Kim Noel N, Min Kweonsik, Huang Yue-hua, Goldstein Irwin, Traish Abdulmaged M
Department of Urology, School of Medicine, Boston University, 700 Albany St. W607, Boston, MA 02118, USA.
Life Sci. 2002 Nov 1;71(24):2909-20. doi: 10.1016/s0024-3205(02)02162-8.
Vascular and non-vascular smooth muscle within the vagina mediate important physiological changes during sexual arousal in women. In this study, we have characterized alpha-adrenergic receptors (AR) in rabbit vagina by assessment of radioligand binding, contractility of isolated tissue strips and genital hemodynamics. [3H]Prazosin and [3H]RX821002 (alpha-1 and alpha-2 AR selective antagonists) bound to rabbit vaginal membrane preparations with high affinity and limited capacity. Competition binding assays using both non-selective and subtype selective ligands for AR (phentolamine, prazosin, delequamine, rauwolscine and UK14304) further confirmed the presence of alpha-1 and alpha-2 AR in vaginal tissue. In organ bath preparations of vaginal tissue strips, norepinephrine-induced contraction was attenuated by alpha-1 and alpha-2 AR antagonists (prazosin, tamsulosin, delequamine and phentolamine). In anesthetized rabbits, intravaginal injection of the alpha-1 AR selective antagonist REC 15/2615 (50 and 100 microg/kg) caused a 2 to 3-fold increase in genital tissue oxyhemoglobin (OHb) concentration. Similar increases in tissue OHb were observed with intravaginal injection of phentolamine (500 microg/kg) or a tri-mixture of vasodilators (PGE1, papaverine, phentolamine). REC 15/2615, phentolamine or the tri-mixture also enhanced the amplitude and/or duration of change in genital tissue OHb after pelvic nerve stimulation. Thus, vaginal tissue expresses functional alpha-1 and alpha-2 AR, which modulate vaginal smooth muscle contractility and genital engorgement.
阴道内的血管平滑肌和非血管平滑肌在女性性唤起过程中介导重要的生理变化。在本研究中，我们通过评估放射性配体结合、离体组织条的收缩性和生殖器血流动力学，对兔阴道中的α-肾上腺素能受体（AR）进行了表征。[3H]哌唑嗪和[3H]RX821002（α-1和α-2 AR选择性拮抗剂）以高亲和力和有限容量与兔阴道膜制剂结合。使用AR的非选择性和亚型选择性配体（酚妥拉明、哌唑嗪、地来夸明、育亨宾和UK14304）进行的竞争结合试验进一步证实了阴道组织中存在α-1和α-2 AR。在阴道组织条的器官浴制剂中，去甲肾上腺素诱导的收缩被α-1和α-2 AR拮抗剂（哌唑嗪、坦索罗辛、地来夸明和酚妥拉明）减弱。在麻醉兔中，阴道内注射α-1 AR选择性拮抗剂REC 15/2615（50和100μg/kg）导致生殖器组织氧合血红蛋白（OHb）浓度增加2至3倍。阴道内注射酚妥拉明（500μg/kg）或血管扩张剂三联混合物（PGE1、罂粟碱、酚妥拉明）也观察到组织OHb有类似增加。REC 15/2615、酚妥拉明或三联混合物还增强了盆腔神经刺激后生殖器组织OHb变化的幅度和/或持续时间。因此，阴道组织表达功能性α-1和α-2 AR，它们调节阴道平滑肌收缩性和生殖器充血。
