% by 60 min. A decrease in hippocampal blood flow to 32% of the preirradiation level was noted at 10 min postirradiation, followed by a slight recovery to 43% at 30 min and a decline to 23% by 60 min. The cortical blood flow for the same animals showed a steady decrease to 29% of the preirradiation levels by 60 min postirradiation. Animals given the mast cell stabilizer disodium cromoglycate and the antihistamines mepyramine and cimetidine before irradiation did not exhibit an abrupt decline in blood pressure but displayed a gradual decrease to a level 33% below preirradiation levels by 60 min postirradiation. Also, the treated, irradiated monkeys displayed rCBF values that were not significantly different from the nonirradiated controls. The plasma neurotensin levels in the irradiated animals, treated and untreated, indicated a nonsignificant postirradiation increase above control levels. However, the postirradiation plasma histamine levels in both irradiated groups showed an increase of approximately 1600% above the preirradiation levels and the postirradiation control levels. These findings implicate histamine in the postirradiation hypotension, but not necessarily in the direct responsibility for the decrease in regional cerebral blood flow seen immediately postirradiation in the primate.

Animals↗
PubMed1988

Mast cell histamine-releasing activity from stimulated rat neutrophils.

Mast cell histamine-releasing activity (HRA) has been observed in medium derived from stimulated rat neutrophils pretreated with cytochalasin B. This HRA did not require cell-cell contact between mast cells and neutrophils, and its concentration was increased by increasing the number of neutrophils or by raising the concentration of chemotactic peptide used to stimulate the neutrophils. The HRA survived boiling for 5 min and storage overnight at -20 degrees C. In the absence of neutrophil stimulation, no HRA was observed.

Animals↗
PubMed1987

Isolation, structures, and biologic activity of neurotensin-related peptides generated in extracts of avian tissue.

Two immunoreactive neurotensin-related peptides generated by the action of endogenous protease(s) on protein substrates during acid extraction of avian tissues have been isolated from extracts of turkey skin and proventriculus. One was identified as the pentadecapeptide, H-Phe-Glu-Arg-Phe-Gln-Gly-Met-Arg-Thy-Arg-Gly-Pro-Tyr-Phe-Leu-OH and the other was its C-terminal octapeptide fragment. Each peptide showed partial homology to the C-terminal, biologically active region of avian neurotensin, and isolated preparations displayed pharmacologic activity at submicromolar concentrations. Synthetic preparations were shown to be indistinguishable from the native peptides during high pressure liquid chromatography (HPLC) and bioassay. Analysis by HPLC indicated that similar peptides could be generated in extracts of proventriculus, pancreas, small intestine, skin, heart, lung, and skeletal muscle. These results, establishing the presence of a neurotensin-related sequence which can be liberated from protein(s) by the action of tissue enzyme(s), suggest that peptide(s) similar to neurotensin may be rapidly formed in order to promote physiologic regulation in multiple tissue(s).

Amino Acid Sequence↗
PubMed1987

Structure of a biologically active neurotensin-related peptide obtained from pepsin-treated albumin(s).

Using a radioimmunoassay toward the COOH-terminal region of neurotensin, an immunoreactive and biologically active neurotensin-related peptide (NRP) has been isolated from pepsin-treated fractions of bovine, canine, human, and rat plasma. Bovine NRP was identified as H-Ile-Ala-Arg-Arg-His-Pro-Tyr-Phe-Leu-OH, which is similar in structure to both neurotensin and angiotensin I. Canine and human NRP also had the above amino acid composition, whereas that obtained from rat plasma had valine substituted for isoleucine. At their concentrations in pepsin-treated plasmas (2-6 microM) rat, human and canine NRP were shown to increase vascular permeability when injected intradermally into rats and to release histamine from rat mast cells in vitro. The pure peptides also cross-reacted very effectively at nanomolar concentrations in a radioreceptor assay for neurotensin. The protein(s) which liberated NRP upon pepsin treatment were purified about 7-fold and shown to behave like albumin during sodium dodecyl sulfate-polyacrylamide gel electrophoresis, isoelectric focusing, and high pressure liquid chromatography on muBondapak C4. In addition, the purified preparations were found to react with anti-albumin antisera during immunodiffusion. Although the amino acid sequence of NRP was not found in albumin, a partial sequence homology was noted for NRP and various segments of bovine albumin. Using V8 protease, glutamyl residues were shown to lie within 3-4 amino acids of each end of NRP, as also occurs for the related segments in albumin. These results suggest that a subset of albumin-related protein(s) could serve as precursor(s) to biologically active neurotensin-related peptide(s).

Amino Acid Sequence↗
PubMed1987

Viability and recovery from degranulation of isolated rat peritoneal mast cells.

