Zinc ions block the intracellular calcium release induced by caffeine in guinea-pig taenia caeci |
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Authors: | T. Nasu |
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Affiliation: | (1) Department of Veterinary Pharmacology, Faculty of Agriculture, Yamaguchi University, 753 Yamaguchi, (Japan) |
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Abstract: | Zn2+ in low concentrations (0.005–0.1 mM) inhibited the transient contractions in response to caffeine (25 mM) in a dose-dependent manner in smooth muscle of intact guinea-pig taenia caeci. At Zn2+ concentrations higher than 0.1 mM, caffeine did not elicit any response. After saponin-treatment of the fibres, which leaves the Ca2+ storage sites intact, caffeine contraction was completely inhibited by Zn2+ at a relatively low concentration (0.03 mM). However, in Triton-X-100-treated fibres, in which the Ca2+ release sites are destroyed, the contraction could be induced in the presence of Zn2+ by an increase in Ca2+. In conclusion, Zn2+ can block the intracellular Ca2+ release from caffeine-sensitive release sites in taenia caeci. |
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Keywords: | Zinc ions caffeine calcium store smooth muscle |
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