PHYSIOLOGICAL-RESPONSES OF RHESUS-MONKEYS TO EXERCISE AT VARIED TEMPERATURES

This research characterizes the effects of selected physiological stre ssors such as work and various environmental heat loads in rhesus monk eys, Non-human primates (N = 6) were behaviorally conditioned to exerc ise in ct wheel ergometer at approximate to 3 METs (1 MET = 3.5 ml O-2 , uptake kg(-1).min(-1)). On separate days, each monkey attempted six work/rest cycles (10 min work: 1 min rest) at 15, 25, and 35 degrees C (Tdb), vapor pressure < 10 mm Hg. Core temperature (Tco), body weight (BW) and blood samples were taken immediately before and after exerci se. Excessively high heat storage rates dictated that the 35 degrees C trial he limited to three work/rest bouts, The change in Tco during e xercise was significantly greater in the 35 degrees C trial than durin g the 15 and 25 degrees C work bouts. Sweat rate, as determined by the change in BW over time, was also significantly greater during the 35 degrees C trial as compared to the IS and 25 degrees C trials, Glucose levels (mean +/- SE) declined significantly during exercise from 4.35 +/- 0.1 and 4.58 +/- 0.4 mmol to surprisingly low levels of 1.67 +/- 0.2 and 1.76 +/- 0.2 mmol in the 15 and 25 degrees C trials, respectiv ely. increases in blood lactate, glycerol, and triglycerides were obse rved independent of environmental temperature, Free fatty acids increa sed during exercise in the 15 and 25 degrees C trials but declined sli ghtly during the shorter 35 degrees C trial. The findings of this stud y indicate that the increased heat storage observed at higher environm ental heat loads appears to substantially limit the amount of work the se primates can perform, possibly the result of a limited sweat produc tion capacity, Additionally, plasma glucose following exercise decreas ed to levels not typically seen in humans, The general metabolic profi le in these primates was otherwise similar to that observed in humans at this work level.