Lack of coupling between membrane stretching and pannexin-1 hemichannels.
We investigated whether pannexin-1, a carbenoxolone-sensitive hemichannel activated in erythrocytes by swelling, could be activated by swelling stress and contribute to swelling-activated chloride currents (I(Cl,swell)) in HEK-293 cells. We used ethidium bromide uptake as an index of pannexin-1 activation and I(C,swell) activation as an index of plasma membrane stretching. I(Cl,swell) activated by a hypotonic solution was reversible inhibited by carbenoxolone (IC(50) 98+/-5 microM). However, the hypotonic solution that activated I(Cl,swell) did not induce ethidium bromide uptake indicating that pannexin-1 was not activated by cell swelling. The mimetic peptide (10)panx1, a pannexin-1 antagonist, did not affect I(Cl,swell) activation but completely inhibited the ATP-induced ethidium bromide uptake coupled to P2X(7) receptors activation. We conclude that carbenoxolone directly inhibited I(Cl,swell) independent of pannexin-1 and that pannexin-1 hemichannels are not activated by swelling in HEK-293 cells.
Reyes
Juan P
JP
Institute of Physics, Universidad Autónoma de San Luis Potosí, Dr. Manuel Nava #6, San Luis Potosí, SLP 78290, Mexico.
Hernández-Carballo
Carmen Y
CY
Pérez-Flores
Gabriela
G
Pérez-Cornejo
Patricia
P
Arreola
Jorge
J
D001692:Biological Transport / Q000187:drug effects; D002229:Carbenoxolone / Q000494:pharmacology; D002460:Cell Line; D002462:Cell Membrane / Q000502:physiology*; D017630:Connexins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004996:Ethidium / Q000378:metabolism; D006801:Humans; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009419:Nerve Tissue Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009995:Osmosis; D013314:Stress, Mechanical
D017630:Connexins; D009419:Nerve Tissue Proteins; C492764:PANX1 protein, human; D004996:Ethidium; D002229:Carbenoxolone