Increased calcium release from sarcoplasmic reticulum stimulated by inositol trisphosphate in spontaneously hypertensive rat heart cells |
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Authors: | Hideaki Kawaguchi Hitoshi Sano Hitoshi Okada Kenji Iizuka Hiroshi Okamoto Toshiyuki Kudo Takeshi Murakami Akira Kitabatake |
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Institution: | (1) Department of Cardiovascular Medicine, Hokkaido University School of Medicine, Sapporo 060, Japan |
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Abstract: | It is known that inositol (1, 4, 5)-trisphosphate (IP3) stimulates Ca2+ release from sarcoplasmic reticulum (SR) in several tissues, but in cardiac myocytes this phenomenon has not been confirmed. The purpose of the present study was to confirm the effect of (1, 4, 5)-IP3 on Ca2+ release from SR in cardiac myocytes. The effect of IP3 on Ca2+ release from SR in hypertrophic cardiac cells was also determined.We examined the effects of IP3 on Ca2+ release from cardiac myocyte SR by the bigital-image method in a single cell. We also determined the effect of IP3 on calcium release from isolated SR. SR was prepared from spontaneous hypertensive rat hearts and Wistar kyoto rat hearts. The SR was prelabeled with45Ca2+, and then incubated with the indicated concentrations of IP3 for 1 min at 37°C. In cardiac myocytes treated with saponin, Ca2+ release stimulated by 10 M (1, 4, 5)-IP3 was detected by fura-2. In45Ca2+ prelabeled SR, the maximal Ca2+ release was achieved at 10 M IP3 incubated for 1 min. The release of Ca2+ was higher in Sr of SHR than in the SR of WKY. IP3 stimulates Ca2+ release from cardiac SR, and this release is greater in SHR than in WKY. However, it is uncertain whether this phenomenon plays a role in cardiac hypertrophy. |
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Keywords: | Inositol-1 4 5-trisphosphate sarcoplasmic reticulum calcium release cardiac hypertrophy PI-response cardiac myocyte |
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