Nitric oxide bioavailability for red blood cell deformability in the microcirculation: A review of recent progress

Nitric oxide: a gas transmitter in healthy and diseased skin

Numerous physiological processes in the human skin are mediated by nitric oxide, a gaseous signalling molecule. Almost every type of skin cell may produce nitric oxide, it is possible to generate nitric oxide without the need of enzymes. Nitric oxide plays a crucial role in regulating apoptosis, keratinocyte differentiation and proliferation, the protective properties of the epidermal barrier, and the structure and functions of the microcirculatory bed. Nitric oxide is involved in immunological and inflammatory responses, hair growth regulation, and wound healing processes. It mediates ultraviolet-induced processes such as erythema and edema development and participates in melanogenesis. Furthermore, the ability of nitric oxide to bind reactive oxygen species and prevent lipid peroxidation gives it antioxidant qualities. This coordinated action of nitric oxide on gene expression and membrane integrity effectively protects cells from ultraviolet A-induced apoptosis and necrosis. Furthermore, nitric oxide can be considered as a molecule that inhibits the development of cancer and photoaging. It directly harms microorganisms and indirectly activates the immune system, exhibiting antibacterial, antiviral, and antifungal qualities. Notably, nitric oxide is effective against antibiotics-resistant bacteria. All of the aforementioned findings suggest that nitric oxide is a gaseous mediator that can protect skin function.

Blood rheology and systemic oxidative status in patients with acromegaly

BackgroundCardiovascular system is known to be affected in acromegaly. However, it was not reported to date if hemorheology was also altered and there is limited data regarding systemic oxidative status in patients with acromegaly.ObjectiveTo investigate alterations in hemorheology and systemic oxidative stress in patients with acromegaly.MethodsThe study comprised 19 active (AA) and 15 controlled (CA) acromegaly patients (n = 34, mean age 48.85 ± 1.69 years) and 29 controls (mean age 52.83 ± 1.37 years). Erythrocyte aggregation index (AI), aggregation half time (t½), amplitude (Amp) and erythrocyte elongation index (EI) were determined by an ektacytometer. Commercial kits were used for measuring serum total oxidant status (TOS) and total antioxidant status (TAS), and oxidative stress index (OSI) was calculated.ResultsThere were statistically significant differences regarding EI at shear stresses of 16.87 ve 30.00 Pa (p = 0.034, p = 0.0001, respectively) and AI (p = 0.050, p = 0.035, respectively) values among the control, AA and CA groups. Decrement of t½ was in line with increment of AI and indicated increased erythrocyte aggregation. Serum TOS, TAS and OSI values were similar between the control, AA and CA groups (p > 0.05).ConclusionsThis pilot study demonstrated reduced erythrocyte deformability and increased erythrocyte aggregation in patients with AA and CA.

Recent advances in the role of gasotransmitters in necroptosis

Necroptosis is a finely regulated programmed cell death process involving complex molecular mechanisms and signal transduction networks. Among them, receptor-interacting protein kinase 1 (RIPK1), receptor-interacting protein kinase 3 (RIPK3) and mixed lineage kinase domain-like protein are the key molecules regulating this process. In recent years, gasotransmitters such as nitric oxide, carbon monoxide and hydrogen sulfide have been suggested to play a regulatory role in necroptosis. This paper reviews the evidence that these gasotransmitters are involved in the regulation of necroptosis by influencing the production of reactive oxygen species, regulating the modification of S subunits of RIPK1 and RIPK3, regulating inflammatory mediators, and signal transduction. In addition, this review explores the potential therapeutic applications of these gasotransmitters in pathological conditions such as cardiovascular disease and ischemia-reperfusion injury. Although some studies have revealed the important role of gasotransmitters in necroptosis, the specific mechanism of action is still not fully understood. Future research is needed to further elucidate the molecular mechanisms of gasotransmitters in precisely regulating necroptosis, which will help develop new therapeutic strategies to prevent and treat related diseases.

