from ~ -110 to -50 mV
||Eisenach C, De Angeli A et al., Ion Transport at the Vacuole during Stomatal Movements. Plant Physiol. 2017 Jun174(2):520-530. doi: 10.1104/pp.17.00130 p.522 left column bottom paragraphPubMed ID28381500
||Roelfsema MRG, Hedrich R (2005) In the light of stomatal opening: new insights into ‘the Watergate.’ New Phytol 167: 665–691 DOI: 10.1111/j.1469-8137.2005.01460.x AND Roelfsema MRG, Hedrich R, Geiger D (2012) Anion channels: master switches of stress responses. Trends Plant Sci 17: 221–229 DOI: 10.1016/j.tplants.2012.01.009PubMed ID16101906, 22381565
||P.522 left column bottom paragraph: "The changed activities of these ion channels result in large changes in the electric potential gradient across the plasma membrane (i.e. the plasma membrane potential), which depolarizes from about −110 to −50 mV during stomatal closure (primary sources). By contrast, there are no in vivo measurements of the vacuolar membrane potential in guard cells and no information regarding how it changes during stomatal opening and closure."