FIGURE 5.

As₂O₃-induced calcium current increases are not blocked by Akt inhibitors. A, Western blot (WB) of whole cell lysates showing total Akt and phospho-Akt Ser⁴⁷³ (p-Akt) in guinea pig ventricular myocytes under control conditions (con), following incubation with 10 μm As₂O₃ for 4 h, and following co-incubation with 10 μm As₂O₃ and 5 μm Akt inhibitor VIII for 4 h. Note that As₂O₃ exposure initiates Akt phosphorylation/activation, which can be completely blocked by Akt inhibitor VIII. B, cardiac calcium current traces in B–D were elicited in guinea pig ventricular myocytes as described in Fig. 1. Averaged I-V relationships show that 5 μm Akt inhibitor VIII does not inhibit As₂O₃-induced calcium current increases. AktVIII was applied for 90 min upon overnight incubation of cardiomyocytes with 3 μm As₂O₃. Note that control currents are not affected by AktVIII. C, averaged I-V relationships showing that 10 μm SH-6 does not inhibit As₂O₃-induced calcium current increases. Cardiomyocytes were co-incubated overnight with both 10 μm SH-6 and 10 μm As₂O₃. D, a 30 μm concentration of the inhibitory peptide TAT-AktVII does not affect As₂O₃-induced calcium current increases. The inhibitory peptide was applied with the extracellular perfusate for 90 min upon overnight incubation of cardiomyocytes with 3 μm As₂O₃ (n = 5–8). Error bars, S.E.