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) inhibi tor, L-Ns-nitro arginine p-nitroanilide (L-Napna), upon the hyper-refl exia of a rat model of persistent visceral pain was investigated. A ba seline cystometrogram (CMG) was performed by measuring intravesical pr essure during vesical inflation. L-Napna (125-1000 mu g) or vehicle (c ontrol) 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 vesic al reflexes in the absence of inflammation. However, following inflamm ation, a vesical hyper-reflexia was demonstrated in the control animal s, 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.