Method for studying the physical effect of extracellular matrix on voltage-dependent ion channel gating

Divalent cations can change the actual electrical potential at the outer surface of the plasma membrane. They do so by the so-called Gouy-Chapman-Stern effect which is due to the electrical “masking” that certain ions, especially divalents, can exert onto the electrically negative charged polar heads of the membrane phospholipids. Chondroitin sulfates can chelate free calcium ions to a different extent based on the spatial arrangement of their sulfate groups and can thus alter the actual availability of screening divalent ions at the outer membrane surface. Voltage-dependent ion channels sense the actual potential difference between the two sides of the plasma membrane and are thus exquisite and extremely sensitive “devices” able to react to changes in the electrical potential across the membrane. Hence, by recording the shift in the activation curve of well-known voltage-dependent ionic channels it will be possible to study the physical effect of ECM chondroitin sulfates on membrane conductances.