Alterations of hemorheological parameters and tubulin content in erythrocytes from diabetic subjects

Tubulin-mediated anatomical and functional changes caused by Ca2+ in human erythrocytes

In previous research, we observed that tubulin can be found in three fractions within erythrocytes, i.e., attached to the membrane, as a soluble fraction, or as part of a structure that can be sedimented by centrifugation. Given that its differential distribution within these fractions may alter several hemorheological properties, such as erythrocyte deformability, the present work studied how this distribution is in turn affected by Ca²⁺, another key player in the regulation of erythrocyte cytoskeleton stability. The effect of Ca²⁺ on some hemorheological parameters was also assessed. The results showed that when Ca²⁺ concentrations increased in the cell, whether by the addition of ionophore A23187, by specific plasma membrane Ca^2 + _ATPase (PMCA) inhibition, or due to arterial hypertension, tubulin translocate to the membrane, erythrocyte deformability decreased, and phosphatidylserine exposure increased. Moreover, increased Ca²⁺ was associated with an inverse correlation in the distribution of tubulin and spectrin, another important cytoskeleton protein. Based on these findings, we propose the existence of a mechanism of action through which higher Ca²⁺ concentrations in erythrocytes trigger the migration of tubulin to the membrane, a phenomenon that results in alterations of rheological and molecular aspects of the membrane itself, as well as of the integrity of the cytoskeleton.

The influence of shorter red blood cell lifespan on the rate of HbA1c target achieved in type 2 diabetes patients with a HbA1c detection value lower than 7

BACKGROUND

Variations in the red blood cell (RBC) lifespan can affect glycosylated hemoglobin (HbA1c) test values, but there is still a lack of evidence regarding how and to what degree the RBC lifespan influences HbA1c in the type 2 diabetes mellitus (T2DM) population owing to the restriction of traditional RBC lifespan-detection means. This study aimed to investigate the influence of RBC lifespan variation on HbA1c values in T2DM patients with a HbA1c detection value lower than 7%.

METHODS

Patients with HbA1c <7% were divided into two groups: RBC lifespan <90 days and RBC lifespan ≥90 days. We collected blood glucose levels at seven time points for three consecutive months, assessed the HbA1c and glycosylated albumin levels, and calculated the hemoglobin glycation index (HGI) for each patient.

RESULTS

There were no statistical differences in the HbA1c value between two groups, but the estimated glycosylated hemoglobin (eHbA1c) was significantly higher in patients with an RBC lifespan <90 days. The proportion of the eHbA1c ≥7% in the group with an RBC lifespan <90 days was significantly higher than the other group (33.87% vs. 12.50%, p < .01). Pearson analysis showed a significant negative correlation between RBC lifespan and the HGI in patients with T2DM (r = -0.348, p < .01).

CONCLUSION

A reduced RBC lifespan in T2DM patients caused a noticeable underestimate of the blood glucose levels as presented by HbA1c detection value.

The microtubule network enables Src kinase interaction with the Na,K-ATPase to generate Ca2+ flashes in smooth muscle cells

Background: Several local Ca²⁺ events are characterized in smooth muscle cells. We have previously shown that an inhibitor of the Na,K-ATPase, ouabain induces spatially restricted intracellular Ca²⁺ transients near the plasma membrane, and suggested the importance of this signaling for regulation of intercellular coupling and smooth muscle cell contraction. The mechanism behind these Na,K-ATPase-dependent “Ca²⁺ flashes” remains to be elucidated. In addition to its conventional ion transport function, the Na,K-ATPase is proposed to contribute to intracellular pathways, including Src kinase activation. The microtubule network is important for intracellular signaling, but its role in the Na,K-ATPase-Src kinase interaction is not known. We hypothesized the microtubule network was responsible for maintaining the Na,K-ATPase-Src kinase interaction, which enables Ca²⁺ flashes.

