Mechanosensitive single channel calcium currents in rat mesangial cells.
Mechanical stimulation of mesangial cells enhances expression of early response protooncogenes in an extracellular Ca(2+)-dependent manner. This has lead investigators to postulate that a mechanosensitive Ca2+ channel may exist in these cells. At the present time, however, very little is known about single channel Ca2+ currents in mesangial cells. To examine this question, cell-attached patches of rat mesangial cells in early passages were studied with 100 mM BaCl2 patch-clamp pipets. Our studies identified a 21 pS, Co(2+)-sensitive channel that responded with an increase in open probability to mechanical stretch, applied through the patch pipet. The channel was also activated by a reduction in extracellular osmolarity. In both instances, channel responses underwent spontaneous adaptation despite continuous stimulation. This Ca2+ channel exhibited electrophysiological and kinetic properties that distinguished it from other cation-selective channels previously reported by us and other investigators on rat mesangial cell membranes.
Chen
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Nephrology Section, Brooklyn Veterans Affairs Hospital, NY 11209.
Guber
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Palant
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D000818:Animals; D017609:Barium Compounds / Q000494:pharmacology; D001696:Biomechanical Phenomena; D015220:Calcium Channels / Q000187:drug effects / Q000502:physiology*; D002462:Cell Membrane / Q000502:physiology; D002478:Cells, Cultured; D002712:Chlorides / Q000494:pharmacology; D003035:Cobalt / Q000494:pharmacology; D004553:Electric Conductivity; D004594:Electrophysiology; D005920:Glomerular Mesangium / Q000502:physiology*; D007700:Kinetics; D008297:Male; D008465:Mechanoreceptors / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley
D017609:Barium Compounds; D015220:Calcium Channels; D002712:Chlorides; C024986:barium chloride; D003035:Cobalt