Presynaptic and postsynaptic effects of mercuric ions on guinea-pig ileum longitudinal muscle strip preparation |
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| Authors: | Zoltan Abram Susan Korossy |
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| Affiliation: | (1) Department of Hygiene and Occupational Medicine, Medical and Pharmacological University, str. Marinescu 38, Tirgu Mures, Roinania;(2) Department of Pharmacology, Institute of Experimental Medicine, Hungarian Academy of Sciences, P.O. Box 67, H-1450 Budapest, Hungary |
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| Abstract: | The toxic effect of mercuric ions on intestinal cholinergic neurotransmission was investigated in vitro. Hg2+ inhibited the evoked release and enhanced the resting release of ACh. Smooth muscle contraction was irreversibly inhibited by Hg2+ in a concentration-dependent manner, and Na2EDTA did not antagonize this effect. We also investigated if Hg2+ enters the nerve terminal through Ca2+-channels, or Na+-channels, or both. The effects of mercuric ions obtained in our study were completely abolished by the combined administration of TTX and Co2+. It is suggested that the site of the action of mercuric ions is intracellular. We concluded that Hg2+ may interfere with cholinergic transmission by blocking [Ca2+]o-dependent release of ACh and by enhancing [Ca2+]o-independent resting release of ACh. The effect of Hg2+ was not only presynaptic since it also inhibited the effect of ACh on smooth muscle. |
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| Keywords: | Mercuric ions release of acetylcholine guinea pig ileum contraction of smooth muscle |
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