Schwinger R H, Böhm M, Uhlmann R, La Rosée K, Koch A, Erdmann E
Medizinische Klinik I, Universität München, Klinikum Grosshadern, Germany.
J Pharmacol Exp Ther. 1992 Dec;263(3):1352-9.
We studied the influence of magnesium on contractility and on force-frequency-relationship as well as on the positive inotropic and toxic effects of ouabain (OUA) on electrically driven human right auricular trabeculae. Radioligand binding experiments were performed with myocardial tissue from nonfailing and from terminally failing patients. Magnesium produced a concentration-dependent negative inotropic effect (P < .05). In contrast, OUA (0.03-0.1 mumol/l) concentration-dependently increased isometric force of contraction. The maximal positive inotropic effect of OUA (5.9 +/- 0.9 mN; 1 mmol/l of magnesium) was unchanged after increasing magnesium from 1 to 2 mmol/l (5.8 +/- 0.9 mN). OUA was as effective as Ca++ (15 mmol/l; 6.7 +/- 0.5 mN). OUA (0.05 and 0.03 mumol/l) exerted toxic effects after 2 hr and 0.08 or 0.1 mumol/l of OUA after 30 min, respectively. Time until toxic effects occurred after OUA (0.1 mumol/l) was significantly longer with 2 mmol/l of magnesium compared to 1 mmol/l of magnesium. In right auricular trabeculae, the force of contraction increased with increasing frequency (0.5-1 .5 Hz) of stimulation. The force-frequency-relationship becomes negative after elevation of extracellular Ca++ (2.4 mmol/l of Ca++) (2 Hz: 92 +/- 5.5% basal). Magnesium restored the force-frequency-relationship in the presence of enhanced Ca++ concentration (2.4 mmol/l of Ca++; 2 mmol/l of Mg++; 2 Hz: 145 +/- 16.9% basal). The receptor-density and affinity measured by [3H]OUA binding was not different in nonfailing and failing myocardium. Magnesium increased concentration-dependently the affinity of [3H]OUA to its receptor.(ABSTRACT TRUNCATED AT 250 WORDS)
我们研究了镁对收缩性、力-频率关系以及哇巴因（OUA）对电驱动的人右心耳小梁的正性肌力和毒性作用的影响。对非衰竭和终末期衰竭患者的心肌组织进行了放射性配体结合实验。镁产生浓度依赖性负性肌力作用（P <.05）。相比之下，OUA（0.03 - 0.1 μmol/l）浓度依赖性地增加等长收缩力。将镁浓度从1 mmol/l增加到2 mmol/l后，OUA的最大正性肌力作用（5.9 ± 0.9 mN；1 mmol/l镁）未改变（5.8 ± 0.9 mN）。OUA与Ca++（15 mmol/l；6.7 ± 0.5 mN）效果相同。OUA（0.05和0.03 μmol/l）分别在2小时后和0.08或0.1 μmol/l的OUA在30分钟后产生毒性作用。与1 mmol/l镁相比，2 mmol/l镁时OUA（0.1 μmol/l）产生毒性作用的时间明显更长。在右心耳小梁中，收缩力随刺激频率（0.5 - 1.5 Hz）增加而增加。细胞外Ca++（2.4 mmol/l Ca++）升高后，力-频率关系变为负性（2 Hz：92 ± 5.5%基础值）。在Ca++浓度升高（2.4 mmol/l Ca++；2 mmol/l Mg++；2 Hz：145 ± 16.9%基础值）时，镁恢复了力-频率关系。通过[3H]OUA结合测量的受体密度和亲和力在非衰竭和衰竭心肌中无差异。镁浓度依赖性地增加[3H]OUA与其受体的亲和力。（摘要截断于250字）
