Lack of anticholinergic activity by baicalin in the isolated trachea of guinea pig.

The anticholinergic effect of baicalin on the trachea from asthmatic guinea pig had been described elsewhere. Using 1 x 10(-5) M bethanechol to induce contraction in the isolated trachea from non-asthmatic guinea pig, baicalin below 1 x 10(-4) M was unable to attenuate the bethanechol-induced tracheal contraction; however, 1 x 10(-4) M baicalin was demonstrated to increase the tracheal contraction in the presence of bethanechol. Baicalin (1 x 10(-4) M) was also able to induce tracheal contraction in the absence of bethanechol, and this baicalin-induced tracheal contraction was shown to be atropine-sensitive. These data suggested that the baicalin effect on the isolated trachea from non-asthmatic guinea pig was not anticholinergic in nature.