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. Author manuscript; available in PMC: 2008 Mar 1.
Published in final edited form as: Am J Physiol Heart Circ Physiol. 2006 Nov 22;292(3):H1568–H1578. doi: 10.1152/ajpheart.00619.2006

Figure 5.

Figure 5

Slopes of the (A) dynamic and (B) S1-S2 RCs as a function of BCL and stimulus site. Data are shown only from pacing at the apex or the base. Data recorded from all three epicardial regions is shown. For both RCs, we tested whether there was a difference in slope as a function of stimulus site using an ANOVA model that used repeated measures to account for inter-animal differences. The S1-S2 RC slope was significantly steeper when pacing from the apex compared with pacing from the base (p = 0.015). The difference in slope was greatest at shorter BCL. The dynamic RC slope appears steeper when pacing at the apex versus pacing at the base over the same range of BCL as the S1-S2 RC slope. Surprisingly, for the dynamic RC the difference was not found to be significant.