Real Time Measurements of Water Flow in Amphibian Gastric Glands

Abstract

The mechanisms for the formation of the osmotic gradient driving water movements in the gastric gland and its modulation via the extracellular Ca 2؉ -sensing receptor (CaR) were investigated. Real time measurements of net water flux in the lumen of single gastric glands of the intact amphibian stomach were performed using ion-selective double-barreled microelectrodes.

Detection and quantification of ppb level potassium in biological samples in the presence of high sodium by ion chromatographic method

“…This surge in K + transport over basal secretion was found to be statistically significant (p < 0.05). Such characteristic phenomenon as was noted by others [4,19,20,22] lends support in favour of the precision and accuracy of this ion chromatographic method. Panels f-h further describe the H + efflux data under the influence of antisecretory agents like cimetidine, omeprazole and SCH28080.…”

“…Additionally, the eluent containing 0.25 mM crown ether was found to be useful for simultaneous quantification of K + , Mg 2+ and Ca 2+ in high NaCl solution in a single run. This later development was intended to permit further probing of such metabolically important divalent cations in gastric acid secretion and regulation [22,23] under different experimental conditions. We felt, such ion chromatographic method with conductivity detection can be employed to screen putative antisecretory agents in vitro that interfere with K + transport pathways.…”

“…Employing a few designed experiments where net K + efflux is expected to get characteristically altered under the influence of different types of gastric antisecretory agents, we have assessed K + secretion over time in secretory solution (luminal side) containing 104 mM NaCl solution (∼6000 ppm NaCl). A histamine H 2 receptor blocker (cimetidine), a suicide inhibitors of gastric H + ,K + -ATPase (omeprazole) and a K + -competitive reversible inhibitor of H + ,K + -ATPase (SCH28080) were used as probes in experimental systems to demonstrate diagnostic changes in net K + efflux [4,[19][20][21][22]. The net efflux of K + under basal secretion followed by histamine-stimulated secretion, and the effects of additions of such modifiers in the presence of histamine were estimated.…”

“…The calibration plots of K + , Ca 2+ and Mg 2+ were found to be linear over two orders of magnitude with excellent correlation coefficient and reasonably low RSD (%). The importance of such divalent cations in gastric HCl secretion and regulation is well known [22,23]; however, validation of the method with appropriate experiments is awaited.…”

Importance of Ca2+ in gastric epithelial restitution—new views revealed by real-time in vivo measurements

“…It has been reported that the Calcium sensing receptor (CaSR) and PMCA protein co-localize with H + /K + ATPase in the oxynopeptic cells, and evidence has been provided for an autocrine feedback loop that involves luminal Ca 2+ sensing to regulate alkali and pepsinogen secretion, and drive water transport [16,44,50]. The mouse surface epithelium is likely to act differently.…”