Controlled Coffee Intake Enhances Erythrocyte Deformability, Na,K-ATPase Activity, and GSH/GSSG Ratio in Healthy Young Adults

BACKGROUND

Published studies suggest that regular coffee consumption may reduce the risk of various diseases. However, many of these studies relied on questionnaire-based data, limiting their ability to identify the specific biological mechanisms behind the observed effects. This study focuses on controlled coffee consumption among healthy young adults to clarify its effects on erythrocyte properties. The functional condition of erythrocytes is important as it affects both macro- and microcirculation. Additionally, since erythrocytes are not true cells, they are particularly sensitive to biochemical and biophysical changes when exposed to biologically active substances.

METHODS

After a washout period, 33 healthy young volunteers were asked to consume a standardized dose of a coffee beverage daily for 3 weeks. Basic hematological and body composition parameters were recorded before and after the intervention. Erythrocyte functional status was evaluated based on the following measurements: deformability, osmotic resistance, Na,K-ATPase activity, and nitric oxide production, along with monitoring oxidative stress markers.

RESULTS

After a coffee consumption period, both erythrocyte count and hematocrit value increased, while body composition remained unchanged. Erythrocyte deformability improved across a range of shear stress values typical of human circulation. This improvement was accompanied with enhanced Na,K-ATPase activity in erythrocyte membranes in the wide range of sodium ion concentrations, as well as increased nitric oxide production by erythrocytes. Additionally, a higher GSH/GSSG ratio, indicating a shift towards a more favorable antioxidant balance, was observed in erythrocytes following the coffee intake period.

CONCLUSIONS

The results of this study suggest that controlled coffee intake in healthy young adults can positively influence various indices of erythrocyte functional status. Although the observed statistically significant changes were modest, the findings consistently indicate a positive modulation of erythrocyte properties-cell deformability, oxidative resilience, and active membrane transport of cations-following coffee consumption.

Effect of Curcumin Intake on Skeletal Muscle Oxygen Saturation Parameters in Older Participants

INTRODUCTION

Aging is associated with increased reactive oxygen species (ROS) and reduced bioavailability of nitric oxide (NO). Curcumin has been shown to increase NO bioavailability due to its ability to neutralize ROS, preventing oxidative stress. The present study aimed to investigate the effect of curcumin intake on skeletal muscle oxygen parameters and exercise tolerance in response to exercise in older people. Changes in circulating levels of NO metabolites were also investigated.

METHODS

Older subjects consumed 10 g of turmeric root extract from Curcuma longa L. (containing 95.33% of the total curcuminoids) or placebo in a randomized, double-blind, crossover study. A time of 2 h after ingestion, the participants performed one set of rhythmic handgrip exercise until the limit of tolerance, followed by 5 min of recovery. During exercise and exercise recovery, skeletal muscle oxygen saturation parameters were recorded.

RESULTS

During exercise, the amplitude of deoxyhemoglobin was greater after curcumin intake compared to placebo (CUR: 13.11 ± 9.52 vs. PLA: 10.22 ± 8.39 μM, p = 0.030). Furthermore, a faster skeletal muscle oxygen resaturation during exercise recovery was observed after curcumin compared to placebo (CUR: 1.01 ± 0.65 vs. PLA: 0.32 ± 0.20%.s-1, p = 0.004). These results were associated with significant changes in plasma nitrite (CUR: 6.82 ± 11.68 vs. PLA: -4.94 ± 17.28%, p = 0.028). There was no statistical difference in the total hemoglobin, exercise time until fatigue, and plasma nitrate between groups.

CONCLUSIONS

The present study suggests that curcumin improves muscle oxygenation status at the capillary level in older adults by possibly improving muscle oxygen extraction and/or delivery, with no effect on exercise tolerance.

Effect of inhaled nitric oxide on intestinal integrity in cardiopulmonary bypass and circulatory arrest simulation: An experimental study

Background and Aims

Cardiopulmonary bypass (CPB) and circulatory arrest (CA) can induce intestinal injury and consequently lead to multiple organ dysfunction. Nitric oxide (NO) has protective effects, but its effect on the intestine has not been studied. The study aimed to investigate intestinal injury variables and prove the intestinal protective effects of exogenous nitric oxide when modelling CPB and CA in an experiment.

