Consequences of long-term hypokinesia as compared to mild exercise in lipid metabolism of the heart, skeletal muscle and adipose tissue

Summary

Two age groups of Wistar male rats (90 and 150 days) subdivided according to motor activity regime (restriction of activity in chambers 8×12×20 cm since weaning; controls; 3 hrs lasting daily exercise of medium intensity on a motor-driven treadmill) were followed. Percent body fat and body weight were lowest in the exercised animals in spite of relatively highest caloric intake, which was, on the other hand, lowest in the hypokinetic animals which had the same weight and body fat as controls. Free fatty acid level and inflow-outflow rate of injected palmitate-¹⁴C ascertained at rest was significantly lowest in hypokinetic animals. The inflow of palmitate-¹⁴C was always higher to the adipose tissue and lower to the soleus, resp. heart muscles in hypokinetic rats; the reverse applied to the exercised rats in which a higher proportion of palmitate-¹⁴C was distributed to the soleus and heart muscles even at rest. The inflow of palmitate-¹⁴C to the soleus and heart muscles of the hypokinetic animals was significantly lower than to soleus and heart muscles of the exercised animals; the reverse results were found in the adipose tissue. Adaptive changes in lipid metabolism due to long-term hypokinesia and/or exercise were obviously permanent and manifested therefore even without work-load, causing inter alia final characteristic changes in fat deposition in spite of correspondingly modified regulation of food intake.