Changes in platelet vasopressin after smoking in relation to platelet function

Abstract

We examined the effects of smoking on plasma and platelet arginine vasopressin (AVP) levels, platelet aggregation with AVP, and AVP binding to platelets in normal subjects. Plasma and platelet AVP levels increased to the peak level at 5 to 10 min after the start of smoking, and decreased thereafter in parallel with plasma nicotine levels. A good correlation was found between plasma nicotine levels and plasma AVP levels, and also between plasma and platelet AVP levels. These results suggest that platelets rapidly take up endogenously released AVP from plathna. We also observed a decreased platelet aggregation with AVP ex vivo when the plasma and platelet AVP levels were elevated in vivo after somking. Binding experiments of washed platelets did not demonstrate any change in receptor number or affinity before and after smoking. These findings indicate that endogenously released AVP taken up by platelets desensitizes platelets to AVP without loss of AVP receptor number or modification of receptor affinity for AVP.