Methods

The study was performed on sheep (n = 24). There were four groups: CPB, CPB + NO, CPB + CA and CPB + CA + NO. Sheep in NO groups received intraoperative inhalation of NO at a dose of 80 ppm. Groups without NO underwent CPB and CA without NO delivery. Defaecation rate, dynamics of intestinal fatty acid binding protein (i-FABP), coefficient of microviscosity and polarity in the areas of lipid-lipid and protein-lipid interactions of erythrocyte membranes were assessed. One hour after CPB, the intestinal tissue was collected and assessed for tissue concentrations of adenosine triphosphate (ATP) and lactate.

Results

The defaecation rate after CPB was higher in the CPB + NO group than in the CPB group. The concentration of i-FABP after CPB was lower in the CPB + NO and CPB + CA + NO groups than in the CPB and CPB + CA groups. Erythrocyte deformability before and after CPB revealed no significant dynamics in groups with NO. The ATP concentration 1 h after CPB was higher in the CPB + NO group than in the CPB group. The morphological picture in groups with NO was better.

Conclusion

When modelling CPB and CA, NO had a positive effect on the functional and structural state of the intestine and also maintained erythrocyte deformability.

Erythrocyte metabolism

Our aim is to present an updated overview of the erythrocyte metabolism highlighting its richness and complexity. We have manually collected and connected the available biochemical pathways and integrated them into a functional metabolic map. The focus of this map is on the main biochemical pathways consisting of glycolysis, the pentose phosphate pathway, redox metabolism, oxygen metabolism, purine/nucleoside metabolism, and membrane transport. Other recently emerging pathways are also curated, like the methionine salvage pathway, the glyoxalase system, carnitine metabolism, and the lands cycle, as well as remnants of the carboxylic acid metabolism. An additional goal of this review is to present the dynamics of erythrocyte metabolism, providing key numbers used to perform basic quantitative analyses. By synthesizing experimental and computational data, we conclude that glycolysis, pentose phosphate pathway, and redox metabolism are the foundations of erythrocyte metabolism. Additionally, the erythrocyte can sense oxygen levels and oxidative stress adjusting its mechanics, metabolism, and function. In conclusion, fine-tuning of erythrocyte metabolism controls one of the most important biological processes, that is, oxygen loading, transport, and delivery.

Flickering of fetal erythrocytes membrane under gestational diabetes observed with dual time resolved membrane fluctuation spectroscopy

The membrane flickering of human fetal red blood cells (RBCs) affected by gestational diabetes mellitus (GDM) was studied with dual time resolved membrane fluctuation spectroscopy (D-TRMFS). This new technique is a modified version of the dual optical tweezers method that has been adapted to measure the mechanical properties of RBCs at two distant membrane points simultaneously. The micro-rheological parameters were obtained from direct membrane flickering measurements, followed by Fourier decomposition and cell membrane model adjustment. Our results show a significant decrease of 6.01 ± 1.19 nm in membrane fluctuations amplitude in healthy fetal, compared with healthy adult RBCs, meanwhile the amplitude in GDM cells increased 3.22 ± 1.10 nm compared with healthy fetal RBCs. Between GDM and healthy fetal RBCs, there are significant differences, especially in the bending modulus. Considering the mean of the two membrane points measured, the tension for GDM RBCs increased by 6.431 ± 3.57 (10-7 [N/m]) compared with healthy fetal RBCs, meanwhile, the bending was increased by 2.483 ± 0.58 (10-19 [J]) in GDM compared with healthy fetal RBCs. These results showed significant increment of 1.23 ± 0.07-fold and 3.29 ± 0.36-fold in tension and bending modulus in GDM, respectively. The strong impact of GDM on bending modulus could be associated with oxidative stress and lipid peroxidation, previously reported in fetal plasma of GDM cases.

