| 1342826 |
Oliveira EM, Vassallo DV: Effects of mercury on the contractility of isolated rat cardiac muscle. . Braz J Med Biol Res. 1992;25(10):1037-40.
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. |
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