Figure 5

Increased sensitivity of SM to EFS during high PKC stimulation is reversed by pre-incubation with Bim-1. A, Experimental design included initial pre-incubation for 30 min with 100 nM of PDBu (bottom panel) followed by frequency response curve to EFS (0.5-32 Hz). Control strips received no PDBu (top panel). 20 minutes after the frequency response curve, Bim-1 (100 nM) was added for 45 minutes to the PDBu treated muscle strips. The frequency response curve was then repeated for both control and drug treated DSM strips. B, Analysis of the peak force shows that addition of Bim-1 to PDBu-treated strips caused a substantial reduction in PF which was similar with baseline levels at 0.5-4 Hz of EFS (N = 5, n = 7 in each group, p ≤ 0.05 to PDBu treatment at respective frequencies). There was no significant enhancement by PDBu, nor reversal by Bim-1, at 8, 16 and 32 Hz of stimulation. C, Ro318220, an alternative PKC inhibitor, significantly reduced the integral force of BSM contractions at both low (4.5-13.5 μM) and high (40.5-121.5 μM) concentrations upon 16 and 32 Hz of EFS (N = 4, n = 6 in each group, p ≤ 0.05 at 16 and 32 Hz to baseline).