Figure 2.

ET-1 induces nuclear export of HDAC5. (A) ET-1 (100 nM) was applied for 60 minutes to quiescent rabbit ventricular myocyte expressing the fusion protein HDAC5-GFP. (B) Individual traces of nuclear and cytosolic fluorescence (F_Nuc/F_Cyto) for a single myocyte, where each trace is normalized to the F_cyto before ET-1 exposure (F_cyto-initial). (C) HDAC5 nuclear export was analyzed as decrease of F_Nuc/F_Cyto, normalized to the initial ratio (6.3 ± 0.4_; n = 12). The control group was treated the same, except without ET-1 application (n = 10). (D) [Ca²⁺]_i measured by Rhod-2 fluorescence upon exposure to 100 nM ET-1 (n = 7). Long-term exposure to ET-1 induced further HDAC5 export, such that after 24 hours the nucleus was virtually depleted of HDAC5 (not shown), analogous to effects in cultured neonatal rat myocytes (31).