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Nitric oxide and cyclic GMP formation following relaxant nerve stimulation in isolated human corpus cavernosum
Author(s) -
Pickard R.S.,
Powell P.H.,
Zar M.A.
Publication year - 1995
Publication title -
british journal of urology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.773
H-Index - 148
eISSN - 1464-410X
pISSN - 0007-1331
DOI - 10.1111/j.1464-410x.1995.tb07275.x
Subject(s) - nitric oxide , cyclic gmp , stimulation , nerve stimulation , chemistry , anesthesia , medicine , pharmacology
Objective To investigate further the role of the nitric oxide (NO)‐cyclic GMP pathway as the mediator of relaxant neurotransmission in human corpus cavernosum and to establish whether impaired activity of this pathway contributes to the pathophysiology of impotence. Patients and methods Samples of cavernosal tissue were obtained from 59 men undergoing penile operations. The controls comprised four men with penile carcinoma and 17 with Peyronie's disease. Of the impotent men, 35 had clinical evidence of penile vascular disease on pre‐operative investigation, whilst three had non‐vascular impotence. Each biopsy was divided into two strips which were then suspended under tension in organ bath chambers. The relaxant inner‐vation of one strip of each pair was stimulated electrically whilst the other strip was left unstimulated. The formation of NO and cyclic GMP was calculated by comparing their respective tissue content in the stimulated and unstimulated strips. Results Overall, stimulation of the relaxant innervation produced significant increases in the tissue content of both NO and cyclic GMP. Incubation with an inhibitor of NO biosynthesis abolished the mechanical relaxant response and the formation of both NO and cyclic GMP. The magnitude of relaxant response and the formation of NO was diminished in tissue from men with vascular impotence compared to controls. The increase in cyclic GMP content was similar in both these groups. Relaxant response, NO formation and cyclic GMP formation in tissue from men with non‐vascular impotence was similar to controls. Conclusions This study provides further evidence that the NO‐cyclic GMP pathway acts as the mediator of nerve‐evoked smooth muscle relaxation in human corpus cavernosum. Diminished NO formation following relaxant nerve stimulation may account for impaired relaxant responses found in tissue from men with vascular impotence and may contribute to the cause of their erectile dysfunction.