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. 2016 Feb 29;291(17):9087–9104. doi: 10.1074/jbc.M115.692384

FIGURE 6.

FIGURE 6.

Static plasma membrane tension of primary afferent neurons is measured by the micropipette aspiration technique. A, schematic diagram illustrates the setup for measuring SPMT using a micropipette aspiration technique. In this setup, a micropipette is connected to an HSPC device via its head stage. Stepwise negative pressures are generated by HSPC and delivered to the micropipette to aspirate a cell. B, image shows a DRG neuron whose membranes are being aspirated into the micropipette (white asterisk indicated). The cell is also patched under the whole-cell mode by a recording electrode (black asterisk indicated) that contains a hypertonic recording internal solution. C, parameters needed for calculating membrane tension based on the Young-Laplace equation. Tc, membrane tension; Rc, cell radius; Pc, intracellular pressure; Pp, pipette aspiration pressure; Rp, pipette radius; L, length of membrane projection within pipette. D, SPMT measured from small-sized cultured DRG neurons (original diameter ≤30 μm) under the whole-cell mode with patch clamp recording electrode containing isotonic (solid squares, n = 8) and hypertonic (solid circles, n = 12) recording internal solution. BL, baseline before establishing the whole-cell mode; Time, time after establishing the whole-cell mode. E, SPMT measured from cells whose original sizes (in diameter) were small (≤30 μm), medium (30–45 μm), and large (≥45 μm). Cells were not patched by recording electrodes. SPMT measurements were performed on cells in isotonic bath solution (open bars, n = 11 for small cells; n = 12 for medium cells; n = 6 for larger cells). SPMT was also measured following the application of hypotonic bath solution (solid bars, n = 9 for small cells; n = 10 for medium cells; n = 6 for larger cells). F, SPMT measured from small-sized cells under the whole-cell patch clamp recording mode with patch clamp recording electrode containing isotonic recording internal solution without (solid squares, n = 10) and with 10 μm CD (solid circles, n = 7). G, SPMT measured from small-sized cells under the whole-cell patch clamp recording mode with electrode containing hypertonic recording internal solution without (solid squares, n = 12) and with 10 μm CD (solid circles, n = 7).