Abstract
Untrained healthy male volunteers were studied to observe the effects of muscular exercise (bicycle ergometer, 920kpm/min for 15min and 30min) on the levels of carbonic anhydrase B (CA-B) and C (CA-C) isozymes and 2, 3-diphosphoglycerate (2, 3-DPG) in the blood. Significant decreases in the levels of CA-B and total esterase activity were observed after 15min and 30min of exercise, but the level of CA-C did not vary much. The level of 2, 3-DPG increased after 30min of exercise. Positive correlations were observed between the levels of CA-B and total esterase activity after each exercise (r=0.675, 0.619). The decrease in total esterase activity is caused by the decrease in CA-B. The mean value of 2, 3-DPG after exercise increased to 19.3per cent after 30min of exercise. This indicates that the magnitude of increase in 2, 3-DPG was sufficient to shift the oxygen dissociation curve to the right. A negative correlation was found between the levels of CA-B and 2, 3-DPG after 30min of exercise (r=-0, 618), but no significant correlation was found after 15min of exercise. The blood lactate-pyruvate ratio increased above the pre-exercise values after 15min, but not after 30min of exercise. After 30min of exercise the increase in lactate concentration and the change in 2, 3-DPG showed good correlation (r=0.667). These observations suggest that the decrease in CA-B plays a part in the combination of 2, 3-DPG and deoxyhemoglobin under hypoxic conditions, and that enhancement of oxygen delivery through an increase in 2, 3-DPG is important for adequate homeostatic adjustment to prolonged exercise.
