Chemoreceptor influence on pulmonary blood flow during unilateral hypoxia in dogs.

Dogs anesthetized with 30 mg/kg pentobarbital were artificially respired after differential cannulation of the main stem bronchi. Following median sternotomy, blood flow was monitored by electromagnetic flow probes on the left pulmonary artery (QL) and on the pulmonary trunk or aorta, QT. Following 10 min of bilateral 100% O2, QL was 42.5 +/- 7% of QT. When 6% O2, was substituted as the gas mixture inspired by the left lung while the right lung remained on 100% O2, PaO2 was above 70 mm Hg and QL fell to 24.5 +/- 5% of QT. Room air was then used to ventilate the right lung while the left lung remained on 6% O2. This caused PaO2 to fall to 42.3 +/- 3 MM Hg and QL to rise to 38.3 +/- 6% QT. This increase in blood flow to the unilaterally hypoxic lung during systemic hypoxemia did not occur in dogs after peripheral chemoreceptor denervation. Therefore, interference with the local response to alveolar hypoxia during systemic hypoxemia appears to be mediated by the arterial chemoreceptors.