Alterations in Myocardial Creatinine Kinase (CK) and Lactate Dehydrogenase (LDH) Isoenzyme-Distribution in a Model of Left Ventricular Dysfunction

The purpose of the current study was to evaluate myocardial creatinine kinase (CK) and lactate dehydrogenase (LDH) systems in a model of epinephrine-induced cardiomyopathy in rabbits. Eight rabbits received four repetitive epinephrine infusions (300 mg/kg/60 min, i.v.) in 12-day intervals and eight untreated rabbits served as controls (CTRL). Echocardiography demonstrated a significant deterioration of LV function as well as increased LV-diameter and -mass index in catecholamine-induced cardiomyopathy. Histological examination revealed that repetitive catecholamine infusion resulted in LV fibrous areas with collagenous content and an increase in myocyte width (16.9+/-0.8 microm vs. CTRL 12.9+/-0.9; P<0.05). LV dysfunction was associated with a decreased total LV lactate dehydrogenase activity (LDH; 0.43+/-0.03 IU/mg protein vs. CTRL 0.52+/-0.04; P<0.05) whereas total creatinine kinase activity was unchanged (CK; 7.30+/-0.63 IU/mg protein vs. CTRL 9.20+/-0.49, n.s.). Furthermore, myocardial LDH isoenzymes were shifted with a decrease in LDH(1) and an increase in LDH2 and LDH3 (LDH(1): 84.90+/-2.60% vs. CTRL 94.50+/-0.40; LDH2: 7.30+/-1.20% vs. 1.50+/-0.13; LDH3: 5.40+/-0.90% vs. 3.20+/-0.25; all P<0.05). Foetal B-CK isoenzymes were significantly increased (CK-MB 5.30+/-0.66 vs. 2.20+/-0.35%; P<0.05). The current study demonstrates changes in cardiac energy metabolism including an impaired LDH activity with a shift towards anaerobic isoenzymes as well as a more efficient CK system in a model of catecholamine-induced LV dysfunction.