Enhanced Cardiac CaMKII Oxidation and CaMKII-Dependent SR Ca Leak in Patients with Sleep-Disordered Breathing

Figures

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  Figure 1. Patient flow chart. After screening, 39 patients were included in the analysis. Abbreviations: CABG, coronary artery bypass graft; CPAP, continuous positive airway pressure; SDB, sleep-disordered breathing.

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  Figure 2. Increased oxidation and activity of CaMKII in patients with SDB. Original Western blot (A) and mean densitometric data (B) investigating the expression of oxidized CaMKII relative to CaMKII expression. Compared to control patients (no SDB), there was a significant increase in the level of oxidized CaMKII (oxCaMKII/CaMKII) in patients with SDB. (C) Scatter plot for the correlation of AHI and oxCaMKII/CaMKII. Linear regression analysis is shown as line plot. Mean densitometric data (D) for the assessment of CaMKII activity by using specific HDAC4 pulldown. There was a significant increase in CaMKII activity in patients with SDB. (E) Scatter plot for the correlation of AHI and CaMKII-activity. Linear regression analysis is shown as line plot. * p < 0.05 vs. no SDB (t-test).

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  Figure 3. Patients with SDB showed increased Ca spark frequency. (A) Original confocal line scans of Fluo–4 loaded atrial cardiomyocytes isolated from patients without SDB and with SDB. The measured fluorescence intensity was color coded according to the calibration bar. (B) Mean data for diastolic Ca spark frequency (CaSpF) is shown as violin plot (left panel) or spaghetti plot (right panel). Compared to control patients (no SDB), the frequency of Ca sparks was significantly enhanced in patients with SDB. Importantly, this increase in CaSpF could be blocked with the selective CaMKII inhibitor autocamtide–2 related autoinhibitory peptide (AIP). * p < 0.05 vs. no SDB, † p < 0.05 vs. vehicle (two–way RM ANOVA, mixed effects model).

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  Figure 4. Patients with SDB display reduced SR Ca content. (A) Original confocal line scans of Fluo–4 loaded atrial cardiomyocytes rapidly exposed to caffeine (10 mmol/L). The measured fluorescence intensity was color coded according to the calibration bar. (B) Mean data for caffeine-induced Ca transient amplitude ΔF/F0 as a measure of SR Ca content. Compared to control patients (no SDB), the caffeine-transient amplitude was significantly lower in patients with SDB. Interestingly, the presence of AIP did not alter the caffeine-transient amplitude in patients without SDB. In contrast, in patients with SDB, there was a trend towards an increase in caffeine–transient amplitude in the presence of AIP. * p < 0.05 vs. no SDB (two–way RM ANOVA, mixed effects model).