Effect of Rate of Heat Gain on Selected Serum Enzymes in Rhesus Monkeys

Cell membrane leakage of sodium and potassium ions results in an energy drain at the cellular level as active transport activity must increase to maintain the membrane potential. This membrane permeability increases as body temperature rises, a result of an increase in the kinetic energy of the ions. Thermal stress and the resultant increased cell membrane permeability poses a challenge to the cell to maintain homeostasis and may contribute to fatigue during physical exertion. Ultimately, the work capacity of an individual may be limited by this cellular energy drain. Hubbard suggests that the rate of heat gain plays a significant role in the energy drain at the cellular level as membrane permeability increases dramatically with faster rates of heat storage. This relationship is described as part of the Energy Depletion Model developed by Hubbard et al. (4) and has been examined in the rat model by both Hubbard at el. and Manjoo et al.