Examination of the Changes in Calcium Homeostasis in the Delayed Antiarrhythmic Effect of Sodium Nitrite

Figures

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  Figure 1. Representative images taken at 12000x magnification (A) and their quantitative analysis (B) of calcium deposits obtained by transmission electron microscopy (TEM) in the sham-operated (SC, n = 4) ischemic control (IR, n = 4) and sodium-nitrite-treated groups with (NaNO2 + ischemia and reperfusion (I/R), n = 4) or without I/R (NaNO2, n = 3). For each n, four or five pictures were evaluated and averaged. The images were taken from the subsarcolemmal, intermyofibrillar, and the perinuclear regions. Data are expressed as means ± SEM. Note: * p < 0.05 compared with SC, # p < 0.05 compared with IR.

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  Figure 2. The effect of NaNO2 on the intracellular calcium transients in isolated cardiac myocytes. The changes in the Ca transient amplitude (A), the diastolic calcium level (B), the time-to-peak value (C), and in the half-time of relaxation (D) are shown. Isolated cardiomyocytes from the sham (n = 6) and nitrite-treated dogs (n = 8) were subjected to a 18 min ischemia and 10 min of reperfusion protocol. In order to assess the excretion of the fluorescent dye over time, some sham control cells (n = 3) were loaded with Fura-4-AM but not subjected to stimulated I/R. A trendline was fitted to these cells in order to measure the loss in fluorescence. Values are means ± SEM. Note: * p < 0.05 compared with the control.

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  Figure 3. Representative images (A) and quantitative data (B) of the mitochondrial calcium retention capacity (CRC) of the mitochondria isolated both from the sham and sodium-nitrite-treated groups (SC-CI, n = 6; NaNO2-CI, n = 6; SC-CII, n = 6, NaNO2-CII, n = 5). The calcium overload was stimulated by repeated administration of 30 µM of CaCl2 at each measured time point. Values are means ± SEM. Note: * p < 0.05 compared with SC.

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  Figure 4. The effect of NaNO2 administration on the complex I (CI (A))- and complex II (CII (B))- dependent basal (state2), ADP-activated active respiration (OXPHOS), and uncoupling of the ETS. The respiratory control ratio (RCR) and the P/E coupling ratio (P/E) were also calculated in mitochondria isolated from the sham and nitrite-treated animals (SC: n = 8, NaNO2: n = 9). Values are means ± SEM. Note: * p < 0.05 compared with SC.

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  Figure 5. CI (A)- and CII (B)-dependent respiratory response to calcium overload of mitochondria isolated from the sham-operated (CI, n = 6; CII, n = 6) and the sodium-nitrite-treated groups (CI, n = 11stimulated by repeated administration of 30 µM of CaCl2 at each measured time point.