Cocaine constriction of rat basilar artery in situ: roles of nitric oxide and endothelin-1.

This study investigated whether cocaine constriction of rat basilar artery in situ is mediated by nitric oxide (NO) inhibition and/or endothelin (ET)-1 release. Cocaine (3-100 µmol/l) concentration-dependently constricted the basilar artery to a maximum of 18%. Nω-nitro-L-arginine (100 µmol/l) was without effect on constriction to 3 and 10 µmol/l cocaine. PD145065 (1 and 10 µmol/l), an ETA/B receptor antagonist, variably and at most partially inhibited the 100 µmol/l cocaine constriction. Capsaicin denervation of sensory nerves innervating the basilar, which contain ET-1 and NO synthase, also failed to influence cocaine constriction. These findings suggest that cocaine constriction of cerebral vessels (1) varies with respect to the involvement of ET-1 release and (2) unlike findings in the peripheral vasculature, the constriction is not mediated by inhibition of NO.