Decreased cardiac pacemaking and attenuated β-adrenergic response in TRIC-A knockout mice

Figures

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  Fig 1. A. RT-PCR and Western blotting. i) RT-PCR. RT-PCR analyses of the sinus nodes of WT (W), TRIC-A–/–(A), and TRIC-B+/–(B) mice (A). n = 4. N, negative control. Primer sets are indicated. ii). Western blotting analyses. Western blotting analyses of adrenergic β1 receptor (β1), KCa1.1, and GAPDH expression in the sinus nodes of WT (W) and TRIC-A–/–mice (A). CREB and pCREB were evaluated before and after injection of isoproterenol. iii) Isoproterenol-induced phosphorylation of CREB in wild-type and TRIC-A–/–SA nodes. WT, wild-type; Wi, WT mice given isoproterenol; Ai, TRIC-A–/–mice given isoproterenol. B. Systolic blood pressure and heart rate Basal systolic blood pressure (SBP) and heart rate (HR) in wild-type (WT) (open bars), TRIC-A–/–(solid bars), and TRIC-B+/–mice (hatched bars). n = 11–19. P < 0.05. C. Scatterplot of systolic blood pressure and heart rate. SBP and HR data of wild-type (WT) (circles, left panel), TRIC-A–/–(dots, middle panel), and TRIC-B+/–mice (solid squares, right panel) were plotted. Calculated regression lines are indicated.

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  Fig 2. Changes in systolic blood pressure and heart rate due to pharmacological manipulation. Systolic blood pressure (SBP) and heart rate (HR) after administration of isoproterenol (0.3 mg/kg; A), caffeine (10 mg/kg; B), and dantrolene (10 mg/kg; C) in wild-type (WT) (open bar), TRIC-A–/–(solid bar), and TRIC-B+/–(hatched bar) mice. A. Isoproterenol significantly decreased SBP in all three groups (upper panel). WT and TRIC-B+/–mice showed significant increases in HR in response to isoproterenol. TRIC-A–/–mice showed a marginal increase in HR due to isoproterenol. n = 9–10. P < 0.05. B. Caffeine induced a slight increase in SBP in WT mice and TRIC-A–/–mice. n = 6 in each group. C. Dantrolene slightly decreased SBP in WT mice and TRIC-A–/–mice. Values are the mean ± standard error of the mean. n = 6–7. SBP, systolic blood pressure; HR, heart rate.

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  Fig 3. Electrocardiography and heart rate variability analyses. A. i) Representative electrocardiography (ECG) traces of WT, TRIC-A–/–, and TRIC-B+/–mice. ii) Statistical analyses of calculated HR in WT (open bar), TRIC-A–/–(solid bar), and TRIC-B+/–(hatched bar) mice. n = 9–11. P < 0.05. B. Representative Poincaré plots of RR (n) on the x-axis vs. RR (n+1) on the y-axis of WT, TRIC-A–/–, and TRIC-B+/–mice. The TRIC-A–/–mice had relatively long and unstable RR intervals. C. Power spectra by frequency domain analyses of WT, TRIC-A–/–, and TRIC-B+/–mice. D. Heart rate variability (HRV) parameters, HF (i), LF/HF (ii), and SDRR (iii) in WT (open bars) and TRIC-A–/–mice (solid bars). There were no significant differences in HF or LH/HF between WT and TRIC-A–/–mice. TRIC-A–/–mice had a longer SDRR than WT mice. n = 9–11. P < 0.05.

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  Fig 4. Atrial contraction. A. Representative atrial contraction of WT (upper panels) and TRIC-A–/–mice (lower panels). Isoproterenol (100 nM) increased heart rate and force in the WT atrium, while TRIC-A–/–atria showed only a limited response. B. Dose-dependent changes in contractility (i) and HR (ii) in response to isoproterenol (10–100 nM) of WT and TRIC-A–/–atria. Values are the mean ± SEM (n = 6–7). P < 0.05, between WT atria and TRIC-A–/–atria. HR, heart rate; WT, wild-type.

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  Fig 5. Sinus nodal action potential (spontaneous sinus rate). A. Representative action potentials of the sinus nodes of WTand TRIC-A–/–mice. B. Spontaneous sinus rates in WT (open bars) and TRIC-A–/–mice (solid bars). TRIC-A–/–SA nodes showed significantly decreased sinus rate. n = 6–8. P < 0.05. C. HR changes in response to isoproterenol (100 nM). TRIC-A–/–SA nodes showed a decreased response. n = 5–6. P < 0.05. D. HR changes in response to the BK antagonist, paxilline (1 μM). TRIC-A–/–SA nodes showed decreased response. n = 6–7. P < 0.0.