Incorporation of partially purified cation channels from cardiac sarcolemmal membrane into planar lipid bilayers.

Voltage-dependent calcium channels are vital to cardiac muscle contraction. Therefore it is very important to isolate physiologically active channel proteins, however there have been few reports on their solubilization and reconstitution. Highly purified sarcolemmal membranes from bovine cardiac muscle were solubilized with octylglucoside, partially purified by gel filtration, and reconstituted into planar lipid bilayer by the direct insertion method. At least, two cation channel activities were observed: one with about 4.2 pS and the other with about 28 pS in conductance. From the reversal potential, it was concluded that Ba2+ ions are the current carrier through these two channels.