Abstract
We have studied arterial blood supply to exercising skeletal muscle and venous return from the muscle in humans. Voluntary exercise were performed for 1 min with 30% of the maximal voluntary contraction in the supine [static or intermittent handgrip exercise]. Each one also experienced respiratory interventions (deep breath and forced inspiratory or expiratory apnea). The B-mode image and blood flow of brachial artery or vein were recorded with Doppler flowmetry. The distinct differences in blood flow response to exercise were found between the brachial artery and vein, although the overall response was the same each other. First, venous blood flow showed stronger respiratory modulation and less pulsatile modulation than arterial blood flow. Second, venous blood flow increased at the onset of exercise, whereas arterial blood flow often decreased. Third, venous blood flow increased at the contraction phase of intermittent exercise, whereas arterial blood flow decreased. On the contrary, venous blood flow decreased at the relaxation phase of intermittent exercise, whereas arterial blood flow increased. The respiratory interventions strongly influenced brachial venous blood flow than arterial blood flow. Particularly, a transient inspiratory movement caused a large increase in venous blood flow but not arterial blood flow. Thus these findings reveal that voluntary exercise and respiration movement cause the differential responses in brachial venous and arterial blood flow in humans. [J Physiol Sci. 2007;57 Suppl:S81]
