Effect of hypoenergetic feeding and refeeding on muscle and mononuclear cell activities of mitochondrial complexes I-IV in enterally fed rats

Background: Previous studies suggested that cell energetics are altered by malnutrition, Objective: We hypothesized that nutritional manipulations influence mitocho ndrial enzyme activities of the electron transport chain in both skeletal m uscle and blued mononuclear cells. Design: After a gastrostomy tube was inserted, 44 rats were randomly assign ed to 1 of 4 experimental groups: control fed (CF; 363 kJ/d for 7 d), hypoe nergetic fed (HF; 92 kJ/d fur 7 d), hypoenergetic protein refed (HPR; 92 kJ /d fur 7 d and then 19 kJ/d fur 1 d), and hypoenergetic glucose refed (HGR; 92 kJ/d for 7 d and then 129 kJ/d fur 1 d), The protein and glucose conten ts of the liquid formulas were different for the HPR and HGR groups. After mitochondria were isolated From the soleus muscle, the activities of comple xes I-IV were measured spectrophotometrically. Because of the lack of avail able tissue, only the activity of complex T was measured in the mononuclear cell extract. Results: The recovery of complex activities in the CF and HF groups was not significantly different in the mitochondrial fraction of the soleus muscle . Compared with that in the CF group, the activities of complexes I-III in the mitochondrial fraction of the soleus muscle and the activity of complex I in mononuclear cells were significantly lower in the HF group. The activ ities of complexes I-III in the mitochondrial fraction of the soleus muscle and the activity of complex I in mononuclear sells were significantly high er in the HPR than in the HF group. The activity of complex IV was generall y not affected by nutritional manipulations. Conclusion: Malnutrition, decreases activities of mitochondrial complexes, which are restored by protein bur not glucose refeeding.