The effect of heat, cold, and work on the central actions of scopolamine

Forty-eight healthy male volunteers were tested in drug-alone (D), drug-and-work (D-and-W), and work-alone (W) groups at 40°, 70°, 85°, and 95° F. and in a drug-alone group at 105° F, to measure the separate and combined effects of work and temperature stress oil the central actions of scopolamine hydrobromide. The dose of scopolamine was the same for all drugged men, 10 mg. per kilogram. The degree o f work (walking a 10 per cent inclined treadmill at 3 miles per hour for 2 hours) was also the same for all subjects tested under stress. Performance and rating tests were used to measure memory function, behavioral variations, attention, and manual dexterity. Major findings were as follows: Mental and motor impairments induced by a low deliriant dose of scopolamine were significantly increased in ambient temperatures of 95° F. and 105° F.; work increased the psychotonrimetic effects of scopolamine only at 95° F. (the highest temperature tested with drug-and-work group); an initial 90 minute period o f elevated ambient temperature (105° F.) was decisive for the accentuation o f the central effects o f scopolamine. It was also noted that the increase in peripheral blood flow caused by scopolamine was most apparent at temperature extremes and that the central effects of the heat-drug stress showed no relationship to body temperature.