L-Hyoscyamine (Daturine) functions as a non-selective, competitive antagonist of muscarinic receptors, thereby inhibiting the parasympathetic activities of acetylcholine on the salivary, bronchial, and sweat glands, as well as the eye, heart, bladder, and gastrointestinal tract. Hyoscyamine is a belladonna alkaloid derivative and the levorotatory form of racemic atropine isolated from the plants Hyoscyamus niger or Atropa belladonna, which exhibits anticholinergic activity. These inhibitory effects cause a decrease in saliva, bronchial mucus, gastric juices, and sweat. Furthermore, its inhibitory action on smooth muscle prevents bladder contraction and decreases gastrointestinal motility.

AChR:7.5 nM

在清醒大鼠体内,L-hyoscyamine（20 mg/kg）使移行性肌电复合波循环周期从17.6 min延长到29.0 min.

在CHO细胞中,L-hyoscyamine防止兴奋剂诱导的cAMP产生（EC50：7.8 nM）。在小鼠心脏(心房和心室)膜中,S-(-)-hyoscyamine增强24%的毛喉素刺激的环AMP合成。 R-(+)-hyoscyamine使[3H]NMS与毒蕈碱乙酰胆碱受体亚型(m1-m5)结合,pKi值分别8.67,8.51,7.46,8.56和8.53。在稳态动力学测量中,L-hyoscyamine使TPase活性的转化数从0.19/min增加到2.11/min。