Using a culture system that allows prolonged maintenance of purified populations of peritoneal mast cells, we have examined them following stimulation by non-immunologic or immunologic agents. Employing phase-contrast microscopy of living cells and various pharmacological manipulations, we have noted that the recovery process includes a reduction in cell size, the probable sealing of exocytotic cavities, a pronounced displacement of the cell nucleus and a resynthesis of histamine. During recovery, mast cells can entrap molecules from the extracellular fluid and later release these substances by a Ca-dependent mechanism. Our results suggest that microfilaments, calmodulin, Ca, and metabolic energy are necessary for recovery.

Animals↗
PubMed1986

Loss of quin 2 accompanies degranulation of mast cells.

Stimulation of quin 2 loaded mast cells in the presence of 1 mM extracellular calcium produced a rapid and sustained increase in quin 2 fluorescence. This was accompanied by degranulation and the release of histamine. When Ca was replaced by EGTA or when Mn was present, a decrease in fluorescence accompanied degranulation. The increase in quin 2 fluorescence accompanying stimulation of mast cells appears to be due to the interaction of extracellular Ca with quin 2 associated with the secretory granule matrix released upon exocytosis.

Aminoquinolines↗
PubMed1986

Mast cell secretion: differences between immunologic and non-immunologic stimulation.

Non-immunologic and immunologic stimulation of mast cells have been compared. Non-immunologic stimulation relys heavily on cellular Ca, is unaffected by neuraminidase treatment, shows a rapid inactivation, and elicits no increase in the incorporation of 3H-methyl groups into the lipid fraction. In contrast, stimulation by immunologic agents relys primarily on extracellular Ca, is inhibited by neuraminidase treatment, shows a comparatively slow rate of inactivation, and causes a significant increase in the incorporation of 3H-methyl groups into the lipid fraction. We found no evidence of cross-inactivation or desensitization between immunologic and non-immunologic agents. However, pretreatment of mast cells with neurotensin desensitized them to subsequent stimulation by compound 48/80. Our results support the hypothesis that immunologic and non-immunologic agents activate exocytotic mast cell secretion via separate mechanisms.

Animals↗
PubMed1986

Neurotensin stimulates histamine release in in vivo skin 'blisters' in rats: an effect inhibited by cromolyn or somatostatin.

Histamine release was directly measured in in vivo skin blisters in rats in response to the intradermal injection of the peptide neurotensin (NT). Histamine release increased as the concentration of NT was raised from 10(-11) to 10(-5) M. This response was rapid in onset and was inhibited by disodium cromoglycate or the peptide somatostatin (SIRF). The inhibitory effect of SIRF was rapid and was evident from 10(-12) to 10(-8) M SIRF. A similar inhibition was observed on isolated peritoneal mast cells. Histamine release in response to substance P was not inhibited by SIRF.

Animals↗
PubMed1984

Parallel secretion of endogenous 5-hydroxytryptamine and histamine from mast cells stimulated by vasoactive peptides and compound 48/80.

The peptides, neurotensin, substance P, somatostatin, and bombesin, several analogues and fragments of neurotensin and compound 48/80, all caused the secretion of both endogenous 5-hydroxytryptamine (5-HT) and histamine. There was no differential effect of any of the secretagogues tested on the secretion of 5-HT and histamine. Amitriptyline prevented the secretion of histamine in response to stimulation by neurotensin, substance P, somatostatin or compound 48/80 but was without effect on the secretion of endogenous 5-HT.

Amitriptyline↗
PubMed1982

Neurotensin stimulates exocytotic histamine secretion from rat mast cells and elevates plasma histamine levels.

1. Neurotensin stimulated histamine release and granule extrusion when applied to isolated rat peritoneal mast cells. 2. This secretory response was prevented by the removal of calcium or energy and was not accompanied by the release of lactic dehydrogenase. 3. The secretory response produced by neurotensin was prevented by prior treatment of mast cells with cromoglycate. 4. The intravenous injection of neurotensin into anaesthetized rats produced a rapid and significant increase in the level of blood histamine that was dependent upon the dose of neurotensin. 5. Treatment of rats with compound 48/80, 24 hr before neurotensin, abolished the elevation in blood histamine caused by neurotensin. The intravenous injection of cromoglycate 1-2 min before neurotensin greatly reduced the response to neurotensin. 6. The intradermal injection of neurotensin (0.03-30 p-mole) increased capillary permeability in rats pre-treated intravenously with Evans Blue. This response was abolished by the antihistamine, diphenhydramine. Increasing the dose of neurotensin to 300 p-mole partially overcame this inhibition by diphenhydramine. 7. Our results demonstrate that neurotensin can elicit an exocytotic secretory response from isolated rat peritoneal mast cells and elevate histamine levels in blood. It is suggested that some of neurotensin's physiological effects may be due to stimulation of mast cell secretion.

Animals↗
PubMed1982

Stimulus-secretion coupling in rat mast cells: inactivation of extracellular calcium dependent secretion.

