Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Fluids and Secretions”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 631 records · Page 35Linked to original sources
PubMed2004

Antisecretory factor expression is regulated by inflammatory mediators and influences the severity of experimental autoimmune encephalomyelitis.

Antisecretory factor (ASF) was originally identified as a potent inhibitor of intestinal fluid secretion induced by a number of enterotoxins. In addition to its involvement in intestinal fluid secretion, ASF modulates the proliferation of memory/effector T cells and is expressed by cells of the immune system. This report describes the role of ASF in modulating immune responses and assesses the regulation of ASF during an in vivo immunological reaction. ASF expression was redistributed during adoptively transferred experimental autoimmune encephalomyelitis (EAE), and in response to other inflammatory stimuli. Administration of the anti-ASF antibody TLD-1A8A increased the clinical severity and duration of the disease. Consistent with these findings, addition of TLD-1A8A to T cell proliferation assays resulted in up-regulation of the proinflammatory cytokines IL-18 and IL-6 and in down-regulation of IL-10. Furthermore, we identified cytokines that regulated the expression of ASF at both the mRNA and protein level. ASF, therefore, appears to play a previously unappreciated and potentially important role in the regulation of immune responses.

Adoptive Transfer↗
PubMed2003

K(+) transport in Malpighian tubules of Tenebrio molitor L: is a K(ATP) channel involved?

The presence of ATP-regulated K(+) (K(ATP)) channels in Tenebrio molitor Malpighian tubules was investigated by examining the effect of glibenclamide on both fluid secretion and basolateral membrane potentials (V(bl)). Glibenclamide, a K(ATP) channel blocker, slowed fluid secretion of Tenebrio tubules. In low bath K(+) concentration (5 mmol l(-1)), glibenclamide either hyperpolarized or depolarized V(bl), resembling the effect seen with Ba(2+). Subsequent addition of 6 mmol l(-1) Ba(2+) caused a further hyper- or depolarization of V(bl). In control Ringer (50 mmol l(-1) KCl, 90 mmol l(-1) NaCl), glibenclamide had no visible effect on V(bl). The effect of ouabain was investigated in low bath [K(+)] in the presence of Ba(2+). V(bl) responded by a small but significant hyperpolarization from -51+/-4 mV to -56+/-4 mV (n=16, P<0.001) in response to 1 mmol l(-1) ouabain. Repeating the experiments in the presence of both glibenclamide and Ba(2+) resulted in a depolarization of V(bl) when ouabain was added. In low bath [K(+)] (high Na(+)), the Na(+)/K(+)-ATPase is expected to function at a high rate. In the presence of Ba(2+), replacing Na(+) by K(+) rapidly depolarized V(bl), but this was followed by a repolarization. Repeating the experiments in the presence of glibenclamide markedly reduced the depolarizing effect and abolished the repolarization, with a gradual decrease in the sensitivity of V(bl) to the surrounding [K(+)]. These results suggest the presence of K(ATP) channels in the basolateral membrane. Glibenclamide had no visible effect on V(bl) in high K(+) or in the absence of Ba(2+), indicating that other highly conductive K(+) channels may mask the effect on K(ATP) channels. This is the first demonstration of the presence of K(ATP) channels in an insect epithelium.

Adenosine Triphosphate↗
PubMed2004

Recent advances in understanding the pathogenesis of polycystic kidney disease: therapeutic implications.

Hereditary polycystic kidney disease (PKD) is a common cause of renal failure. Increasing knowledge is available regarding mechanisms of cyst development and progression, and renal functional deterioration in PKD. On the basis of this information and theories regarding the pathophysiology of these processes, studies to alter progression and potentially treat PKD have been reported. Cyst development and progression requires epithelial cell proliferation, transepithelial fluid secretion and extracellular matrix remodelling. Several interventions designed to inhibit cell proliferation or alter fluid secretion modify the progression of PKD in selected animal models. Renal functional deterioration appears to involve interstitial inflammation and fibrosis, and tubular apoptosis. Glucocorticoids with anti-inflammatory and antifibrotic properties slow the progression of cystic disease and renal functional deterioration in animal models of PKD. Other interventions, such as dietary modification and angiotensin antagonism, shown to be of benefit in non-PKD models of slowly progressive renal disease, are also of benefit in animal models of PKD. Caution should be used in extrapolating interventional studies in one animal model to another model and certainly to human disease, since examples exist in which treatments in one model of PKD have different effects in another model. Nonetheless, early attempts to determine whether potential treatments are tolerated and of potential benefit in patients with PKD are beginning to appear. Ultimately, treatment of PKD may involve efforts to identify patients at greatest risk for disease progression, thus allowing targeted therapy, use of surrogate markers for disease progression to assist assessment of therapeutic efficacy, and combination therapy to retard disease progression and renal functional deterioration in this common hereditary cause of chronic renal failure.

