Kim N, Vardi Y, Padma-Nathan H, Daley J, Goldstein I, Saenz de Tejada I
Department of Urology, Boston University School of Medicine, Massachusetts 02118.
J Clin Invest. 1993 Feb;91(2):437-42. doi: 10.1172/JCI116220.
Relaxation of the trabecular smooth muscle of the corpus cavernosum (the erectile tissue) of the penis is mediated by nitric oxide released by the nerves and endothelium. We have investigated the physiological role of oxygen tension in the regulation of trabecular smooth muscle tone. In human subjects, measurement of intracavernosal PO2 in blood drawn from corpus cavernosum in the flaccid state was comparable to that of venous blood (25-43 mmHg). Vasodilatation of the resistance arteries and trabecular smooth muscle relaxation by intracavernosal injection of papaverine and phentolamine caused oxygen tension to rise rapidly to arterial levels (PO2 approximately 100 mmHg). Isolated human and rabbit corpus cavernosum tissue strips in organ baths, exposed to arterial-like PO2 relaxed to the endothelium-dependent dilator acetylcholine and to electrical stimulation of the autonomic dilator nerves. These nitric oxide-mediated responses were progressively inhibited as a function of decreasing PO2 to levels measured in the flaccid penis. Reverting to normoxic conditions readily restored endothelium-dependent and neurogenic relaxation. Relaxation to exogenous nitric oxide was not impaired in low PO2. In rabbit corpus cavernosum, low PO2 reduced basal levels of cGMP and prevented cGMP accumulation induced by stimulation of dilator nerves. Furthermore, low PO2 inhibited nitric oxide synthase activity in corpus cavernosum cytosol. It is concluded that physiological concentrations of oxygen modulate penile erection by regulating nitric oxide synthesis in corpus cavernosum tissue.
阴茎海绵体（勃起组织）小梁平滑肌的舒张是由神经和内皮释放的一氧化氮介导的。我们研究了氧张力在调节小梁平滑肌张力中的生理作用。在人类受试者中，测量处于疲软状态的海绵体抽取的血液中的海绵体内PO2，其与静脉血的PO2相当（25 - 43 mmHg）。海绵体内注射罂粟碱和酚妥拉明导致阻力动脉血管舒张和小梁平滑肌松弛，使氧张力迅速上升至动脉水平（PO2约为100 mmHg）。置于器官浴中的分离的人体和兔海绵体组织条，暴露于类似动脉的PO2时，会对内皮依赖性舒张剂乙酰胆碱和自主舒张神经的电刺激产生舒张反应。随着PO2降低至疲软阴茎中测得的水平，这些一氧化氮介导的反应逐渐受到抑制。恢复到常氧条件下可迅速恢复内皮依赖性和神经源性舒张。在低PO2条件下，对外源性一氧化氮的舒张反应并未受损。在兔海绵体中，低PO2降低了cGMP的基础水平，并阻止了由舒张神经刺激诱导的cGMP积累。此外，低PO2抑制了海绵体细胞质中的一氧化氮合酶活性。得出的结论是，生理浓度的氧通过调节海绵体组织中的一氧化氮合成来调节阴茎勃起。
