PERMEABILITY OF RAT LIVER MITOCHONDRIA TO ALPHA-KETOGLUTARATE ANTIPYRINE AND CARNITINE

The study of the permeability of rat liver mitochondria under conditions supporting oxidative phosphorylation compares the uptake of 14C-labeled α-ketoglutarate, antipyrine and carnitine by mitochondria incubated briefly at 0 ° and those incubated up to 90 min at 30 ° Uptake is measured in pellets produced by centrifugation in the cold. The α-ketoglutarate was incubated in the presence of malonate with mitochondria in which oxygen consumption was followed with an oxygen electrode. Less than 4% of the isotope equivalent to the amount of substrate oxidized remains with the unwashed pellets. Antipyrine uptake appears to be the same at 0 ° and at 30 °, and is greater than would be predicted if simple diffusion were responsible; adsorption to the mitochondrial membranes is indicated. The uptake of carnitine is enhanced at the higher temperature and is greater in mitochondria carrying out oxidative phosphorylation than in those suspended in 0.25 m sucrose. The extent to which these compounds can be removed from the pellets by washing with isotonic sucrose varies. © 1969.