Cardiac expression of ryanodine receptor subtype 3; a strategic component in the intracellular Ca2+ release system of Purkinje fibers in large mammalian heart

摘要

Background: Three distinct Ca2+ release channels were identified in dog P-cells: the ryanodine receptor subtype 2 (RyR2) was detected throughout the cell, while the ryanodine receptor subtype 3 (RyR3) and inositol phosphate sensitive Ca2+ release channel (InsP3R) were found in the cell periphery. How each of these channels contributes to the Ca2+ cycling of P-cells is unclear. Recent modeling of Ca2+ mobilization in P-cells suggested that Ca2+ sensitivity of Ca2+ induced Ca2+ release (CICR) was larger at the P-cell periphery. Our study examined whether this numerically predicted region of Ca2+ release exists in live P-cells. We compared the regional Ca2+ dynamics with the arrangement of intracellular Ca2+ release (CR) channels.