Methods: We characterized Ca²⁺ flashes in cultured smooth muscle cells, A7r5, and freshly isolated smooth muscle cells from rat mesenteric artery. Cells were loaded with Ca²⁺-sensitive fluorescent dyes, Calcium Green-1/AM and Fura Red/AM, for ratiometric measurements of intracellular Ca²⁺. The Na,K-ATPase α2 isoform was knocked down with siRNA and the microtubule network was disrupted with nocodazole. An involvement of the Src signaling was tested pharmacologically and with Western blot. Protein interactions were validated with proximity ligation assays.

Results: The Ca²⁺ flashes were induced by micromolar concentrations of ouabain. Knockdown of the α2 isoform Na,K-ATPase abolished Ca²⁺ flashes, as did inhibition of tyrosine phosphorylation with genistein and PP2, and the inhibitor of the Na,K-ATPase-dependent Src activation, pNaKtide. Ouabain-induced Ca²⁺ flashes were associated with Src kinase activation by phosphorylation. The α2 isoform Na,K-ATPase and Src kinase colocalized in the cells. Disruption of microtubule with nocodazole inhibited Ca²⁺ flashes, reduced Na,K-ATPase/Src interaction and Src activation.

Conclusion: We demonstrate that the Na,K-ATPase-dependent Ca²⁺ flashes in smooth muscle cells require an interaction between the α2 isoform Na, K-ATPase and Src kinase, which is maintained by the microtubule network.

Erythrocyte osmotic fragility is not linked to vitamin C nutriture in adults with well-controlled type 2 diabetes

Erythrocyte fragility is amplified by oxidative stress and linked to diabetes-specific microvascular disease. Vitamin C supplementation improves glycemic indices in adults with type 2 diabetes (T2D) by improving antioxidant status. This cross-sectional study examined the relationships between vitamin C status and erythrocyte osmotic fragility in adults with or without T2D. Participants provided a fasting blood sample for erythrocyte osmotic fragility testing as a function of hypotonic NaCl concentrations. Additionally, plasma was stabilized with metaphosphoric acid prior to vitamin C analysis using isocratic reverse-phase UV-HPLC separation. Participants were grouped as diagnosed T2D (n = 14; 36% female; 55.5 ± 8.2 y; 31.5 ± 9.0 kg/m²; HbA1c: 7.4 ± 1.9%; plasma vitamin C: 36.0 ± 12.2 μM) or no diabetes (n = 16; 69% female; 38.7 ± 13.5 y; 26.8 ± 6.6 kg/m²; HbA1c: 5.4 ± 0.3%; plasma vitamin C: 34.8 ± 10.9 μM). Participant characteristics differed between groups only for age and hemoglobin A1c (HbA1c; p < 0.05). All hemolysis parameters were in normal ranges for the participants with T2D, and no significant differences in hemolysis parameters were noted between those with or without T2D. However, among participants with T2D, the NaCl concentration eliciting 50% hemolysis was higher for those with low (<7%) vs. high (>7%) HbA1c values (p = 0.037) indicating a slightly higher erythrocyte fragility in the former group. Vitamin C status did not impact any of the hemolysis parameters in adults with or without T2D. Thus, erythrocyte fragility was not elevated in T2D, and vitamin C nutriture was not related to erythrocyte fragility in adults with well-controlled T2D.

The Aneugenicity of Ketone Bodies in Colon Epithelial Cells Is Mediated by Microtubule Hyperacetylation and Is Blocked by Resveratrol

