Effect of voluntary exercise on urinary excretion of catecholamines after traumatic shock in rats

Thirteen rats were kept in cages equipped with running wheels for 10 months (exercise group), and 12 rats were kept in cages without running wheels during the same period (control group). Rats in both groups were subjected to a Noble-Collip drum trauma (40 rpm, 350 revolutions in total) after the 10-month conditioning period. Urine output, urinary epinephrine (E), and norepinephrine (NE) were measured until the seventh day after the trauma. Urine output decreased after the trauma in both groups to the same extent, but the recovery of urine output after trauma was accomplished faster in the exercise group than in the control group, and diuresis after trauma was seen only in the exercise group. Urinary E increased in both groups within 24 hours after trauma, but the increase in the exercise group was significantly less than in the control group. The amount of NE excreted depended somewhat on the urine volume, but there was no significant difference in changes in urinary NE after trauma between the groups. These results suggest that rats bred in an active condition suffered less severe traumatic shock accompanied by a reduced sympathoadrenal activity as compared with rats bred in a relatively sedentary condition.