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KMID : 0811720040080000185
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Korean Journal of Physiology & Pharmacology
2004 Volume.8 No. 0 p.185 ~ p.0
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Hyperosmolality Attenuates Cardiac Effects of C-type Natriuretic Peptide
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Quan He Xiu
Kim Hyun-Soon
Kim Sung-Zoo
Kim Sun-Hee
Lee Ho-Sub
Cho Kyung-Woo
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Abstract
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Cardiac atrium is sensitive to detect changes in fluid osmolality and to respond by increasing atrial myocytic ANP release. The mechanism by which hyperosmolality activates ANP release is related to the cross-talk between the sarcolemmal L-type Ca2+ channel activity and sarcoplasmic reticulum Ca2+ release. The purpose of the present study was to define the effect of hyperosmolality on the C-type natriuretic peptide (CNP)-induced changes in the endocrine cardiac function. Experiments were performed in perfused rabbit left atria allowing atrial pacing and measurements of changes in atrial volume during contraction (stroke volume), pulse pressure, transmural extracellular fluid translocation, cyclic nucleotides (cAMP, cGMP) efflux, and atrial natriuretic peptide (ANP) secretion. Cyclic nucleotides and ANP in the perfusate were measured by a specific radioimmunoassay. CNP increased atrial cGMP and cAMP efflux, and decreased atrial dynamics, stroke volume and pulse pressure, and ANP release. Hyperosmolality (100 mM mannitol added) increased atrial stroke volume and pulse pressure and myocytic ANP release. Hyperosmolality attenuated CNP-induced increases in cGMP and cAMP levels and decreases in atrial dynamics and secretory functions. These findings indicate that hypertonicity attenuates CNP-induced decreases in atrial dynamics and ANP release via NPR-B-cGMP signaling.
Source: Korean Journal of Physiology & Pharmacology.2004 Oct;8(Suppl I):S137-S137
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KEYWORD
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Atrial natriuretic peptide, Atrium, cGMP, CNP, Hyperosmolality
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