Properties of vasopressin-activated human platelet high affinity GTPase.
Effect of 8-arginine vasopressin (AVP) was examined on human platelet membrane GTPase activity as an index of a G-protein involvement. AVP stimulated a high-affinity GTPase activity in a dose-dependent manner (Kact = 1.1 +/- 0.2 nM). This stimulation was blocked by a V1a antagonist, thus confirming the V1a nature of the platelet AVP receptor. There were important variations among individuals in the AVP-induced stimulation of GTPase activity, that were in relation with the AVP-maximal binding capacity. These data suggest a causal relationship between the binding of AVP to its receptor and transduction elicited by a G-protein, without amplification. In addition, in view of the variable AVP responsiveness observed among individuals, platelet AVP-receptor appears to be subject to regulation.
Vittet
D
D
INSERM U.300, Faculté de Pharmacie, Montpellier, France.
Cantau
B
B
Mathieu
M N
MN
Chevillard
C
C
D001127:Arginine Vasopressin / Q000097:blood / Q000494:pharmacology*; D001792:Blood Platelets / Q000201:enzymology*; D002462:Cell Membrane / Q000378:metabolism; D004789:Enzyme Activation; D020558:GTP Phosphohydrolases / Q000097:blood*; D006801:Humans; D007700:Kinetics; D010744:Phosphoric Monoester Hydrolases / Q000097:blood*; D011945:Receptors, Angiotensin / Q000378:metabolism; D017483:Receptors, Vasopressin
D011945:Receptors, Angiotensin; D017483:Receptors, Vasopressin; D001127:Arginine Vasopressin; D010744:Phosphoric Monoester Hydrolases; D020558:GTP Phosphohydrolases