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KMID : 0811720030070000179
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Korean Journal of Physiology & Pharmacology
2003 Volume.7 No. 0 p.179 ~ p.0
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Sarcoplasmic Reticulum Calcium Release is Involved in the Regulation of Hypertonicity-Induced ANP Release
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Jin Jing-Yu
Li Dan
Jin Fu Wen
Kim Sung-Zoo
Kim Sun-Hee
Lee Ho-Sub
Cho Kyung-Woo
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Abstract
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Hypertonicity has been shown to increase atrial myocytic atrial natriuretic peptide (ANP) release. However, the mechanism by which hypertonicity increases ANP release has to be defined. The purpose of the present study was to define the mechanism responsible for the hypertonicity-induced increase in ANP release. Experiments were performed in beating rabbit atria allowing atrial pacing and measurements of changes in atrial volume during contraction (stroke volume), pulse pressure, transmural extracellular fluid translocation, cAMP efflux, and ANP secretion. The atrium was perfused with HEPES-buffered solution by means of a peristaltic pump (1 ml/min). Hypertonic solution (mannitol 100 mM) increased atrial myocytic ANP release concomitantly with increases in atrial stroke volume and pulse pressure and cAMP efflux. Blockade of sarcoplasmic reticulum function by combined treatment with thapsigargin and ryanodine attenuated the hypertonicity- induced increase in ANP release. Hypertonicity-induced increase in atrial dynamics was also attenuated by thapsigargin plus ryanodine. The treatment with thapsigargin plus ryanodine had no effect on hypertonicity-induced increase in cAMP efflux. These data suggest that sarcoplasmic reticulum calcium metabolism is involved in the regulation of hypertonicity-induced ANP release.
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KEYWORD
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Atrial natriuretic peptide, Atrium, Calcium release, Ryanodine, Sarcoplasmic reticulum
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