title: Influence of pulmonary blood flow and O2 flux on DO2 in avian lungs.
abstract: O2 diffusing capacity (DO2) was measured in anesthetized, unidirectionally ventilated ducks during hypercapnic hypoxia. DO2 averaged 78.2 mumol X (min X Torr)-1. This value increased to 97.3 mumol X (min X Torr)-1 after correction for ventilation-perfusion inequality. DO2 increased when pulmonary O2 exchange (MO2) and pulmonary blood flow (Q) were increased by either 2,4 dinitrophenol (DNP,ca. 5 mg/kg i.v.) or temporary unilateral pulmonary artery occlusion (TUPAO). DO2 increased with MO2 42.4 mumol X (mmol X Torr)-1 (R = 0.664), and with Q 80.3 mumol X (L X Torr)-1 (R = 0.895). Since there is evidence against expansion of membrane diffusing capacity through recruitment and distention of pulmonary capillaries in avian lungs, we suggest that the close coupling of DO2 to Q reflects a reduction of functional lung heterogeneity at higher blood flows, perhaps due to better matching of V to D, or D to Q.
mesh_terms: D019297:2,4-Dinitrophenol; D000818:Animals; D004140:Dinitrophenols / Q000494:pharmacology; D004372:Ducks / Q000502:physiology*; D006400:Hematocrit; D008168:Lung / Q000378:metabolism*; D010101:Oxygen Consumption / Q000187:drug effects; D011652:Pulmonary Circulation; D011653:Pulmonary Diffusing Capacity; D014692:Ventilation-Perfusion Ratio
chemical_list: D004140:Dinitrophenols; D019297:2,4-Dinitrophenol