title: Stimulation of specific GTPase activity by vasopressin in isolated membranes from cultured rat hepatocytes.
abstract: Membranes were isolated by isotonic homogenization and differential centrifugation from rat hepatocytes cultured overnight. The specific GTPase activity of the membranes was 1-1.3 pmol gamma-labelled GTP hydrolysed/mg protein per min in the presence of 1.2 mM Na+, 2 mM EGTA, 1 mM ATP and 0.2 mM 5-adenylyl imidodiphosphate. Under these conditions there was a stimulation of specific GTPase activity of no more than 20% by 11-115 nM vasopressin. No effect of vasopressin was seen in the presence of 1.7 microM free Ca2+ or 100 mM Na+. The findings indicate that vasopressin is able to influence GTPase activity as well as accelerate phosphoinositide breakdown in rat hepatocytes.
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000266:Adenylyl Imidodiphosphate / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D002462:Cell Membrane / Q000187:drug effects / Q000201:enzymology; D002478:Cells, Cultured; D020558:GTP Phosphohydrolases / Q000378:metabolism*; D007700:Kinetics; D008099:Liver / Q000187:drug effects / Q000201:enzymology*; D008297:Male; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D010761:Phosphorus Radioisotopes; D051381:Rats; D011919:Rats, Inbred Strains; D014667:Vasopressins / Q000494:pharmacology*
chemical_list: D010761:Phosphorus Radioisotopes; D014667:Vasopressins; D000266:Adenylyl Imidodiphosphate; D000255:Adenosine Triphosphate; D010744:Phosphoric Monoester Hydrolases; D020558:GTP Phosphohydrolases; D002118:Calcium