Rodríguez-Cruz M E, Pérez-Ordaz L, Serrato-Barajas B E, Juárez-Oropeza M A, Mascher D, Paredes-Carbajal M C
Instituto de Investigaciones Químico Biológicas, UMSNH, Morelia, Mich, Mexico.
J Ethnopharmacol. 2003 Jun;86(2-3):213-8. doi: 10.1016/s0378-8741(03)00073-4.
The mistletoe Psittacanthus calyculatus (Loranthaceae) is used in Mexican traditional medicine for the treatment of hypertension. In the present study the effects of a crude ethanolic extract of this mistletoe, on the vasomotor reactivity of superfused rat aortic rings (with or without a functional endothelium) were analyzed. Either in the absence or in the presence of L-NAME or indomethacin, the extract (12.5-800 microg/ml) had no effect on the basal tone of both types of rings. In phenylephrine-precontracted rings, low concentrations of the extract (up to 300 microg/ml) induced a small additional tension development in both types of rings; however, the tension increase was slightly larger in rings having an intact endothelium. At higher concentrations (400-800 microg/ml), the extract relaxed, concentration-dependently, phenylephrine-precontracted rings with an intact endothelium. This relaxation was completely reverted by the addition of L-NAME. When the extract was applied in the continuous presence of L-NAME to phenylephrine-precontracted rings, instead of a relaxation a marked additional tension development occurred. Indomethacin did not modify the relaxation induced by the extract. The results indicate that the ethanolic extract of this mistletoe induces, predominantly, an endothelium-dependent relaxation which seems to be mediated by the synthesis/release of nitric oxide.
槲寄生Psittacanthus calyculatus（桑寄生科）在墨西哥传统医学中用于治疗高血压。在本研究中，分析了这种槲寄生的粗乙醇提取物对灌流大鼠主动脉环（有或无功能性内皮）血管舒缩反应性的影响。无论在不存在或存在L-精氨酸甲酯（L-NAME）或吲哚美辛的情况下，提取物（12.5 - 800微克/毫升）对两种类型的血管环的基础张力均无影响。在去氧肾上腺素预收缩的血管环中，低浓度的提取物（高达300微克/毫升）在两种类型的血管环中均诱导出小的额外张力增加；然而，在具有完整内皮的血管环中张力增加略大。在较高浓度（400 - 800微克/毫升）时，提取物浓度依赖性地使具有完整内皮的去氧肾上腺素预收缩血管环松弛。加入L-NAME可完全逆转这种松弛。当在L-NAME持续存在的情况下将提取物应用于去氧肾上腺素预收缩的血管环时，未出现松弛，反而出现明显的额外张力增加。吲哚美辛未改变提取物诱导的松弛。结果表明，这种槲寄生的乙醇提取物主要诱导内皮依赖性松弛，这似乎是由一氧化氮的合成/释放介导的。
