Functional studies of synthetic gramicidin hybrid ion channels in CHO cells.
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.
Wesolowski
Ryszard
R
Experimentelle Ophthalmologie, Klinik und Poliklinik für Augenheilkunde, Universitätsklinikum Hamburg-Eppendorf, Martinistrasse 52, 20246 Hamburg, Germany.
Sommer
Anna
A
Arndt
Hans-Dieter
HD
Koert
Ulrich
U
Reiss
Philipp
P
Wimmers
Sönke
S
Strauss
Olaf
O
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
D000596:Amino Acids; D007473:Ion Channels; D008055:Lipids; D006096:Gramicidin; D002586:Cesium; D012964:Sodium; D011188:Potassium