Optical mapping of sarcoplasmic reticulum Ca2+ in the intact heart: ryanodine receptor refractoriness during alternans and fibrillation.

ABSTRACT:

Rationale

Sarcoplasmic reticulum (SR) Ca(2+) cycling is key to normal excitation-contraction coupling but may also contribute to pathological cardiac alternans and arrhythmia.

Objective

To measure intra-SR free [Ca(2+)] ([Ca(2+)]SR) changes in intact hearts during alternans and ventricular fibrillation (VF).

Methods and results

Simultaneous optical mapping of Vm (with RH237) and [Ca(2+)]SR (with Fluo-5N AM) was performed in Langendorff-perfused rabbit hearts. Alternans and VF were induced by rapid pacing. SR Ca(2+) and action potential duration (APD) alternans occurred in-phase, but SR Ca(2+) alternans emerged first as cycle length was progressively reduced (217±10 versus 190±13 ms; P<0.05). Ryanodine receptor (RyR) refractoriness played a key role in the onset of SR

SUBMITTER: Wang L 

PROVIDER: S-EPMC4000583 | biostudies-literature | 2014 Apr

REPOSITORIES: biostudies-literature