Chen Jun, Liu Jihong, Wang Tao, Xiao Hengjun, Yin Chunping, Yang Jun, Chen Xiaowen, Ye Zhangqun
Department of Urology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China.
Nat Prod Res. 2009;23(2):112-21. doi: 10.1080/14786410801886831.
The relaxation mechanisms of tetrandrine (Tet) on the rabbit corpus cavernosum tissue in vitro were investigated. Strips of rabbit corpus cavernosum were mounted in organ chambers. The effects of Tet were examined on isolated muscle strips pre-contracted with phenylephrine (PE) alone, in the presence of N(W)-nitro-L-arginine (LNNA, a nitric oxide synthase inhibitor), 1-H-[1,2,4]oxadiazolo[4,3-alpha]quinoxalin-1-one(ODQ, a guanylyl cyclase inhibitor), indomethacin (cyclooxygenase inhibitor), tetraethylammonium (TEA, Ca(2+)-activated K(+) channel blocker), 4-aminopiridine (4-AP, voltage dependent K(+) channel blocker) and glibenclamide (ATP sensitive K(+)channel blocker). The effects of Tet on KCl-induced contraction of isolated muscle strips were also investigated. The procedure of calcium absence-calcium addition was designed to observe the effect of Tet on the two components of the contractile responses to PE based on the source of Ca(2+) (extracellular vs. intracellular). Corpus cavernosum strips showed relaxation in response to Tet (10(-8) approximately 10(-3) mol L(-1)) in a concentration-dependent manner with an IC(50) of 3.73 x 10(-5) mol L(-1). However, they were not affected by LNNA, ODQ, indomethacin and K(+)-channel blockers. Tet (10 micromol L(-1), 30 micromol L(-1)) concentration dependently reduced the maximal contraction response of isolated strips induced by KCl to (73.0 +/- 3.8) and (41.5 +/- 3.4)%, respectively (p < 0.01). In the procedure of calcium absence-calcium addition, Tet 100 micromol L(-1) inhibited both intracellular calcium-dependent and extracellular calcium-dependent contraction induced by PE (20 micromol L(-1)) (p < 0.05). The inhibition ratios were (23.8 +/- 7.1) and (40.7 +/- 11.2)%, respectively. The results of the present study suggest that Tet possesses a relaxant effect on rabbit corpus cavernosum tissues, which is attributable to the inhibition of extracellular Ca(2+) influx and the inhibition of release of intracellular-stored Ca(2+), but not mediated by the release of nitric oxide, prostaglandins or by the activation of potassium channels.
研究了粉防己碱（Tet）对兔海绵体组织的体外舒张机制。将兔海绵体条带安装在器官浴槽中。考察了Tet对单独用去氧肾上腺素（PE）预收缩的离体肌条的作用，以及在存在N（W）-硝基-L-精氨酸（LNNA，一种一氧化氮合酶抑制剂）、1-H-[1,2,4]恶二唑并[4,3-α]喹喔啉-1-酮（ODQ，一种鸟苷酸环化酶抑制剂）、吲哚美辛（环氧化酶抑制剂）、四乙铵（TEA，Ca（2+）激活的K（+）通道阻滞剂）、4-氨基吡啶（4-AP，电压依赖性K（+）通道阻滞剂）和格列本脲（ATP敏感性K（+）通道阻滞剂）时的作用。还研究了Tet对KCl诱导的离体肌条收缩的影响。设计了无钙-加钙程序，以根据Ca（2+）的来源（细胞外与细胞内）观察Tet对PE收缩反应的两个组成部分的影响。海绵体条带对Tet（10（-8）约10（-3）mol L（-1））呈浓度依赖性舒张，IC（50）为3.73×10（-5）mol L（-1）。然而，它们不受LNNA、ODQ、吲哚美辛和K（+）通道阻滞剂的影响。Tet（10μmol L（-1），30μmol L（-1））浓度依赖性地将KCl诱导的离体条带的最大收缩反应分别降低至（73.0±3.8）%和（41.5±3.4）%（p<0.01）。在无钙-加钙程序中，100μmol L（-1）的Tet抑制了PE（20μmol L（-1））诱导的细胞内钙依赖性和细胞外钙依赖性收缩（p<0.05）。抑制率分别为（23.8±7.1）%和（40.7±11.2）%。本研究结果表明，Tet对兔海绵体组织具有舒张作用，这归因于对细胞外Ca（2+）内流的抑制和对细胞内储存Ca（2+）释放的抑制，但不是由一氧化氮、前列腺素的释放或钾通道的激活介导的。
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