Fig. 1.
Mechanical properties of A7 cells on glass as a function of cell volume under external osmotic pressures. (A) Osmotic bulk modulus (gray triangles), cortical shear modulus (red triangles), and cytoplasmic shear modulus (open triangles) increase as cell volume is decreased upon external osmotic compression. The dashed line through gray triangles represents the least-squares fit using the functional form, B = NkBTV/(V − Vmin)2 (R2 = 0.99). Dashed lines through the cortical and cytoplasmic moduli are exactly the same fit, simply scaled by a factor of 500 and 100,000, respectively. (B) Cortical shear modulus of a single A7 cell, measured by OMTC, increases immediately after the application of an osmotic compression with 0.26 M PEG 300; this is concurrent with a decrease in cell volume after osmotic compression.