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Malathion administration: effects on physiological and physical performance in the heat
Pharmacology, Biochemistry, and Behavior
|December 1, 1983
Summary
Low-dose malathion did not impair exercise performance or thermoregulation in rats exposed to heat. Organophosphate exposure did not worsen physiological responses to heat stress during treadmill exercise.
Area of Science:
- Environmental Physiology
- Toxicology
- Exercise Science
Background:
- Organophosphate pesticides can inhibit cholinesterase, an enzyme crucial for nerve function.
- Exercise in hot environments poses significant physiological challenges, including heat stress.
Purpose of the Study:
- To investigate the impact of low-dose organophosphate (malathion) exposure on physiological and thermoregulatory responses during exercise in a hot environment.
Main Methods:
- Rats were administered malathion (7.5 mg/day for 4 days) or a placebo.
- Animals underwent treadmill exercise at 9.14 m/min in a 35°C environment until hyperthermic exhaustion (core temperature ~43°C).
- Plasma cholinesterase, creatine phosphokinase, lactate dehydrogenase, lactate, potassium, urea nitrogen, and creatinine levels were measured. Skin temperature and heat gain rates were also assessed.
Main Results:
- Malathion administration significantly reduced plasma cholinesterase levels by 35%.
- Treadmill endurance and rates of heat gain were not significantly affected by malathion treatment.
- Malathion-treated rats showed slightly higher skin temperatures during exercise.
- Exercise in heat increased lactate dehydrogenase, lactate, potassium, urea nitrogen, and creatinine, but these changes were not exacerbated by malathion.
Conclusions:
- Low-dose malathion exposure did not adversely affect exercise performance or thermoregulatory efficacy in rats during heat stress.
- The findings suggest that moderate cholinesterase inhibition does not compromise physiological responses to exercise in a hot environment at this exposure level.