Calcium channel blocker decreases pentagastrin-stimulated alkaline-tide: a role for extracellular calcium in gastric acid secretion.
We previously showed that repeated stimulation of the gastrin receptor may lead to down-regulation. We hypothesized that entry of extracellular Ca2+ may replenish cytosolic Ca2+ and enable continuation of the acid-secretion process. Pentagastrin-stimulated alkaline-tide study was performed in seven duodenal ulcer patients on 2 separate days--with and without pretreatment with verapamil (Ca2+ channel blocker). The alkaline-tide test may substitute the conventional gastric acid collection as previously described. A significant rise in base excess after pentagastrin injection was found on the first day of the study, from 0.400 +/- 1.233 to 2.230 +/- 1.330 (mean +/- SD, P = 0.02). On the second day the rise was not statistically significant, from -0.200 +/- 0.838 to 0.440 +/- 1.200 (mean +/- SD, P = 0.27). In 6 of the 7 patients the alkaline-tide decreased from 45.29 +/- 21.75 mEq/45 min on the first day to 21.56 +/- 17.48 mEq/45 min on the second day of the study (mean +/- SD, P = 0.029), a decrease of 63.6 +/- 36.2%. Our findings may support a dual source for Ca2+, the second messenger in gastrin-dependent gastric acid secretion. The first increase of intracellular Ca2+ comes from cellular stores, and the second from extracellular source by Ca2+ channels, which can be blocked by verapamil.
Niv
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Department of Gastroenterology, Soroka Medical Center, Beer Sheva, Israel.
Vardi
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D000136:Acid-Base Equilibrium / Q000502:physiology*; D000328:Adult; D000368:Aged; D002118:Calcium / Q000378:metabolism*; D015536:Down-Regulation; D004381:Duodenal Ulcer / Q000378:metabolism*; D005744:Gastric Acid / Q000378:metabolism*; D005745:Gastric Acidity Determination; D006801:Humans; D008297:Male; D008875:Middle Aged; D010418:Pentagastrin / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D011292:Premedication; D014700:Verapamil / Q000494:pharmacology
D014700:Verapamil; D010418:Pentagastrin; D002118:Calcium