Partition of carotid baroreceptor response in two-kidney renal hypertensive dogs

This study evaluated the mechanism of carotid sinus baroreceptor resetting in two-kidney one-clip Goldblatt hypertension in dogs by partitioning the resetting between carotid sinus wall compliance and receptor neural elements. With dogs under halothane anesthesia, the left renal artery was constricted 70-80% with a Goldblatt clamp without disturbing the contralateral kidney. Ten weeks later, when mean blood pressure had risen to 151 +/- 6 mmHg (means +/- SE) compared with 105 +/- 5 mmHg in controls, we measured simultaneously whole nerve action potentials (N) and carotid sinus volume (V) during step changes in intrasinus pressure (P). Hypertensive N vs. P relationship was sigmoid shaped and shifted toward the P-axis compared with controls. Hypertensive V vs. P relationship was not significantly different from controls. The hypertensive N vs. V relationship derived from the composite plots of N vs. P and V vs. P was sigmoid shaped and shifted toward the V-axis compared with controls. These results suggest that the resetting of baroreceptors is due to changes in receptor properties rather than carotid sinus wall compliance.