title: Membrane-potential changes in vacuoles isolated from storage roots of red beet (Beta vulgaris L.).
abstract: The membrane potential in vacuoles isolated from storage roots of red beet (Beta vulgaris L.) has been studied by following changes in the fluorescence of the dye 3,3'-diethylthiodicarbocyanine iodide, and by determining the uptake of the lipophilic triphenylmethylphosphonium cation. The vacuoles have a membrane potential, internal negative, which is estimated to be around-60 mV. These potentials become less negative by nearly 10 mV on addition of ATP. This ATP-dependent depolarisation is inhibited by the protonophore carbonylcyanide p-trifluoromethoxyphenylhydrazone and by the ATPase inhibitors, N,N'-dicyclohexylcarbodiimide and trimethyltin chloride, but it is largely insensitive to sodium orthovanadate. Fusicoccin had no significant effect on the isolated vacuoles, but its addition to excised tissue caused a hyperpolarisation of the cells measured using a microelectrode.
authors.affiliation: Department of Agricultural Botany, Plant Science Laboratories, University of Reading, RG6 2AS, Reading, UK.
authors.forename: A J
authors.initials: AJ
authors.lastname: Miller
authors.forename: J J
authors.initials: JJ
authors.lastname: Brimelow
authors.forename: P
authors.initials: P
authors.lastname: John