Beta-agonists enhance the lactic dehydrogenase (LDH) expression in serum and ventricular myocytes of mice.

Beta-agonists have skeletal muscle specific protein anabolic effects and are also known to cause cardiac hypertrophy. Changed total LDH and its isozymic patterns are conveniently employed for the detection of different pathophysiological states of the tissues. The purpose of this study is to confirm total LDH and its isozymic expression in ventricular tissue and serum in mice following oral administration of single but higher dose of isoproterenol (Iso) and clenbuterol (Cl) (100 mg/kg body wt. and 20 mg/kg body wt., respectively), after 4, 8 and 20 hours of drug administration. Mice heart witnessed increased total LDH levels with time. Serum on the other hand showed decline in total LDH concentrations at the initial points of the drug treatment. No doubt, total LDH expression increased towards 20th h post-drug treatment but this increase is mainly due to anaerobic isozymes, i.e. LDH4 and LDH5. The findings of the present study suggest that tissue damage is definitely caused by two beta-agonists after giving single dose for shorter time span (20 hours) and the impact of the damage varies from drug to drug. Increase in total LDH in serum is not due to release from heart but from some other tissues having anaerobic metabolism.