Increased Erythrocyte Deformability Research Articles

Effect of Whole-Body Vibration Training on Hemorheological Blood Indices in Young, Healthy Women.

The aim of the study is to assess the effect of single and 12-week WBVT and training without vibration on changes in hemorheological blood indices and plasma fibrinogen levels in young, healthy women. Three groups are distinguished: the experimental group-participating in WBVT (n = 17); the comparison group-implementing the same physical exercise protocol without the vibration factor (n = 12); and the control group-no intervention (n = 17). In the experimental and comparison group, blood is collected before and after the first and last training, while in the control group, blood is collected twice, 3 months apart. After a series of WBVT, a significant decrease in the mean erythrocyte volume and mean hemoglobin mass in erythrocytes, as well as a slight increase in the mean erythrocyte hemoglobin concentration, is found, and the effect of the last training is a significant decrease in plasma volume. Under the influence of repeated WBVT, there is an increase in erythrocyte deformability at low shear stress and an increase in the aggregation amplitude. The study shows that WBVT improves blood flow in the vessels and does not affect erythrocyte aggregation and the level of fibrinogen, which confirms the safety of this form of exercise.

Effect of Intermittent Hypoxic Training on Selected Biochemical Indicators, Blood Rheological Properties, and Metabolic Activity of Erythrocytes in Rowers.

Simple SummaryRowing is among the oldest sports disciplines. Involving multiple muscle groups, it poses a considerable challenge to athletes and amateurs. To improve training efficiency, the hypoxic method (decreasing arterial oxygen concentration) is sometimes applied. The study determined the effect of 3-week hypoxic training on blood indicators in competitive rowers. The reported findings demonstrated that the phenomenon of hypoxia could be an extremely effective training measure in rowers as it exerted a beneficial impact on the athletes’ performance.The study assessed the effect of 3-week intermittent hypoxic training on blood biochemical indicators (blood morphology, fibrinogen), blood rheological properties (erythrocyte deformability, aggregation), erythrocyte enzymatic activity (acetylcholinesterase), and maximal oxygen uptake in competitive rowers. Fourteen male rowers were divided into two equal groups: experimental, training on ergometers under normobaric hypoxia (FiO2 = 16.0%), and control, training on ergometers under normoxia (FiO2 = 21%). Fasting blood was taken before and after training. A significant between-group difference in neutrophil levels before training was noted and a significant decrease in white blood cells in the hypoxia group. Both groups exhibited an increase in elongation index. In the normoxia group, a significant increase in erythrocyte aggregation amplitude was revealed. No significant changes occurred in the other biochemical indicators or those evaluating erythrocyte metabolic activity. Normobaric hypoxia increased erythrocyte deformability, improving blood rheological properties. Maximal oxygen uptake significantly increased only in the experimental group.

Monocrotaline-Induced Pulmonary Arterial Hypertension and Bosentan Treatment in Rats: Focus on Plasma and Erythrocyte Parameters.

The objective of our study was to contribute to the characterization of monocrotaline-induced pulmonary arterial hypertension (PAH) in a rat model, with emphasis on the renin–angiotensin–aldosterone system, parameters of oxidative stress, the activity of matrix metalloproteinases, and erythrocyte parameters. Moreover, we aimed to analyze the effects of bosentan. Experiments were performed on 12-week-old male Wistar rats randomly assigned to 3 groups: control, monocrotaline-treated (60 mg/kg), and monocrotaline combined with bosentan (300 mg/kg/day). Our study confirmed the well-known effects of monocrotaline administration on lungs and the right ventricle, as well as pulmonary arterial pressure. In addition, we observed activation of the alternative pathway of the renin–angiotensin system, namely an increase in angiotensin (Ang) 1–7 and Ang 1-5 together with an increase in Ang I, but without any change in Ang II level, and downregulation of aldosterone 4 weeks after monocrotaline administration. For the first time, modifications of erythrocyte Na,K-ATPase enzyme kinetics were demonstrated as well. Our observations do not support data obtained in PAH patients showing an increase in Ang II levels, increase in oxidative stress, and deterioration in RBC deformability. Although bosentan primarily targets the vascular smooth muscle, our study confirmed its antioxidant effect. The obtained data suggest that besides the known action of bosentan, it decreases heart rate and increases erythrocyte deformability, and hence could have a beneficial hemodynamic effect in the PAH condition.

