Respiration of Isolated Liver Mitochondria from Chickens Fed “Carbohydrate-free” Diets

Abstract
One-day-old chickens were fed either a glucose control diet or diets in which all nonprotein calories were provided by either soybean oil or soybean oil fatty acids. Since feeding these “carbohydrate-free” diets has previously been found to reduce the liver mitochondrial NAD/NADH ratio without altering the ATP/ADP ratio in liver extracts, the possibility was considered that either the rate or efficiency of oxidative phosphorylation in liver mitochondria was adversely affected by feeding these diets. The rates of oxygen uptake per milligram of mitochondrial protein (in the presence and absence of added ADP) and the P/O ratios were measured in isolated mitochondria using either succinate, malate, α-ketoglutarate or citrateas electron donors. These parameters did not change as a function of diet. There was, however, an increase in the rate of NADH oxidation in uncoupled mitochondria when the “carbohydrate-free” diets were fed, and an increase in mitochondrial protein in response to feeding the soybean oil fatty acid diet. It is concluded that the change in the NAD/NADH ratio in liver mitochondria in response to feeding the “carbohydrate-free” diets is not directly attributable to a simple mitochondrial lesion.