Augmentation of release of gastric somatostatin-like immunoreactivity by adenosine, adenosine triphosphate and their analogs.
The effect of adenosine, adenosine 5'-triphosphate (ATP) and ATP analogs on basal gastric somatostatin-like immunoreactivity (SLI) release was studied using the vascularly perfused rat stomach. The release of gastric SLI was stimulated by adenosine (0.6-60 microM) concentration dependently, while the release of immunoreactive gastrin was inhibited by 1 and 10 microM adenosine. The stimulatory action of adenosine was probably mediated by adenosine receptors because the receptor antagonist, 8-phenyltheophylline, abolished the action of adenosine. In addition, the adenosine-induced release of SLI was not mediated by a cholinergic or beta-adrenergic mechanism, since atropine, hexamethonium or propranolol did not block the action of adenosine. Dipyridamole enhanced the adenosine-stimulated, but not 2-chloroadenosine-induced SLI release. Since the adenosine analog, 2-chloroadenosine, is resistant to the adenosine uptake mechanism, it is likely that adenosine-stimulated release of gastric SLI is due to the activation of extracellular receptors. ATP also stimulated gastric SLI release. The analogs alpha,beta-methyleneadenosine triphosphate and diphosphate, which are resistant to metabolic breakdown, did not stimulate basal SLI release, while gamma,beta-methyleneadenosine triphosphate, which can be metabolized, increased the release of SLI. In addition, the ATP-induced release of SLI was abolished by 8-phenyltheophylline. Therefore, the action of ATP is likely to be a result of its metabolism to adenosine.
Kwok
Y N
YN
Department of Physiology, Faculty of Medicine, University of British Columbia, Vancouver, Canada.
McIntosh
C
C
Brown
J
J
D015762:2-Chloroadenosine / Q000494:pharmacology; D000109:Acetylcholine / Q000378:metabolism; D000241:Adenosine / Q000031:analogs & derivatives / Q000494:pharmacology*; D000255:Adenosine Triphosphate / Q000031:analogs & derivatives / Q000494:pharmacology*; D000818:Animals; D004176:Dipyridamole / Q000494:pharmacology; D005753:Gastric Mucosa / Q000187:drug effects / Q000378:metabolism*; D018738:Hexamethonium; D006584:Hexamethonium Compounds / Q000494:pharmacology; D008297:Male; D010455:Peptides / Q000378:metabolism*; D010477:Perfusion; D051381:Rats; D011919:Rats, Inbred Strains; D013806:Theophylline / Q000031:analogs & derivatives / Q000494:pharmacology
D006584:Hexamethonium Compounds; D010455:Peptides; C029993:somatostatin-like peptides; D015762:2-Chloroadenosine; D018738:Hexamethonium; D004176:Dipyridamole; D000255:Adenosine Triphosphate; D013806:Theophylline; C028322:8-phenyltheophylline; D000241:Adenosine; D000109:Acetylcholine