Figure 3.

Varying the bath solution osmolarity changes the rate of rapid endocytosis and the membrane tension at chromaffin cells. (A) Shown here is the averaged I_Ca and capacitance (C_m, mean + SE) induced by depol_1s (arrow) from bovine chromaffin cells (20 cells, three bovines) with a control bath solution (mean: 303 mOsm). Mean + SE is plotted every 50 ms in the I_Ca trace, but every 0.5 s in the C_m trace. (B) Shown here is the averaged I_Ca and C_m (mean + SE) induced by depol_1s (arrow) from chromaffin cells (nine cells, three bovines) with a bath solution at lower osmolarity (mean: 215 mOsm). (C) Given here is the averaged I_Ca and C_m (mean + SE) induced by depol_1s (arrow) from chromaffin cells (14 cells, three bovines) with a bath solution at higher osmolarity (mean: 653 mOsm). (D) Shown here is the Rate_decay, ΔC_m, and calcium current charge (QI_Ca) induced by depol_1s in bovine chromaffin cells with a mean bath osmolarity of 303 mOsm (control, 20 cells for Rate_decay measurements), 215 mOsm (nine cells for Rate_decay measurements), or 653 mOsm (14 cells for Rate_decay measurements). ^∗p < 0.05 (t-test in comparison with control group). (E) Decreasing the bath solution osmolarity increased membrane tension. (Left) Given here are drawings of micropipette aspiration technique. A negative pressure (ΔP) on the pipette (with a diameter D) draws the cell membrane into the pipette by a length L. (Right) Given here is a normalized projection length (L/D, mean + SE) for aspirated cells in a bath solution with a mean osmolarity of 303 mOsm (control, n = 10 cells for L/D measurements) or 174 mOsm (n = 9 cells for L/D measurements; ^∗p < 0.05; unpaired two-tailed student’s t-test). ΔP = 1500 Pa.