Sustained interruption of the aortic baroreflex by left cervical vagotomy in dogs

Previous experiments demonstrated that acute left vagotomy interrupted 90% of the aortic baroreflex. The present study determined whether or not this interruption was sustained over a period of weeks. Bilateral carotid occlusions (BCO) were performed in conscious dogs before and for 3 wk after left vagotomy and immediately after subsequent right vagotomy. Prior to left vagotomy, BCO induced a rise in arterial pressure of 28 +/- 8 mmHg but no change in heart rate. After left vagotomy, BCO resulted in a rise in arterial pressure of 71 +/- 7 mmHg and a rise in heart rate of 43 +/- 6 beats/min. The BCO-induced elevations in arterial pressure and heart rate did not change significantly during the next 3 wk. Subsequent right vagotomy did not alter the rise in arterial pressure to BCO. These data indicate that left cervical vagotomy interrupts the aortic baroreflex for at least a 3-wk period and suggest that this procedure, when combined with reversible vascular isolation of the carotid sinuses, provides a method for studying cardiovascular adaptation to the acute loss of sinoaortic reflexes in the conscious dog.