Rapid resetting of baroreflexes in hypertensive dogs

The hypothesis tested was that the rapid resetting of the arterial baroreflex control of arterial pressure in normotension could be demonstrated in experimental hypertension. After the development of experimental hypertension (using a bilateral renal wrap technique), rapid resetting of arterial pressure and heart rate (HR) was acutely assessed under pentobarbital sodium anesthesia in hypertensive and normotensive vagotomized dogs. The carotid sinus area was isolated and perfused at controlled carotid sinus pressures (CSPs). Baroreflex response [mean arterial pressure (MAP) and HR] curves were measured after three carotid sinus conditioning pressures (50, 125, and 200 mmHg) were applied. For the MAP response, the CSPo (CSP at point of maximum reflex gain) increased significantly to the same extent in both groups with increasing conditioning pressures (with 22.2 and 16.7% resetting in the normotensive group, and 20.3 and 14.2% resetting in the hypertensive group). We conclude that short-term adjustments to changes in prevailing pressure (rapid resetting) occur in the arterial pressure response in experimental hypertension to the same extent seen in normotension.