An assessment of the cardiovascular sympathectomy induced by guanethidine

Abstract

Abstract Guanethidine treatment of rats (30 mg kg−1, i.p. daily for 6 weeks) produced a profound reduction in the catecholamine present (as indicated by fluorescence histochemistry and catecholamine determinations) in tissues taken from the cardiovascular system, but there was evidence of the return of catecholamines within 8 weeks. While these changes are consistent with a sympathectomy, the unaltered pressor responses to physostigmine (100 μg kg−1, i.v.) and to carotid occlusion indicate an unimpaired functional capacity of noradrenergic nerves supplying the cardiovascular system. Although part of the response may be attributed to the unaffected adrenal medulla enhanced by the presence of considerable supersensitivity as shown to exogenous noradrenaline, there would appear to be a dissociation between the results obtained from physical and functional tests of the sympathectomy induced by guanethidine.