Animals↗
PubMed1991

Studies to determine whether there is tolerance or cross-tolerance to the antisecretory effect of morphine and clonidine in the rat intestine.

Intra-arterial infusions (4 micrograms min-1) of prostaglandin E2 (PGE2) were used to stimulate intestinal fluid secretion in anaesthetized rats. Morphine (0.625-40 mg kg-1) produced a dose-dependent restoration of fluid transport from secretion to the normal rate of absorption. Pretreatment with up to eight doses of morphine (20 mg kg-1) did not induce tolerance, rather it enhanced the antisecretory effect of a subsequent acute dose of morphine. It seems probable that this was caused by the accumulation of morphine in the intestine. Clonidine (4-1000 micrograms kg-1, like morphine, produced a dose-dependent reversal of stimulated fluid secretion. Pretreatment with clonidine (4 x 0.25 mg kg-1) caused a shift of the clonidine antisecretory dose-response curve to the right, demonstrating tolerance. Pretreatment with clonidine also caused cross-tolerance to the antisecretory effect of morphine. The results suggest that there is a close relationship between opioid- and alpha 2-adrenoceptors in controlling inhibition of intestinal fluid secretion.

Animals↗
PubMed2005

Diuretic factors and second messengers stimulate secretion of the organic cation TEA by the Malpighian tubules of Drosophila melanogaster.

This study showed that four factors which stimulate transepithelial fluid secretion and inorganic ion transport across the main segment of the Malpighian tubules of Drosophila melanogaster also stimulate transepithelial secretion of the prototypical organic cation tetraethylammonium (TEA). TEA fluxes across the Malpighian tubules and gut were measured using a TEA-selective self-referencing (TEA-SeR) microelectrode. TEA flux across isolated Malpighian tubules was also measured using a TEA-selective microelectrode positioned in droplets of fluid secreted by tubules set up in a modified Ramsay assay. TEA flux was stimulated by the intracellular second messengers cAMP and cGMP, which increase the lumen-positive transepithelial potential (TEP), and also by tyramine and leucokinin-I (LK-I), which decrease TEP. The largest increase was measured in response to 1 micromol l-1 LK-I which increased transepithelial TEA flux by 72%. TEA flux in the lower tubule was stimulated slightly (13%) by 1 micromol l-1 tyramine but not by any of the other factors. TEA flux across the midgut was unaffected by cAMP, cGMP or tyramine. This is the first study to demonstrate the effects of insect diuretic factors and second messengers on excretion of organic cations.

Animals↗
PubMed1983

Ultrastructural responses by Golgi apparatus of rat submandibular gland to beta-adrenergic, alpha-adrenergic, and cholinergic stimulation.

Rat submandibular gland tissue pieces were stimulated in vitro for 30 min with a beta-adrenergic agent or a cyclic AMP analog to stimulate protein secretion, or with alpha-adrenergic or cholinergic agents or a Ca2+ ionophore to stimulate fluid secretion. Acinar cells were examined by transmission electron microscopy. In control tissue, acinar cells showed little evidence of secretory activity. The Golgi apparatus was sparse and was associated with a few small, immature secretory granules with fine fibrillar contents. Following secretory granule discharge stimulated by isoproterenol or dibutyryl cyclic AMP, acinar cells were constricted, and had extensive basolateral membrane folding and tightly packed rough endoplasmic reticulum. Golgi complexes were prominent and had multiple small granules with filamentous contents. After stimulation of fluid secretion by alpha-adrenergic agents (epinephrine, phenylephrine), or cholinergic agents (acetylcholine, carbachol, pilocarpine), or a Ca2+ ionophore (A23187), the Golgi apparatus had compact concave cisternae enclosing aggregates of tubulovesicles. Acinar cells were distended, basolateral membranes were expanded, and rough endoplasmic reticulum was dilated and vesiculated.

