抄録
It is known that estrogen affects endothelial function, and that the vasodilatory response to reactive hyperemia is enhanced by estrogen. It is still unknown whether the female reproductive hormones have an influence in the regulation of muscle blood flow to the exercising muscle. We hypothesize that estrogen improves muscle blood flow to the exercising muscle under reduced perfusion pressure via improved endothelial function. In the present study, we examined the muscle blood flow response to static handgrip exercise (20% MVC) under reduced perfusion pressure in female and male subjects. In female subjects, we conducted experiments three times; ovulatory (O), luteal (L), and menstrual (M) phases. Perfusion pressure during exercise was reduced by inflating upper arm cuff at 20 or 40 mmHg. We also measured blood flow response following forearm ischemia (upper arm cuff at 200 mmHg for 5 min) in order to evaluate endothelial function. The reduction of blood flow to the exercising muscle induced by the reduction of perfusion pressure was relatively small in O and L than in M and male subjects. The blood flow response following forearm ischemia was higher in O than other conditions. These results suggest that female reproductive hormones might play a role in the regulation of muscle blood flow to the exercising muscle. [J Physiol Sci. 2006;56 Suppl:S233]
