OBJECTIVETo investigate the expressions of cystathionine gamma-lyase (CSE) and cystathionine beta-synthase (CBS) in the corpus cavernosum of spontaneous hypertensive rats (SHR) and their relationship with erectile dysfunction.

METHODSThis study included 10 male SHRs and 10 healthy male Wistar-Kyoto (WKY) rats as controls, all aged 12 weeks. We applied a series of electric stimuli to the major pelvic ganglions of the rats, observed changes in the ratio of intracavernosal to mean arterial blood pressure (ICP/MAP), measured the levels of serum testosterone (T) and endogenous H2S, and determined the expressions of CSE and CBS in the corpus cavernosum by Western blot and immunohistochemistry.

RESULTSNo obvious difference was found in the serum T level between the two groups. Compared with the WKY rats, the SHRs showed significant reduction in the ICP/MAP ratio, the contents of plasma H2S ([21.92 +/- 2.75] micromol/L vs [10.49 +/- 1.35] micromol/L, P < 0.05) and endogenous corpus cavernosal H2S ([87.67 +/- 2.12] nmol/mg prot vs [52.60 +/- 3.44] nmol/mg prot, P < 0.05), the level of endogenous H2S synthesis ([4.35 +/- 0.32] nmol/mg per min vs [1.14 +/- 0.07] nmol/mg per min, P < 0.05) and the expressions of CBS and CSE (P < 0.05). Immunohistochemistry showed that CSE and CBS were distributed mainly in the smooth muscle cells and vascular endothelial cells of the corpus cavernosum. The ICP/MAP ratio was highly positively correlated with the expressions of CSE (r = 0.977, P < 0.05) and CBS (r = 0.955, P < 0.05) in the corpus cavernosal tissue.

CONCLUSIONHypertension inhibits endogenous H2S synthesis by suppressing the expressions of CSE and CBS in the corpus cavernosum, which might be related with hypertension-induced reduction of erectile function.