aminase and uric acid in ISO-treated (100 mg/kg) rats. The increased serum levels of cholesterol, triglyceride, low-density lipoprotein cholesterol and atherogenic index after ISO administration were decreased to nearly nor- mal levels by C oxycantha extract. Pretreatment with C oxycantha in ISO- treated animals produced significant decrease in lipid peroxidation and significant increase in endogenous antioxidant superoxide dismutase, cata- lase and reduced glutathione in myocardial tissue. C oxycantha extract sig- nificantly inhibited Na+-K+ ATPase enzyme present in heart homogenate by virtue of presence of ursolic acid as evidenced by high-performance thin layer chromatography analysis of C oxycantha extract, which may be a possible mechanism of cardiotonic activity of C oxycantha. ConCluSIon: C oxycantha may be viewed as potentially cardiotonic, cardioprotective and antioxidant. ardiovascular disease is considered to be the major cause of mor- bidity and mortality throughout the world. It is a group of disorders of the heart and the vasculature, which includes high blood pressure, coronary artery disease, congestive heart failure (CHF), stroke and congenital heart defects. The term 'CHF' describes the common clini- cal syndrome arising when delivery of oxygen to the metabolizing tissue is impaired because of decreased contractility of heart muscles, particu- larly the left ventricle (LV). The syndrome is characterized by breath- lessness, exercise intolerance and edema. Left ventricular myocardial damage is commonly caused by hypertension and coronary artery dis- ease, usually myocardial infarction. LV dysfunction produces activation of cardiac and peripheral neurohormonal mechanisms that promote fluid retention. Untreated patients with heart failure demonstrate chronic, sustained, neurohormonal activation and show progressive enlargement of the LV with an associated decline in systolic function. However, these neurohormonal pathways are initially compensatory and beneficial, but eventually they are deleterious. In patients with CHF, improvement in myocardial contractility and LV function is the fundamental treatment for survival. Despite the availablity of treat- ments, including diuretics, digitalis, vasodilators and angiotensin- converting enzyme inhibitors, the morbidity and mortality risks of CHF remain high. Digoxin has been the drug of choice for the treatment of CHF due to its positive inotropic effect. The adverse effects of digoxin are cardiac and extracardiac, which include cardiac slowing, reduced conduction through atrioventricular (AV) node, bigeminy, paroxys- mal atrial tachycardia, ventricular arrhythmias, hypokalemia, nau- sea, vomiting and diarrhea. It also possesses a very low therapeutic index; therefore, extreme medical care is needed when a patient is receiving treatment. Crataegus oxycantha is another such plant that has been described by many pharmacopoeias. C oxycantha extract has been traditionally used to treat the early stages of CHF and angina pectoris (1). It has been reported that C oxycantha may increase the myocardium blood supply (2). C oxycantha extract is traditionally used as a cardiotonic in China, India and many European countries; however, to date, very few authentic investigational studies address- ing its cardioprotective use have been performed. Although C oxy- cantha has been shown to improve cardiac function, the exact mechanism of action remains unclear. METHodS Materials