AJP - Regulatory, Integrative and Comparative Physiology, Vol 234, Issue 3 146-R154, Copyright © 1978 by American Physiological Society
Blood flow distribution in the duck lung and its control by respiratory gases
J. P. Holle, N. Heisler and P. Scheid
Blood flow to subunits of the lung was studied in the duck by use of
radioactive microspheres. In spontaneously breathing, unanesthetized
animals (series I) neopulmo was slightly better perfused than the average
lung and along the paleopulmonic parabronchi, blood flow was found to
decrease in the direction of ventilatory gas flow and thus of decreasing
PO2 and increasing PCO2 in lung gas. The effects of respiratory gases on
regional lung perfusion were investigated in unidirectionally ventilated
animals (series II) in which gas mixtures offered to both lungs could be
controlled independently. Local hypoxia resulted in reduction of local
blood flow, whereas effects from hyperoxia or CO2 could not be
substantiated. Reversal of the direction of unidirectional ventilatory flow
(series III), and thus reversal of the profiles of respired gas
concentrations along the parabronchi, suggest that the inhomogeneity in
blood flow observed in spontaneously breathing animals of series I can only
in part be explained as an acute adjustment to the local hypoxia.
Calculations show that this inhomogeneity of blood flow constitutes an only
minor impairment of the overall gas exchange efficacy of the parabronchial
lung.
