Fig. 6.

Romidepsin inhibition of cardiac HDAC activity and gap junction conductance. A: total HDAC activity was measured in NMVM cultures exposed to increasing concentrations of FK228 using the deacetylated Fluor-de-Lys fluorescence method. All data were normalized to the background subtracted maximum relative fluorescence of the control well. The data from three experiments were averaged and fitted with a second-order exponential decaying function and equilibrium inhibition constants (K_i) were calculated from the decay constant for each exponential component. B: the gap junction conductance (g_j) was measured in NMVM cell pairs from control and FK228-treated culture dishes and a dose-dependent decrease in g_j was observed, consistent with published results with TSA and VOR (71).