The Effects of Acute Exercise on Renal Energy Metabolism in Rats

We assessed the effects of treadmill exercise on the renal arterial blood flow and the renal energy metabolism in both fed and starved rats. Male Wistar rats were randomly assigned to one of four groups. The first group did treadmill running on fed condition (fed-EX (+) group). The second group did no treadmill running on fed condition (fed-EX (-) group). The third group did treadmill running after fasting for 24 hours (starved-EX (+) group). The fourth group did no treadmill running after fasting for 24 hours (starved-EX (-) group). Treadmill running was done with 30m/min, grade 0 for 30 minutes. Immediately after the exercise, renal arterial blood flow was measured using an electromagnetic flowmeter. Afterwards, blood samples were collected from both abdominal aorta and renal vein for the measurement of concentrations of glucose, lactate, pyruvate, free fatty acid and immunoreactive insulin. The kidneys were removed for the determination of the contents of lactate, pyruvate and adenine nucleotides. Renal arterial blood flow, the atriovenous difference of the concentration of glucose, and the renal uptake of glucose in both fed-EX (+) and starved-EX (+) groups were significantly lower than those of both fed-EX (-) and starved-EX (-) groups. Renal content of adenosine triphosphate in the fed-EX (+) group was lower than that of the fed-EX (-) group. Meanwhile, the arteriovenous difference of the concentration of the free fatty acid, and renal uptake of the free fatty acid both in the fed-EX (+) and starved-EX (+) groups were significantly higher than those of both fed-EX (-) and starved-EX (-) groups. Renal content of pyruvate, the ATP/ADP ratio, and the energy charge in the starved-EX (+) group were significantly higher than those of the starved-EX (-) group. There was no significant difference in the concentration of immunoreactive insulin among the 4 groups. These results suggest that aerobic exercise after a meal may not give good influence to the renal energy metabolism, and suggest that aerobic exercise before a meal may not be harmful to the renal energy metabolism.