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. Author manuscript; available in PMC: 2015 Oct 1.
Published in final edited form as: Trends Cardiovasc Med. 2014 Jul 10;24(7):273–278. doi: 10.1016/j.tcm.2014.07.001

Figure 1.

Figure 1

Chain reaction leading to delayed after-depolarizations (DAD) in a cardiac myocyte. Spontaneous diastolic Ca release from the SR can generate Ca induced Ca releases from neighbouring RyR2 channels [1-2]. The resulting increase in cytosolic Ca concentration activates the Na/Ca exchanger with a net inward Na current that can trigger depolarization of the cell membrane [3-4] and potentially an ectopic beat [5]. Beta adrenergic stimulation enhances the likelihood of diastolic Ca releases from the SR and subsequently DADs through a protein kinase A (PKA)-mediated phosphorylation [P] of RyR2, SERCA and L-type Ca channels.