Impedance analysis of renal vascular smooth muscle cells

Impedance of renal vascular smooth muscle cells (VSMCs) cultured on microelectrodes was measured by electric cell-substrate impedance sensing. Changes in measured impedance as a function of frequency were compared with the calculated values obtained from an extended cell-electrode model to estimate the junctional resistance, distance between the ventral cell surface and the substratum, and apical and basolateral membrane capacitances of renal VSMCs. This cell-electrode model was derived to accommodate the slender and rectangular shape of VSMCs. The calculated changes in impedance (Z(cal)) based on the model agreed well with the experimental measurement (Z(exp)), and the percentage error defined as |(Z(cal)-Z(exp))/Z(exp)| was 1.0%. To test the sensitivity of the new model for capturing changes in cell-cell and cell-substrate interactions induced by changes in cellular environment, we then applied this model to analyze impedance changes induced by an integrin binding peptide in renal VSMCs. Our result demonstrates that integrin binding peptide decreases junctional resistance between cells, increases the distance between the basolateral cell surface and substratum, and increases the apical membrane capacitance, whereas the basolateral membrane capacitance stays relatively stable. This model provides a generic approach for impedance analysis of cell layers composed of slender, rectangular cells.