Inositol 1,4,5-trisphosphate releases Ca2+ from intracellular store sites in skinned single cells of porcine coronary artery |
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Authors: | E Suematsu M Hirata T Hashimoto H Kuriyama |
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Institution: | 1. Department of Biochemistry, Faculty of Dentistry, Kyushu University, Fukuoka 812, Japan;2. Department of Pharmacology, Faculty of Medicine, Kyushu University, Fukuoka 812, Japan |
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Abstract: | Effects of inositol 1,4,5- trisphosphate , extracted from human erythrocyte ghosts, on Ca2+ release from intracellular store sites were studied in saponin-treated single muscle cells of the porcine coronary artery. Application of micromolar concentrations of inositol 1,4,5- trisphosphate released Ca2+ from the intracellular non-mitochondrial store sites, within 1 min. However, when the concentrations of free Ca2+ were over 1.5 X 10(-6) M, the release of Ca2+ by this agent was inhibited. The Ca2+ releasing mechanism differed from that seen with A23187, therefore this release of Ca2+ from store sites was not due to Ca2+ ionophore actions. This agent may play the role of messenger in increasing the cytosolic Ca2+, provoking pharmaco-mechanical coupling, and thus producing the contraction. |
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