Sulphydryl groups involved in Na⁺–Li⁺ exchange in human erythrocytes

Abstract

Oxidative stress causes cellular injury that is thought to be due to increased cytosolic cation levels. Disturbances of a variety of mechanisms which normally maintain intracellular anion/cation homeostasis, occur during oxidative stress. Reactivity of the SH- groups essential for oubain-resistant Na(+)-Li(+) exchange by N-ethylmaleimide (NEM) and selenite was studied in human erythrocytes. In addition, the reactivity of the substances on SH- groups and Li(+) influx have been studied as a function of pH of the medium. The results show that NEM induces an irreversible inhibition of Li(+) influx. It diminishes progressively with the increasing pH of the medium. Whereas we obtain increasing intracellular Li(+) concentration with the rising selenite concentration in the medium. The maximum effect with this substance is reached at about pH 8.0. We can state that the -SH reagents (NEM and selenite) studied behave differently: NEM inhibits Li(+) influx by modifying the essential SH-groups of the membrane proteins in such a way that the exchange is reduced, whereas it maintains the Na(+) permeability almost unaltered. The slight increase in intracellular Na(+) induced by selenite suggests that the oxidative changes in the intracellular sulphydryl groups may constitute an important mechanism for the regulation of the intracellular cations.

Effect of N‐ethylmaleimide, chymotrypsin, and H2O2 on the viscoelasticity of human erythrocytes: Experimental measurement and theoretical analysis

“…As noted earlier, since the effects of each of these chemicals on the molecular structures are by no means specific or exclusive, detailed biochemical analyses (which is beyond the scope of this paper) will be required to further dissect the effects of each chemical [44,45] to tell a more complete story.…”

Aging Injury Impairs Structural Properties and Cell Signaling in Human Red Blood Cells; Açaì Berry Is a Keystone

“…In addition, band 3 hyper-tyrosine phosphorylation provoked relevant alterations in RBC features, such as the disruption of the band 3-ankyrin bound that connects spectrin to the plasma membrane, as well as metabolic alterations via anion transport alterations in band 3. With regard to this latter point, band 3 anion exchange capability [ 69 , 70 , 71 , 72 , 73 , 74 , 75 , 76 , 77 ] represents a suitable method to explore functional features by determining the rate constant for SO 4 2− uptake [ 78 ]. The evidence that band 3 displays alterations in the rate constant for SO 4 2− uptake after the treatment of RBCs to d -Gal-induced oxidation has also been previously showed.…”

Mechanisms Underlying the Effects of Chloroquine on Red Blood Cells Metabolism

“…The absorbance of this suspension was then measured within the range of 350–425 nm. The sulfate concentration was determined using a calibrated standard curve, established by measuring the absorbance of suspensions containing known quantities of sulfate [ 73 ]. Experimental data on sulfate concentration over time were analyzed using the following equation: 𝑐(𝑡) = 𝑐∞(1 − 𝑒−𝑘𝑡) where c ( t ) is the sulfate concentration at time t , c ∞ is intracellular sulfate concentration at equilibrium, and k is the rate constant of sulfate influx.…”