汞对离体大鼠心肌收缩性的影响。

Effects of mercury on the contractility of isolated rat cardiac muscle.

作者信息

Oliveira E M, Vassallo D V

机构信息

Departamento de Ciências Fisiológicas, Universidade Federal do Espírito Santo, Vitória, Brasil.

出版信息

Braz J Med Biol Res. 1992;25(10):1037-40.

PMID:1342826

Abstract

The effects of increasing concentrations of mercury (Hg2+) chloride (1, 2.5, 5 and 10 microM) were studied on isometrically contracting papillary muscles from female rats (Wistar, EPM strain) weighing 150 to 180 g. Hg2+ promoted an increase of 12.7 +/- 2.2% in the developed force at 1 microM. At 2.5 microM, force values were similar to control, decreasing progressively as Hg2+ concentration increased to 5 (-13 +/- 6.4%) and 10 microM (-37 +/- 12.3%). Potentiated post-rest contractions (PRC) were also determined after 15-, 30- and 60-s pauses. There was a progressive reduction of the potentiated PRCs relative to their respective steady-state control contractions with increasing concentrations of HgCl2. Since in several tissues including myocardium Hg2+ inhibits the activity of Ca2+ and Na(+)-K(+)-ATPases the results described here suggest that Hg2+, at lower concentrations, could increase force by inhibiting Na(+)-K(+)-ATPase, while at higher concentrations Hg2+ would decrease relative PRC potentiation by inhibiting sarcoplasmic reticulum Ca(2+)-ATPase.

摘要

研究了氯化汞（Hg2+）浓度增加（1、2.5、5和10微摩尔）对体重150至180克雌性大鼠（Wistar，EPM品系）等长收缩乳头肌的影响。在1微摩尔浓度时，Hg2+使收缩力增加了12.7±2.2%。在2.5微摩尔浓度时，力值与对照组相似，随着Hg2+浓度增加到5微摩尔（-13±6.4%）和10微摩尔（-37±12.3%），力值逐渐降低。在15秒、30秒和60秒的暂停后，还测定了增强的后静息收缩（PRC）。随着HgCl2浓度增加，相对于各自的稳态对照收缩，增强的PRC逐渐减少。由于在包括心肌在内的几种组织中，Hg2+会抑制Ca2+和Na(+)-K(+)-ATP酶的活性，此处描述的结果表明，较低浓度的Hg2+可能通过抑制Na(+)-K(+)-ATP酶来增加收缩力，而在较高浓度时，Hg2+会通过抑制肌浆网Ca(2+)-ATP酶来降低相对PRC增强作用。