Passive Ca2+ Binding In Ventricular Myocardium Of Neonatal And Adult Rats.

dc.creatorBassani, R A
dc.creatorShannon, T R
dc.creatorBers, D M
dc.date1998-Jun
dc.date2015-11-27T12:19:28Z
dc.date2015-11-27T12:19:28Z
dc.date.accessioned2018-03-29T00:53:14Z
dc.date.available2018-03-29T00:53:14Z
dc.identifierCell Calcium. v. 23, n. 6, p. 433-42, 1998-Jun.
dc.identifier0143-4160
dc.identifier
dc.identifierhttp://www.ncbi.nlm.nih.gov/pubmed/9924635
dc.identifierhttp://repositorio.unicamp.br/jspui/handle/REPOSIP/194294
dc.identifier9924635
dc.identifier.urihttp://repositorioslatinoamericanos.uchile.cl/handle/2250/1294527
dc.descriptionIn this study, passive Ca2+ binding was determined in ventricular homogenates (VH) from neonatal (4-6 days) and adult rats, as well as in digitonin-permeabilized adult ventricular myocytes. Ca2+ binding sites, both endogenous and exogenous (Indo-1 and BAPTA) were titrated. Sarcoplasmic reticulum and mitochondrial Ca2+ uptake were blocked by thapsigargin and Ru360, respectively. Free [Ca2+] ([Ca2+]F) was measured with Indo-1 and bound Ca2+ ([Ca2+]B) was the difference between [Ca2+]F and total Ca2+. Apparent Ca2+ dissociation constants (Kd) for BAPTA and Indo-1 were increased by 10-20 mg VH protein/ml (from 0.35 to 0.92 microM for Indo-1 and from 0.20 to 0.76 microM for BAPTA) and also by ruthenium red in the case of Indo-1. Titration with successive CaCl2 additions (2.5-10 nmoles) yielded delta[Ca2+]B/delta[Ca2+]F for the sum of [Ca2+]B at all three classes of binding sites. From this function, the apparent number of endogenous sites (Ben) and their Kd (Ken) were determined. Similar Ken values were obtained in neonatal and adult VH, as well as in adult myocytes (0.68 +/- 0.14 microM, 0.69 +/- 0.13 microM and 0.53 +/- 0.10 microM, respectively). However, Ben was significantly higher in adult myocytes than in adult VH (1.73 +/- 0.35 versus 0.70 +/- 0.12 nmol/mg protein, P < 0.01), which correspond to approximately 300 and 213 mumol/l cytosol. This indicates that binding sites are more concentrated in myocytes than in other ventricular components and that Ben determined in VH underestimates cellular Ben by 29%. Although Ben values in nmol/mg protein were similar in adult and neonatal VH (0.69 +/- 0.12), protein content was much higher in adult ventricle (125 +/- 7 versus 80 +/- 1 mg protein/g wet weight, P < 0.01). Expressing Ben per unit cell volume (accounting for fractional mitochondrial volume, and 29% dilution in homogenate), the passive Ca2+ binding capacity at high-affinity sites is approximately 300 and 176 mmol/l cytosol in adult and neonatal rat ventricular myocytes, respectively. Additional estimates suggest that passive Ca2+ buffering capacity in rat ventricle increases markedly during the first two weeks of life and that adult levels are attained by the end of the first month.
dc.description23
dc.description433-42
dc.languageeng
dc.relationCell Calcium
dc.relationCell Calcium
dc.rightsfechado
dc.rights
dc.sourcePubMed
dc.subjectAging
dc.subjectAnimals
dc.subjectAnimals, Newborn
dc.subjectCalcium
dc.subjectChelating Agents
dc.subjectDose-response Relationship, Drug
dc.subjectEgtazic Acid
dc.subjectHeart Ventricles
dc.subjectIndoles
dc.subjectKinetics
dc.subjectMyocardium
dc.subjectRats
dc.subjectRats, Sprague-dawley
dc.subjectRuthenium Compounds
dc.subjectRuthenium Red
dc.subjectSpectrometry, Fluorescence
dc.subjectTime Factors
dc.titlePassive Ca2+ Binding In Ventricular Myocardium Of Neonatal And Adult Rats.
dc.typeArtículos de revistas


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