7-Nitroindazole: a selective inhibitor of penile erection: an in vivo study in a rat animal model.
OBJECTIVE
The neuronal isoform of nitric oxide synthase (nNOS) has been localized in neurons innervating the penis and is believed to be an important mediator of erection. Using the selective inhibitor 7-nitroindazole (7-NI), we evaluated the possible role of nNOS in penile erection using a rat animal model.


METHODS
Eighteen Sprague-Dawley rats were divided into three study groups. A sham group (n = 6) received the vehicle arachis oil, a low-dose group received 5 mg/kg (n = 6), and a high-dose group received 50 mg/kg (n = 6) of 7-NI prior to measurement of blood pressure and cavernous nerve stimulation-induced rise in intracavernous pressure.


RESULTS
A dose-dependent inhibition of erection by 7-NI was seen. Control animals had an intracavernous pressure rise of 55.5 +/- 4.0 cm H2O, whereas the low-dose group had 26.5 +/- 2.8 cm H2O and the high-dose group had 6.2 +/- 2.1 cm H2O. A partial recovery of erection was seen in the low- and high-dose groups after 3 hours. Blood pressure was unaffected by 7-NI administration.


CONCLUSIONS
7-NI induced a reversible, dose-dependent inhibition of erection without affecting blood pressure. This in vivo study provides further evidence of the role played by nNOS in erection.
Spiess
P E
PE
Urology Research Laboratories, Lady Davis Institute, Jewish General Hospital, McGill University, Montreal, Canada.
Dion
S B
SB
Zvara
P
P
Merlin
S L
SL
Chan
P T
PT
Brock
G B
GB
D000704:Analysis of Variance; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D007191:Indazoles / Q000494:pharmacology*; D008297:Male; D010410:Penile Erection / Q000187:drug effects* / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley
D004791:Enzyme Inhibitors; D007191:Indazoles; C080122:7-nitroindazole