Myocardial lactate dehydrogenase isoenzyme distribution in the normal heart.

The isoenzyme pattern of the lactate-dehydrogenase (LDH) in different parts of the heart was measured by micro-isoelectric focusing. Samples were taken from the right and left auricle, the outer, middle and inner layer of the myocardial wall of both ventricles and from the papillary muscle of the left ventricle. The results show that the activity of LDH total and the isoenzyme pattern are different in the various parts of the heart. In both auricles the isoenzymes LDH 3,4,5 were mostly found, whereas in the ventricles a significant increase of LDH 1,2 could be seen. Additionally, there was a shift in the isoenzyme pattern from the outside to the inner part of the myocardium wall with a significant increase of LDH1.