Male Carworth (CFN) rats 5 weeks of age were divided into two groups designated trained (T) and untrained (UT). T rats were subjected to 13 weeks of intensive treadmill running while UT rats remained sedentary. One half of each group received 4 daily subcutaneous injections of cortisol (1.25 mg/100 g) prior to sacrifice. Fat cells were isolated from epididymal adipose tissue following collagenase treatment. Cell size and number and epinephrine sensitive lipase activity (ESL) were determined on identical aliquots of the adipocytes. Adipocyte numbers were similar in epididymal fat pads from T and UT rats (12.7 vs 15.3 x 106); however, T rats had smaller fat pads containing smaller cells than UT rats (67 vs 86 μ diameter). Adipocytes from T rats possessed greater ESL than those from UT rats. Cortisol administration was without effect on ESL in both T and UT rats. The results of this study indicate that exercise training increases the potential of adipose tissue to release free fatty acids in response to epinephrine stimulation. This adaptation appears to involve factors other than, or in addition to, the effect of exercise on plasma glucocorticoid titer reported in a previous study. Exercise training was not effective in significantly reducing epididymal fat pad cell numbers when initiated at 5 weeks of age, but did decrease cell size.
|Original language||English (US)|
|Number of pages||1|
|Issue number||3 (I)|
|State||Published - Jan 1 1973|
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