Publicação: Hypertrophied myocardium is more dependent on extracellular calcium than the normal cardiac muscle
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2010-08-13
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Background: The aim of this study was to analyze stable hypertrophied myocardial function and its response to inotropic maneuvers in rats submitted to renovascular hypertension for a 10-week period (RHT group, n=10). Material/Methods: Myocardial performance was studied in isolated left ventricle papillary muscles in isometric contraction under the following conditions: at postrest contraction of 30 seconds (PRC), at extracellular calcium (ECa 2+) chloride concentration of 1.25 and 5.20 mM, and after beta-adrenergic stimulation with 10 -6 M isoproterenol (ISOP). Results: The results were compared with normotensive Wistar controls rats (C group, n=10). In basal condition, resting tension, and contraction time (TPT) were greater, while relaxation time (RT 50) tended to be longer in RHT than C group. PRC and ISOP promoted a similar change in muscle function response intensity (Δ) in both groups. ECa 2+ shift did not change TPT in the C group and decreased TPT in the RHT animals; Δ was different between these groups. RT 50 increased in C and decreased in RHT, both without statistical significance; however, Δ was different. Conclusions: These results suggest that hypertrophied myocardial dysfunction may be attibuted to changes in intracellular calcium cycling. © Med Sci Monit, 2010.
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Calcium isoproterenol, Myocardium function, Papillary muscle, Renovascular hypertension, calcium ion, chloride, isoprenaline, animal experiment, animal model, animal tissue, beta adrenergic stimulation, calcium cell level, concentration (parameters), controlled study, extracellular calcium, heart contraction, heart function, heart muscle fiber membrane steady potential, heart muscle relaxation, heart papillary muscle, heart performance, heart ventricle hypertrophy, inotropism, male, muscle isometric contraction, nonhuman, rat, renovascular hypertension, Wistar rat
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Case Reports and Clinical Practice Review, v. 16, n. 8, 2010.
