Role of vagal and sinoaortic baroreflexes in restoration of arterial pressure after acute mild haemorrhage in rabbits.

To evaluate the contribution of vagal and sinoaortic baroreflexes (SBR) in circulatory adjustments, anaesthetized rabbits were subjected to acute mild haemorrhage and the extent of recovery produced after haemorrhage was estimated. The recovery of arterial pressure after acute mild haemorrhage with reflexes intact was 96.19%, after elimination of SBR it was 79.20%, after bilateral vagotomy 87.38%, and after eliminating both reflex systems it was 75.66%. The results suggest that vagally mediated baroreflexes from cardiopulmonary baroreceptors contribute significantly in restoring the arterial pressure in response to haemorrhage while the sinoaortic baroreflexes play the major role.