Stereospecific inhibition by naloxone of histamine-stimulated acid secretion in isolated guinea pig parietal cells.
Acid secretion from isolated and enriched guinea-pig parietal cells stimulated by histamine and measured by the 14C-aminopyrine accumulation technique was enhanced by nanomolar concentrations of D-ala2-D-leu5-enkephalin (DADLE). This effect was blocked by naloxone. Naloxone inhibited histamine-stimulated acid secretion even in the absence of exogenous opioids. The effect of naloxone was stereospecific, i.e. (+)-naloxone was ineffective. The DADLE effect varied between different cell preparations and changed from stimulation to inhibition as the inhibitory effect of naloxone alone increased. Thus, an inverse relationship between the magnitude of inhibition by naloxone and enhancement by DADLE was observed. The data suggest that endogenous opioids modulate acid secretion in gastric mucosal cells.
D000818:Animals; D004347:Drug Interactions; D004743:Enkephalin, Leucine / Q000031:analogs & derivatives / Q000494:pharmacology; D016308:Enkephalin, Leucine-2-Alanine; D005744:Gastric Acid / Q000378:metabolism*; D006168:Guinea Pigs; D006632:Histamine / Q000494:pharmacology*; D066298:In Vitro Techniques; D008297:Male; D009270:Naloxone / Q000494:pharmacology*; D010295:Parietal Cells, Gastric / Q000187:drug effects* / Q000378:metabolism; D013237:Stereoisomerism
D009270:Naloxone; D004743:Enkephalin, Leucine; D016308:Enkephalin, Leucine-2-Alanine; D006632:Histamine