U.S. Army Research Institute of Environmental Medicine, Natick, MA 01760-5007, U.S.A.
Abstract:
1. 1.|Dinitrophenol (DNP) was administered to rats in two equal dosages (20 mg/kg, 30 min interval); the second injection was followed immediately by exercise (9.14 m/min) in the heat (30°C) or at room temperature (21°C).
2. 2.|At 21°C control (saline-treated) rats manifested a mean endurance of 94 min which was reduced to 32 min among DNP-treated animals.
3. 3.|At 30°C, control rats ran for 65 min (δTre/min = 0.05°C) while DNP-treated animals had a mean endurance of only 12 min (δTre/min = 0.22°C).
4. 4.|DNP-treated rats (30°C) manifested no decrements in tail-skin heat loss (δTsk/min = 0.17°C vs 0.10°C) or saliva secretion (0.78 g/min, DNP vs. 0.19 g/min, control) for their brief treadmill duration.
5. 5.|The increased metabolic heat production of DNP severely reduced performance.
Author Keywords: Dinitrophenol; exercise; heat stress; endurnace; temperature regulation