Abstract
We compared the effects of the extract from fruits of Nandina domestica THUNBERG (NDE) and its constituents, higenamine and nantenine, on contractile responses in isolated guinea-pig trachea. NDE (1 mg/ml) caused biphasic relaxation of the trachea precontracted with high-K+ stimulation: the fast component was blocked by propranolol and mimicked by higenamine; and the slow was resistant to propranolol and mimicked by nantenine. Ca2+-induced contraction under high-K+ stimulation was antagonized by nantenine or NDE + propranolol. These results suggest that NDE relaxes the trachea quickly through β-adrenoceptor stimulation by higenamine and slowly through Ca2+ antagonism by nantenine.
