Studies on the Energy Metabolism of Human Leukocytes

Abstract

Abstract 1. Oxidative phosphorylation has been studied in mitochondrial preparations from human leukocytes, using recently developed methods for homogenization, measuring respiration, and assaying for ATP. 2. Appreciable stimulation of both respiration and phosphorylation was limited to 3 substrates: succinate, malate, and α-glycerophosphate. The effects of other substrates were minimal. 3. The stimulating effects of these 3 substrates responded to inhibitors in a manner typical of mitochondrial oxidative phosphorylation. There was also considerable endogenous activity which, however, was insensitive to inhibitors. It is concluded the endogenous respiration and phosphorylation are not associated with electron transport. Subtracting their values from the data, P/O ratios consistent with good phosphorylation with the 3 substrates are obtained. 4. Studies with oligomycin and dinitrophenol suggest the presence of respiratory control. This indicates the mitochondria are intact. It is concluded that in the intact leukocyte the mitochondria are a major source of ATP.