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. Author manuscript; available in PMC: 2013 Aug 22.
Published in final edited form as: J Cardiovasc Electrophysiol. 2011 Oct 10;23(3):309–318. doi: 10.1111/j.1540-8167.2011.02191.x

Figure 2. Intracellular Ca2+ handling proteins control the dominant automaticity of E8.5 hearts.

Figure 2

A: Raw MEA tracings from the LIFT of E8.5 hearts and from the SAN of E12.5 hearts at baseline (Pre; before drug application) and 10 minutes after drug application (Post) are shown. B: Raw tracings from left and right pacemaker sites are shown to illustrate the effect on HRs by co-application of Ryanodine (Rya) and KB after either Rya (E8.5) or KB (E12.5) blockade. At E8.5, combination of Rya and KB completely arrested LIFT pacemaking activity in all hearts, and 3 of 8 hearts displayed residual pacemaker activity in the RIFT (pacemaker location switch, left bottom tracing). C: Summary of effects of 10 Rya, 50 KB, and 10 APB (in µM) on HRs of E8.5 and E12.5 hearts. Values of residual HRs after drugs relative to controls in this histogram for E8.5 and E12.5 hearts are: KB: 95.3±4.9 and 85.8±4.3%; APB: 92.1±8.1 and 95.2±3.0%; Rya: 81.6±6.9 and 72.1±12.1%; Rya+APB: 67.0±13.7 and 61.5±8.8%; and Rya+KB: 15.9±25.0 and 55.0±9.9%, respectively. Asterisks indicate p<0.05. The number in each column represents the number of hearts tested. Vertical bars represent 50 µV at E8.5 and 250 µV at E12.5 hearts in this and following figures unless otherwise indicated. Horizontal bars denote 200 ms.