Blood Calcium Levels in Immature Rats: Influence of Extracellular Calcium Concentration on Myocardial Calcium Handling

Autor(es)

Bassani, Rosana A. ^[1] ; Gilioli, Rovilson ^[2] ; Oliveira, Elizangela S. ; Hoehr, Nelci F. ^[3]

Afiliação do(s) autor(es)

^[1] Univ Estadual Campinas, UNICAMP, Ctr Biomed Engn, BR-13083881 Campinas, SP - Brazil

^[2] Univ Estadual Campinas, Multidisciplinary Ctr Biol Invest Lab Anim Sci, BR-13083877 Campinas, SP - Brazil

^[3] Univ Estadual Campinas, Dept Clin Pathol, Sch Med Sci, BR-13083881 Campinas, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: EXPERIMENTAL ANIMALS; v. 61, n. 4, p. 399-405, JUL 2012.
• Citações Web of Science: 5

Resumo

Calcium ions play an important role in several cell functions, from fertilization to cell death. The cytosolic Ca2+ concentration is much lower than the extracellular concentration ({[}Ca2+](o)). The latter may markedly affect Ca2+ fluxes across the cell membrane and thus the cellular Ca2+ load. Thus, when working with preparations in vitro, it is important to keep {[}Ca2+](o) close to the in vivo value. In this study, we determined the calcemia in immature rats, for which values are currently unavailable, and investigated how supraphysiological {[}Ca2+](o) affects myocardial Ca2+ handling. Blood ionized {[}Ca2+] was similar in neonatal (2-5 days old) and adults Wistar rats (1.28 +/- 0.03 and 1.31 +/- 0.03 mmol/l; n=6 and 5, respectively, P>0.37), and lower than the {[}Ca2+](o) range often used in experiments with neonatal myocardial preparations. Cytosolic Ca2+ transients, measured with indo-1 in neonatal ventricular myocytes, were enhanced by an increase in {[}Ca2+](o) from 1.2 to 2 mM, which also increased the Ca2+ content in the sarcoplasmic reticulum (SR), and changed the pattern of competition between the main transporters that remove Ca2+ from the cytosol (SR Ca2+-ATPase and Na+/Ca2+ exchanger). These observations stress the importance of using physiological {[}Ca2+](o) values for reliability of results. It is expected that the present calcemia data, reported for the first time in immature rats, may contribute to the refinement of in vitro experiments with neonatal rat preparations. (AU)

• Processo FAPESP: 08/54795-6 - Regulacao adrenergica do cronotropismo atrial e do inotropismo ventricular durante o desenvolvimento pos-natal do rato.
• Beneficiário: Rosana Almada Bassani
• Modalidade de apoio: Auxílio à Pesquisa - Regular