Acetylcholine↗
PubMed1984

Influence of sex and body size on pancreatic bicarbonate and enzyme output.

The study was aimed both at defining normal values of pancreatic function and at looking at variables (age, sex, body weight, height, and body surface) which may influence the range of normality in 271 normal controls evaluated consecutively by duodenal intubation from 1974 to 1981. Frequency distribution of all functional values were consistent with a Gaussian curve. A positive, linear correlation was found between secretory parameters and both volume secretion and output values, while no correlation was detected with bicarbonate and enzymes values. Duodenal fluid secretion and both bicarbonate and enzymes output were approximately 20% higher in males than in females, the difference being statistically significant. Mean values of both bicarbonate and enzyme concentration were not statistically different between sexes. When related to body surface, both volume and outputs values in males were no more different from those observed in females. The study has shown that body size influences pancreatic functional values and, therefore, the values should be related to some parameters of body size as body surface. The difference between males and females in fluid secretion and output values is linked primarily to differences in body size. The normal distribution of all functional parameters implies that normal limits may be calculated with standard parametric statistical analysis.

Adult↗
PubMed1985

Treatment of ovariectomized ewes with bovine follicular fluid decreases secretion of FSH without changing secretion of LH.

Ovariectomized ewes were injected with 0, 0.25, 0.5, 1.0 or 2.0 ml of charcoal-extracted bovine follicular fluid. Treating ewes with 2 ml of follicular fluid resulted in a decrease in circulating concentrations of FSH to 72.8% of the pretreatment value. With smaller doses of follicular fluid, the magnitude of the decrease was less. Concentrations of LH did not change significantly. Pretreatment of ovariectomized ewes with estradiol and/or progestogen did not alter the magnitude of the FSH decrease. This action of follicular fluid extract fits the effect of the non-steroidal substance known as inhibin or folliculostatin.

Journal Article↗
PubMed1981

Sites of carbonic anhydrase in avian gastric mucosa identified by electron microscope autoradiography.

Carbonic anhydrase was localized at the ultrastructural level by autoradiography of [3H]acetazolamide in quail gastric mucosa. Grains were associated predominantly with mucin granules at the apical end of surface mucosal cells. Secreted mucin was also labeled. Oxynticopeptic cells of the multilobular glands were not labeled. The pH of fluid secreted by was 7.0-7.4 compared with a pH of 1.3-1.8 of freshly secreted fluid in the gastric lumen. The results of this study suggest that surface mucosal cells, which are strikingly similar in birds, amphibians, and mammals, are the site of acid secretion in the vertebrate stomach.

Acetazolamide↗
PubMedDate not supplied

Role of the neuropeptide, bombesin, in bile secretion.

Since ancient times, bile secretion has been considered vital for maintaining health. One of the main functions of bile secretion is gastric acid neutralization with biliary bicarbonate during a meal or Pavlovian response. Although the liver has many extrinsic and intrinsic nerve innervations, the functional role of these nerves in biliary physiology is poorly understood. To understand the role of neural regulation in bile secretion, our recent studies on the effect of bombesin, a neuropeptide, on bile secretion and its underlying mechanisms will be reviewed. Using isolated perfused rat livers (IPRL) from both normal and 2 week bile duct ligated rats, as well as hepatocyte couplets and isolated bile duct units (IBDU) from normal rat livers, bombesin was shown to stimulate biliary bicarbonate and fluid secretion from bile ducts. Detailed pH studies indicated that bombesin stimulated the activity of Cl-/HCO3- exchanger, which was counterbalanced by a secondary activation of electrogenic Na+/HCO3- symport. Quantitative videomicroscopic studies showed that bombesin-stimulated fluid secretion in IBDU was dependent on Cl- and HCO3- in the media, anion exchanger(s), Cl- and K+ channels, and carbonic anhydrase, but not on the microtubular system. Furthermore, this bombesin response is inhibited by somatostatin but not substance P. Finally, studies of secondary messengers in isolated cholangiocytes and IBDU indicated that bombesin had no effect on intracellular cAMP, cGMP, or Ca++ levels in cholangiocytes. These results provide evidence that neuropeptides such as bombesin can directly stimulate fluid and bicarbonate secretion from cholangiocytes by activating luminal Cl-/HCO3- exchange, but by different mechanisms from those established for secretin. These findings, in turn, suggest that neuropeptides may play an important regulatory role in biliary transport and secretion. Thus, this neuropeptidergic regulation of bile secretion may provide a plausible mechanism for the bicarbonate-rich choleresis seen with meals or Pavlovian response.

