Fluid replacement needs of well-trained male and female athletes during indoor and outdoor steady state running.

Twelve male and six female well-trained middle distance athletes performed a series of six one hour runs at 75% VO2 peak pace under similar environmental states indoors (treadmill) and outdoors (track). Running was undertaken in control (C, no fluid), followed by water (W) and sports drink (SD) treatments, with each run separated by a one week interval. Both fluid treatments were supplied in volumes equivalent to individual body mass (fluid) losses incurred in the respective indoor and outdoor C treatments.

Interaction of 5-hydroxykynurenamine, L-kynurenine and kynuramine with multiple serotonin receptors in smooth muscle.

The enzymatic formation of kynurenine derivatives from tryptophan and the regulation of this metabolic pathway by both tryptophan concentrations and plasma cortisol concentrations have raised the possibility that the kynurenine derivatives, L-kynurenine, kynuramine and 5-hydroxykynurenamine (5-OH-kynurenamine) may be important as endogenous agonists or antagonists at serotonin (5-HT) receptors in smooth muscle. In fact, 5-OH-kynurenamine was an agonist at 5-HT2 receptors in the rat jugular vein and aorta, at 5-HT3 (neuronal "M") receptors in the guinea pig ileum and at 5-HT receptors in the rat stomach fundus. Maximal contractile responses to 5-OH-kynurenamine in these three smooth muscle preparations were similar to those produced by 5-HT, although 5-OH-kynurenamine was approximately 10- to 100-fold less potent than 5-HT as a contractile agonist.