Use of electrochemical impedance measurements to monitor β-adrenergic stimulation of bovine aortic endothelial cells

Abstract

Due to the high permeability of endothelial cell layers derived from macrovascular vessels, precise determination of their barrier function towards ion movement requires refined experimental techniques. We thus cultured bovine aortic endothelial cells (BAEC) directly on thin gold-film electrodes and measured the electrochemical impedance to study their passive electrical properties in general and during beta-adrenergic stimulation. Impedance spectra (10-2.10(6) Hz) of confluent cell monolayers revealed that the electrical characteristics of the cells can be modelled by a simple resistor-capacitor parallel network. Under control conditions the overall resistance of confluent BAEC monolayers was 3.6+/-0.6 Omega.cm2 (n=30) and the capacitance was 0. 6+/-0.1 microF/cm2. Both quantities are discussed with respect to morphological characteristics of these cells. Stimulation of BAECs with the synthetic beta-adrenoceptor agonist isoproterenol leads to a concentration-dependent, highly specific increase of the cell layer resistance characterized by a concentration for half-maximal response (EC50) of 0.3+/-0.1 microM. The cell layer capacitance, however, remained unaffected. Using impedance measurements at a single frequency, we analysed the response of BAECs to treatment with isoproterenol in comparison with several chemically unrelated compounds known to stimulate the adenosine 3',5'-cyclic monophosphate (cAMP)-dependent signal transduction cascade. These studies confirmed that the enhancement of the cell layer resistance after beta-adrenergic stimulation is mediated by an increase in intracellular cAMP.

Bioelectrical impedance assay to monitor changes in cell shape during apoptosis

“…macrovascular endothelial cells). ECIS analysis for these cell monolayers provides R b values of 3 cm 2 and below (Giaever and Keese, 1991;Wegener et al, 1999) with no cells missing in the cell sheet.…”

“…However, instead of using ultrastructural imaging techniques like EM that are confined to a field of view of one or a few cells at the most, we applied the electrochemical ECIS device that is capable of recording average alterations in cell shape integrated over a cell monolayer of hundreds of cells. ECIS has proven to be extraordinary sensitive to changes in cell-cell and cell-substrate contacts (Wegener et al, 1999;Tiruppathi et al, 1992;Lo et al, 1994). Since the shape of individual cells within a confluent monolayer is determined by their various contacts to their nearest neighbors as well as by their molecular interactions with the growth substrate, ECIS should be well suited to monitor the onset and the dynamics of apoptosis.…”

Cellular Dielectric Spectroscopy: A Powerful New Approach to Label-Free Cellular Analysis

“…[7][8][9] In addition to these efforts, some researchers have attempted to monitor cellular ligand-receptor interactions using bioimpedance. [26][27][28] This ligand interaction work has focused on the use of a single frequency and has shown that activation of a GPCR can be observed with this technique. 27 However, the results were of limited scope, with no consideration of how receptor specificity, if any, could be manifest in the measurements.…”

Electrical wound-healing assay for cells in vitro

“…Impedance changes have been used to monitor cell attachment and spreading (3), cell locomotion and micromotion (4), and changes in cell morphology in response to physical and biochemical changes (5,6). Furthermore, these measurements can be coupled with assays as a means to measure the toxicity of compounds (7), signal transduction (8), and the invasive activities of transformed cells in culture (9).…”