Influence of K-Cl cotransporter activity on activation of volume-sensitive Cl- channels in human osteoblasts.
The whole cell recording mode of the patch-clamp technique was used to study the effect of hypotonic NaCl or isotonic high-KCl solution on membrane currents in a human osteoblast-like cell line, C1. Both hypotonic NaCl or isotonic high-KCl solution activated Cl- channels expressed in these cells as described previously. The reversal potential of the induced Cl- current is more negative when activated through hypotonic NaCl solution (-47 +/- 5 mV; n = 6) compared with activation through isotonic high-KCl solution (-35 +/- 3 mV; n = 8). This difference can be explained by an increase in intracellular [Cl-] through the activity of a K-Cl cotransporter. Potassium aspartate was unable to activate the current, and furosemide or DIOA suppressed the increase in Cl- current induced by isotonic high-KCl solution. In addition, we used the polymerase chain reaction to demonstrate the presence of KCC1-KCC4 mRNA in the osteoblast-like cell line. From these results, we conclude that human osteoblasts express functional K-Cl cotransporters in their cell membrane that seem to be able to induce the indirect activation of volume-sensitive Cl- channels by KCl through an increase in the intracellular ion concentration followed by water influx and cell swelling.
Bräuer
Margot
M
Department of Applied Physiology, University of Ulm, 89081 Ulm, Germany. heike.jaeger@medizin.uni-ulm.de
Frei
Eva
E
Claes
Lutz
L
Grissmer
Stephan
S
Jäger
Heike
H
D001224:Aspartic Acid / Q000494:pharmacology; D002461:Cell Line, Transformed; D018118:Chloride Channels / Q000378:metabolism*; D002712:Chlorides / Q000493:pharmacokinetics; D015870:Gene Expression / Q000502:physiology; D006801:Humans; D007038:Hypotonic Solutions / Q000494:pharmacology; D007552:Isotonic Solutions / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D011189:Potassium Chloride / Q000493:pharmacokinetics; D012333:RNA, Messenger / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012965:Sodium Chloride / Q000494:pharmacology; D027981:Symporters / Q000235:genetics / Q000378:metabolism*; D000096922:K Cl- Cotransporters
D001224:Aspartic Acid; D018118:Chloride Channels; D002712:Chlorides; D007038:Hypotonic Solutions; D007552:Isotonic Solutions; D011189:Potassium Chloride; D012333:RNA, Messenger; D012965:Sodium Chloride; D027981:Symporters; D000096922:K Cl- Cotransporters; C119650:SLC12A6 protein, human; C119651:SLC12A7 protein, human