Diabetes mellitus (DM) is considered to be associated with an increased risk of colorectal cancer. Recent studies have also revealed that tubulin hyperacetylation is caused by a diabetic status and we have reported previously that, under microtubule hyperacetylation, a microtubule severing protein, katanin-like (KL) 1, is upregulated and contributes to tumorigenesis. To further explore this phenomenon, we tested the effects of the ketone bodies, acetoacetate and β-hydroxybutyrate, in colon and fibroblast cells. Both induced microtubule hyperacetylation that responded differently to a histone deacetylase 3 knockdown. These two ketone bodies also generated intracellular reactive oxygen species (ROS) and hyperacetylation was commonly inhibited by ROS inhibitors. In a human fibroblast-based microtubule sensitivity test, only the KL1 human katanin family member showed activation by both ketone bodies. In primary cultured colon epithelial cells, these ketone bodies reduced the tau protein level and induced KL1- and α-tubulin acetyltransferase 1 (ATAT1)-dependent micronucleation. Resveratrol, known for its tumor preventive and tubulin deacetylation effects, inhibited this micronucleation. Our current data thus suggest that the microtubule hyperacetylation induced by ketone bodies may be a causal factor linking DM to colorectal carcinogenesis and may also represent an adverse effect of them that needs to be controlled if they are used as therapeutics.

Beneficial Effect of Quercetin on Erythrocyte Properties in Type 2 Diabetic Rats

Diabetes mellitus is characterized by tissue oxidative damage and impaired microcirculation, as well as worsened erythrocyte properties. Measurements of erythrocyte deformability together with determination of nitric oxide (NO) production and osmotic resistance were used for the characterization of erythrocyte functionality in lean (control) and obese Zucker diabetic fatty (ZDF) rats of two age categories. Obese ZDF rats correspond to prediabetic (younger) and diabetic (older) animals. As antioxidants were suggested to protect erythrocytes, we also investigated the potential effect of quercetin (20 mg/kg/day for 6 weeks). Erythrocyte deformability was determined by the filtration method and NO production using DAF-2DA fluorescence. For erythrocyte osmotic resistance, we used hemolytic assay. Erythrocyte deformability and NO production deteriorated during aging-both were lower in older ZDF rats than in younger ones. Three-way ANOVA indicates improved erythrocyte deformability after quercetin treatment in older obese ZDF rats only, as it was not modified or deteriorated in both (lean and obese) younger and older lean animals. NO production by erythrocytes increased post treatment in all experimental groups. Our study indicates the potential benefit of quercetin treatment on erythrocyte properties in condition of diabetes mellitus. In addition, our results suggest potential age-dependency of quercetin effects in diabetes that deserve additional research.

Prevention of tubulin/aldose reductase association delays the development of pathological complications in diabetic rats

In recent studies, we found that compounds derived from phenolic acids (CAFs) prevent the formation of the tubulin/aldose reductase complex and, consequently, may decrease the occurrence or delay the development of secondary pathologies associated with aldose reductase activation in diabetes mellitus. To verify this hypothesis, we determined the effect of CAFs on Na⁺,K⁺-ATPase tubulin-dependent activity in COS cells, ex vivo cataract formation in rat lenses and finally, to evaluate the antidiabetic effect of CAFs, diabetes mellitus was induced in Wistar rats, they were treated with different CAFs and four parameters were determinates: cataract formation, erythrocyte deformability, nephropathy and blood pressure. After confirming that CAFs are able to prevent the association between aldose reductase and tubulin, we found that treatment of diabetic rats with these compounds decreased membrane-associated acetylated tubulin, increased NKA activity, and thus reversed the development of four AR-activated complications of diabetes mellitus determined in this work. Based on these results, the existence of a new physiological mechanism is proposed, in which tubulin is a key regulator of aldose reductase activity. This mechanism can explain the incorrect functioning of aldose reductase and Na⁺,K⁺-ATPase, two key enzymes in the pathogenesis of diabetes mellitus. Moreover, we found that such alterations can be prevented by CAFs, which are able to dissociate tubulin/aldose reductase complex.

