title: Functional studies of synthetic gramicidin hybrid ion channels in CHO cells.
abstract: The function of a gramicidin hybrid ion channel in living Chinese hamster ovary (CHO) cells was investigated by the patch clamp method. The synthetic ion channel 1 consists of two cyclohexyl ether amino acids that link two mini-gramicidin strands. With 1 at a concentration of 1.0 microM, an increase in the whole-cell membrane conductance was observed after 1.37 min. The conductance showed larger currents when Cs(+) was used as charge carrier than when Na(+) and K(+) were used. In single-channel recordings with Cs(+) as charge carrier, the substance showed comparable single-channel amplitudes in the membrane of living cells and artificial black lipid bilayers. In addition to functioning as a cation channel, compound 1 appeared to be a water channel. Exposure of the CHO cells to an extracellular hypoosmotic solution did not substantially change the cell volume. Extracellular hypoosmotic conditions in the presence of 1 increased the cell size to 146.5 % that of the control. Thus, the synthetic hybrid channel 1 can function as a cation channel with some Cs(+) specificity, and as a water channel in CHO cells.
authors.affiliation: Experimentelle Ophthalmologie, Klinik und Poliklinik für Augenheilkunde, Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany.
authors.forename: Ryszard
authors.initials: R
authors.lastname: Wesolowski
authors.forename: Anna
authors.initials: A
authors.lastname: Sommer
authors.forename: Hans-Dieter
authors.initials: HD
authors.lastname: Arndt
authors.forename: Ulrich
authors.initials: U
authors.lastname: Koert
authors.forename: Philipp
authors.initials: P
authors.lastname: Reiss
authors.forename: Sönke
authors.initials: S
authors.lastname: Wimmers
authors.forename: Olaf
authors.initials: O
authors.lastname: Strauss
mesh_terms: D000596:Amino Acids / Q000737:chemistry; D000818:Animals; D016466:CHO Cells; D002586:Cesium / Q000737:chemistry; D006224:Cricetinae; D003412:Cricetulus; D004553:Electric Conductivity; D006096:Gramicidin / Q000737:chemistry*; D007473:Ion Channels / Q000737:chemistry*; D008055:Lipids / Q000737:chemistry; D008566:Membranes / Q000737:chemistry; D008956:Models, Chemical; D010539:Permeability; D011188:Potassium / Q000737:chemistry; D012964:Sodium / Q000737:chemistry
chemical_list: D000596:Amino Acids; D007473:Ion Channels; D008055:Lipids; D006096:Gramicidin; D002586:Cesium; D012964:Sodium; D011188:Potassium