Hypertrophied myocardium is more dependent on extracellular calcium than the normal cardiac muscle

• Autor(a) principal: de Barros, Reginaldo [UNESP]
• Data de Publicação: 2010
• Outros Autores: Zornoff, Leonardo Antonio Mamede [UNESP], Ribeiro, Henrique B. [UNESP], Okoshi, Marina Politi [UNESP], Padovani, Carlos Roberto [UNESP], Aragon, Flávio F. [UNESP], Cicogna, Antonio Carlos [UNESP]
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://www.medscimonit.com/download/index/idArt/881100; http://www.ncbi.nlm.nih.gov/pubmed/20671609; http://hdl.handle.net/11449/71818
• topic: 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

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.