Figure 2

Hyperglycemia alters the force-pCa relationship in single permeabilized diaphragm fibers. Average force-Ca curves were constructed for single fibers from control (black) and two week hyperglycemic animals (red) using the Hill equation (15 fibers from each of six animals per condition for a total of 90 fibers per group). Symbols and error bars represent the mean ± SEM of the data points obtained for each individual fiber. Force (Fmax) is the absolute force generation per cross sectional area of each individual fiber normalized to the percentage of the control fibers. pCa represents the (-log [Ca ²⁺]) indicating that the calcium content in the solution increases along the X-axis. As shown, two weeks of hyperglycemia significantly alters the force-pCa relationship in single permeabilized diaphragm fibers, indicating that most of the hyperglycemia-induced diaphragm force reductions are due to alterations at the level of the contractile proteins (P <0.001 for force in fibers from hyperglycemic groups compared to control fibers at all pCa values greater than 6.0). SEM, standard error of the mean.