The mechanical effects of the muscle pump and arterial vasodilation are thought to be two important determinants of exercise hyperemia. The contributions of either to exercise hyperemia in humans are not clear. In addition, the possible interactions of chemically induced dilation (e.g. metabolites) and mechanical factors in determining exercise hyperemia have not been determined. The proposed experiments are designed to determine 1) whether increasing resting forearm blood flow alters the hyperemic response to a single mechanical compression or voluntary contraction, 2) whether increasing resting forearm blood flow alters the hyperemic responses to steady state exercise or rhythmic mechanical compression, and 3) whether endothelium-derived vasodilators contribute to the hyperemic response of a single muscle contraction or mechanical compression. This unique approach will measure forearm hyperemia to compression or contraction at three different levels of """"""""resting"""""""" blood flow. Most studies of exercise hyperemia focus on the contribution of a single factor, rather than how mechanisms interact. The strength of the proposed experiments is that we will manipulate both mechanical and chemical factors and assess their combined effects on muscle blood flow during acute and steady state exercise in humans.
|Schrage, William G; Eisenach, John H; Joyner, Michael J (2007) Ageing reduces nitric-oxide- and prostaglandin-mediated vasodilatation in exercising humans. J Physiol 579:227-36|
|Wilkins, Brad W; Schrage, William G; Liu, Zhong et al. (2006) Systemic hypoxia and vasoconstrictor responsiveness in exercising human muscle. J Appl Physiol 101:1343-50|
|Schrage, William G; Dietz, Niki M; Joyner, Michael J (2006) Effects of combined inhibition of ATP-sensitive potassium channels, nitric oxide, and prostaglandins on hyperemia during moderate exercise. J Appl Physiol 100:1506-12|
|Schrage, William G; Wilkins, Brad W; Dean, Vicki L et al. (2005) Exercise hyperemia and vasoconstrictor responses in humans with cystic fibrosis. J Appl Physiol 99:1866-71|
|Schrage, William G; Joyner, Michael J; Dinenno, Frank A (2004) Local inhibition of nitric oxide and prostaglandins independently reduces forearm exercise hyperaemia in humans. J Physiol 557:599-611|
|Schrage, William G; Eisenach, John H; Dinenno, Frank A et al. (2004) Effects of midodrine on exercise-induced hypotension and blood pressure recovery in autonomic failure. J Appl Physiol 97:1978-84|