Cocaine-induced hypertension: Role of the peripheral sympathetic system

Cocaine causes hypertension at least in part by stimulating the sympathetic nervous system, but it is not clear if this effect is centrally or periphe rally mediated. To address this issue we studied the vasoconstrictive effec t of cocaine in vivo and in isolated artery segments. In vivo cocaine incre ased mean arterial blood pressure (MAP) by 40 mmHg within 1 min of administ ration. Pretreatment with prazosin blocked this response by 62%. With cloni dine the pre-cocaine MAP was lower and the hypertensive effect of cocaine w as blocked by 50%, indicating an important role for central alpha-adrenergi c mechanisms. In isolated rat carotid arteries cocaine-induced vasoconstric tion was completely blocked by prazosin, phentolamine, and 6-hydroxydopamin e, indicating a clear role for a peripheral effect. However, the relative c ontribution of the central alpha-adrenergic mechanism to the total vasocons trictive response of cocaine was not clarified. (C) 1999 Academic Press.