The development of a spectrophotometric stopped-flow method to measure ion flux in membrane vesicles in the millisecond to minute time region is described in detail. The technique is based on fluorescence quenching of an entrapped fluorophore (anthracene-1,5-disulfonic acid) by Cs+. The method has been applied to the measurement of acetylcholine-receptor-mediated ion flux in membrane vesicles prepared from the electric organs of both Electrophorus electricus and Torpedo californica. The method is applicable to any vesicle system in which Cs+ can substitute for either Na+ or K+. Loading of vesicles with the fluorescent dye is accomplished using the routine procedure for making the vesicles. The dye-loaded vesicles can be stored in liquid nitrogen before use. Neither the dye-loading procedure nor the presence of Cs+ changes the permeability of the membrane to ions, allowing ion-translocation measurements to be made in the millisecond to minute time region. The stopped-flow design presented allows two sequential mixings of solutions. The relationship between fluorescence quenching and ion flux as well as the interpretation of the ion flux data is described. It is shown that the data obtained with stopped-flow and Cs+ is identical to data obtained previously using a quench-flow technique and 86Rb+. The advantages of the present method over the quench-flow technique and a similar stopped-flow technique developed previously based on T1+ are described in detail.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1016/0003-2697(83)90734-0 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
The effect of environmental factors on transepithelial potential in a model Amazonian teleost, the tambaqui (Colossoma macropomum): Implications for sodium balance in harsh environments.
J Fish Biol
January 2025
Laboratory of Ecophysiology and Molecular Evolution, Brazilian National Institute for Research of the Amazon (INPA), Manaus, Brazil.
The tambaqui (Colossoma macropomum, G. Cuvier 1818) thrives both in the ion-poor waters of the Amazon and in commercial aquaculture. In both, environmental conditions can be harsh due to low ion levels, occasional high salt challenges (in aquaculture), low pH, extreme PO levels (hypoxia and hyperoxia), high PCO levels (hypercapnia), high ammonia levels (in aquaculture), and high and low temperatures.
View Article and Find Full Text PDFImproving ultrafiltration efficiency of acidified skim milk using bipolar membrane electrodialysis: Impact on protein concentrate composition, process performance, and fouling.
Food Res Int
January 2025
Department of Food Science, University of Copenhagen, Rolighedsvej 26, 1958 Frederiksberg, Denmark. Electronic address:
The efficiency of ultrafiltration (UF) of acidified skim milk (SM) is impaired by protein aggregation and mineral scaling. The aim of this study is to assess the potential of acidification by electrodialysis with bipolar membranes (EDBM), in comparison with citric acid (CA), prior to the UF process on filtration performance, fouling and composition of the protein concentrates. Electro-acidification, facilitated by a water-splitting reaction, decreased the pH of milk to ∼ 5.
View Article and Find Full Text PDFConsecutive oxidative stress in CATALASE2-deficient Arabidopsis negatively regulates Glycolate Oxidase1 activity through S-nitrosylation.
Physiol Plant
January 2025
National Engineering Laboratory of Crop Stress Resistance Breeding, School of Life Sciences, Anhui Agricultural University, Hefei, China.
Glycolate oxidase (GOX) is a crucial enzyme of photorespiration involving carbon metabolism and stress responses. It is poorly understood, however, how its activities are modulated in response to oxidative stress elicited by various environmental cues. Analysis of Arabidopsis catalase-defective mutant cat2 revealed that the GOX activities were gradually repressed during the growth, which were accompanied by decreased salicylic acid (SA)-dependent cell death, suggesting photorespiratory HO may entrain negative feedback regulation of GOX in an age-dependent manner.
View Article and Find Full Text PDFEpicatechin Influence on Biochemical Modification of Human Erythrocyte Metabolism and Membrane Integrity.
Int J Mol Sci
December 2024
Department of Chemical, Biological, Pharmaceutical and Environmental Sciences, University of Messina, Viale Ferdinando Stagno d'Alcontres 31, 98166 Messina, Italy.
Red blood cells (RBCs) are the main cells of the blood, perform numerous functions within the body and are in continuous contact with endogenous and exogenous molecules. In this context, the study aims to investigate the effect of epicatechin (EC) (flavan-3-ols) on the erythrocytes, analyzing the protective effect of the molecule and the action exerted on metabolism and RBC membrane. The effect of EC on RBC viability has been evaluated through the change in hemolysis and methemoglobin, assessing caspase 3 activity and performing a cytofluorometric analysis.
View Article and Find Full Text PDFStructure and Dynamics of the Bacterial Flagellar Motor Complex.
Biomolecules
November 2024
Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamadaoka, Suita Osaka 565-0871, Japan.
Many bacteria swim in liquids and move over solid surfaces by rotating flagella. The bacterial flagellum is a supramolecular protein complex that is composed of about 30 different flagellar proteins ranging from a few to tens of thousands. Despite structural and functional diversities of the flagella among motile bacteria, the flagellum commonly consists of a membrane-embedded rotary motor fueled by an ion motive force across the cytoplasmic membrane, a universal joint, and a helical propeller that extends several micrometers beyond the cell surface.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!