Temperature dependence and thermodynamic properties of Ca2+ sparks in rat cardiomyocytes.
Biophys J
; 89(4): 2533-41, 2005 Oct.
Article
em En
| MEDLINE
| ID: mdl-16113119
ABSTRACT
To elucidate the temperature dependence and underlying thermodynamic determinants of the elementary Ca2+ release from the sarcoplasmic reticulum, we characterized Ca2+ sparks originating from ryanodine receptors (RyRs) in rat cardiomyocytes over a wide range of temperature. From 35 degrees C to 10 degrees C, the normalized fluo-3 fluorescence of Ca2+ sparks decreased monotonically, but the Delta[Ca2+]i were relatively unchanged due to increased resting [Ca2+]i. The time-to-peak of Ca2+ sparks, which represents the RyR Ca2+ release duration, was prolonged by 37% from 35 degrees C to 10 degrees C. An Arrhenius plot of the data identified a jump of apparent activation energy from 5.2 to 14.6 kJ/mol at 24.8 degrees C, which presumably reflects a transition of sarcoplasmic reticulum lipids. Thermodynamic analysis of the decay kinetics showed that active transport plays little role in early recovery but a significant role in late recovery of local Ca2+ concentration. These results provided a basis for quantitative interpretation of intracellular Ca2+ signaling under various thermal conditions. The relative temperature insensitivity above the transitional 25 degrees C led to the notion that Ca2+ sparks measured at a "warm room" temperature are basically acceptable in elucidating mammalian heart function.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Temperatura
/
Cálcio
/
Canal de Liberação de Cálcio do Receptor de Rianodina
/
Sinalização do Cálcio
/
Miócitos Cardíacos
/
Modelos Biológicos
Tipo de estudo:
Prognostic_studies
Limite:
Animals
Idioma:
En
Revista:
Biophys J
Ano de publicação:
2005
Tipo de documento:
Article
País de afiliação:
China