ULTRASTRUCTURAL LOCALIZATION OF GLUTAMIC OXALACETIC TRANSAMINASE ACTIVITY IN CARDIAC MUSCLE FIBER AND CARDIAC MITOCHONDRIAL FRACTION OF RAT

The ventricular heart muscle of the rat was fixed in glutaraldehyde-formaldehyde mixture. The tissue blocks were incubated in a medium containing 20 mM 1-aspartic acid, 2 mM α-ketoglutaric acid and 6 mM lead nitrate as major ingredients. The enzymatic reaction product due to glutamic oxalacetic transaminase (GOT) activity was found to be localized in the cristae and at the surface of the mitochondria, in the cisternae of the nuclear envelope and in the sarcoplasmic reticulum. Isolation of the mitochondrial fraction from the homogenate of the fixed heart muscle was performed, and GOT activity in this fraction was demonstrated both histochemically and biochemically. © 1969 Springer-Verlag.