Alcohol consumption in rats: effects on work capacity in the heat.

To quantitate the effects of ingestion of ethanol (EtOH)-water mixtures on the ability to work in the heat (35 degrees C), adult male rats (250-350 g) were given 0, 4, 8, 12, or 16% EtOH as the sole source of drinking water for 14 days. The endurance capacity (treadmill time) of rats drinking 4% EtOH was similar to that of rats consuming water (32 vs. 32.9 min, respectively). However, the treadmill time of rats drinking of 16% EtOH was significantly (P less than 0.05) reduced when compared with that of animals drinking 4 or 8% EtOH. Maximal rectal and skin temperatures were likewise lower in the group consuming 16% EtOH, whereas increments in rectal and skin temperatures during treadmill exercise were unaffected. Although hematocrit and plasma protein levels were unaltered, plasma levels of the commonly reported indices of heat-exercise injury were exacerbated by consumption of increasing concentrations of EtOH. We concluded that ingestion of EtOH for 2 wk had minimal effects on thermoregulation and that the decrements in work capacity noted were probably the result of alterations in hepatic and muscle metabolism.