Response of resistance and capacitance vessels to central nervous system stimulation

Abstract

Responses of precapillary and postcapillary vessels, i.e., resistance and capacitance vessels, to electrical stimulation of the central nervous system of the cat were investigated. The hindquarters were perfused at constant flow, and changes in the tone of the resistance and capacitance vessels were indicated by changes in perfusion pressure and hindquarters volume, respectively. The hypothalamus, midbrain reticular formation, medulla, and lumbar sympathetic chains were stimulated at various voltages and frequencies. The most consistent finding was that changes in perfusion pressure were accompanied by oppositely directed changes in hindquarters volume. This was the case regardless of whether a pressor or depressor response was obtained and regardless of the central area stimulated. Stimulation of pressor sites frequently caused biphasic responses in perfusion pressure and volume. Maximal effects in both perfusion pressure and volume were usually produced by the same frequencies of stimulation. No central areas were found which predominantly and consistently affected perfusion pressure in preference to volume or vice versa. It is concluded that veins as well as arteries respond actively to stimulation of the central nervous system.