Resistance Training Enhances Muscle Function and Hemorheological Properties in Middle‐aged Obese Women

PurposeThe present study investigated the effects of resistance training for 12‐week on body composition, blood pressure, blood lipid level, cross sectional area (CSA) of muscles, isokinetic muscle function, and hemorheological properties in middle‐aged obese women.MethodsThirty obese women (50.79 ± 5.80 years), with no history of any injuries to the musculoskeletal system and no participating any regular exercise program, were included in the present study. All participants were randomly assigned to a control group (CON, n = 15) or an experimental group (EXP, n = 15); but two participants in the CON voluntarily withdrew because of personal reasons, and thirteen participants in the CON finally participated. The EXP underwent resistance training program composed of warm‐up, main resistance exercise (bench press, preacher bench biceps curl, barbell rowing, dumbbell shoulder press, dead lift, barbell squat, seated leg extension, and lying leg curl), and cool‐down. Main resistance exercise was consisted of three sets of 8–10 repetitions (reps) performed with 80% of 1‐RM. The training frequency was 80 min, 3 days per week for 12 weeks. The CON maintained their daily lifestyle without training. All participants underwent body composition (weight, body mass index, lean body mass, fat mass, and %body fat), blood pressure (systolic blood pressure, diastolic blood pressure, mean arterial pressure, and pulse pressure), blood lipid level (triglyceride, total cholesterol, high‐density lipoprotein cholesterol, and low‐density lipoprotein cholesterol), cross sectional area (CSA) of muscles (quadriceps CSA, hamstring CSA, and total thigh muscle CSA), isokinetic muscle function (peak torque, relative peak torque, mean power, and total work in quadriceps femoris and hamstrings), and hemorheological properties (erythrocyte deformability and erythrocyte aggregation) were measured before and after 12‐week of training.ResultsThe EXP showed a significant decrease in fat mass (p = .018) via 12‐week of resistance training. Also, the EXP yielded more significant improved muscle function including peak torque (p < .001), relative peak torque (p < .001), and total work (p = .001) in quadriceps femoris and total work (p = .018) in hamstrings. Regarding hemorheological properties, the EXP showed a significant increase in erythrocyte deformability (p = .001) via 12‐week of resistance training. However, there was no significant change in blood pressure and muscle CSA parameters via 12‐weeks of resistance training.ConclusionThe present study verified our resistance training program shows greater muscle strength and endurance, decreasing fat mass, and improving hemorheological properties such as erythrocyte deformability.

POSSIBILITIES OF THE METHOD OF DIELECTROPHORESIS OF ERYTHROCYTES IN DISTINCTION OF PATIENTS WITH FATTY LIVER DISEASE OF ALCOHOLIC AND NON-ALCOHOLIC GENESIS

