Relaxant effects of mercury and mercury uptake in the smooth muscle of guinea-pig taenia coli.

Hg2+ (0.005-0.5 mM) induced a concentration-dependent reduction on high-K+-induced contraction of taenia coli. The K+-induced increase in 45Ca uptake was significantly reduced in the presence of Hg2+ (0.05-0.5 mM). The contractions of the glycerinated taenia coli were inhibited by an increase in Hg2+ concentration. Mercury uptake increased along the duration of Hg2+ incubation. When muscles were rinsed with a medium containing 5 mM EDTA after 0.5 mM Hg2+ treatment for 90 min about 30% of the original level of tissue mercury was retained. Possible mechanism for the tension inhibitory action of Hg2+ include: (1) that Hg2+ bound to cell membrane initially interferes with the permeability of Ca2+ and that (2) the cellular mercury fraction that is not eliminated by EDTA subsequently correlates with the tension inhibitory action.