Subcellular distribution of LDH isoenzymes in neuronal- and glial-enriched fractions

The LDH isoenzymes of cell organelles (nuclei, mitochondria, microsomes, cytosol) obtained from neuronal- and glial-enriched fractions were determined by disc polyacrylamide electrophoresis and stained for enzyme activity. The quantitative estimation was made either by elution of isoenzymes or by densitometric measurements. The neuronal fraction was found to contain mainly H forms of LDH. The glial fraction also contained H forms but its M/H ratio was higher than that of the neuronal fraction. The cell organelles displayed some specificities with respect to the LDH isoenzymes distribution. The nuclei contained mainly M forms, the mitochondria H forms and the glial microsomal fraction M forms. It is suggested that the different LDH isoenzymes are related to the specific function of the different cell organelles.