Effect of Cyclopropane on Reflexly Induced Circulatory Responses in the Dog

Abstract

The present study was undertaken because of previously published divergent conclusions regarding the action of cyclopropane on vasomotor control mechanisms. The magnitude of reflexly-induced pressor and depressor responses elicited by carotid occlusion or stimulation of afferent nerves was used on an index of the reactivity of vasomotor mechanisms. Cyclopropane, in the dog, decreased the magnitude of reflexly-induced venous and arterial pressor responses, but did not alter significantly reflexly-induced depressor responses. These results were obtained whether cyclopropane was allowed to reach the whole animal or its distribution was limited to the cephalad portion of the circulation during periods of major vessel occlusion. In the dog, cyclopropane obtunds the activity of those central functions responsible for increasing both venous and arterial vascular tone in response to afferent stimulation. Contrarily, the function of central pathways, which mediate reflexly induced reductions in peripheral venous and arterial tone are not depressed by cyclopropane.