Chemostimulation during Bilateral Carotid Occlusion in the Rat

Abstract

Bilateral common carotid occlusion (BCO) causes mechanical and chemical changes at the level of the carotid bifurcations. A fall in intrasinusal blood pressure and the disappearance of intrasinusal pulse pressure suppress the baroreceptor’s afferent signals and release sympathetic cardiovascular activities. Concomitantly, when blood flow to the carotid bodies stops, a state of stagnant hypoxia with hypercapnia is induced, which stimulates the arterial chemoreceptors. In such a case, BCO increases ventilation. The intensity and duration of the different reflex responses vary according to animal species. When the collateral circulation is well developed, as in the dog, some responses are reduced or absent: in particular, hyperventilation does not occur (1). During unilateral carotid occlusion, in the cat, systemic hypertension is induced without hyperventilation, indicating that barosensitivity dominates (2).