ROLE OF PHOSPHOLIPIDS IN MITOCHONDRIAL RESPIRATION

Abstract

The addition of heated snake venom solutions to suspensions of rat liver, kidney, or brain mitochondria results in an initial stimulation of the rate of respiration, which is approximately the same for a variety of substrates, followed by a rapid decline.The presence of phospholipase A in heated snake venom is demonstrated by the formation of lysolecithin from mitochondrial lecithin. Various phospholipids, when added to mitochondria, have a protective influence against the inhibitory effects of phospholipase of heated venoms on respiration. Clostridium welchii toxin, which contains phospholipase C, has an effect on mitochondrial respiration which is similar to that of venom phospholipase A but the addition of phospholipid has no protective effect.Glutathione exercises a protective action against the inhibitory effects of phospholipase A on rat liver or kidney mitochondrial respiration, the action consisting of a prolongation of the initial stimulated phase of respiration. The effect does not seem to obtain with rat brain mitochondria.Exposure of rat brain cortex slices, but not those of rat kidney or liver, to heated venom results in changes of respiratory rates similar to those obtained with brain mitochondria.