Figure 4.

S100A1 prevents compound Ca²⁺ sparks and Ca²⁺ waves in quiescent ventricular cardiomyocytes with Ca²⁺ sensitized RyR2s. (a) and (c) Representative fluorescent line-scan and surface plot images of Ca²⁺ sparks in basal and ISO-stimulated (100 nmol/l) control (AdGFP) and S100A1-treated (AdS100A1) NCs (a) and FCs (c) with RyR2 sensitized to Ca²⁺ by low-dose (0.5 mmol/l) caffeine treatment. ISO triggers compound sparks and Ca²⁺ waves while S100A1-treatment entails solitary SR Ca²⁺ release events. Note that S100A1 inhibits the detrimental effects of ISO on SR Ca²⁺ leak. (b) and (d) Corresponding statistical analysis of Ca²⁺ spark frequency and Ca²⁺ wave incidence in NCs (b) and FCs (d) in indicated groups. n = 40 cells derived from four different isolations. ^#P < 0.05 versus ISO. Data are given as mean ± SEM.