title: Stimulation of high-affinity hormone-sensitive GTPase of human platelets by 1-O-alkyl-2-O-acetyl-sn-glyceryl-3-phosphocholine (platelet activating factor).
abstract: 1-O-Alkyl-2-O-acetyl-sn-glyceryl-3-phosphocholine (platelet activating factor) inhibits human platelet adenylate cyclase via the GTP-dependent mechanism. Inhibition of adenylate cyclase correlates with the stimulation of high affinity hormone-sensitive GTPase. The half-maximal effects of PAF on both enzymes are observed at concentrations about 10(-8) M. Phentolamine, an alpha-adrenergic antagonist, does not abolish the PAF-induced inhibition of adenylate cyclase. The obtained data suggest that PAF receptors are coupled with the GTP-binding inhibitory protein.
mesh_terms: D000067956:Adenylyl Cyclase Inhibitors; D001792:Blood Platelets / Q000201:enzymology*; D002462:Cell Membrane / Q000201:enzymology; D004837:Epinephrine / Q000494:pharmacology; D020558:GTP Phosphohydrolases / Q000097:blood*; D006160:Guanosine Triphosphate / Q000378:metabolism / Q000494:pharmacology; D006801:Humans; D010646:Phentolamine / Q000494:pharmacology; D010744:Phosphoric Monoester Hydrolases / Q000097:blood*; D010972:Platelet Activating Factor / Q000502:physiology*; D011942:Receptors, Adrenergic, alpha / Q000502:physiology
chemical_list: D000067956:Adenylyl Cyclase Inhibitors; D010972:Platelet Activating Factor; D011942:Receptors, Adrenergic, alpha; D006160:Guanosine Triphosphate; D010744:Phosphoric Monoester Hydrolases; D020558:GTP Phosphohydrolases; D004837:Epinephrine; D010646:Phentolamine