The effect of the calcium antagonist verapamil on gastric acid secretion in humans.
Studies on isolated gastric glands and parietal cells suggest that calcium plays a role in the stimulus-secretion coupling of acid secretion. To determine which stimulants of human gastric secretion depend on calcium-mediated receptors, the effect of the calcium antagonist verapamil on gastric secretion was studied. Gastric secretion was stimulated by intravenous infusion of 50 micrograms/kg/h bethanechol, 10 micrograms/kg/h impromidine, 0.5 micrograms/kg/h pentagastrin, 4 mg/kg/h Ca++, or by sham feeding. Each type of stimulation was tested twice in six healthy subjects, alone and together with verapamil. Verapamil was administered as an intravenous bolus of 200 micrograms/kg followed by an infusion of 150 micrograms/kg/h. Six subjects had 2 step tests in which 4 doses of pentagastrin were administered consecutively in increasing dosage. Pentagastrin was given either alone or superimposed on a verapamil bolus followed by an intravenous infusion. Verapamil left gastric secretion stimulated by bethanechol, impromidine, or sham feeding unaffected. During Ca++ infusion verapamil caused a significant drop in volume, but not acid output. Pentagastrin-stimulated acid and volume output were significantly inhibited by intravenous verapamil, the inhibition resembling an uncompetitive pattern. Pentagastrin-stimulated gastric secretion was also inhibited by the calcium antagonist diltiazem. The results confirm earlier reports that calcium is involved in the stimulus-secretion coupling of the human gastric mucosa. Calcium appears to mediate the stimulation of acid secretion by gastrin.
D000328:Adult; D018723:Bethanechol; D001626:Bethanechol Compounds / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology; D005744:Gastric Acid / Q000378:metabolism*; D005753:Gastric Mucosa / Q000378:metabolism*; D006801:Humans; D007093:Imidazoles / Q000494:pharmacology; D017446:Impromidine; D007700:Kinetics; D008297:Male; D010418:Pentagastrin / Q000494:pharmacology; D014700:Verapamil / Q000494:pharmacology*
D001626:Bethanechol Compounds; D007093:Imidazoles; D018723:Bethanechol; D017446:Impromidine; D014700:Verapamil; D010418:Pentagastrin; D002118:Calcium