Dynamic calcium movement inside cardiac sarcoplasmic reticulum during release.

Rationale: Intra-sarcoplasmic reticulum (SR) free [Ca] ([Ca](SR)) provides the driving force for SR Ca release and is a key regulator of SR Ca release channel gating during normal SR Ca release or arrhythmogenic spontaneous Ca release events. However, little is known about [Ca](SR) spatiotemporal dynamics.

Objective: To directly measure local [Ca](SR) with subsarcomeric spatiotemporal resolution during both normal global SR Ca release and spontaneous Ca sparks and to evaluate the quantitative implications of spatial [Ca](SR) gradients.

Selective down-regulation of sub-endocardial ryanodine receptor expression in a rabbit model of left ventricular dysfunction.

Defective sarcoplasmic reticulum (SR) Ca2+ handling is evident in cardiomyopathy and may be mediated by selective dysregulation of SR Ca2+ handling proteins. To assess whether regulation of SR Ca2+ release may vary regionally within the normal and diseased heart, left ventricular transmural expression and activity of the ryanodine receptor (RyR2) was studied in a rabbit coronary artery ligation model of left ventricular dysfunction (LVD). Tissue/cells were isolated from both the sub-endocardial and subepicardial layers of the left ventricular free wall from sham-operated and coronary artery ligated rabbit hearts.

Assessment of sarcoplasmic reticulum Ca(2+) flux pathways in cardiomyocytes from rabbits with infarct-induced left-ventricular dysfunction.

The aim of the study was to correlate intracellular Ca(2+) transients with Ca(2+) uptake and efflux characteristics of the sarcoplasmic reticulum (SR) in ventricular myocytes isolated from rabbits with left-ventricular dysfunction (LVD). Chronic (8 weeks) ligation of a coronary artery caused marked LVD in rabbits. Measurements of intracellular [Ca(2+)] were made using Fura-2 on intact, single, left-ventricular myocytes.