OBJECTIVETo evaluate the effect of aging on the endothelial function of the penile corpus cavernosum in rats.

METHODSThe intracavernosal pressure (ICP) was compared in response to acetylcholine (Ach, endothelium-dependent vasodilator), sodium nitroprusside (SNP, an NO donor) and A23187 (a calcium ionophore)in the young (5 months old) and aged (20 months old) rats. In addition, the activity of nitric oxide synthase (NOS)in penile cavernosal tissues was examined.

RESULTSAch-mediated ICP was significantly attenuated from the maximum of (54.8 +/- 4.2) in the young rats to (40.3 +/- 2.8) mm Hg in the aged ones (Ach = 0.1 mmol/L), P < 0.01. The ICP to SNP (0.1 mmol/L) was (58.9 +/- 4.7) mm Hg in the young rats and (51.7 +/- 5.3) mm Hg in the aged. No statistically significant difference was noted between the two groups, P > 0.05. The Ach-mediated ICP in the young rats was not significantly augmented from the maximum of (54.8 +/- 4.2) to (55.8 +/- 4.7) mm Hg in the presence of the calcium ionophore A23187 (10 micromol/L), P > 0.05. However, A23187 significantly augmented Ach-mediated ICP in the aged from the maximum of (40.3 +/- 2.8) to (56.2 +/- 4.1) mm Hg, P < 0.01. Finally the activity of nitric oxide synthase was not significantly attenuated in either the aged or the young, P > 0.05.

CONCLUSIONThe endothelial function of the penile cavernosum declines with the advance of age. And endothelial dysfunction may play some role in the mechanisms of age-related erectile dysfunction.