[The endothelium of the corpus cavernosum]

Recently, it has been demonstrated that the endothelium of corpus cavernosum plays an important role in the physiology of erection. Endothelial cells synthesize and release constricting and relaxing factors. These factors are essentially represented by endothelin and nitric oxide. Endothelin is a peptide generated by endothelial cells with potent vasoconstrictor properties. This peptide provokes more sustained constriction of corpus cavernosum smooth muscles than noradrenaline. This effect suggested that endothelin may play a role in the regulation of tone in penile vascular and cavernous tissues in man. In addition, recent experimental studies showed an important role of nitric oxide for cavernous smooth muscle relaxation. This factor may act as an inhibitory neurotransmitter in penile corpus cavernosum smooth muscle. The characteristics of these substances are reviewed.