Temperature dependence of human gastrocnemius pH and high-energy phosphateconcentration by noninvasive techniques

It is well established that ADP is an important regulator of the oxidative phosphorylation in the mitochondria. Thus, by means of noninvasive techniqu es it is demonstrated that the relationship between O-2 consumption of the human gastrocnemius at rest and its temperature is likely determined by at least two factors: 1) the modulation of the rate of the chemical reactions imposed by the "physical" temperature-effect; 2) the influence of temperatu re-induced ADP concentration changes (similar to 0.83 mu M degrees C-1) on oxidative phosphorylation. ADP was assessed by applying the temperature-cor rected Lohmann equilibrium equation. PCr and ATP were found to increase, wi th decreasing temperature (-0.54 +/- 0.05 and -0.17 +/- mM degrees C-1, res pectively), while pH varies following the or-slat hypothesis (-0.016 +/- 0. 001 pH degrees C-1). These findings should be of value when dealing with mu scle physiology in extreme environments or clinical applications of hypothe rmia. (C) 2000 Wiley-Liss, Inc.