Blood flow distribution during artificially induced respiratory hypocapnic alkalosis in the fowl

In birds, hyperthermia is normally associated with panting and progressive respiratory alkalosis. The effect of respiratory alkalosis on capillary blood flow distribution was examined by artificially hyperventilating normothermic fowls, thereby dissociating it of the normally occuring concomitant hyperthermia. In contrast with mammals, in which hyperventilation associated with hypocapnia reduced blood flow to the brain, uterus and other organs, in the hen blood flow distribution in most organs remained unaltered. This indicates that the potential change in acid-base balance which develops in the hyperthermic birds during panting is not likely to affect the regulation of blood flow. The comb and wattles were the only affected organs, in which capillary blood flow diminished to about 45% of normal values. This reduction did not prevent a vasodilation in those organs in hyperthermic fowls, though it probably limited its full expression.