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. Author manuscript; available in PMC: 2013 Apr 1.
Published in final edited form as: Circ Arrhythm Electrophysiol. 2012 Mar 9;5(2):371–379. doi: 10.1161/CIRCEP.111.969493

Figure 3.

Figure 3

Composite data of electrophysiological parameters of superior vena cava (SVC) sleeve preparations with and without phase 4 depolarization. In SVC with phase 4, action potential duration measured at 85% and 50% repolarization (APD85 and APD50, A and B) were significantly increased, action potential amplitude (APA) and maximum upstroke velocity of action potential upstroke (Vmax) (C and D) were significantly decreased. Vmax shows a progressive decrease with acceleration in SVC cells with no phase 4 depolarization but a biphasic relationship for cells with phase 4. No differences were observed in resting membrane potential (RMP, E), but a significant increase in take-off potential (TOP, F) was observed at slow rates in SVC cells with phase 4. P<0.05, * SVC with phase 4 vs. SVC with no phase 4.