Myocardial calcium overload during graded hypothermia and after rewarming in an in vivo rat model.
Acta Physiol (Oxf)
; 207(3): 460-9, 2013 Mar.
Article
en En
| MEDLINE
| ID: mdl-22950548
AIM: Mechanisms underlying cardiac contractile dysfunction during and after rewarming from hypothermia remain largely unknown. We have previously reported myocardial post-hypothermic calcium overload to be the culprit. The aim of the present study was to measure changes in myocardial [Ca(2+) ](i) during graded hypothermia and after rewarming in an anesthetized, intact rat model, using the (45) Ca(2+) technique. METHODS: Rats were randomized and cooled to 15 °C. Hearts were excised and perfusion-washed to remove extracellular calcium after 0.5 h of hypothermia (n = 9), 4 h of hypothermia (n = 8), and after 4 h of hypothermia and 2 h rewarming (n = 9). A normothermic group, kept at 37 °C for 5 h, served as control (n = 6). [Ca(2+) ](i) was determined in perchloric acid extracts of heart tissue. Spontaneous cardiac electromechanic work was maintained during hypothermia without cardiac arrest or ischaemia. RESULTS: Between 0.5 and 4 h at 15 °C, a six-fold increase in cardiac [Ca(2+) ](i) was observed (0.55 ± 0.10 vs. 2.93 ± 0.76 µmol (g dry wt)(-1) ). Rewarming resulted in a 33% decline in [Ca(2+) ](i) , but the actual value was significantly above the value measured in control hearts. CONCLUSION: We show that calcium overload is a characteristic feature of the beating heart during deep hypothermia, which aggravates by increasing duration of exposure. The relatively low decline in [Ca(2+) ](i) during the rewarming period indicates difficulties in recovering calcium homoeostasis, which in turn may explain cardiac contractile dysfunction observed after rewarming.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Calcio
/
Función Ventricular Izquierda
/
Recalentamiento
/
Disfunción Ventricular Izquierda
/
Hipotermia Inducida
/
Miocardio
Tipo de estudio:
Prognostic_studies
Límite:
Animals
Idioma:
En
Revista:
Acta Physiol (Oxf)
Asunto de la revista:
FISIOLOGIA
Año:
2013
Tipo del documento:
Article
País de afiliación:
Noruega
Pais de publicación:
Reino Unido