Existence of a triple layered system of Ca-generators in swine purkinje cells

Daniels, Rebecca Elizabeth (2013) Existence of a triple layered system of Ca-generators in swine purkinje cells. Masters thesis, Memorial University of Newfoundland.

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Abstract

Background: Spontaneous electrical signals from cardiac Purkinje fibers trigger life threatening arrhythmias. This abnormal signaling was associated with increased spontaneous intracellular Ca²⁺ activity following myocardial infarction. The present study aimed to understand the Ca²⁺ cycling within the endoplasmic reticulum (ER) in Purkinje cells (Pcells) in the large mammalian heart. -- Methods: Immunofluorescence, electron microscopy, and fast confocal Ca²⁺ imaging were used with normal porcine Pcells, to examine the Ca²⁺ activity under various conditions including addition of specific agonist/antagonists of ER-Ca²⁺ channels. -- Results: Spontaneous Ca²⁺ activity was different between 3 distinct subcellular regions: 1) the "Near SL" region was in close apposition with the sarcolemma (SL) and contained IP₃R₁; 2) the "SubSL" region, contained a thin layer of RyR ₃, and 3) the core region contained RyR₂. -- Conclusions: These results are consistent with the existence of 3 distinct layers of ER Ca²⁺ -generators in porcine Pcells, which highlights potential new mechanisms for Purkinje arrhythmogenicity.

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