Cultured normal (N) and cystic fibrosis (CF) keratinocytes were evaluated for their Cl−-transport properties by patch-clamp-, Ussing chamber- and isotopic efflux-measurements. Special attention was paid to a 32 pS outwardly rectifying Cl− channel which has been reported to be activated upon activation of cAMP-dependent pathways in N, but not in CF cells. This depolarization-induced Cl− channel was found with a similar incidence in N and CF apical keratininocyte membranes. However, activation of this channel in excised patches by protein kinase (PK)-A or PK-C was not successfull in either N or CF keratinocytes. Forskolin was not able to activate Cl− channels in N and CF cell-attached patches. The Ca2+-ionophore A23187 activated in cell-attached patches a linear 17 pS Cl− channel in both N and CF cells. This channel inactivated upon excision. No relationship between the cell-attached 17 pS and the excised 32 pS channel could be demonstrated. Returning to the measurement of Cl− transport at the macroscopic level, we found that a drastic rise in intracellular cAMP induced by forskolin did in N as well as CF cells not result in a change in the short-circuit current (Isc) or the fractional efflux rates of 36Cl− and 125I−. In contrast, addition of A23187 resulted in an increase of the Isc and in the isotopic anion efflux rates in N and CF cells. We conclude that Cl−-transport in cultured human keratinocytes can be activated by Ca2+, but not by cAMP-dependent pathways.

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doi.org/10.1016/0925-4439(92)90081-W, hdl.handle.net/1765/67877
Biochimica et Biophysica Acta - Molecular Basis of Disease
Department of Reproduction and Development

Kansen, M., Keulemans, J. L. M., Hoogeveen, A., Scholte, B., Vaandrager, A., van der Kamp, A., … Bijman, J. (1992). Regulation of chloride transport in cultured normal and cystic fibrobis keratinocytes. Biochimica et Biophysica Acta - Molecular Basis of Disease, 1139(1-2), 49–56. doi:10.1016/0925-4439(92)90081-W