Oocyte water permeability
Osmotic water permeability (Pos) of oocytes injected with water or cRNA was determined following Byrt et al., (2017) with the following important exception based on the previous finding of rapid Na+ efflux when the external Na+ concentration is reduced related to PIP2;1 expression (Byrt et al., 2017): oocytes were pre-incubated in 3 mL iso-osmotic solution (5 mM NaCl, 2 mM KCl, 1 mM MgCl2, 50 µM CaCl2, pH 8.5) with an osmolality of 240 mosmol.kg-1 (adjusted with D-mannitol) for 1 h prior to being transferred to a solution with the same ionic composition (5 mM NaCl, 2 mM KCl, 1 mM MgCl2, 50 µM CaCl2, pH 8.5) with an osmolality of 45 mosmol.kg-1 for the photometric swelling assay.