A mechanosensitive ion channel regulating cell volume.
Cells respond to a hyposmotic challenge by swelling and then returning toward the resting volume, a process known as the regulatory volume decrease or RVD. The sensors for this process have been proposed to include cationic mechanosensitive ion channels that are opened by membrane tension. We tested this hypothesis using a microfluidic device to measure cell volume and the peptide GsMTx4, a specific inhibitor of cationic mechanosensitive channels. GsMTx4 had no effect on RVD in primary rat astrocytes or Madin-Darby canine kidney (MDCK) cells but was able to completely inhibit RVD and the associated Ca(2+) uptake in normal rat kidney (NRK-49F) cells in a dose-dependent manner. Gadolinium (Gd(3+)), a nonspecific blocker of many mechanosensitive channels, inhibited RVD and Ca(2+) uptake in all three cell types, demonstrating the existence of at least two types of volume sensors. Single-channel stretch-activated currents are present in outside-out patches from NRK-49F, MDCK, and astrocytes, and they are reversibly inhibited by GsMTx4. While mechanosensitive channels are involved in volume regulation, their role for volume sensing is specialized. The NRK cells form a stable platform from which to screen drugs that affect volume regulation via mechanosensory channels and as a sensitive system to clone the channel.
Hua
Susan Z
SZ
Department of Physiology and Biophysics, SUNY, Buffalo, NY 14214, USA. zhua@buffalo.edu
Gottlieb
Philip A
PA
Heo
Jinseok
J
Sachs
Frederick
F
D000818:Animals; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism*; D002118:Calcium / Q000378:metabolism; D002460:Cell Line; D048429:Cell Size / Q000187:drug effects; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D005682:Gadolinium / Q000378:metabolism; D036341:Intercellular Signaling Peptides and Proteins; D015640:Ion Channel Gating / Q000187:drug effects; D007473:Ion Channels / Q000037:antagonists & inhibitors / Q000378:metabolism*; D007668:Kidney / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D007700:Kinetics; D040542:Mechanotransduction, Cellular / Q000187:drug effects; D008564:Membrane Potentials; D049990:Membrane Transport Modulators / Q000494:pharmacology; D046210:Microfluidic Analytical Techniques; D018408:Patch-Clamp Techniques; D010455:Peptides / Q000494:pharmacology; D051381:Rats; D013111:Spider Venoms / Q000494:pharmacology
D036341:Intercellular Signaling Peptides and Proteins; D007473:Ion Channels; C411249:MTx4 protein, Grammostola spatulata; D049990:Membrane Transport Modulators; D010455:Peptides; D013111:Spider Venoms; D005682:Gadolinium; D002118:Calcium
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