Topical spinal administration of a nitric oxide synthase inhibitor prevents the hyper-reflexia associated with a rat model of persistent visceral pain.
The effects of a neuronal selective nitric oxide synthase (NOS) inhibitor, L-Ng-nitro arginine p-nitroanilide (L-Napna), upon the hyper-reflexia of a rat model of persistent visceral pain was investigated. A baseline cystometrogram (CMG) was performed by measuring intravesical pressure during vesical inflation. L-Napna (125-1000 micrograms) or vehicle (control) was then administered topically onto the exposed spinal cord, followed by another CMG. The bladder was then inflamed with turpentine and a final CMG performed. Neither L-Napna nor vehicle affected vesical reflexes in the absence of inflammation. However, following inflammation, a vesical hyper-reflexia was demonstrated in the control animals, which was prevented by L-Napna. Therefore, spinal NOS does not have a role in the generation of normal bladder reflexes, however it does modulate them during vesical inflammation.
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Sherrington School of Physiology, UMDS, St. Thomas' Hospital, London, UK.
D000594:Amino Acid Oxidoreductases / Q000037:antagonists & inhibitors*; D000700:Analgesics / Q000494:pharmacology; D000813:Anilides; D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives* / Q000494:pharmacology; D003556:Cystitis / Q000139:chemically induced / Q000503:physiopathology; D005260:Female; D007278:Injections, Spinal; D019001:Nitric Oxide Synthase; D010146:Pain / Q000503:physiopathology*; D051381:Rats; D017208:Rats, Wistar; D012018:Reflex / Q000187:drug effects; D012021:Reflex, Abnormal / Q000187:drug effects*; D014425:Turpentine; D001743:Urinary Bladder / Q000187:drug effects; D014781:Viscera / Q000503:physiopathology*
D000700:Analgesics; D000813:Anilides; C080840:N(G)-nitroarginine-4-nitroanilide; D001120:Arginine; D019001:Nitric Oxide Synthase; D000594:Amino Acid Oxidoreductases; D014425:Turpentine