d'Emmanuele di Villa Bianca Roberta, Sorrentino Raffaella, Maffia Pasquale, Mirone Vincenzo, Imbimbo Ciro, Fusco Ferdinando, De Palma Raffaele, Ignarro Louis J, Cirino Giuseppe
Department of Experimental Pharmacology, University of Naples Federico II, Via Domenico Montesano 49, 80131 Naples, Italy.
Proc Natl Acad Sci U S A. 2009 Mar 17;106(11):4513-8. doi: 10.1073/pnas.0807974105. Epub 2009 Mar 2.
Hydrogen sulfide (H(2)S) is synthesized by 2 enzymes, cystathionine beta-synthase (CBS) and cystathionine gamma-lyase (CSE). L-Cysteine (L-Cys) acts as a natural substrate for the synthesis of H(2)S. Human penile tissue possesses both CBS and CSE, and tissue homogenates efficiently convert L-Cys to H(2)S. CBS and CSE are localized in the muscular trabeculae and the smooth-muscle component of the penile artery, whereas CSE but not CBS is also expressed in peripheral nerves. Exogenous H(2)S [sodium hydrogen sulfide (NaHS)] or L-Cys causes a concentration-dependent relaxation of strips of human corpus cavernosum. L-Cys relaxation is inhibited by the CBS inhibitor, aminoxyacetic acid (AOAA). Electrical field stimulation of human penile tissue, under resting conditions, causes an increase in tension that is significantly potentiated by either propargylglycine (PAG; CSE inhibitor) or AOAA. In rats, NaHS and L-Cys promote penile erection, and the response to L-Cys is blocked by PAG. Our data demonstrate that the L-Cys/H(2)S pathway mediates human corpus cavernosum smooth-muscle relaxation.
硫化氢（H₂S）由两种酶合成，即胱硫醚β-合酶（CBS）和胱硫醚γ-裂解酶（CSE）。L-半胱氨酸（L-Cys）作为合成H₂S的天然底物。人类阴茎组织同时拥有CBS和CSE，并且组织匀浆能有效地将L-Cys转化为H₂S。CBS和CSE定位于阴茎动脉的肌小梁和平滑肌成分中，而CSE而非CBS也在外周神经中表达。外源性H₂S [硫氢化钠（NaHS）]或L-Cys可引起人类海绵体条带浓度依赖性舒张。L-Cys诱导的舒张被CBS抑制剂氨氧基乙酸（AOAA）抑制。在静息条件下，对人类阴茎组织进行电场刺激会导致张力增加，而炔丙基甘氨酸（PAG；CSE抑制剂）或AOAA可显著增强这种张力增加。在大鼠中，NaHS和L-Cys可促进阴茎勃起，并且对L-Cys的反应被PAG阻断。我们的数据表明，L-Cys/H₂S途径介导人类海绵体平滑肌舒张。
