Respiratory and Circulatory Responses of Anesthetized Dogs to Induced Muscular Work

Abstract

Respiratory and circulatory responses to induced muscular work were studied in 10 urethan-chloralosed dogs. It was revealed from 44 experiments that during a steady state of exercise ventilation increases in direct proportion to O2 consumption whereas cardiac output increases curvilinearly as a function of O2 consumption. The increase in ventilation is brought about by an increase in both tidal volume and respiratory rate. The increase in cardiac output is accompanied by an increase in both stroke volume and heart rate. The ventilation-perfusion ratio also changes during exercise: Ventilation (1/minute BTPS) = 2.7 cardiac output (1/minute) - 1.99. It was further revealed that ventilatory and circulatory responses in anesthetized dogs during induced exercise were analogous to those in man.