Neuropeptide Y in cerebrovascular function: comparison of membrane potential changes and vasomotor responses evoked by NPY and other vasoconstrictors in the guinea pig basilar artery.

The membrane depolarization and vasomotor response evoked by NPY and other vasoconstrictors were compared in guinea pig basilar artery. Concentrations below the pD2 value of amines and PGF2 alpha induced contractions without significant membrane depolarization, while higher agonist concentrations depolarized the membrane slightly. Potassium-induced contractions were paralleled by strong depolarization. NPY evoked a slow depolarization which correlated to vasoconstriction over a wide concentration range. The mechanism of activation did not appear to involve the endothelium. The results suggest that NPY induces prolonged cerebrovascular smooth muscle tone by evoking longlasting depolarization, at least partly in conjunction with activation of voltage-operated calcium channels.