Abstract

Oxidation of lactate at rest (RE, n = 4), or after short strenuous exercise (EX, n = 6) was investigated in rats. Food and water were given ad libitum before experiment. In EX, rats ran to exhaustion at the speed of 80-100 m/min. Immediately after exercise, lactate was injected into aorta through an indwelling catheter. In RE, lactate was injected into the rats at rest. Expired gas was collected by a Brooks type bottomless chamber on treadmill belt for 120 min. n EX, exercise duration was 109 +/- 18 sec (mean +/- SE), and maximum blood lactate concentration after the exercise was 23.7 +/- 2.1 mM (mean +/- SE). Cumulative percent recovery of 14C as 14CO2 for 120 min was 48.5 +/- 2.8 for Ex and 61.7 +/- 0.9 for RE (mean +/- SE). Significant difference was found between these two rates. After 50 min of recovery, mean volume of 14CO2 expired per min in RE was significantly greater than that in EX. Mean volume of 14CO2 expired per min per VCO2 in RE was always greater than that in EX, and significant difference was found at 7.5 min of recovery. It is concluded that although the rate of recovery of 14C as 14CO2 after exercise is lower than that at rest, the major pathway of lactate metabolism after short strenuous exercise is oxidation. Verf.-Referat