CIC   05421
CENTRO DE INVESTIGACIONES CARDIOVASCULARES "DR. HORACIO EUGENIO CINGOLANI"
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
CAMKII EXACERBATES CALCIUM WAVES DURING REPERFUSION OF ISCHEMIC HEART
Autor/es:
VALVERDE CA; MATTIAZZI A; ESCOBAR AL
Lugar:
San Francisco
Reunión:
Congreso; 58th Annual Meeting; 2014
Institución organizadora:
Biophysical Society
Resumen:
Cardiac dysfunction is associated with an abnormal intracellular Ca2+
cycling, particularly during the setting of ischemia/reperfusion (I/R).
Hearts submitted to ischemia suffer an increase in diastolic Ca2+,
accompanied with an increase in sarcoplasmic reticulum (SR) Ca2+ load.
At the onset of reperfusion there is a massive increase in cytosolic
Ca2+, associated with an abrupt release of Ca2+ from the SR (Cardiovasc
Res, 2006,2010). In a previous work we showed that arrhythmogenic Ca2+
waves are the subcellular events associated with this SR-Ca2+ release
(Circulation, 2013). Moreover, Ca2+/calmodulin-dependent protein kinase
II (CaMKII) has been associated with reperfusion arrhythmias,
particularly associated with a CaMKII-dependent phosphorylation of
Ser2814 site of ryanodine receptors (RyR2) (JMCC,2011). The aim of the
present work was to evaluate the role of CaMKII on the abrupt SR-Ca2+
release and enhanced frequency of Ca2+ waves during reperfusion. The
experiments were done in perfused mouse (C57BL/6) hearts loaded with the
Ca2+ indicator Fluo-4, on an upright confocal microscope. Hearts were
submitted to ischemia and reperfusion (15/30 min) at 32ºC, in the
presence and absence of a CaMKII inhibitor (KN-93, 2.5 μM). We evaluated
Ca2+ waves at the epicardial layer of the heart. Inhibition of CaMKII
did not prevent the increase in Ca2+ wave frequency (0.15±0.05
pre-ischemia vs. 0.29±0.04 waves/100μm/s, ischemia) nor the velocity of
the Ca2+ wave propagation (122.01±4.62 vs. 126.06±1.02 μm/s). During
reperfusion in the presence of KN-93, we observed a reduction in Ca2+
waves frequency (0.28±0.06 vs. 0.14±0.02 waves/μm/s, control vs. KN-93),
and also in the velocity of its propagation (114.99±3.02 vs. 94.75±1.45
μm/s, control vs. KN-93). The results indicate that the increase in the
proarrhythmogenic Ca2+ waves at the onset of reperfusion are mainly
mediated by a CaMKII-dependent phosphorylation.