Skajaa K, Forman A, Andersson K E
Department of Obstetrics and Gynecology, University of Aarhus, Denmark.
Acta Physiol Scand. 1990 Aug;139(4):551-9. doi: 10.1111/j.1748-1716.1990.tb08958.x.
The effects of Mg2+ were studied in human umbilical arteries, stem villous arteries and maternal intramyometrial arteries. The vessels were dissected and mounted in organ baths, and isometric tension was recorded. In all fetal preparations investigated, Mg2+ (0.5-6.0 mM) in a concentration-related way decreased pD2 values for prostaglandin F2 alpha responses. The maximum response to prostaglandin F2 alpha was depressed in umbilical arteries, but remained unaffected in stem villous artery preparations. In stem villous arteries pretreated in Ca2(+)-free medium, increasing concentrations of Mg2+ markedly depressed the response to Ca2+ after stimulation with K+ or prostaglandin F2 alpha, suggesting that Mg2+ inhibited transmembrane calcium influx and interfered with intracellular calcium effects. In both stem villous and intramyometrial arteries, increasing concentrations of Mg2+ increased EC50 values for responses to K+, whereas Emax values were unaffected. Mg2+ produced relaxation of agonist-induced contractions by up to 60% in stem villous arteries and up to 40% in intramyometrial artery preparations. The relaxant effect of Mg2+ did not seem to be mediated through the endothelium or through changes in the synthesis of prostanoids, since endothelial disruption and treatment with indomethacin left the responses to Mg2+ unaffected. Relaxation of vessels important for resistance regulation in the human uteroplacental vascular bed may be of benefit when uteroplacental blood flow is impaired, and the present results support the established use of magnesium sulphate in the treatment of pre-eclampsia.
研究了镁离子（Mg2+）对人脐动脉、绒毛干动脉和母体子宫肌层内动脉的影响。将血管分离并安装在器官浴槽中，记录等长张力。在所有研究的胎儿血管标本中，Mg2+（0.5 - 6.0 mM）以浓度依赖的方式降低了前列腺素F2α反应的pD2值。脐动脉对前列腺素F2α的最大反应受到抑制，但在绒毛干动脉标本中未受影响。在无钙培养基中预处理的绒毛干动脉中，随着Mg2+浓度的增加，在用钾离子（K+）或前列腺素F2α刺激后，对钙离子（Ca2+）的反应明显受到抑制，这表明Mg2+抑制跨膜钙内流并干扰细胞内钙效应。在绒毛干动脉和子宫肌层内动脉中，随着Mg2+浓度的增加，对K+反应的半数有效浓度（EC50）值增加，而最大效应值（Emax）未受影响。Mg2+使绒毛干动脉中激动剂诱导的收缩松弛高达60%，在子宫肌层内动脉标本中高达40%。Mg2+的松弛作用似乎不是通过内皮介导的，也不是通过前列腺素合成的变化介导的，因为内皮破坏和用吲哚美辛处理后，对Mg2+的反应未受影响。当子宫胎盘血流受损时，对人体子宫胎盘血管床中阻力调节重要的血管松弛可能有益，目前的结果支持硫酸镁在治疗先兆子痫中的既定应用。
