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. 2010 Jul 2;299(3):H634–H642. doi: 10.1152/ajpheart.00347.2010

Fig. 1.

Fig. 1.

Effects of ZD-7288 (ZD; n = 3) or ryanodine alone (n = 3) on the sinoatrial node (SAN) in the absence of isoproterenol (Iso). Shown are pseudo-ECGs of the canine isolated right atrium (RA). A,a: Baseline. Regular atrial activations (p) were found on the pseudo-ECG. b, ZD-7288 (3 μmol/l) infusion for 30 min. B,a: baseline. b, Ryanodine (3 μmol/l) infusion for 30 min in the first dog reduced heart rate (HR) by 16%. C: ryanodine (3 μmol/l) infusion for 30 min in the second dog caused an irregular sinus rhythm. a, Intermittent sinus pause induced by ryanodine infusion. b, Extended view of period 1 in C,a. c, Membrane voltage (Vm) tracings recorded from the inferior (traces a and b), middle (trace c), and superior (trace d) SAN and RA (traces f–h) during period 2 in C,b. Numbers on Vm tracings show the cycle length (CL; in ms). d, Isochronal map of period 3 in C,c. The isochronal lines are shown in colors. The time of each isochrone is marked by a number (in ms), with the time of the first activation as time 0. Numbers on Vm isochronal maps are in milliseconds. SVC; superior vena cava, RAA; right atrial appendage, A, anterior; P, posterior; S, superior; I, inferior; bpm, beats/min.