Inhibition of G protein-gated K+ channels by tertiapin-Q rescues sinus node dysfunction and atrioventricular conduction in mouse models of primary bradycardia

Figures

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  Figure 1. PP rate, heart rate and atrioventricular conduction in Cav1.3−/− and Cav1.3−/−/Cav3.1−/− mice under basal conditions. PP rate, heart rate and PR interval recorded in WT (black circle), Cav1.3−/− (red circle, (A–C) and Cav1.3−/−/Cav3.1−/− mice (orange circle, G-I), together with corresponding representative samples of telemetric ECG recordings (WT in (D), Cav1.3−/− in (E) and Cav1.3−/−/Cav3.1−/− in (F). (J) PR interval recorded in Cav1.3−/− and Cav1.3−/−/Cav3.1−/− mice during 24 h telemetric recording. Statistics: unpaired t test. (K) Number of 2nd-degree atrioventricular blocks per minutes (AVBII/min) in Cav1.3−/− and Cav1.3−/−/Cav3.1−/− mutant animals. Statistics: Mann-Whitney test. Error bars define the s.e.m.

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  Figure 2. ECG characteristics of HCN4-CNBD and Nav1.5+/− mice under basal conditions. 24 h heart rate and PR interval in WT (black circle) and HCN4-CNBD (green circle, A,B) together with the corresponding representative samples of telemetric ECG recordings (WT in C, HCN4-CNBD in D). 24 h averaged value of PR (E) and QRS (F) intervals recorded in WT (black circle) and Nav1.5+/− (gray bars) mice. G: Close up of two superimposed ECG complexes from WT (black line) and Nav1.5+/− (gray circle) mouse. Statistics: unpaired t test. Error bars define the s.e.m.

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  Figure 3. Tertiapin-Q effect in Cav1.3−/− SND mice. (A) Representative samples of telemetric ECG recordings from Cav1.3−/− mice before (left) and after (right) tertiapin-Q (Tert) injection; arrow indicates AVBII. B: PP rate increase following injection of tertiapin-Q. C: PR interval duration before (filled red circle) and after (horizontally red-striped circle) injection of 5 mg/kg tertiapin-Q. Statistics (B,C): paired t-test Number of AVBII (D) and SAN pause (E) counted in Cav1.3−/− animals in the absence (filled red circle) and in the presence (horizontally red-striped circle) of 5 mg/kg tertiapin-Q. Statistics (D,E): Wilcoxon test. Dot-plots of RR versus PR intervals measured in Cav1.3−/− mice, and relative linear regression line, in control conditions (F) and after injection of 5 mg/kg tertiapin-Q (G). (H) r-Spearman correlation coefficients calculated in control condition (full red circle) and after (horizontally red-striped circle) of 5 mg/kg tertiapin-Q. Statistics: Wilcoxon test. (I) Angular coefficients of the regression line between the RR and the respective PR intervals before (filled red circle), after injection of the peptide in Cav1.3−/− (horizontally red-striped bar) and…

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  Figure 4. Tertiapin-Q effect in Cav1.3−/−/Cav3.1−/− SND mice. (A) Representative samples of telemetric ECG recording in Cav1.3−/−/Cav3.1−/− animals in absence (left) and in presence (right) of tertiapin-Q 5 mg/kg. Arrows indicate AVBII. (B) Effect of tertiapin-Q on PP rate in mutant mice. (C) Averaged value of PR interval before (filled orange circle) and after (horizontally orange-striped circle) injection of 5mg/kg tertiapin-Q. Statistics (B,C): paired t-test. AVBII (D) and SAN pauses (E) per minutes recorded in control conditions (filled orange circle) and after injection (horizontally red-striped circle) of the peptide. Statistics (D,E): Wilcoxon test. Cav1.3−/−/Cav3.1−/− mice dot-plots of RR versus PR interval and relative linear regression lines in control condition (F) and in 5 mg/kg tertiapin-Q (G). (H) r-Spearman correlation coefficients calculated in control condition (filled orange circle) and after (horizontally orange-striped circle) of 5 mg/kg tertiapin-Q. Statistics: Wilcoxon test. (I) Angular coefficient values of the regression line of RR-PR intervals in control condition (full orange circle), after injection of the tertiapin-Q both in Cav1.3−/−/Cav3.1−/− (horizontally…

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  Figure 5. Effect of tertiapin-Q on heart rate and atrioventricular conduction in HCN4-CNBD and Nav1.5+/− mice. (A) Representative samples of telemetric ECG recording HCN4-CNBD animals in absence (left) and in presence (right) of tertiapin-Q 5 mg/kg. Heart rate (B) and PR interval (C) in HCN4-CNBD mice before (filled light green circle) and after (horizontally green-striped circle) injection of 5 mg/kg tertiapin-Q. Statistics: paired t-test. (D) Values of the PR interval difference measured in tertiapin-Q 5 mg/kg and control (NaCl) condition in Nav1.5+/+ homozygous (Nav1.5+/+, black circle) and heterozygous (Nav1.5+/−, gray circle) mice. (E) PR intervals in Nav1.5+/+ mice in control condition (black circle) and in heterozygous mice injected with tertiapin-Q (horizontally gray-striped circle). (F) Values of the difference of QRS interval measured in tertiapin-Q 5 mg/kg and control (NaCl) condition in Nav1.5+/+ (black circle) and Nav1.5+/− (gray circle) mice. (G) QRS interval in Nav1.5+/+ mice in control condition (black circle) and in heterozygous Nav1.5+/− mice injected with tertiapin-Q (horizontally gray-striped circle). Statistics (D-G): unpaired t-test. *p < 0.05, **p < 0.01, ****p <…

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  Figure 6. Tertiapin-Q effect on heart rate and PR interval in Girk4−/− animals. (A) Representative samples of telemetric ECG recordings from Girk4−/− mice before (left) and after (right) 5 mg/kg tertiapin-Q injection. Heart rate (B) and PR interval (C) in Girk4−/− mice before (full green circle) and after (horizontally green-striped circle) injection of tertiapin-Q. Statistics: paired t-test.

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  Figure 7. Effect of different molecules employed to treat bradycardia and cardiac conduction dysfunctions in comparison to tertiapin-Q in Cav1.3−/− mice. Heart rate (A) and corresponding representative ECG traces (B) recorded in Cav1.3−/− animals before and after injection of 5 mg/kg tertiapin-Q, 0.5 mg/kg atropine (Atro), 0.1 mg/kg isoproterenol (Iso) or 10mg/kg theophylline (Theo). (C) Duration of effect on the heart rate of the different molecules injected in Cav1.3−/− mice. (D) PR interval values measured in control condition and after injection of 5 mg/kg tertiapin-Q, 0.5 mg/kg atropine, 0.1 mg/kg isoproterenol or 10 mg/kg theophylline. Legend: control condition (red bar); 5 mg/kg tertiapin-Q (horizontally red-striped bar); 0.5 mg/kg atropine (vertically red-striped bar); 0.1 mg/kg isoproterenol (red-dotted bar); 10 mg/kg theophylline (transversally red-striped bar). Statistics: Kruskal-Wallis test followed by multiple comparison Dunn’s test. *p < 0.05; **p < 0.01, ***p < 0.001, ****p < 0.0001. Error bars define the s.e.m.