DEPENDENCE ON THE EXTRA-MITOCHONDRIAL ATP - ADP-RATIO OF THE OXIDATIVE-PHOSPHORYLATION IN MITOCHONDRIA ISOLATED BY A NEW PROCEDURE FROM RAT SKELETAL-MUSCLE

Abstract

A simple method for preparation of rat skeletal muscle mitochondria is presented using gentle mechanical homogenization in a syringe and nagarse treatment (EC 3.4.4.16). This method enables the preparation of skeletal muscle mitochondria, whose outer membrane is intact to 95%. With mitochondria prepared by this method the regulation of respiration and phosphorylation by the extramitochondrial ATP/ADP-ratio can be demonstrated. In accordance with rat liver and heart mitochondria and with mitochondria of rabbit reticulocytes, the regulation by the extramitochondrial ATP/ADP-ratio lies in the range from 5 (corresponding to 98% of the maximum respiration) to 100 (corresponding to state 4). At extramitochondrial ATP/ADP-ratios of 0.01-1, the respiration rate is nearly constant (maximum rate of respiration).