In silico, in vitro, and in vivo investigation of antioxidant potential and toxicity of ethyl ferulate

By submitting this manuscript, each author certifies that they have made a direct and substantial contribution to the work reported in the manuscript. In this manuscript the conception, design, investigation, acquisition of data and analysis, interpretation of data and writing of the article were conducted by author Camila Bomfim de Sá under the guidance of professors Margareth de Fátima Formiga Melo Diniz, Hilzeth de Luna Freire Pessôa and Caliandra Maria Bezerra Luna Lima, who also approved the final version of the manuscript. Professor Damião Pergentino de Sousa and his student Mayara Castro de Morais performed the production, synthesis and chemical characterization of ethyl ferulate (EF). Professor Abrahão Alves de Oliveira Filho assessed the in silico tests. PhD student Andressa Brito Lira participated in the critical review of the text for important intellectual content and assisted in the in vitro antioxidant activity and cytotoxicity tests. Kardilandia Mendes de Oliveira participated in acute oral toxicity tests evaluating the biochemical parameters. Students, Tafaela Dias and Cinthia Rodrigues Melo also assisted in the acute oral toxicity testing and preparing of slides for histopathological analysis. Pathologist Alexandre Rolim da Paz analyzed the histopathology results. EF, a phenolic compound of the large class of phenylpropanoids, is derived from ferulic acid and is produced both naturally and synthetically. Its principal pharmacological activities are: anti-inflammatory and antioxidant activity. This study aimed to investigate the in silico, in vitro and in vivo toxicity and antioxidant activity of EF. The in silico prediction showed more than 20 biological activities as well as good absorption at the biological membranes and no theoretical toxicity. However, EF presented high environmental toxicity. EF presented low hemolytic potential and exerted protective activity for the erythrocyte membrane for only blood type O. EF presented antioxidant activity against H₂O₂ at all concentrations and all blood types, but no effect against phenylhydrazine, being unable to prevent its oxidative effects. In the acute nonclinical toxicological trial, the treated animals presented behavioral changes (e.g., sedation). Feed intake was higher for the 2000 mg/kg group, but with no significant difference in weight change. The biochemical parameters presented no differences between treated and control animals, and the organs remained intact with no change. Thus, EF presents a low toxic profile and this study provides important information about the toxicity of this compound, suggesting future safe use.

Inhibition of flippase-like activity by tubulin regulates phosphatidylserine exposure in erythrocytes from hypertensive and diabetic patients

Plasma membrane tubulin is an endogenous regulator of P-ATPases and the unusual accumulation of tubulin in the erythrocyte membrane results in a partial inhibition of some their activities, causing hemorheological disorders like reduced cell deformability and osmotic resistance. These disorders are of particular interest in hypertension and diabetes, where the abnormal increase in membrane tubulin may be related to the disease development. Phosphatidylserine is more exposed on the membrane of diabetic erythrocytes than in healthy cells. In most cells, phosphatidylserine is transported from the exoplasmic to the cytoplasmic leaflet of the membrane by lipid flippases. Here we report that phosphatidylserine is more exposed in erythrocytes from both hypertensive and diabetic patients than in healthy erythrocytes, which could be attributed to the inhibition of flippase activity by tubulin. This is supported by: (i)- the translocation rate of a fluorescent phosphatidylserine analog in hypertensive and diabetic erythrocytes was slower than in healthy cells, (ii)- the pharmacological variation of membrane tubulin in erythrocytes and K562 cells was linked to changes in phosphatidylserine translocation, (iii)- the P-ATPase-dependent phosphatidylserine translocation in inside-out vesicles from human erythrocytes was inhibited by tubulin. These results suggest that tubulin regulates flippase activity and hence the membrane phospholipid asymmetry.

Human erythrocytes: cytoskeleton and its origin

In the last few years, erythrocytes have emerged as the main determinant of blood rheology. In mammals, these cells are devoid of nuclei and are, therefore, unable to divide. Consequently, all circulating erythrocytes come from erythropoiesis, a process in the bone marrow in which several modifications are induced in the expression of membrane and cytoskeletal proteins, and different vertical and horizontal interactions are established between them. Cytoskeleton components play an important role in this process, which explains why they and the interaction between them have been the focus of much recent research. Moreover, in mature erythrocytes, the cytoskeleton integrity is also essential, because the cytoskeleton confers remarkable deformability and stability on the erythrocytes, thus enabling them to undergo deformation in microcirculation. Defects in the cytoskeleton produce changes in erythrocyte deformability and stability, affecting cell viability and rheological properties. Such abnormalities are seen in different pathologies of special interest, such as different types of anemia, hypertension, and diabetes, among others. This review highlights the main findings in mammalian erythrocytes and their progenitors regarding the presence, conformation and function of the three main components of the cytoskeleton: actin, intermediate filaments, and tubulin.

