Alterations of lactate dehydrogenase isoenzymes with subacute adriamycin toxicity

Single doses of Adriamycin (ADR) and isoproterenol in CDF rats produce significant increases in total serum lactate dehydrogenase (LDH) activity, LDH isoenzymes, and LDH-1/LDH-2 ratio. Isoproterenol produced significant increases in LDH-1, LDH-2, and LDH-3 and the LDH-1/LDH-2 ratio; ADR produced significant increases in all isoenzymes, reflecting widespread toxicity, with peak levels of total LDH, LDH isoenzymes, and LDH-1/LDH-2 ratio at 48 hours after injection. While the increased LDH-1/LDH-2 ratio may suggest myocardial leakage with ADR administration, the results are too nonspecific to conclude that the heart is the primary source of serum LDH-1 and LDH-2.