Nitric oxide synthase activity in the human urogenital tract

I. Ehrén, J. Adolfsson, N. P. Wiklund

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Nitric oxide (NO) has been suggested as a non-adrenergic non-cholinergic neurotransmitter in the urogenital tract and has previously been shown to have a smooth muscle relaxing effect in the urogenital organs both in various animals and in humans. It has been shown that NO is a mediator of the erection and the dilatation of the bladder neck and urethra. The aim of the study was to analyse nitric oxide synthase (NOS) activity in the human urogenital tract. NOS activity was measured by the conversion of l-[U-14C] arginine to l-[U-14C] citrulline. In the upper urinary tract there was Ca2+-dependent NOS activity in the renal pelvis, but no significant NOS activity could be found in the ureter. In the lower urinary tract we found high Ca2+-dependent NOS activity in the urethra, intermediate activity in the bladder neck and comparatively low activity in the detrusor muscle. In the male genital tract the testis and epididymis had no significant NOS activity. The vas deferens, prostate, seminal vesicle and corpus cavernosum were found to have high levels of Ca2+-dependent NOS activity. Ca2+-independent NOS activity was not obtained in the urogenital tract. Our results correspond well with previous functional studies indicating NO to be an important nerve-induced mediator of erection and in the micturition reflex, but also suggest that NO may be involved in several other functions in the human urogenital tract.

Original languageEnglish
Pages (from-to)287-290
Number of pages4
JournalUrological Research
Issue number5
StatePublished - Nov 1994
Externally publishedYes


  • Human
  • Male genital tract
  • Nitric oxide
  • Nitric oxide synthase
  • Urinary tract


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