Responses to serotonin (5HT) in isolated corpus cavernosum penis of rabbit.

This study was aimed at determining serotonin (5-hydroxytryptamine: 5HT) receptor subtypes participating in 5HT-induced response in the isolated corpus cavernosum penis (CCP) of rabbits. 5HT contracted the CCP in a concentration-dependent manner. Both WAY100635 (5HT(1A) antagonist) and LY53857 (5HT(2) antagonist) concentration-dependently suppressed the 5HT-induced contraction. The suppression of the 5HT-induced contraction by ketanserin (5HT(2A) antagonist) was weaker than that by LY53857. LY278584 (5HT(3) antagonist) did not affect the 5HT-induced contraction. SDZ205557 (5HT(4) antagonist) showed a tendency to potentiate the 5HT-induced contraction. The above results suggest that 5HT(1A) and 5HT(2) receptor subtypes partially participate in the contractile response to 5HT in rabbit CCP, and the potentiation by SDZ205557 of the 5HT-induced contraction implies the existence of dual contractile and relaxing responses to 5HT via 5HT(1) and 5HT(2), and 5HT(4) receptors, respectively. The relaxing response to 5HT(4) receptor stimulation may be masked by 5HT-induced contraction.