The Product of Red Blood Cells and Hematocrit Can Be Used as a Novel Indicator of Impaired Fasting Blood Glucose Status

OBJECTIVE

To explore whether the red blood cell count multiplied by hematocrit index (RBCHct) in blood routine parameters can indicate the risk of impaired fasting blood glucose (IFG), and whether it is related to insulin resistance and inflammation.

METHODS

In this cross-sectional study, previous history of diabetes was excluded, and people with normal and impaired IFG were included. We use Spearman analysis to evaluate the correlation between RBCHct index and fasting plasma glucose, insulin resistance homeostasis model assessment (HOMA-IR), and hypersensitive C-reactive protein (hs-CRP). Binary logistic regression analysis was used to evaluate the RBCHct index for assessing the potential risk of IFG, and the receiver operating characteristic (ROC) curve was used to evaluate the RBCHct index for diagnosing insulin resistance and chronic low-grade inflammatory efficacy among those with IFG.

RESULTS

Correlation analysis showed that the RBCHct index and fasting plasma glucose (r=0.088, P=0.003); HOMA-IR (r=0.199, P<0.001); and hs-CRP (r=0.097, P=0.001) were positively correlated. After adjusting for confounding factors, the risk of IFG in the third and fourth quartiles of the RBCHct index increased to 1.889 and 3.048 times. The area under the ROC curve of the RBCHct index for diagnosis of insulin resistance state (HOMA-IR) was 0.695 (p<0.001), and the area under the ROC curve of the RBCHct index for the diagnosis of chronic low-inflammatory state (hs-CRP) was 0.641 (P=0.010).

CONCLUSION

The RBCHct index may be a potential indicator for assessing the risk of prediabetes and is closely related to whether the body is in a state of insulin resistance and inflammation under IFG.

The role of oxidant stress and gender in the erythrocyte arginine metabolism and ammonia management in patients with type 2 diabetes

OBJECTIVES

To study the differences in the levels of nitrogen metabolites, such as ammonia and nitric oxide and the correlations existing among them in both red blood cells (RBCs) and serum, as well as the possible differences by gender in healthy subjects and patients with type 2 Diabetes Mellitus (DM).

DESIGN AND METHODS

This cross-sectional study included 80 patients diagnosed with type 2 DM (40 female and 40 male patients) and their corresponding controls paired by gender (40 female and 40 male). We separated serum and RBC and determined metabolites mainly through colorimetric and spectrophotometric assays. We evaluated changes in the levels of the main catabolic by-products of blood nitrogen metabolism, nitric oxide (NO), and malondialdehyde (MDA).

RESULTS

Healthy female and male controls showed a differential distribution of blood metabolites involved in NO metabolism and arginine metabolism for the ornithine and urea formation. Patients with DM had increased ammonia, citrulline, urea, uric acid, and ornithine, mainly in the RBCs, whereas the level of arginine was significantly lower in men with type 2 DM. These findings were associated with hyperglycemia, glycosylated hemoglobin (Hb A1C), and levels of RBC's MDA. Furthermore, most of the DM-induced alterations in nitrogen-related metabolites appear to be associated with a difference in the RBC capacity for the release of these metabolites, thereby causing an abrogation of the gender-related differential management of nitrogen metabolites in healthy subjects.

