Iono- and chronotropic effects of aqueous extract of berberis lycium royle root bark and berberine on in situ frog-heart preparation

Abstract

Berberis lycium Royle is used in folk medicines for treating various ailments however it has not been investigated in cardiac problems at pharmacological level. Here, iono- and chronotropic effects of B. lycium root bark’s aqueous extract and berberine were studied on frog-heart. Present data showed that aqueous extracts of B. lycium and berberine exhibited dose-dependent negative chronotropic and ionotropic effects and at higher doses both caused a heart block. Berberine also displayed a positive ionotropic effect but at very low doses. Diltiazem did not antagonize positive ionotropic effect of berberine indicating that this activity is independent of L-type calcium channels, while propranolol antagonized the positive ionotropic effect, suggesting involvement of β1 - adrenoceptors. It is concluded that ionotropic and chronotropic effects exerted by aqueous extract of B. lycium may be due to berberine while its negative ionotropic actions and heart block may attribute to other active principle(s) present in the extract.