Saenz de Tejada I, Moroukian P, Tessier J, Kim J J, Goldstein I, Frohrib D
Department of Urology, Boston University Medical Center, Massachusetts 02118.
Am J Physiol. 1991 May;260(5 Pt 2):H1590-5. doi: 10.1152/ajpheart.1991.260.5.H1590.
We investigated the role of trabecular smooth muscle tone in regulation of intracavernosal pressure, venous outflow resistance, and penile capacitance. In an isolated rabbit whole penis model, corpora cavernosa were infused with either contracting (high K(+)-norepinephrine combination) or relaxing (no added Ca(2+)-papaverine combination) physiological salt solutions while intracavernosal pressure was recorded. An infusion pump regulated by an intracavernosal pressure feedback mechanism enabled the measurement of flow necessary to maintain intracavernosal pressures at 30, 60, 90, 120, and 150 mmHg under steady-state conditions (inflow = outflow). These experiments allowed resistance to outflow from corpora to be calculated when trabecular smooth muscle was either constricted or relaxed. Decay in intracavernosal pressure over time from various predetermined intracavernosal pressures (150, 120, 90, 60, and 30 mmHg) was studied under conditions of zero inflow following contraction or relaxation of trabecular smooth muscle. This permitted calculation of the time constant, which together with the outflow resistance, permitted the calculation of penile capacitance. When smooth muscle is relaxed, venous outflow resistance is high, constant, and independent of intracavernosal pressure. Furthermore, relaxation of smooth muscle allows expansion of corpora with accumulation of volume under pressure, enabling the penis to act as a capacitor. This capacitor function is limited in the presence of constant high outflow resistance by stiffness of the fibroelastic elements of penis, tunica, and fibroelastic frame, which exhibit nonlinear deflection trends. Analysis of these variables has led us to propose a model for penile erection.
我们研究了小梁平滑肌张力在调节海绵体内压、静脉流出阻力和阴茎容量方面的作用。在一个离体兔全阴茎模型中，向海绵体注入收缩性（高钾 - 去甲肾上腺素组合）或舒张性（不添加钙 - 罂粟碱组合）生理盐溶液，同时记录海绵体内压。由海绵体内压反馈机制调节的输液泵能够测量在稳态条件下（流入 = 流出）将海绵体内压维持在30、60、90、120和150 mmHg所需的流量。这些实验可以在小梁平滑肌收缩或舒张时计算海绵体的流出阻力。在小梁平滑肌收缩或舒张后零流入的条件下，研究了从各种预定海绵体内压（150、120、90、60和30 mmHg）随时间的海绵体内压衰减情况。这允许计算时间常数，该常数与流出阻力一起可用于计算阴茎容量。当平滑肌舒张时，静脉流出阻力高、恒定且与海绵体内压无关。此外，平滑肌的舒张允许海绵体在压力下随着体积的积累而扩张，使阴茎能够起到电容器的作用。在存在恒定高流出阻力的情况下，这种电容器功能受到阴茎、白膜和纤维弹性框架的纤维弹性元件刚度的限制，这些元件呈现非线性偏转趋势。对这些变量的分析使我们提出了一个阴茎勃起模型。