CONCLUSIONS

We found evidence of a putative role of RBC as an extra-hepatic mechanism for controlling serum levels of nitrogen-related metabolites, which differs according to gender in healthy subjects. Type 2 DM promotes higher ammonia, citrulline, and MDA blood levels, which culminate in a loss of the differential management of nitrogen-related metabolites seen in healthy women and men.

Tubulin-Na+ , K + -ATPase interaction: Involvement in enzymatic regulation and cellular function

A new function for tubulin was described by our laboratory: acetylated tubulin forms a complex with Na⁺ ,K ⁺ -ATPase (NKA) and inhibits its activity. This process was shown to be a regulatory factor of physiological importance in cultured cells, human erythrocytes, and several rat tissues. Formation of the acetylated tubulin-NKA complex is reversible. We demonstrated that in cultured cells, high concentrations of glucose induce translocation of acetylated tubulin from cytoplasm to plasma membrane with a consequent inhibition of NKA activity. This effect is reversed by adding glutamate, which is coctransported to the cell with Na ⁺ . Another posttranslational modification of tubulin, detyrosinated tubulin, is also involved in the regulation of NKA activity: it enhances the NKA inhibition induced by acetylated tubulin. Manipulation of the content of these modifications of tubulin could work as a new strategy to maintain homeostasis of Na ⁺ and K ⁺ , and to regulate a variety of functions in which NKA is involved, such as osmotic fragility and deformability of human erythrocytes. The results summarized in this review show that the interaction between tubulin and NKA plays an important role in cellular physiology, both in the regulation of Na ⁺ /K ⁺ homeostasis and in the rheological properties of the cells, which is mechanically different from other roles reported up to now.

Isopropyl Caffeate: A Caffeic Acid Derivative-Antioxidant Potential and Toxicity

Phenolic compounds, among them isopropyl caffeate, possess antioxidant potential, but not without toxicity and/or adverse effects. The present study aimed to evaluate the antioxidant activity and toxicity of isopropyl caffeate through in silico, in vitro and in vivo testing. The results showed that isopropyl caffeate presents no significant theoretical risk of toxicity, with likely moderate bioactivity: GPCR binding, ion channel modulation, nuclear receptor binding, and enzyme inhibition. Isopropyl caffeate induced hemolysis only at the concentrations of 500 and 1000 μg/ml. We observed types A and O erythrocyte protection from osmotic stress, no oxidation of erythrocytes, and even sequestrator and antioxidant behavior. However, moderate toxicity, according to the classification of GHS, was demonstrated through depressant effects on the central nervous system, though there was no influence on water and food consumption or on weight gain, and it did present possible hepatoprotection. We conclude that the effects induced by isopropyl caffeate are due to its antioxidant activity, capable of preventing production of free radicals and oxidative stress, a promising molecule with pharmacological potential.

Mass Spectrometric Quantitation of Tubulin Acetylation from Pepsin-Digested Rat Brain Tissue Using a Novel Stable-Isotope Standard and Capture by Anti-Peptide Antibody (SISCAPA) Method

Acetylation of α-tubulin at Lys-40 is a potential biomarker for cognitive deficits in various neurological disorders. However, this key post-translational modification (PTM) has not been previously studied with mass spectrometry, due to the inadequate distribution of tryptic cleavage sites. Following peptic digestion, a surrogate sequence containing this key PTM site was identified and was found to be stable and quantitatively reproducible. A highly sensitive and specific SISCAPA-LC-MS method for quantitating rat brain tubulin acetylation was developed, validated, and applied, and only required a small amount of tissue (2.2 mg). This workflow includes peptic digestion, stable-isotope dilution, capture with antiacetylated peptide antibody bound on protein G beads, and quantitation using LC-MS. The method allowed a lower limit of quantitation at 2.50 pmol/mg and provided a linear range of 2.50-62.50 pmol/mg. Selectivity, intra and interday precision and accuracy were also validated. This method has been successfully applied in a preclinical study of organophosphate neurotoxicity, and we found that chronic exposure to chlorpyrifos led to a significant and persistent inhibition of brain tubulin acetylation.

