Mechanism of the Aortic Relaxation Induced by Low Concentrations of Berberine

Abstract

The mechanism of the aortic relaxation induced by a low concentration of berberine was investigated in rat isolated aorta. It was found that the aortic relaxation induced by berberine below 1 × 10^-6M was solely endothelium dependent. Denuded aorta and methylene blue pretreated aorta did not demonstrate aortic relaxation with such berberine concentrations. Higher concentrations (above 1 × 10^-6M berberine), however, induced aortic relaxation irrespective of the presence of intact endothelium or methylene blue pretreatment. Since methylene blue is known as a direct inhibitor of nitric oxide synthase beside being a nonspecific guanylyl cyclase inhibitor, the present data suggest that the mechanism of the aortic relaxation induced by a low berberine concentration is solely dependent on the presence of endothelium.