Question

You study cardiac myocytes to understand cell permeability during action potentials and how that influences differentiation of the cell. Modeling the cell and its environment in 1-D, calculate the flux of water across the membrane (~15nm) if the cell is in a hypotonic solution (H2Ooutside=2 mol/m3, H2Oinside=3 mol/m3). The diffusion coefficient of water at 35oC is ~3x10-3 mm2/s

Answer 1

Solution:

• Concentration on one side of the membrane, C1 = 2 mol/m3
• Concentration on other side of the membrane, C2 = 3 mol/m3
• Diffusion coefficient, D = 3 x 10-3 mm2/s
• Thickness of the membrane, x = 15 nm

From Fick's Ist law of 1-D diffusion,

Unit conversion:

Therefore, the flux of water through the membrane is given by

J = 0.2 mol/m2-s