Functional studies of synthetic gramicidin hybrid ion channels in CHO cells |
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Authors: | Wesolowski Ryszard Sommer Anna Arndt Hans-Dieter Koert Ulrich Reiss Philipp Wimmers Sönke Strauss Olaf |
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Affiliation: | 1. Experimentelle Ophthalmologie, Klinik und Poliklinik für Augenheilkunde, Universit?tsklinikum Hamburg‐Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany, Fax: (+49)?40‐42803 5017;2. Fachbereich Chemie der Philipps‐Universit?t Marburg, Biegenstrasse 10, 35037 Marburg, Germany |
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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. |
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Keywords: | gramicidin hybrid channels ion channels peptides potassium sodium volume regulation |
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