Immunochemical and electrophysiological characterization of murine connexin40 and -43 in mouse tissues and transfected human cells

Abstract

Human HeLa or SkHep1 cells, defective in intercellular communication through gap junctions, were transfected with coding sequences of murine connexin40 (Cx40) and -43. The transfected cells were restored in gap junctional coupling as shown by 100-fold increased electrical conductance. When studied by the double whole-cell patch-clamp technique, Cx40 HeLa transfectans exhibited single channel conductances of γ=121 ± 7 pS and γ=153 ± 5 pS. They were voltage gated with an equivalent gating charge of z=4.0 ± 0.5 for a voltage of half-maximal inactivation U 9= 44 ± 7 mV. The corresponding values or connexin43 (Cx43) HeLa transfectants are: γ=60 ± 4 pS and γ=40 ± 2 pS as well as z=3.7 ± 0.8 and U 0 = 73 ± 7 mV. Transfer of the dye Lucifer Yellow was always considerably lower in Cx4- than in Cx43-transfectants though their total junctional conductance was similar or even higher than for Cx43-transfectants.