Central nervous system control of pulmonary vascular resistance; effect of anesthesia after unilateral denervation

Seven beagles were subjected to left pulmonary denervation (autotransplantation) and allowed one to two months for complete recovery. The relative resistances of each dog's pair of lungs were determined by the distribution of 99mTc microspheres delivered intravenously while the subject was awake and then under barbiturate anesthesia. In each case, relative blood flow to the right lung increased at the expense of flow to the left. This is interpreted as a direct decrease in pulmonary vascular resistance on the right under the effects of anesthesia. The implications of such central nervous system control of pulmonary vascular resistance was discussed in relation to the pathophysiology of the respiratory distress syndrome.