Alteration of centrally mediated cardiovascular manifestations by intraventricular pronethalol and phentolamine

It has been observed that (1) in chloralosed cats, centrally pretreated with either reserpine, imipramine or chlorpromazine, injection of phentolamine (3mg) or pronethalol (2mg) into the lateral cerebral ventricle, significantly reduces noradrenaline-induced pressor responses and heart rate increases, respectively; (2) equal intravenous doses of phentolamine or pronethalol lead to a less marked blockade of the cardiovascular effects of intraventricular noradrenaline in cats centrally pretreated with imipramine. These findings would suggest that sympathetic receptor mechanisms showing responses like those of “alpha” and “beta” types, as postulated at peripheral adrenergic sites, might also be involved in the central nervous system regulation of cardiovascular manifestations.