Figure 1.

(A) Telemetric surface ECGs of freely moving WT, Ca_v3.1^−/−, Ca_v1.3^−/− and Ca_v1.3^−/−/Ca_v3.1^−/− mice showed additive effect of Ca_v gene inactivation on AV conduction dysfunction. Solid bars indicate PR interval duration in different genotypes. Dotted bars indicate RR intervals. Arrows indicate isolated P waves. Note that in Ca_v1.3^−/−/Ca_v3.1^−/− mice, some P waves elicited a QRS complex and some isolated P waves fall into the T wave of the QRS complex. PR intervals were progressively longer in Ca_v3.1^−/−, Ca_v1.3^−/− and Ca_v1.3^−/−/Ca_v3.1^−/− mice. (B) Stars indicate statistical significance compared to WT (one-way ANOVA). (C) Isolated P waves were not found in WT and Ca_v3.1^−/− mice. The number of two or three consecutive isolated P waves measured was higher in Ca_v1.3^−/−/Ca_v3.1^−/− than in Ca_v1.3^−/− mice, indicating that AV conduction dysfunction in a Ca_v1.3^−/− genetic background was worsened by additional loss of Ca_v3.1 channels. Stars indicate statistical significance compared to WT (Kruskal-Wallis).