Influence of the anteroventral third ventricle region and sinoaortic denervation on the pressor response to carotid occlusion.

The effect of anteroventral third ventricle (AV3V) lesion on the pressor response to occlusion of the common carotid artery was studied in freely moving rats with cuffs implanted 1 day before the tests. Short-term (6 hours) and long-term (2, 14, and 30 days) lesions greatly depressed the pressor responses to 60 seconds of common carotid occlusion. The initial peak, which depends on carotid innervation, was reduced by 55% (from 42 +/- 2 to 20 +/- 2 mm Hg), and the maintained response, which is of central origin (probably ischemic), was reduced by 32% (from 31 +/- 2 to 21 +/- 2 mm Hg). The effect of carotid or aortic denervation (or both) was also studied on control and lesioned rats. Carotid denervation produced similar extent of depression of the normal and reduced responses of the AV3V-lesioned rats 35% and 37%, respectively. Aortic denervation produced similar relative potentiation of the responses to common carotid occlusion of control and lesioned rats (72% and 66%, respectively). These data indicate the following: 1) Both short-term and long-term lesions greatly reduce the reflex and central (ischemic) components of the pressor responses to common carotid occlusion in freely moving rats; and 2) the importance of carotid innervation for development of the initial peak and the marked inhibitory effect of the aortic baroreceptor on both components are unchanged after AV3V lesion, when the depressed responses are evaluated as percent changes of the control values rather than as absolute changes.