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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: OBJECTIVE, METHODS, RESULTS. Meshes: Animals, Anti-Arrhythmia Agents, Atrial Natriuretic Factor, Calcium Channel Blockers, Cyclooxygenase Inhibitors, Dose-Response Relationship, Drug, Endothelin A Receptor Antagonists, Endothelin-1, Female, Heart, Heart Atria, In Vitro Techniques, Indomethacin, Male, Mitogen-Activated Protein Kinases, Nifedipine, Ouabain, Peptides, Cyclic, Rabbits, Radioimmunoassay, Receptor, Endothelin B, Sodium-Calcium Exchanger, Thiourea.
user
Does ouabain stimulate atrial natriuretic peptide secretion via the endothelin-1/ET ( B ) receptor-mediated pathway in beating rabbit atria? Context: Ouabain has been reported to increase the secretion of atrial natriuretic peptide (ANP) in vitro. However, the mechanism by which ouabain increases ANP secretion is not well known. Therefore, the purpose of the present study was to investigate the underlying mechanism of ouabain-stimulated ANP secretion. A perfused beating rabbit atrial model was used. The ANP and ET-1 levels in the atrial perfusates were measured by radioimmunoassays. Ouabain (1.0, 3.0 and 6.0 μmol/L) significantly increased atrial ANP secretion in a dose-dependent manner, while the endothelin (ET)-1 levels were increased by the higher doses (3.0 and 6.0 μmol/L) of ouabain. Ouabain-increased atrial ET-1 release was blocked by PD98059 (30.0 μmol/L), an inhibitor of mitogen-activated protein kinase (MAPK). Nifedipine (1.0 μmol/L), an inhibitor of L-type Ca(2+) channels, completely abolished ouabain-increased ANP secretion without changing the ouabain-induced atrial dynamics. KB-R7943 (3.0 μmol/L), an inhibitor of Na(+)-Ca(2+) exchangers, completely blocked the effects of ouabain-increased atrial dynamics, but did not modulate ouabain-increased ANP secretion. ET-1 significantly stimulated atrial ANP release in a dose-dependent manner. The effects of ET-1 and ouabain on ANP secretion were completely blocked by BQ788 (0.3 μmol/L), an inhibitor of ET-1 type B (ET(B)) receptors, but not by BQ123 (0.3 μM), an inhibitor of ET-1 type A receptors. Ouabain-increased atrial ANP secretion was blocked by PD98059 and indomethacin (30.0 μmol/L), an inhibitor of cyclooxygenase.
assistant
Ouabain significantly stimulated atrial ANP secretion via an ET-1-ET(B) receptor-mediated pathway involving MAPK signaling pathway activation and prostaglandin formation. Final Decision: yes