Figure 7.
Frequency dependence of RA activation. A, Representative dominant frequency maps of RA paced at 10 Hz (top) and 25 Hz (bottom) in Cx40+/+ (left) and Cx40−/− (right) mice. Color bar indicates frequency. At 10 Hz, 1:1 activation occurs throughout the RA in both genotypes. At 25 Hz, the Cx40+/+ RA follows 1:1; in the Cx40−/− RA, a breakup of conduction with several lower frequency domains is seen. Single-pixel recordings show complex patters of activation at various sites. B, Percentage of RA following 1:1 is plotted as a function of pacing frequency. Note conduction breakdown between 12 and 16 Hz in Cx40−/− mice.