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KMID : 0811720030070000184
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Korean Journal of Physiology & Pharmacology
2003 Volume.7 No. 0 p.184 ~ p.0
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Alteration in Sarcoplasmic Reticulum-related Regulation of ANP Release in the Atrium from Hyperthyroid Rabbit
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Quan He Xiu
Jin Jing-Yu
Li Dan
Kim Sung-Zoo
Kim Sun-Hee
Cho Kyung-Woo
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Abstract
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It was shown that inhibition of sarcoplasmic reticulum calcium release with ryanodine increased atrial myocytic ANP release. This indicates that intracellular calcium release as well as calcium entry through sarcolemmal calcium channel is involved in the regulation of atrial myocytic ANP release. The purpose of the present study was to disclose the role of sarcoplasmic reticulum calcium release in the regulation of ANP release in the atrium from the hyperthyroid rabbits. New Zealand White rabbits were used. Hyperthyroid or sham rabbits were subcutaneously injected with thyroxine (0.5 mg/kg, daily) or vehicle, respectively, for one week. Experiments were performed in perfused beating left atria allowing atrial pacing and measurements of changes in atrial stroke volume, pulse pressure, transmural extracellular fluid translocation, cAMP efflux, and ANP release. The concentration of cAMP and ANP was measured by using radioimmunoassay. Ryanodine increased atrial myocytic ANP release concomitantly with decreases in atrial stroke volume and pulse pressure. Ryanodine-induced increase in ANP release and decrease in atrial dynamics were accentuated in the atria from hyperthyroid rabbits. These results suggest that sarcoplasmic reticulum-related regulation of ANP release is altered in the atrium from hyperthyroid rabbits.
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KEYWORD
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atrial natriuretic peptide, atrium, hyperthyroidism, ryanodine, sarcoplasmic reticulum
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