Fig. 3: Microglia membrane properties change over time after stroke.
a Whole-cell patch-clamp experiments on microglia 2 days, 1 week, and 8 weeks after 30-min MCAo are shown. Control cells were examined in the contralateral uninjured hemisphere (Contra). Exemplary traces recorded at a holding potential of −70 mV. Voltage steps from −170 mV to +60 mV for 50 ms each (schematic on the left). b Corresponding IV-curves at −20 mV holding potential (black) and −70 mV (gray). Data are represented as mean ± standard deviation. Note the increasing variance after 8 weeks. Number of cells n (−20 mV, −70 mV) = 26, 25 (Contra); 21, 21 (2 d); 31, 31 (1w); 25, 24 (8w). c Calculation of membrane resistance (holding potential −20 mV), capacitance (holding potential −20 mV), and reversal potential (holding potential −70 mV) derived from the IV-curves. Specific outward conductance derived from steps at 0 mV and −20 mV, 40 ms after the beginning of pulse, and normalized to each cell’s capacitance (holding potential −70 mV). Specific inward conductance derived from steps at −120 mV and −100 mV, 10 ms after the beginning of pulse, and normalized to each cell’s capacitance (holding potential −20 mV), showing high variance at 8 weeks. Data are represented as median and interquartile range. Statistical analysis with Kruskal-Wallis test. n = 26 (Contra) for Cm, Gout, and Gin, 25 for Rm, and Vrev; 21 (2 d); 31 (1w); 25 (8w) for Cm, Vrev, and Gout, 23 for Rm and Gin. d Histogram plotted for specific inward conductance (−120 mV to −100 mV, 10 ms after stimulus onset, holding potential −20 mV) for cells with inward but no outward current. This provides the basis for differentiating the two groups of cells with moderate and cells with strong inward currents (threshold 0.5 nS/pF). e Distribution of inward and outward currents over different time points with exemplary IV-curves (holding potential −70 mV) showing four different types of cells based on the types of displayed currents. Nine cells under control conditions showed moderate inward currents. Please note the homogeneous response at 2 days and the increased heterogeneity over time.
