Action and specificity of ventral medullary vasopressor neurones in the cat

Abstract

An investigation has been made into the mode and specificity of action of ventral medullary pressor neurones. These were activated by microinjections of excitant amino acid into the ventral brain surface of chloralose-anaesthetized. artificially ventilated cats, and a number of autonomic responses were measured. Indirect assessment of cardiac output (by CO2 delivery to the lungs) suggested that it was either unchanged or fell during pressor responses. The inference that activating the pressor neurones caused vasconstriction was confirmed directly for hindlimb and mesenteric vascular beds, by a rise in inflow pressure when they were perfused at constant flow. Sympathetic activity also increas..