Characterization of stretch-activated ion channels in cultured astrocytes.
The presence of a stretch-activated channel in rat cerebellar astrocytes in culture is described. This stretch-sensitive channel is K(+)-selective and its open probability increases with suction following a Boltzmann-like distribution with half activation at 45 mm Hg. Kinetic analysis of the single-channel data indicated that there are two open and two closed states and that the shortest time constants of both open and closed states are the most sensitive to suction. A symmetrical two-barrier-one-site permeation model can quantitatively describe the inward rectification of the single-channel current to voltage relations. It is suggested that this stretch-activated channel plays a role in the regulatory volume response of astrocytes to hyposmotic conditions.
Islas
L
L
Institute of Cell Physiology, National A. University of Mexico, Mexico City.
Pasantes-Morales
H
H
Sanchez
J A
JA
D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism*; D003994:Bucladesine / Q000494:pharmacology; D002412:Cations / Q000378:metabolism; D048429:Cell Size; D002478:Cells, Cultured; D007038:Hypotonic Solutions / Q000494:pharmacology; D015640:Ion Channel Gating; D007700:Kinetics; D008465:Mechanoreceptors / Q000378:metabolism*; D008564:Membrane Potentials; D011188:Potassium / Q000378:metabolism*; D015221:Potassium Channels / Q000378:metabolism*; D011312:Pressure; D051381:Rats
D002412:Cations; D007038:Hypotonic Solutions; D015221:Potassium Channels; D003994:Bucladesine; D011188:Potassium