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.
