7-Nitroindazole: A selective inhibitor of penile erection: An in vivo study in a rat animal model

• Published in: Urology (Ridgewood, N.J.) Vol. 47; no. 1; pp. 93 - 96
• Main Authors: Spiess, Philippe E., Dion, Stéphane B., Zvara, Peter, Merlin, Scott L., Chan, Peter T.K., Brock, Gerald B.
• Format: Journal Article
• Language: English
• Published: New York, NY Elsevier Inc 1996; Elsevier Science
• Subjects: Analysis of Variance; Animals; Biological and medical sciences; Blood Pressure - drug effects; Dose-Response Relationship, Drug; Enzyme Inhibitors - pharmacology; Fundamental and applied biological sciences. Psychology; Indazoles - pharmacology; Male; Mammalian male genital system; Morphology. Physiology; Penile Erection - drug effects; Penile Erection - physiology; Rats; Rats, Sprague-Dawley; Vertebrates: reproduction; Human; Animal model; Rat; Enzyme; Erection; Rodentia; Enzyme inhibitor; Male; Biological activity; Nitric-oxide synthase; Vertebrata; Mammalia; Oxidoreductases
• ISSN: 0090-4295; 1527-9995
• DOI: 10.1016/S0090-4295(99)80389-6

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. 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. A dose-dependent inhibition of erection by 7-NI was seen. Control animals had an intracavernous pressure rise of 55.5 ± 4.0 cm H 2O, whereas the low-dose group had 26.5 ± 2.8 cm H 2O and the high-dose group had 6.2 ± 2.1 cm H 2O. 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. 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. UROLOGY ® 47: 93–96, 1996.