Fig. 1.
Chemical structures of endogenous agonist 5-HT, 5-HT3 receptor antagonists granisetron, tropisetron and SDZ-ICT 322, scopolamine, atropine and the radioligand [3H]N-methylscopolamine. Note that scopolamine is a single enantiomer whereas atropine is a mixture of epimers at the indicated (asterisk) carbon atom.