Intrapulmonary bronchial blood flow of rats as studied by the microsphere method.

The intrapulmonary bronchial blood flow of the left lung (systemic arterial blood flow to the left lung via the bronchial artery) was determined in 45 anesthetized and artificially ventilated male Wistar rats, weighing 263 +/- 5 g (mean +/- SEM). The microsphere method was employed and designed so that recirculating microspheres across the peripheral arteriovenous anastomoses were prevented from lodging in the left lung, and disturbances of the isovolemic state of the animals became minimal. Under normal conditions with a mean arterial pressure of 115 +/- 2 mmHg (n = 40), the bronchial blood flow of the left lung was found to be 0.307 +/- 0.033 ml/min on average, and amounted to 0.52 +/- 0.06% of the cardiac output. The flow (ml/min) normalized per kg body weight, 100 g wet lung, or 100 g dry lung was 1.14 +/- 0.12, 76 +/- 8, or 368 +/- 39, respectively. The total intrapulmonary bronchial blood flow of the left and right lungs could be estimated by multiplying the intrapulmonary bronchial flow of the left lung by the weight ratio (total:left) of 2.9. The variability of the flow data was small, as confirmed in a study with simultaneous injection of two differently radiolabeled microspheres. The reproducibility of duplicate measurements was excellent.