PYRIDOSTIGMINE BROMIDE DOES NOT ALTER THERMOREGULATION DURING EXERCISE IN COLD-AIR

This study examined the effects of acute and chronic pyridostigmine br omide (PB) administration on thermoregulatory and metabolic responses to exercise in cold air (5 degrees C). Seven healthy men completed two 7-day trials in a double-blind, crossover experimental design: during one trial they received PB (30 mg three times daily) and during the o ther trial they received placebo. For each trial, subjects attempted f our (3 h) exercise tests: low-intensity exercise (similar to 25% VO(2) max) and moderate-intensity exercise (similar to 50% VO(2)max), on day s 2 and 3 and again on days 6 and 7. Metabolic rate, body temperatures , and venous blood samples were obtained before and during exercise. R ed blood cell acetylcholinesterase inhibition induced by PB increased (p < 0.05) from 34% on day 1 to 43% on days 3-7. Metabolic rate, body temperatures, and regional heat conductance responses were not differe nt between trials. Plasma glucose, glycerol, free fatty acid, lactate, sodium, and potassium concentrations were not different between trial s. In addition, differences were not found between acute and chronic e xperiments for any thermoregulatory or metabolic responses. These find ings demonstrate that the PB dosage used by military personnel, as a p harmacological defense against nerve-agent poisoning, should not cause any adverse thermoregulatory or metabolic effects during moderate act ivity in cold climates.