Figure 2

Concentration-dependence of acetate effect on fractional shortening and diastolic sarcomere length. (A) Single averaged contractions acquired in experiments as described in Figure 1 at different concentrations of sodium acetate. Contractions in normal Tyrode (Control, dotted line) and at 2 minutes following exposure to acetate solution (Acetate, solid line) are shown. 10 mM NaCl, instead of sodium acetate, was added to normal Tyrode to collect the zero acetate data. (B) Acetate concentration response curve for maximum contraction inhibition. Data were fit with a modified Hill equation (solid line): FS/FS₀ = 1/(1 + ([Acetate]/IC₅₀)^h), where IC₅₀ is the half-maximal inhibitory concentration of acetate (IC₅₀ = 5.6 mM) and h is the Hill coefficient (h = 1.3). (C) There was no apparent acetate concentration dependence on diastolic sarcomere length.