The relationship between extracellular K+ and Ca2+ on aminopyrine accumulation in rat parietal cells.
The effects of extracellular K+ in relation to extracellular Ca2+ on acid production were studied. Studies were performed in vitro using isolated cells from rat stomachs, and acid production was indirectly determined by 14C-aminopyrine (AP) accumulation. In the absence of K+ in the incubation medium histamine-stimulated AP accumulation ratios were significantly decreased independently in the presence or absence of extracellular Ca2+. Under basal conditions, in the absence of extracellular Ca2+, increasing concentrations of extracellular K+ enhanced AP accumulation ratios to significantly higher than those found in the presence of Ca2+. In histamine-, cAMP-, and carbachol-stimulated parietal cells, high K+ concentrations increased AP accumulation significantly less in Ca(2+)-free than in Ca(2+)-containing media. High K+ also induced significantly both an increase in cytosolic free Ca2+ concentration and 45Ca2+ uptake. The present results confirmed the importance of K+ in gastric acid production and suggested a role for Ca2+ as a modulator of mechanisms of parietal cell stimulation.
Ostrowski
J
J
Department of Gastroenterology and Metabolism, Medical Center of Postgraduate Education, Warsaw, Poland.
Zych
W
W
Dołowy
K
K
Butruk
E
E
D000632:Aminopyrine / Q000493:pharmacokinetics*; D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology*; D002217:Carbachol / Q000494:pharmacology; D002478:Cells, Cultured; D004492:Edetic Acid; D005110:Extracellular Space / Q000378:metabolism; D005260:Female; D005744:Gastric Acid / Q000378:metabolism; D006982:Hypertonic Solutions; D009994:Osmolar Concentration; D010295:Parietal Cells, Gastric / Q000187:drug effects / Q000378:metabolism*; D011188:Potassium / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012965:Sodium Chloride
D006982:Hypertonic Solutions; D000632:Aminopyrine; D000001:Calcimycin; D012965:Sodium Chloride; D002217:Carbachol; D004492:Edetic Acid; D011188:Potassium; D002118:Calcium