ACTION OF NITRIC OXIDE ON THE INTERNAL URETHRAL SPHINCTER FUNCTION

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The present study was performed to investigate action of nitric oxide on the internal urethral sphincter function. Female rats were anesthetzed with urethane. The bladder neck was ligated in order to measure independently intravesical pressure and internal urethral pressure. Under condition of abolishment of the urethral striated muscle activity by the intravenous administration of pancronium bromide, the bladder and urethral pressure were continuosly recorded during rhythmic isovolumetric bladder contractions before and after intraarterial administration of the following drugs. Used drugs were L-arginine from which nitric oxide is synthetized, L-NMMA,L-NAME which inhibit the synthesis of nitric oxide from L-arginine, and methylene blue which inhibits the activation of soluble guanylyl cyclase. Before the administration of each drug, rhythmic bladder contractions with concomitant urethral relaxations were occurred. Administration of L-arginine produced a decrese in urethral pressure. A … More dministration of L-NMMA,L-NAME and methylene blue produced an inhibition of the internal urethral sphincter relaxation during rhythmic bladder contractions. The nitric oxide/cyclic GMP pathway seems to take an important role for the internal urethral sphincter relaxation.Decerebrate dogs were used to examine the effect of L-arginine and methylene blue on the isovolumetric bladder contractions in response to bladder fillig and electrical stimulation of pontine micturition center. In the isovolumetric bladder contractions in response to bladder filling, L-arginine produced an increase in bladder capacity and a decrease in bladder contraction pressure. Methylene blue produced an inhibition of effect of L-arginine. In the isovolumetric bladder contractions in response to electrical stimulation of pontine micturition center, methylene blue produced an increase in the bladder contraction pressure and duration of bladder contraction. The nitric oxide/cyclic GMP pathway seems to take certain role for bladder activity. Less