Regional pulmonary blood flow in the lung of the chicken

Abstract

It is known that alterations in respiratory gases in birds can cause a nonhomogenous redistribution of pulmonary blood flow between the 2 separate gas-exchanging regions of the avian lung, the paleopulmo (PALEO) and neopulmo (NEO); however, the effect of alterations in respired gas content on the distribution of pulmonary blood flow in birds, such as the chicken, that possess a highly developed NEO is not known. This study used a colorimetric microsphere method to determine the effects of hypoxia and hypercapnia on the relative distribution of pulmonary blood flow in anesthetized chickens (Gallus domesticus) during control (normoxic) and experimental (hypoxic or hypercapnic) conditions, where the relative regional distribution of blood flow in the lung is expressed as the ratio NEO/PALEO. Administration of a hypoxic gas mixture (16.0% O(2)) produced a 13.4% increase in NEO/PALEO, and, administration of a hypercapnic gas mixture (5.0% CO(2)) resulted in a 27.8% increase in NEO/PALEO. Our results are consistent with a mechanism in which the regional redistribution of pulmonary blood flow is mediated by local intrapulmonary factors.