Reanalyzing the data from our previous umbrella sampling MD simulations of lipid flipping for an indolicidin/membrane system , we estimated the diffusion coefficient of ions through a transient pore (D), using the Einstein relation (see SI). The previously reported simulations consisted of one indolicidin molecule peripherally bound to a 3:1 DMPC:DMPG phospholipid bilayer, in the presence of 0.150 M NaCl solution. The CHARMM-36m force field was used in combination with the TIP3P water model , at 303.15 K and 1 bar. For the mean square displacement analysis, we used the 26th window of the umbrella sampling, corresponding to the transition state of the indolicidinassisted flipping lipid, where a transient water pore was fully formed. For more information on the computational details, please refer to ref. The diffusion coefficient obtained from MD simulations was applied in a diffusion model of the salt equilibration between the vesicle interior and the environment. We assume that the pores are transient, and have a lifetime in the order of 1 -100 ns , leading to pores opening and closing throughout the experiment. In addition, our hypothesis is that the osmotic pressure further facilitates the flipping of lipids mediated by indolicidin peristalsis, and as more ions enter the vesicles, the fewer pores open. Integrating a modified Fick's law for a sphere, we obtain an equation for the concentration at the center of the vesicle as a function of time (t) and of the initial average number of pores (N ). For N = 1, the equation becomes: