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PHYSIOLOGY 
Figure 1. — Form of the ventricular action potential and electrocardiogram in different species. Phases of the 
action potential: 0 = rapid depolarization; 1 = rapid initial repolarization (spike); 2 = plateau; 3 = rapid 
terminal repolarization. 
A: Human right ventricular trabecula carnae (constructed from data of Trautwein et al.'-). Below, typical 
human ECG. 
B: Perfused cat heart, synchronous with electrogram from aortic cannula to apex (from personal data). 
C: Perfused pig moderator band with synchronous Purkinje action potential (constructed from data of 
Gettes et al.°^). Below, typical pig ECG. 
D: Guinea pig heart in situ, with synchronous ECG ( constructed from data of GargouiP). 
E: Rat heart in situ, with synchronous ECG (constructed from data of GargouiP). 
