VASOCONSTRICTOR ACTIONS OF DELTA-8-TETRAHYDROCANNABINOL AND DELTA-9-TETRAHYDROCANNABINOL IN RAT

  • 1 January 1976
    • journal article
    • research article
    • Vol. 196  (3) , 649-656
Abstract
Cardiovascular effects of .DELTA.8- and .DELTA.9-tetrahydrocannabinol (THC) were studied after systemic i.v. and intra-arterial [i.a.] administration into a perfused vascular bed in the urethane-anesthetized rat. .DELTA.8- and .DELTA.9-THC, i.v., produced dose-related transient increases in blood pressure followed by more prolonged hypotensive responses and bradycardia. .DELTA.8- and .DELTA.9-THC, i.a., into the perfused hindquarters of the rat increased perfusion pressure indicative of vasoconstriction. The vasoconstrictor response to the cannabinoids corresponded temporally to a similar response produced by i.a. norepinephrine and was in contrast to the more prolonged vasoconstrictor responses produced by vasopressin. Phentolamine, in a dose which reduced the vasoconstrictor effect of norepinephrine by 90%, significantly reduced the response to i.a. .DELTA.9-THC while having no effect on the actions of i.a. vasopressin. Reserpine pretreatment significantly reduced vasoconstrictor actions of i.a. tyramine and .DELTA.9-THC but did not alter the responses to norepinephrine. .DELTA.8- and .DELTA.9-THC have peripheral vasoconstrictor activity in the rat which may be mediated, in part, through a tyramine-like action on adrenergic nerve terminals.