Membrane Potential Probes

The main classes of dyes nsed as potentiometric probes are cationic or zwitterionic styryl dyes, cationic carbocyanines and rhodamines, anionic oxonols and hybrid oxonols and merocyanines. The particular class of dye determines factors snch as accnmnlation in cells, response mechanism and toxicity. 

The styryl dye Di-4-ANEPPS (3.69) is a fast-responding membrane potential probe, particnlarly nsefnl for the studies of neuronal membrane potentials. 

---

Perry SW, Norman IP, Barbieri J, Brown EB, Gelbard HA (2011) Mitochondrial membrane potential probes and the proton gradient a practical usage guide. Biotechniques 50(2) 98-115... 

A neutral, carrier-based calcium ion-selective microelectrode has been used in the determination of tetraphenylphosphonium ions (used as membrane potential probes) during respiratory-state transitions in rat mitochondria. ... 

Figure 5. Compound VGP-318 does not alter the plasma membrane potential in Leishmania lines. Promastigotes were incubated with 30 pM of compound VGP-318 for 3 h and then treated with 2 pM of the specific plasma membrane potential probe D1BAC4(3) for 10 min at 28 Untreated parasites were used as control, and treatment with 10 pM CCCP was used as 100% depolarization of the plasma membrane potential. Data are means SD of three independent e)q eriments. Significant differences were determined using Student s f-test p< 0.01).

Staining Applications Brainstem cortex neurons" Biological Applications Measuring membrane potential " probes for Na, K-ATPase reaction mechanism examining activity of ion channels ... 

Castranova, V. Van Dyke, K. Analysis of oxidation of the membrane potential probe, Di-S-C3(5), during granulocyte activation. Microchem. J. 1984, 29, 151-161. 

IV. MOLECULAR PROBE FOR ISE MEMBRANE POTENTIALS BASED ON PHOTOSWITCHABLE AZOBIS(BENZO-15-CROWN-5) lONOPHORES [17]... 

In addition to their use as reference electrodes in routine potentiometric measurements, electrodes of the second kind with a saturated KC1 (or, in some cases, with sodium chloride or, preferentially, formate) solution as electrolyte have important applications as potential probes. If an electric current passes through the electrolyte solution or the two electrolyte solutions are separated by an electrochemical membrane (see Section 6.1), then it becomes important to determine the electrical potential difference between two points in the solution (e.g. between the solution on both sides of the membrane). Two silver chloride or saturated calomel electrodes are placed in the test system so that the tips of the liquid bridges lie at the required points in the system. The value of the electrical potential difference between the two points is equal to that between the two probes. Similar potential probes on a microscale are used in electrophysiology (the tips of the salt bridges are usually several micrometres in size). They are termed micropipettes (Fig. 3.8D.)... 

Fig. 6.18 Experimental arrangement for measurement of the membrane potential of a nerve fibre (axon) excited by means of current pulses (1) excitation electrodes, (2) potential probes. (According to B. 

Mandala M, Serck-Hanssen G, Martino G, Helle KB (1999) The fluorescent cationic dye rhodamine 6G as a probe for membrane potential in bovine aortic endothelial cells. Anal Biochem 274 1-6... 

The method described here can be applied to gain insight about environmental effects on the absorption and fluorescence of other chromophores and environments, including dyes used to probe the membrane potentials. 

Grinvald A, Hildesheim R, Farber IC, Anglister L (1982) Improved fluorescent-probes for the measurement of rapid changes in membrane-potential. Biophys J 39(3) 301—308... 

Loew LM, Bonneville GW, Surow J (1978) Charge shift optical probes of membrane-potential - theory. Biochemistry 17(19) 4f)65—4071... 

Loew LM, Scully S, Simpson L, Waggoner AS (1979) Evidence for a charge-shift electro-chromic mechanism in a probe of membrane-potential. Nature 281(5731 ) 497—499... 

Electric field sensitive dyes respond to changes in electrical membrane potential by a variety of different mechanisms with widely varying response times depending on their chemical structure and their interaction with the membrane. An understanding of the mechanisms of dye response and their response mechanisms is important for an appropriate choice of a probe for a particular application. The purpose of this chapter is, therefore, to provide an overview of the dyes presently available, how they respond to voltage changes, and give some examples of how they have been applied. Finally, because there is still scope for the development of new dyes with improved properties, some directions for future research will be discussed. 

Waggoner A (1976) Optical probes of membrane potential. J Membr Biol 27 317-334... 

Waggoner AS (1985) Dye probes of cell, organelle, and vesicle membrane potentials. In Martonosi AN (ed) The enzymes of biological membranes, 2nd edn. Plenum, New York... 

The studies on phospholipid bilayers with defined amounts of charged component are helpful to explain the partition characteristics in biological membranes. Liposome water partition data of propranolol in lipids from kidney epithelial cells (a common model system in pharmaceutical sciences for the uptake into the gastrointestinal tract) have been successfully described with partition models developed for pure bilayers or defined mixtures [159]. Since lipophilic cations and anions can be used as probes for the membrane potential, their interaction with microbial and mitochondrial membranes has been studied... 

Figure 5.3. (a) Example for a compound used in the study of membrane potentials and (b) principle of funcboning of visualizing nerve pulses in a living cell. When a nerve pulse passes, the membrane potential changes, and this induces a change in the fluorescence intensity of the probe. The temporal and spatial profile of these changes can be followed by time-resolved methods. 

L. B. Cohen, B. M. Salzberg, H. V. Davila, W. N. Ross, D. Landowne, A. S. Waggoner, and C. H. Wang, Changes in axon fluorescence during activity Molecular probes of membrane potential, J. Membrane Biol. 19, 1 (1974). 

R. E. London, S.A. Gabel, Determination of membrane potential and cell volume by F NMR using trifluoroacetate and trifluoroacetamide probes. Biochemistry 28 (1989) 2378-2382. 

---