| Abstract: | The tricyclic antidepressant irniprarnine is widely utilized in treating a number of the disorders of micturition. Its effect on urinary tract smooth muscle is believed to occur through several mechanisms including direct antimuscarinic activity, direct smooth muscle relaxation, and indirectly by the inhibition of noradrenaline uptake into adrenergic neurons. The present study compared the potency of five tricyclic compounds on the contractile response of the rabbit urinary bladder to bethanechol. In addition, the direct antimuscarinic potency of these agents on radioligand binding to muscarinic receptors isolated from rabbit urinary bladder was determined. Of the five agents tested (imipramine, desrnethylirnipramine, amitriptyline, nortripty-line, and doxapine), doxapine was found to be significantly more potent than the other agents with respect to both antimuscarinic and musculotropic relaxant activity. |