Tubulin is retained throughout the human hematopoietic/erythroid cell differentiation process and plays a structural role in sedimentable fraction of mature erythrocytes

We investigated the properties of tubulin present in the sedimentable fraction ("Sed-tub") of human erythrocytes, and tracked the location and organization of tubulin in various types of cells during the process of hematopoietic/erythroid differentiation. Sed-tub was sensitive to taxol/nocodazole (drugs that modify microtubule assembly/disassembly), but was organized as part of a protein network rather than in typical microtubule form. This network had a non-uniform "connected-ring" structure, with tubulin localized in the connection areas and associated with other proteins. When tubulin was eliminated from Sed-tub fraction, this connected-ring structure disappeared. Spectrin, a major protein component in Sed-tub fraction, formed a complex with tubulin. During hematopoietic differentiation, tubulin shifts from typical microtubule structure (in pro-erythroblasts) to a disorganized structure (in later stages), and is retained in reticulocytes following enucleation. Thus, tubulin is not completely lost when erythrocytes mature; it continues to play a structural role in the Sed-tub fraction.

Red blood cell distribution width as a prognostic marker in patients with heart failure and diabetes mellitus

Background

Red blood cell distribution width (RDW) is an established prognostic marker in acute and chronic heart failure (HF). Recent studies have pointed out a link among RDW, diabetes mellitus (DM) and inflammation. We sought to investigate the prognostic value and longitudinal pattern of RDW in patients with concomitant HF and DM, which remains unknown.

Methods

A total of 218 patients (71 diabetics) who presented with acute HF had RDW measured at admission, discharge and 4, 8 and 12 months post-discharge. The study endpoint was all-cause mortality or rehospitalization for HF during 1-year follow-up.

Results

The study endpoint was met in 33 patients (46.5%) with DM and in 54 patients (36.7%) without DM. RDW at admission was associated with higher event rate both in HF patients with and without DM (adjusted HR: 1.349, p = 0.002, 95% CI 1.120–1.624 and adjusted HR: 1.142, p = 0.033, 95% CI 1.011–1.291 respectively). In addition, a significant interaction was found between diabetes and RDW longitudinal changes (β_interaction = −0.002; SE = 0.001; p = 0.042).

Conclusions

Despite the similar prognostic significance of RDW in diabetic and non-diabetic HF patients regarding the study endpoint, longitudinal changes were found to be significantly different between these two groups of HF patients. This might be due to the higher inflammatory burden that diabetic HF patients carry and may provide new insights to the pathophysiological mechanism of RDW increase in HF, which remains unknown.

The role of red blood cell deformability and Na,K-ATPase function in selected risk factors of cardiovascular diseases in humans: focus on hypertension, diabetes mellitus and hypercholesterolemia

Deformability of red blood cells (RBC) is the ability of RBC to change their shape in order to pass through narrow capillaries in circulation. Deterioration in deformability of RBC contributes to alterations in microcirculatory blood flow and delivery of oxygen to tissues. Several factors are responsible for maintenance of RBC deformability. One of them is the Na,K-ATPase known as crucial enzyme in maintenance of intracellular ionic homeostasis affecting thus regulation of cellular volume and consequently RBC deformability. Decreased deformability of RBC has been found to be the marker of adverse outcomes in cardiovascular diseases (CVD) and the presence of cardiovascular risk factors influences rheological properties of the blood. This review summarizes knowledge concerning the RBC deformability in connection with selected risk factors of CVD, including hypertension, hyperlipidemia, and diabetes mellitus, based exclusively on papers from human studies. We attempted to provide an update on important issues regarding the role of Na,K-ATPase in RBC deformability. In patients suffering from hypertension as well as diabetes mellitus the Na,K-ATPase appears to be responsible for the changes leading to alterations in RBC deformability. The triggering factor for changes of RBC deformability during hypercholesterolemia seems to be the increased content of cholesterol in erythrocyte membranes.