Indocyanine Green Clearance and Estimated Hepatic Blood Flow during Mild to Maximal Exercise in Upright Man *

Krogh in 1912 (1) postulated the necessity for a large capacity venous reservoir capable of quickly delivering an autotransfusion of blood into the right heart during exercise, particularly in upright man, where Krogh felt venous return may at times be inadequate. Bock and co-workers (2) in their classical work reasoned that increased blood flow to working muscle, related in part to local vasodilation, must be partially effected by de- creased splanchnic blood flow. Since the splanch- nic region receives 20 to 25% of the total left ven- tricular output but extracts only 10 to 25% of the available oxygen (3), the splanchnic bed is ideally suited for rapid correction for any residual in- balance between left ventricular output and peripheral distribution of flow.