POSSIBLE MECHANISM OF CARDIAC DEPRESSANT ACTIVITY OF BERBERIS ORTHOBOTRYS ROOTS IN ISOLATED RABBIT HEART

Berberis orthobotrys Bien. ex Aitch. (B.o.) has been reported to have antihypertensive effect in dif- ferent experimental models. The aim of present study was to evaluate the possible antihypertensive mechanism. Aqueous methanolic extract of B.o. roots and its various fractions namely (ethyl acetate, n-butanol or aqueous) in different concentrations (10 ng/mL, 100 ng/mL, 1 µg/mL, 10 µg/mL, 100 µg/mL ) were evaluated in isolat- ed perfused rabbit heart to assess their effect on force of contraction, HR and perfusion pressure. The crude extract of B.o. and its fractions exhibited a significant decrease in heart rate, contractility and perfusion pres- sure of isolated rabbit heart, however, butanolic fraction produced more prominent effect and was selected for further study. The effects of butanol fraction were not blocked by atropine (10 -5 M) in isolated perfused heart. However, butanol fraction significantly blocked the effects of adrenaline (10 -5 M). It is therefore conceivable that cardiac depressant activity of B.o. butanol fraction might be due to the presence of certain β-blocking agents which might be responsible for antihypertensive effect However, further experiments are required to iso- late the active compound(s) and elucidate exact mechanism of action.