title: Characterization of a vasoactive intestinal peptide-sensitive adenylate cyclase in rat intestinal epithelial cell membranes.
abstract: A vasoactive intestinal peptide-sensitive adenylate cyclase in intestinal epithelial cell membranes was characterized. Stimulation of adenylate cyclase activity was a function of vasoactive intestinal peptide concentration over a range of 1 . 10(-10)-1 . 10(-7) M and was increased six-times by a maximally stimulating concentration of vasoactive intestinal peptide. Half-maximal stimulation was observed with 4.1 +/- 0.7 nM vasoactive intestinal peptide. Fluoride ion stimulated adenylate cyclase activity to a higher extent than did vasoactive intestinal peptide. Under standard assay conditions, basal, vasoactive intestinal peptide- and fluoride-stimulated adenylate cyclase activities were proportional to time of incubation up to 15 min and to membrane concentration up to 60 microgram protein per assay. The vasoactive intestinal peptide-sensitive enzyme required 5-10 mM Mg2+ and was inhibited by 1 . 10(-5) M Ca2+. At sufficiently high concentrations, both ATP (3 mM) and Mg2+ (40 mM) inhibited the enzyme. Secretin also stimulated the adenylate cyclase activity from intestinal epithelial cell membranes but its effectiveness was 1/1000 that of vasoactive intestinal peptide. Prostaglandins E1 and E2 at 1 . 10(-5) M induced a two-fold increase of cyclic AMP production. Vasoactive intestinal peptide was the most potent stimulator of adenylate cyclase activity, suggesting an important physiological role of this peptide in the cyclic AMP-dependent regulation of the intestinal epithelial cell function.
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000067956:Adenylyl Cyclase Inhibitors; D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002462:Cell Membrane / Q000201:enzymology; D004789:Enzyme Activation / Q000187:drug effects; D005768:Gastrointestinal Hormones / Q000494:pharmacology*; D007413:Intestinal Mucosa / Q000201:enzymology* / Q000648:ultrastructure; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D008297:Male; D051381:Rats; D013379:Substrate Specificity; D014660:Vasoactive Intestinal Peptide / Q000494:pharmacology*
chemical_list: D000067956:Adenylyl Cyclase Inhibitors; D005768:Gastrointestinal Hormones; D014660:Vasoactive Intestinal Peptide; D000255:Adenosine Triphosphate; D000262:Adenylyl Cyclases; D008274:Magnesium; D002118:Calcium