Prostanoid inhibition of canine parietal cells: mediation by the inhibitory guanosine triphosphate-binding protein of adenylate cyclase.
We have investigated the mechanisms underlying prostaglandin inhibition of histamine-stimulated parietal cell function. Enzyme-dispersed canine parietal cells were enriched by elutriation. The accumulation of the weak base [14C]aminopyrine was used as an index of parietal cell function and cyclic adenosine monophosphate content was measured by radioimmunoassay. Step density gradients of the elutriator-enriched parietal cell fractions indicated that parietal cells accounted for the histamine stimulation of cyclic adenosine monophosphate production and inhibition by the prostaglandin E analogue Enprostil. Pertussis toxin adenosine diphosphate-ribosylates a subunit with a molecular weight of 41,000, thereby inactivating the inhibitory guanine nucleotide-binding protein of adenylate cyclase. Pertussis toxin treatment of parietal cells in overnight suspension culture was used to determine if inhibitory guanosine triphosphate-binding protein mediated prostanoid inhibition. In control cultured cells, prostaglandin E2 and Enprostil markedly inhibited forskolin- and histamine-stimulated aminopyrine accumulation. In parietal cells treated with pertussis toxin (300 ng/ml) for 18 h, stimulation of parietal cell function by histamine, isobutylmethylxanthine, and forskolin was unaltered compared with control cells, whereas prostaglandin E2 and Enprostil inhibition was markedly reduced. In pertussis toxin-treated cells, histamine-stimulated cyclic adenosine monophosphate generation was unaltered, whereas Enprostil inhibition of histamine-stimulated cyclic adenosine monophosphate production was markedly reduced. Pertussis toxin treatment of membranes from control, but not from pertussis toxin-treated, cells induced the [32P]adenosine diphosphate-ribosylation of a membrane protein with a molecular weight of 41,000, presumably the alpha-subunit of inhibitory guanosine triphosphate-binding protein. We conclude that prostanoids inhibit parietal cell function by receptor-mediated interaction with the inhibitory guanine nucleotide-binding protein of adenylate cyclase.
Chen
M C
MC
Center for Ulcer Research and Education, Veterans Administration Wadsworth Hospital Center, Los Angeles, California.
Amirian
D A
DA
Toomey
M
M
Sanders
M J
MJ
Soll
A H
AH
D000246:Adenosine Diphosphate Ribose / Q000096:biosynthesis; D037361:Adenylate Cyclase Toxin; D000262:Adenylyl Cyclases / Q000502:physiology*; D000632:Aminopyrine / Q000378:metabolism; D000818:Animals; D000242:Cyclic AMP / Q000096:biosynthesis; D015232:Dinoprostone; D004285:Dogs; D016620:Enprostil; D019204:GTP-Binding Proteins / Q000502:physiology*; D006632:Histamine / Q000494:pharmacology; D066298:In Vitro Techniques; D010295:Parietal Cells, Gastric / Q000187:drug effects* / Q000378:metabolism; D037342:Pertussis Toxin; D011458:Prostaglandins E / Q000494:pharmacology*; D011459:Prostaglandins E, Synthetic / Q000494:pharmacology*; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D037361:Adenylate Cyclase Toxin; D011458:Prostaglandins E; D011459:Prostaglandins E, Synthetic; D010566:Virulence Factors, Bordetella; D000632:Aminopyrine; D000246:Adenosine Diphosphate Ribose; D006632:Histamine; D000242:Cyclic AMP; D037342:Pertussis Toxin; D019204:GTP-Binding Proteins; D000262:Adenylyl Cyclases; D016620:Enprostil; D015232:Dinoprostone