AJP - Cell Physiology, Vol 234, Issue 1 1-C6, Copyright © 1978 by American Physiological Society
Characterization of frog muscle mitochondria
C. Skoog, U. Kromer, R. W. Mitchell, J. Hoogstraten and N. L. Stephens
Studies on oxidative phosphorylation revealed that, in frog skeletal muscle
mitochondria (SKMM) from the thigh, the adenosine diphosphate/oxygen ratio
(ADP/O) was 2.8 +/- 0.1 SE, and the respiratory control ratio was 9.5 +/-
0.9, with pyruvate/malate as the substrate. Oxygen uptake rate (Qo2) was
225 mumol O2 per minute per gram mitochondrial protein +/- 13;
phosphorylation rate (ADP/O X Qo2 X 2) was 1,230 mumol ADP phosphorylation
per minute per gram mitochondrial protein +/- 77; and the phosphorylation
capacity (phosphorylation rate times tissue mitochondrial protein content)
was 3.6 mumol ADP phosphorylated per gram wet weight of muscle +/- 0.2.
Tissue mitochondrial protein content was determined by the measurement of
nicotinamide adenine dinucleotide (NADH) oxidase activity. Electron
microscopy (EM) revealed intact, isolated, energized twisted mitochondria
of a condensed form. Frog sartorius muscle mitochondria gave similar
oxidative phosphorylation parameters when investigated independently of the
rest of the thigh. These values of SKMM respiration from the frog are
similar to those values obtained from pigeon and rabbit heart and rat
skeletal muscles. However, because of the low NADH-oxidase activity
indicating reduced mitochondrial content (this was verified in
low-magnification EM pictures), phosphorylation capacity was significantly
reduced in frog skeletal muscle mitochondria.