Animals↗
PubMed1984

Stimulation of lacrimal secretion by sympathetic nerve impulses in the rabbit.

Direct electrical stimulation of the preganglionic nerve trunk of the ipsilateral superior cervical sympathetic ganglion induced fluid secretion from the cannulated main excretory duct of the non-stimulated rabbit lacrimal gland. The optimum strength and frequency of stimulation were 4 volts and 25 Hz. At this stimulus parameter, the rate of secretion was 2.1 +/- 0.2 microliter/10 min. The sympathetic-induced lacrimal secretion was markedly depressed after intravenous administration of hexamethonium (1 mg/kg) and by post-ganglionic neurectomy. The results suggest that, in addition to parasympathetic nerve activity, sympathetic nerve impulses, which pass through the superior cervical sympathetic ganglion, also play a role in initiating fluid secretion in the rabbit lacrimal gland.

Animals↗
PubMed2001

Gastric secretion in cystic fibrosis in relation to the migrating motor complex.

BACKGROUND: Patients with cystic fibrosis (CF) have been claimed to have defect intestinal motility and gastric acid secretion. The aim of this work was to study the interdigestive motility and the motility-related secretions in the upper gastrointestinal tract in patients with CF compared to healthy controls. METHODS: Concomitant gastroduodenal manometry combined with intragastric perfusion was performed in 12 healthy volunteers and 10 patients with CF. RESULTS: Eight CF patients showed a normal migrating motor complex. Motility-related gastric secretion of acid and bicarbonate was evaluated in six patients and did not differ from healthy subjects. Gastric net fluid secretion was significantly decreased in the CF patients and bilirubin reflux was significantly increased. The CF patients with pancreatic insufficiency lacked motility-related variations in plasma levels of motilin and pancreatic peptide. CONCLUSIONS: No defect in fasting motility or gastric secretion of acid or bicarbonate could be seen in well-nourished adult CF patients. The main finding was a significantly lower net fluid secretion and higher bilirubin reflux compared to healthy subjects. Indications of a genetic relationship could be seen.

Adult↗
PubMed1989

Acetate stimulates secretion in the rabbit mandibular gland.

In isolated perfused rabbit mandibular glands undergoing stimulation with 0.8 microM acetylcholine, replacement of HCO3- with acetate (25 mM) increased fluid secretion by more than 100%. Other short-chain fatty acids, except for propionate, had a similar effect. We focused our further studies on acetate, and in order to find out the cause of its stimulatory effect we investigated whether acetate itself was transported. In the absence of any other transportable anions 25 mM acetate supported secretion at the same rate as 25 mM HCO3- or 25 mM Cl-, i.e. 20% of the control rate. In solutions containing acetate as the only major anion (146 mM), fluid secretion was maintained at about 50% of the control rate. Amiloride (1 mM) inhibited this secretion by about 90%. In glands perfused with acetate/Cl- solutions, when the stimulatory effect was normally observed, amiloride (1 mM) inhibited secretion by 50-60% and SITS (0.1 mM) had no effect. Probenecid reversibly inhibited 75% of secretion in these glands, but it also inhibited 92% of secretion in glands perfused without any acetate. Interestingly, the acetate effect was abolished in glands stimulated with a higher concentration of acetylcholine (80 microM). Results of this study suggest that acetate can be transported by salivary endpieces and that this transport involves an amiloride-sensitive Na+-H+ antiport. We postulate that acetate may in addition have some regulatory or modifier role in salivary secretion.

Acetates↗