Potentiation of apomorphine effect on sildenafil-induced penile erection in conscious rabbits.
OBJECTIVE
To investigate a possible potentiation effect of apomorphine (APO) on sildenafil-induced penile erection in the conscious rabbit.


METHODS
Erection of male New Zealand White rabbits (3.5 - 4.0 kg, n=12) was assessed by measuring the length of the uncovered penile mucosa and the duration of erection before and after intravenous administration of agents. After injection of APO (0, 0.05, 0.1 and 0.4 mg/kg), sildenafil was administered intravenously in a dose-response manner (0.5, 1 and 5 mg/kg). In additional experiments, the effect of increasing doses of sildenafil in combination with APO on systemic blood pressure was evaluated.


RESULTS
Systemic administration of sildenafil induced a dose-dependent increase in the penile length. Intravenous injection of APO alone did not produce any change in the penile length, while significantly enhanced the penile erection induced by sildenafil. The co-administration of 0.1 mg/kg of APO and 1 mg/kg of sildenafil was found to be the most effective combination in producing penile erection. Intravenous administration of sildenafil caused a concentration-dependent decrease in systemic blood pressure, but no additional decrease was observed with co-administration of APO.


CONCLUSIONS
APO enhances the penile erection induced by sildenafil in the conscious rabbit without causing an additional decrease in blood pressure.
Department of Urology, Seoul National University College of Medicine, 28 Yongon-dong, Chongno-gu, Seoul 110-744, Korea. jspaick@snu.ac.kr
Jae-Young
JY
Park
Hwancheol
H
Son
Soo Woong
SW
Kim
Jae-Seung
JS
Paick
D000818:Animals; D001058:Apomorphine / Q000494:pharmacology*; D001794:Blood Pressure / Q000187:drug effects; D003243:Consciousness; D004357:Drug Synergism; D008297:Male; D010410:Penile Erection / Q000187:drug effects* / Q000502:physiology; D010879:Piperazines / Q000494:pharmacology*; D011687:Purines; D011817:Rabbits; D000068677:Sildenafil Citrate; D013450:Sulfones
D010879:Piperazines; D011687:Purines; D013450:Sulfones; D000068677:Sildenafil Citrate; D001058:Apomorphine