1. Stimulation by compound 48/80 of mast cells deprived of Ca failed to release histamine. Secretion of histamine was elicited from such cells by the subsequent introduction of Ca. 2. Histamine secretion declined as the interval between stimulation by compound 48/80 and the introduction of Ca increased. This decline is called inactivation. 3. The addition of the ionophore, A23187, with Ca restored maximum histamine secretion overcoming inactivation. 4. Increasing the concentration of Ca introduced after stimulation, from 2 to 8 mM, or to 20 mM reduced the amount of histamine released. This reduction was proportional to the interval between stimulation and the introduction of Ca. The addition of A23187 with the higher concentrations of Ca fully restored histamine secretion. 5. Stimulation of mast cells in Ca-free media by the secretagogues polymyxin B or bradykinin, and the subsequent introduction of Ca, resulted in a similar inactivation or decline in histamine release. 6. Mast cells inactivated by compound 48/80 stimulation in Ca-free media showed no increase in histamine release when the secretagogues polymyxin B plus Ca or bradykinin plus Ca were added. However, when A23187 plus Ca was added, a full secretory response was obtained. 7. It is suggested that the process of inactivation involves time-dependent change in the Ca permeability of the mast cell membrane. The concentration of introduced Ca is suggested to influence the regulation of this permeability.

Animals↗
PubMed1982

Association of 45calcium with rat mast cells stimulated by 48/80: effects of inactivation, calcium and metabolic inhibition.

1. Stimulation by compound 48/80 of mast cells deprived of Ca released histamine when Ca was subsequently added. This secretory response was accompanied by a pronounced increase in the amount of cell-associated (45)Ca.2. The level of cell-associated (45)Ca declined as the interval between stimulation by compound 48/80 and the introduction of (45)Ca increased.3. This decline in the amount of (45)Ca paralleled the decline in histamine secretion that is called inactivation and each curve could be fitted by linear regression to a first-order equation with a half-life of between 1 and 2 min.4. When histamine secretion was held constant, the amount of cell-associated (45)Ca steadily and significantly declined as the interval between stimulation and the addition of (45)Ca increased. This decline in the level of (45)Ca was significantly reduced when fully inactivated cells were used.5. The amount of cell-associated (45)Ca could not be significantly reduced by repeated or prolonged washing with EGTA or LaCl(3).6. The addition of the ionphore, A23187, or compound 48/80, to mast cells loaded with (45)Ca by prior stimulation with 48/80 and bathed in Ca-free media, significantly reduced the level of cell-associated (45)Ca. This effect of 48/80 but not of A23187 was prevented by including either dinitrophenol or (45)Ca in the extracellular solution.7. When [(3)H]N-methyl-methoxy-inulin was included with the (45)Ca or added alone, no significant change in the level of cell-associated [(3)H]inulin was found during the course of inactivation.8. Increasing the Ca concentration increased the amount of cell-associated (45)Ca when Ca was added 10 sec after stimulation by 48/80 but not when Ca was added 10 min after stimulation.9. Incubation of mast cells in media containing deoxyglucose and either antimycin A or dinitrophenol prevented both histamine release and any increase in the level of cell-associated (45)Ca in response to stimulation by 48/80. A similar result was obtained using sensitized mast cells stimulated by antigen. The addition of the ionophore, A23187, to the mast cells prompted a significant increase in the level of cell-associated (45)Ca.10. These results are considered to be support for the hypothesis that the process of inactivation to compound 48/80 results from a time-dependent decay in membrane permeability. It is suggested that those events associated with initiating changes in membrane permeability are effected by metabolic inhibition and calcium.

Animals↗
PubMed1976

Histamine release by exocytosis from rat mast cells on reduction of extracellular sodium: a secretory response inhibited by calcium, strontium, barium or magnesium.

1. Histamine release from peritoneal mast cells of the rat was stimulated when the cells were exposed for 10 min to sodium-deficient media where all NaCl had been replaced by KC1, RbC1, glucose, sucrose, mannitol, or Tris, provided calcium was less than about 0-5 mM. 2. Light and electron microscopy showed the response to be exocytosis. 3. The chelating agents, EDTA and EGTA, abolished the response to sodium lack and their inhibitory effects were reversed by re-incubating cells with calcium but not magnesium. 4. The response was inhibited by dinitrophenol combined with glucose-deprivation. 5. The response was inversely related to the concentrations of sodium and calcium below 137-5 and 0-5 mM respectively. 6. The related alkaline earth metals, barium, strontium, and magnesium, resembled calcium in inhibiting the response to sodium lack. 7. No secretory response was seen when the cells were exposed for 10 min to calcium-free medium in which lithium replaced sodium. Exposure to this medium for 60 min, however, elicited secretion. 8. It is concluded that when extracellular calcium is low, a reduction in extracellular sodium induces a conventional exocytotic secretory response dependent on energy and cellular calcium. It is suggested that sodium lack may mobilize calcium from a cellular site possibly the inner aspect of the plasma membrane.

Animals↗