Mechanical and Electrophysiological Properties of the Sarcolemma of Muscle Fibers in Two Murine Models of Muscle Dystrophy: Col6a1 and Mdx
Figure 5
Analysis of resistance and capacity of the sarcolemma based on the kinetics of the membrane potential change during a hyperpolarizing step. Panels (a) and (b) show examples of fitting to the curves of membrane charging (expressed as the ratio V/I, membrane potential divided by injected current) with a step of hyperpolarizing current of 1 nA from a holding potential of−100 mV. Only the first 90 ms, corresponding to 5000 data points are shown. Note the initial instantaneous jump in potential. The values of the parameters calculated with the analysis are shown in the histograms (c)—(f) as means and standard errors. Rm and Cm are the resistance and the capacity calculated by the model, their product being equal to the time constant . Ri denotes the instantaneous, time-independent resistance. Wild type (black column), Col6a1 (gray columns), mdx (white columns) are reported in each histogram with P < .05, P < .01, P < .001 compared to wild type. The numbers of fibers studied is the same as in Figure 4.
