IVA altered the properties of Ca2+ sparks
Fig 6A depicts line-scan images of Fluo-4 AM fluorescence with the corresponding profiles of Ca2+ sparks. Under control conditions, the average Ca2+ spark frequency, amplitude, FWHM and FDHM were 2.68 ± 1.17 sparks/100 μm/s, 0.74 ± 0.45, 0.48 ± 0.14 µm, and 29.81 ± 7.63 ms (n= 239 sparks/22 cells), respectively. After IVA treatment, spark frequency, amplitude and FWHM gradually increased in concentration-dependent manners and FDHM remained unchanged (Fig 6B). IVA (0.3 μM) increased spark frequency, amplitude and width of Ca2+ spark by 1.9, 4.2 and 2.7 fold (p<0.05 vs. baseline), respectively. These results suggest that IVA mainly affects the spatial characteristics but not the temporal properties of Ca2+ sparks.
IVA regulated RyR2, SERCA2 and NCX1 protein expression in rabbit atriums
The expression of RyR2 and SERCA2 were increased and decreased, respectively, in the hearts treated with IVA (1-10 µM) in a manner of concentration (n=4-5, p<0.05 vs. baseline). NCX1 expression was up-regulated by 10 µM IVA (n=4-5, p<0.05vs. baseline, Fig 7).