Oxidative stress and intracellular pH in the young and old erythrocytes of rat

Age-Related Modulations in Erythrocytes under Blood Bank Conditions

Background

During storage of erythrocytes, storage lesions are formed that reduce the safety and efficacy of the stored blood. Thus, there is a need to understand the changes that occur during storage. Most studies have focused on storage of a mixed population of erythrocytes. The aim of this study is to analyze the changes in young and old erythrocytes over the course if storage.

Materials and Methods

Blood was collected from the blood bank at the Kempegowda Institute of Medical Sciences (KIMS) Hospital (Bengaluru, India) and stored for 35 days in CPDA-1 at 4°C. Every 5 days, erythrocytes were separated based on the blood's age using a Percoll-BSA gradient. Young and old erythrocytes obtained were used for analysis of the following oxidative stress (OS) markers: hemoglobin (Hb), hemolysis, mechanical fragility, antioxidant enzymes (superoxide dismutase and catalase [CAT]), superoxides, sialic acid, glutamic oxaloacetate transaminase (GOT), glucose, plasma membrane redox system (PMRS), total antioxidant capacity-cupric ion reducing antioxidant capacity assay (TAC_CUPRAC), lactate dehydrogenase (LDH), lipid peroxidation products (malondialdehyde [MDA] and conjugate dienes), and protein oxidation products (advanced oxidation protein products and protein sulfhydryls).

Result

Young cells had higher amounts of Hb, sialic acid, GOT, LDH, TAC_CUPRAC, CAT, and superoxides compared to old cells. Old cells, however, had higher PMRS and MDA levels with respect to young cells.

Discussion

Young cells could endure OS during storage more efficiently than old cells. In conclusion, the efficacy of stored blood depends on the ratio of young cells in the population. This study highlights the prospects of storing young erythrocytes for a prolonged shelf life of blood.

Erythrocyte Senescence in a Model of Rat Displaying Hutchinson-Gilford Progeria Syndrome

Background

Increased oxidative stress is a major cause of aging and age-related diseases. Erythrocytes serve as good model for aging studies. Dihydrotachysterol is known to induce premature aging feature in rats mimicking Hutchinson-Gilford progeria syndrome.

Aim

In the present study, attempts have been made to explore the differential response of young and senescent erythrocytes separated by density gradient centrifugation from accelerated senescence model of rats mimicking Hutchinson-Gilford progeria syndrome and naturally aged rats.

Methods

The erythrocytes of naturally aged and progeroid rats were separated into distinct, young and old cells on the basis of their differential densities. The parameters of oxidative stress and membrane transport systems were studied.

Discussion and Conclusion

Our study provides evidence that organismal aging negatively affects oxidative stress markers and membrane transport systems in both young and old erythrocytes. This study further substantiates that the changes in progeria model of rats resemble natural aging in terms of erythrocyte senescence.

Rapamycin mitigates erythrocyte membrane transport functions and oxidative stress during aging in rats

Erythrocyte membrane is a suitable model to study various metabolic and physiological functions as it undergoes variety of biochemical changes during aging. An age-dependent modulatory effect of rapamycin on erythrocyte membrane functions is completely unknown. Therefore, the present study was undertaken to investigate the effect of rapamycin on age-dependent impaired activities of transporters/exchangers, altered levels of redox biomarkers, viz. protein carbonyl (PC), lipid hydroperoxides (LHs), total thiol (-SH), sialic acid (SA) and intracellular calcium ion [Ca²⁺]i, and osmotic fragility of erythrocyte membrane. A significant reduction in membrane-bound activities of Na⁺/K⁺-ATPase (NKA) and Ca²⁺-ATPase (PMCA), and levels of -SH and SA was observed along with a simultaneous induction in Na⁺/H⁺ exchanger (NHE) activity and levels of [Ca²⁺]i, PC, LH and osmotic fragility in old-aged rats. Rapamycin was found to be a promising age-delaying drug that significantly reversed the aging-induced impaired activities of membrane-bound ATPases and altered levels of redox biomarkers.

Erythrocyte senescence and membrane transporters in young and old rats

Alterations at the level of plasma membrane are reported to play an important role in cellular senescence. The present study was undertaken to correlate cellular senescence, membrane transport processes and organismal aging. To achieve this objective activities of membrane linked Na⁺/K ⁺ ATPase (NKA), Na⁺/H⁺ exchanger (NHE) and correlation with membrane hydrxyperoxide level, sialic acid content and membrane protein oxidation was studied in density-gradient fractionated young and old erythrocytes from 4 and 24 month old Wistar rats. The results reveal that cellular aging within the tissue is associated with significant decrease in activities of NKA and NHE of senescent erythrocytes in comparison to younger cell population of same age group. The result shows that impaired ion homeostasis due to altered membrane transporters including functional and compositional changes may be one of the reasons responsible behind rat erythrocyte aging.

