tokens: The subcutaneous injection of isoproterenol ( 30 mg / kg ) into rats twice at an interval of 24 h , for two consecutive days , led to a significant increase in serum lactate dehydrogenase , creatine phosphokinase , alanine transaminase , aspartate transaminase , and angiotensin - converting enzyme activities , total cholesterol , triglycerides , free serum fatty acid , cardiac tissue malondialdehyde ( MDA ) , and nitric oxide levels and a significant decrease in levels of glutathione and superoxide dismutase in cardiac tissue as compared to the normal control group ( P < 0 . 05 ) .