Respiratory influence on the vasomotor center.

Abstract

Respiration, blood pressure, and splanchnic and phrenic discharges were recorded from cats (anesthetized with chloralose, immobilized with Syncurine and artificially ventilated) under conditions of asphyxia, vagotomy, hyperventilation and pneumothorax. The results indicate a close relationship between the vasomotor and respiratory center. Both the respiratory center and ventilation can influence the vasomotor center. The ventilatory influence is exerted through blood pressure changes synchronous with respiration. Although unaffected by decerebration, respiratory grouping of splanchnic discharge was completely abolished by spinal transection at C1, and is probably controlled by the medullary vasomotor center. Since sinus denervation and vagotomy did not abolish respiratory grouping of splanchnic discharge, blood pressure changes can affect the vasomotor center through mechanisms other than sino-aortic reflexes. The difference between positive and negative pressure breathing in effecting the respiratory influence on the vasomotor center is discussed.