Response of oxidative phosphorylation in liver of protein-energy malnourished rats

State 3, state 4 respiratory rates, respiratory control ratio (RCR = state 3/state 4), ADP/O ratio and swelling in salt medium were determined in liver mitochondria from three groups of rats: group 1--controls; group 2--energy-restricted, and group 3--protein-deficient. Experiments were carried out between 3 and 5 weeks and between 7 and 9 weeks after initiation of the experimental diets. State 3 respiration of mitochondria from group 2 rats was reduced after 3-5 weeks on the experimental diet as compared to group 1 rats. However, state 4 respiration, RCR and ADP/O ratio were not different in groups 2 and 3 as compared to those in controls. Between 7 and 9 weeks it was found that state 3 respiration with both the substrates was higher in groups 2 and 3 as compared to group 1. State 4 respiration was increased in group 2 but was unaltered in group 3, compared to controls. Mitochondrial preparations from group 2 rats showed faster rates of swelling in KC1 medium, compared to group 1, at both periods. On the other hand, the rates of swelling were slower as compared to controls in the case of mitochondria isolated from group 3 rats. Results of these experiments indicate that the terminal effect of severe restriction of calories and protein on mitochondrial oxidative phosphorylation is similar.