Continuous mechanical loading alters properties of mechanosensitive channels in G292 osteoblastic cells.
G292 osteoblastic cells were cultured in dishes made with a flexible base of polytetrafluoroethylene (PTFE) and stretched ( approximately 1% strain level) continuously for 48 hours. Patch-clamp recording techniques were then used to monitor single channel currents of mechanosensitive ion channels in these cells. To stimulate mechanosensitive channels, we applied suction to the membrane, expressed as -cm Hg, directly through the patch pipette. GigaOhm seals were obtained on a total of 33 osteoblasts that contained a high-conductance ( approximately 180 pS) mechanosensitive channel, all in the cell attached configuration. Of these, 18 were obtained from cells that had been stretched for either 1 (n = 6), 24 (n = 4), or 48 (n = 8) hours, and 15 were obtained in control (nonstretched) cells at either 1 (n = 2), 24 (n = 5), or 48 (n = 8) hours. For unstrained cells, applied pressures ranging from -1 to -5 cm Hg increased the probability of channel opening (Popen) from 0.05 +/- 0. 01 (mean + SEM) to 0.12 +/- 0.07. By contrast, for the same values of applied pressure in stretched cells, Popen ranged from 0.06 +/- 0. 01 to 0.49 +/- 0.15. Our results suggest that intrinsic properties of mechanosensitive ion channels in the G292 osteoblastic cell may be modulated by continuous mechanical loading of the cell itself.
Davidson
R M
RM
Basic Science Division, NYU College of Dentistry, 345 E. 24th St., New York, NY 10010, USA.
Lingenbrink
P A
PA
Norton
L A
LA
D006801:Humans; D007473:Ion Channels / Q000187:drug effects* / Q000502:physiology; D010006:Osteoblasts / Q000166:cytology / Q000187:drug effects* / Q000502:physiology; D018408:Patch-Clamp Techniques; D011138:Polytetrafluoroethylene / Q000494:pharmacology*; D014407:Tumor Cells, Cultured
D007473:Ion Channels; D011138:Polytetrafluoroethylene