Low postoperative perfused vessel density is associated with increased soluble endothelial cell adhesion molecules during circulatory shock after cardiac surgery

INTRODUCTION

Microcirculatory dysfunction after cardiovascular surgery is associated with significant morbidity and worse clinical outcomes. Abnormal capillary blood flow can occur from multiple causes, including cytokine-mediated vascular endothelial injury, microthrombosis, and an inadequate balance between vasoconstriction and vasodilation. In response to proinflammatory cytokines, endothelial cells produce cellular adhesion molecules (CAMs) which regulate leukocyte adhesion, vascular permeability, and thus can mediate tissue injury. The relationship between changes in microcirculatory flow during circulatory shock and circulating adhesion molecules is unclear. The objective of this study was to compare changes in plasma soluble endothelial cell adhesion molecules (VCAM-1, ICAM-1, and E-Selectin) in patients with functional derangements in microcirculatory blood flow after cardiovascular surgery.

METHODS

Adult patients undergoing elective cardiac surgery requiring cardiopulmonary bypass who exhibited postoperative shock were enrolled in the study. Sublingual microcirculation imaging was performed prior to surgery and within 2 h of ICU admission. Blood samples were taken at the time of microcirculation imaging for biomarker analysis. Plasma soluble VCAM-1, ICAM-1, and E-selectin in addition to plasma cytokines (IL-6, IL-8, and IL-10) were measured by commercially available enzyme-linked immunoassay.

RESULTS

Of 83 patients with postoperative shock who were evaluated, 40 patients with clinical shock had a postoperative perfused vessel density (PVD) >1 SD above (High PVD group = 28.5 ± 2.3 mm/mm2, n = 20) or below (Low PVD = 15.5 ± 2.0 mm/mm2, n = 20) the mean postoperative PVD and were included in the final analysis. Patient groups were well matched for comorbidities, surgical, and postoperative details. Overall, there was an increase in postoperative plasma VCAM-1 and E-Selectin compared to preoperative levels, but there was no difference between circulating ICAM-1. When grouped by postoperative microcirculation, patients with poor microcirculation were found to have increased circulating VCAM-1 (2413 ± 1144 vs. 844 ± 786 ng/mL; p < 0.0001) and E-Selectin (242 ± 119 vs. 87 ± 86 ng/mL; p < 0.0001) compared to patients with increased microcirculatory blood flow. Microcirculatory flow was not associated with a difference in plasma soluble ICAM-1 (394 ± 190 vs. 441 ± 256; p = 0.52).

CONCLUSIONS

Poor postoperative microcirculatory blood flow in patients with circulatory shock after cardiac surgery is associated with increased plasma soluble VCAM-1 and E-Selectin, indicating increased endothelial injury and activation compared to patients with a high postoperative microcirculatory blood flow. Circulating endothelial cell adhesion molecules may be a useful plasma biomarker to identify abnormal microcirculatory blood flow in patients with shock.

Aging in Normotensive and Spontaneously Hypertensive Rats: Focus on Erythrocyte Properties

Erythrocyte deformability, crucial for oxygen delivery to tissues, plays an important role in the etiology of various diseases. As the factor maintaining the erythrocyte deformability, nitric oxide (NO) has been identified. Reduced NO bioavailability also plays a role in the pathogenesis of hypertension. Our aim was to determine whether aging and hypertension affect erythrocyte deformability and NO production by erythrocytes in experimental animals divided into six groups according to age (7, 20 and 52 weeks), labeled WKY-7, WKY-20 and WKY-52 for normotensive Wistar-Kyoto (WKY) rats, and SHR-7, SHR-20 and SHR-52 for spontaneously hypertensive rats (SHR). The filtration method for the determination of erythrocyte deformability and the fluorescent probe DAF-2 DA for NO production were applied. Deformability and NO production by erythrocytes increased at a younger age, while a decrease in both parameters was observed at an older age. Strain-related differences in deformability were observed at 7 and 52 weeks of age. SHR-7 had reduced deformability and SHR-52 had increased deformability compared with age-matched WKY. Changes in NO production under hypertensive conditions are an unlikely primary factor affecting erythrocyte deformability, whereas age-related changes in deformability are at least partially associated with changes in NO production. However, an interpretation of data obtained in erythrocyte parameters observed in SHRs of human hypertension requires precaution.