Hypertension following arterial baroreceptor denervation in the unanesthetized dog

Studies were conducted on unanesthetized dogs (1) in the control state, (2) after carotid sinus denervation plus section of the cervical aortic nerves (SCAD), and (3) after carotid sinus denervation plus section of intrathoracic vegal branches which innervate arterial and cardiopulmonary baroreceptors, the heart, lungs, and other structures (STD). Mean values and standard deviations of blood pressure and heart rate were measured during many 75-minute recording sessions. The control mean arterial pressure was 94.8 +/- 8.9 mm Hg. The mean pressure after SCAD was 105.5 +/- 9.5 mm Hg, 10.0 mm Hg higher (P less than 0.05) than in the control state, whereas after STD, the mean pressure was 119.5 +/- 16.8 mm Hg, 25.3 mm Hg higher (P less than 0.001) than in the control state. The standard deviation of pressure was increased (P less than 0.01) by either denervation procedure. The mean pressure after STD was higher than after SCAD (P less than 0.05). Ten of 12 animals with SCAD showed residual baroreceptor reflexes (seven from intrathoracic receptors) whereas, after STD, six of 11 animals showed reflexes (one from intrathoracic receptors). SCAD only occasionally produces denervation as complete as that produced by STD. A larger increase in arterial pressure follows a more complete denervation of vagally innervated baroreceptors. We believe that our procedures do not denervate all arterial baroreceptors. Chronic denervation of arterial baroreceptors leads to a widely varying, elevated arterial pressure. The increase in pressure has persisted more than 1 1/2 years.