Changes in osmolality, volume and voltage induced by an increase in extracellular osmolality in the presence or absence of a WB.

The extracellular solution is initially 147 mM Na+, 3 mM K+, 130 mM Cl- and 20 mM impermeant anions (X-) (300 mOsm) and changed to 330 mOsm at 1 min. The starting radius of the cell is 3.58, and the cell contains 2.6×10−14 moles of an impermeant molecules with valence -1. The osmotic permeability coefficient, of the membrane is 2 × 10−4 cm s-1. The rate of water release by the WB is 3.3 × 10−16 L s-1. The cell has Na, K+ and Cl- leak conductances and a NKA, all with the same parameters as in Aminzare and Kay (2024). The dashed lines show the responses in the absence of an NKA, with initial radius 3.5 moles of impermeant molecules. and 3.58 x10−14 The system of equations was solved using the stiff ordinary differential equation solver ode15s in MATLAB (R2023b).