PURPOSE: To compare the inhibitory effects of various tricyclic antidepressants (TCAs) on contractile response of the rat vas deferens to electrical stimulation of hypogastric nerve. MATERIALS AND METHODS: A total of forty Spraque Dawley rats (weight 300-350gm) were divided into 8 groups (n=5 in each): doxepine, amitriptyline, trimipramine, desipramine, imipramine, clomipramine, protriptyline, and prazosin treated groups. Before (baseline pressure) and 20 minutes after intravenous injection of each agent (0.1-, 1-, 10-, and 20-fold of therapeutic doses for human in each agent), the hypogastric nerves, iden tified under operative microscope, were electrically stimulated with rectangular pulses of 0.5 mseconds duration, 10 Hz, and 10 V for 10 seconds. Dose of drug administered was gradually increased in order of 0.1- to 20-fold dose. RESULTS: All drugs tested in this study caused dose-dependent inhibition of the rat intravasal pressure induced by the electrical stimulation of hypogastric nerve. Inhibitory potency of each drug was doxepine (88.5% and 96.5% at 10- and 20-fold dose)> OR = amitriptyline (76.8% and 91.8%)>clomipramine (66.7% and 74.4%)> OR =imipramine (48.2% and 67.0%)=prazosin (45.6% and 63.5%)=trimipramine (52.7% and 65.4%)> OR =desi pramine (45.3% and 49.0%)> protriptyline (18.9% and 19.9%). CONCLUSIONS: Inhibitory effects of TCAs on contractile response of the rat vas deferens to electrical stimulation of hypogastric nerve would increase in proportion to their potency of alpha1-adrenoceptor blocking actions.
Amitriptyline ; Animals ; Antidepressive Agents, Tricyclic* ; Clomipramine ; Desipramine ; Doxepin ; Electric Stimulation* ; Humans ; Imipramine ; Injections, Intravenous ; Prazosin ; Protriptyline ; Rats* ; Trimipramine ; Vas Deferens*