Biological effects of the electrostatic field: red blood cell-related alterations of oxidative processes in blood

The aim of this study was to determine activities of pro-/antioxidant enzymes, reactive oxygen species (ROS) content, and oxidative modification of proteins and lipids in red blood cells (RBCs) and blood plasma of rats exposed to electrostatic field (200 kV/m) during the short (1 h) and the long periods (6 day, 6 h daily). Short-term exposure was characterized by the increase of oxidatively damaged proteins in blood of rats. This was strongly expressed in RBC membranes. After long-term action, RBC content in peripheral blood was higher than in control (P < 0.01) and the attenuation of prooxidant processes was shown.

HIGHLIGHTS

External electrostatic field (200 kV/m) alters the balance in pro-/antioxidant processes. We examine oxidative processes in plasma and RBC (hemolysate and membranes). Biological effects of static electric field depend on exposure time. Acute action of electrostatic field (ESF) characterized by activation of the prooxidant processes. Long-term exposure reflected with prevalence of antioxidant activities.

Formation of glutathionyl dinitrosyl iron complexes protects against iron genotoxicity

Dinitrosyl iron(i) complexes (DNICs), intracellular NO donors, are important factors in nitric oxide-dependent regulation of cellular metabolism and signal transduction. It has been shown that NO diminishes the toxicity of iron ions and vice versa. To gain insight into the possible role of DNIC in this phenomenon, we examined the effect of GS-DNIC formation on the ability of iron ions to mediate DNA damage, by treatment of the pUC19 plasmid with physiologically relevant concentrations of GS-DNIC. It was shown that GS-DNIC formation protects against the genotoxic effect of iron ions alone and iron ions in the presence of a naturally abundant antioxidant, GSH. This sheds new light on the iron-related protective effect of NO under the circumstances of oxidative stress.

Markers of oxidative stress in senescent erythrocytes obtained from young and old age rats

The role of oxidative stress during aging is well documented. Evidence is available linking animal life span to the development of oxidative stress. Up to a certain limit of oxidative stress, cells function to counteract the oxidant effects and to restore redox balance by resetting critical homeostatic parameters. Red blood cells (RBCs) offer a very good model to study cellular senescence. In vivo aging of red blood cells is associated with increased cellular density, which corresponds to increased cell age. The present study aims to investigate age-dependent oxidative stress in RBC subpopulations obtained after Percoll density gradient centrifugation from young and old rats. We observe an increase in plasma membrane redox system (PMRS) activity (p<0.001) and lipid peroxidation (p<0.001) between less dense and senescent RBCs in both young and old rats. Our findings provide evidence of a higher level of oxidative stress in senescent erythrocytes, with the effect being more pronounced in old (24-month-old) rats compared to young (4-month-old) rats. The present findings emphasize the role of oxidative stress not only in organismal aging but also in cell senescence.

Regulation of acid-base transporters by reactive oxygen species following mitochondrial fragmentation

Mitochondrial morphology is determined by the balance between the opposing processes of fission and fusion, each of which is regulated by a distinct set of proteins. Abnormalities in mitochondrial dynamics have been associated with a variety of diseases, including neurodegenerative conditions such as Alzheimer's disease, Parkinson's disease, and dominant optic atrophy. Although the genetic determinants of fission and fusion are well recognized, less is known about the mechanism(s) whereby altered morphology contributes to the underlying pathophysiology of these disease states. Previous work from our laboratory identified a role for mitochondrial dynamics in intracellular pH homeostasis in both mammalian cell culture and in the genetic model organism Caenorhabditis elegans. Here we show that the acidification seen in mutant animals that have lost the ability to fuse their mitochondrial inner membrane occurs through a reactive oxygen species (ROS)-dependent mechanism and can be suppressed through the use of pharmacological antioxidants targeted specifically at the mitochondrial matrix. Physiological approaches examining the activity of endogenous mammalian acid-base transport proteins in rat liver Clone 9 cells support the idea that ROS signaling to sodium-proton exchangers contributes to acidification. Because maintaining pH homeostasis is essential for cell function and viability, the results of this work provide new insight into the pathophysiology associated with the loss of inner mitochondrial membrane fusion.

Peroxyl-induced oxidative stress in aging erythrocytes of rat

This study aims at determining the possible changes in intracellular calcium (Ca (i) (2+) ), plasma membrane calcium ATPase (PMCA) activity and phosphatidylserine (PS) along with glutathione (GSH) level in response to an oxidant challenge in vitro. Erythrocytes were isolated on Percoll and incubated with 2, 2'azobis (2-aminopropane) hydrochloride (AAPH) as well as with vitamin C preceding AAPH incubation. Membrane integrity in terms of hemolysis was negatively related to acetylcholine esterase (AChE) activity with the extent of reduction under OS being higher in the old erythrocyte than in the young. A divergent pattern was seen towards lower PMCA and higher (Ca (i) (2+) ) in the young and old cells. However, the PMCA activity in the stressed young cell was high when pre-treated with vitamin C. PS externalization in the young under OS is perhaps analogous to normal aging, with vitamin C preventing premature death. These findings suggest that young erythrocytes may benefit from vitamin C in therapies addressed towards the mechanisms underlying the reduced effects of OS.