This process is primarily a function of vasodilation of the arterioles (distal, proximal, and feed) and the pre-capillary sphincters, which is to a great degree Akt inhibitor induced by factors such as adenosine, carbon dioxide, and potassium, which are released in proportion to intensity of effort by adjacent muscle fibers during exercise [4]. The close coupling of muscular blood flow and exercise intensity supports the theory that further elevations in localized blood flow during exercise may, in some cases, result in increased peak work capacity and/or increased resistance to local muscle fatigue, thereby enhancing exercise performance. The process of vasodilation

selleck screening library as a primary component of exercise hyperemia involves mechanisms other than the aforementioned muscle metabolite induced vasodilatory mechanisms (adenosine, CO2, K+). For example, the initial increases of blood flow (first 1 – 2s) during exercise are now believed to be related to increased concentrations of acetylcholine

as released by the motor end-plate during muscle activation [5]. Tschakovsky and Joyner [6] outlined several mechanisms believed to contribute to the secondary phase of vasodilation (3+ sec) including flow mediated mechanisms, the mechanical muscle pump, mechanically induced responses, muscle activation I-BET151 supplier mechanisms, and red blood cell HbO2 desaturation mechanisms. Each of these mechanisms can be associated with Galeterone different variations and intensities of exercise stresses. However, each of these distinct mechanisms shares the common function of initiating the synthesis of nitric oxide (NO). Nitric oxide (NO) is a very short-lived, reactive gaseous nitrogen molecule that is involved in a variety of physiological functions. Approximately twenty years ago, it was revealed that NO was the endothelial factor responsible for regulating muscle tone of vascular

structures, originally referred to as endothelial dependent relaxation factor (EDRF) several years prior. However, a viable means to manipulate this molecule has not been identified. Therefore, it is uncertain at this time what influence increased production of NO would have on cardiovascular functioning and/or resistance to local muscle fatigue. Nitric oxide is synthesized in endothelial cells from arginine via enzymatic action of endothelium nitric oxide synthase. This molecule diffuses easily into the vascular smooth muscle where it binds to the enzyme guanylyl cyclase, which in turn catalyzes the phosphorylation of gunaosine-5-triphosphate (GTP) into cyclic gyanosine monophosphate (cGMP). Cyclic GMP serves as an important second messenger for many physiological functions, including relaxation of smooth vascular muscle. The amino acid, arginine, acts as a precursor to NO synthesis. Due to this role, a significant nutritional supplement market has developed for arginine-based products which supposedly enhance the production of NO.