Fig. 4. Suppression of Ca²⁺ sparks by diphenyleneiodonium (DPI) in the absence of external Na⁺ and Ca²⁺. (A) A series of sequential confocal Ca²⁺ images recorded at 30 Hz from a representative resting rat ventricular myocyte in the control condition (“1”) and after brief exposure to zero Na⁺ and zero Ca²⁺ external solutions (0 Na, 0 Ca) for 10 s (“2”), followed by additional application of DPI (0 Na, 0 Ca, DPI) for 3 min (“3”). The images were selected from the periods marked with the boxes correspondingly numbered (“1”, “2”, and “3”) in the panel B. After 3-min DPI application, DPI was removed from the zero Na⁺ and zero Ca²⁺ solutions (2 min; (0 Na, 0 Ca, DPI)`), which was followed by the exchange of external solution with control solutions (5 min; “Wash”). Arrows indicate distinct Ca²⁺ sparks. (B) Plots of the total numbers of sparks occurred in each frame (33 frames/s) versus 2-s-long recording periods under each condition labeled above the plots. (C) Summary of mean spark frequency detected under each condition indicated underneath the graphs. Paired t-test was used.

Korean J Physiol Pharmacol 2024;28:335-344 https://doi.org/10.4196/kjpp.2024.28.4.335

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