Inhibition of carbachol stimulated acid secretion by interleukin 1beta in rabbit parietal cells requires protein kinase C.
BACKGROUND
Interleukin 1beta (IL-1beta) is a potent inhibitor of gastric acid secretion. Regulatory actions at several levels have previously been demonstrated, including direct inhibition of parietal cell acid secretion. Although IL-1beta may activate several intracellular signalling pathways, the mechanisms responsible for inhibition of carbachol stimulated acid secretion have not been determined.


OBJECTIVE
To investigate the roles of protein kinase C (PKC) and the sphingomyelinase signalling pathways in the regulation of acid secretion by IL-1beta.


METHODS
Rabbit parietal cells were obtained by collagenase-EDTA digestion and centrifugal elutriation. Acid secretion stimulated by carbachol and A23187 (to mimic elevations in intracellular calcium) was assessed by 14C aminopyrine uptake in response to IL-1beta, PKC, and sphingomyelinase manipulation.


RESULTS
IL-1beta inhibited carbachol and A23187 stimulated acid secretion in a dose dependent manner. The inhibitory actions were completely reversed by each of three different PKC inhibitors, staurosporine, H-7, and chelerythrine, as well as by PKC depletion with high dose phorbol ester pretreatment. IL-1beta did not downregulate parietal cell muscarinic receptor. IL-1beta significantly increased membrane PKC activity. Activation of the sphingomyelinase/ceramide pathway had no effect on basal or stimulated acid secretion. The inhibitory action of IL-1beta was independent of protein kinase A and protein kinase G activity.


CONCLUSIONS
IL-1beta directly inhibits parietal cell carbachol stimulated acid secretion. This action occurs distal to muscarinic receptor activation and elevations in intracellular calcium and requires PKC.
Beales
I L
IL
Department of Gastroenterology, Royal Postgraduate Medical School, Hammersmith Hospital, Du Cane Road, London W12 0NN, UK. ian.beales@jpaget.nhs.uk
Calam
J
J
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine / Q000494:pharmacology; D000470:Alkaloids; D000704:Analysis of Variance; D000818:Animals; D053119:Benzophenanthridines; D002217:Carbachol / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D002273:Carcinogens / Q000494:pharmacology; D002450:Cell Communication / Q000502:physiology; D002478:Cells, Cultured; D018679:Cholinergic Agonists / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005744:Gastric Acid / Q000502:physiology*; D007375:Interleukin-1 / Q000502:physiology*; D010295:Parietal Cells, Gastric / Q000187:drug effects* / Q000502:physiology; D010617:Phenanthridines / Q000494:pharmacology; D011493:Protein Kinase C / Q000502:physiology*; D011817:Rabbits; D013108:Sphingomyelin Phosphodiesterase / Q000502:physiology; D019311:Staurosporine / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D000470:Alkaloids; D053119:Benzophenanthridines; D002273:Carcinogens; D018679:Cholinergic Agonists; D004791:Enzyme Inhibitors; D007375:Interleukin-1; D010617:Phenanthridines; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D002217:Carbachol; C016299:chelerythrine; D011493:Protein Kinase C; D013108:Sphingomyelin Phosphodiesterase; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate