EFFECTS OF EXERCISE ON THE METABOLISM OF NAD IN RATS

We investigated how much exercise affects the content of NAD when anim als were forced to saim until exhausted, because NAD is involved in th e re-production of ATP from ADP and inorganic phosphate. The content o f NAD in blood decreased when rats swam to fatigue. The degree of the decrease was not related to the training periods. This means that the decreased NAD by exercise was restored during rest. In fact, when rats had swum and then took a rest the next day, the blood NAD content was not different between the exercise and control group. The marginal sw imming period of rats was elongated by an intraperitoneal injection of nicotinamide, which is a precursor of NAD. A similar phenomenon was a lso observed in mice. These data showed NAD is important in continuing exercise.