The aim of the work is to study the possibilities of distinguishing between men with fatty disease of alcoholic and non-alcoholic origin using the viscoelastic parameters of erythrocytes - deformation amplitude, summerized indicators of viscosity and rigidity (baseline and after exposure to ethanol in vitro) obtained using the method of erythrocyte dielectrophoresis; to determine associations of the amplitude of deformation, summerized viscosity and rigidity of erythrocytes with blood lipid levels. The study involved 54 men (44,62±1.52 years) with fatty liver disease according to ultrasound of the abdominal organs, the severity of fibrosis corresponded to 0-1 (FibroScan® 502 Echosens, France). All patients underwent a study of the viscoelastic parameters of erythrocytes - the amplitude of deformation, summerized indicators of viscosity and rigidity by the dielectrophoresis method: the baseline level of indicators was determined, as well as their values after exposure of red blood cells with 10 μl of 0,0 2% ethanol solution in vitro for 300 s. The dynamics of changes in the viscoelastic parameters of erythrocytes during the experiment with alcohol in patients with fatty liver disease of unknown origin made it possible to highlight two groups with diametrically opposite trends in erythrocyte indices. The group with a decrease in the amplitude of erythrocyte deformation against the background of an increase in summerized viscosity and rigidity ( n = 26) consisted mainly of patients with metabolic syndrome who do not drink or occasionally consume alcohol in low doses (less than 20 g in terms of pure ethanol). Group with increased erythrocyte deformability and decrease in summerized viscosity and rigidity ( n = 28) includes systematic alcohol consumers who were in a state of abstinence. Ethanol exposure, important energy substrate of this group, built into metabolic processes, led to an increase in the amplitude of cell deformation. Correlations of the viscoelastic parameters of erythrocytes with the style of alcohol consumption, components of the metabolic syndrome, lipid profile indicators, and liver tests were established. Direct associations of the amplitude of erythrocyte deformation with the level of HDL cholesterol and inverse - with the values of total cholesterol, LDL cholesterol, triglycerides were identified. Summarized viscosity and rigidity correlated with the levels of these lipid indicators inversely compared with the amplitude of deformation. The diagnostic accuracy of distinguishing between NAFLD and AFLD using models, including the viscoelastic parameters of erythrocytes and their changes after exposure to ethanol, using Random Forest and SVM methods reached 99 %, sensitivity of 98 % and specificity of 99 %.

Nitrite may serve as a combination partner and a biomarker for the anti-cancer activity of RRx-001.

RRx-001 is an anti-cancer immunotherapeutic that increases the sensitivity of drug resistant tumors via multiple mechanisms which involve binding to hemoglobin and enhancing nitrite reductase activity of deoxyhemoglobin. In the present study, the effect of clinically used doses of RRx-001 on erythrocyte deformability was examined. A dose dependent effect of RRx-001 (1-1000 micro molar) on erythrocyte deformability was measured by ektacytometer under hypoxia (n =8). Low dose RRx-001 (20 micro molar) in the presence of ODQ (1H-[1,2,4]Oxadiazolo[4,3-a]quinoxalin-1-one), L-NAME (L-NG-Nitroarginine methyl ester) or nitrite were examined both in normoxia and hypoxia. Intracellular nitric oxide (NO) levels were measured fluorometrically with DAF-FM-DA. Higher doses of RRx-001 (100, 1000 micro molar) significantly decreased erythrocyte deformability under hypoxia (p <0.01; p <0.05, respectively). RRx-001 (20 micro molar), alone or in combination with ODQ or L-NAME, did not change deformability. However, RRx-001 and nitrite caused an increase in deformability (p <0.01) under hypoxia. RRx-001 induced NO production was more pronounced in the presence of nitrite (p <0.05). Co-administration of RRx-001 and nitrite under hypoxic conditions results in a significant increase in erythrocyte deformability that is related to increased NO production. We suggest that measurement of serum nitrite level in RRx-001 treated cancer patients should be routinely undertaken and supplemented if levels are low for maximal activity.

Shear‐thinning behaviour of blood in response to active hyperaemia: Implications for the assessment of arterial shear stress‐mediated dilatation

What is the central question of this study? Quantitative values of shear rate-specific blood viscosity and shear stress in the human macrovasculature in response to exercise hyperaemia are unknown. What is the main finding and its importance? Using the handgrip exercise model, we showed that an increase in brachial artery shear rate led to a decrease in blood viscosity, despite concomitant haemoconcentration. This shear-thinning behaviour of blood, secondary to increased erythrocyte deformability, blunted the expected increase in brachial artery shear stress based on shear rate prediction. Our data yield new insights into the magnitude and regulation of macrovascular blood viscosity and shear stress in physiological conditions of elevated metabolic demand and blood flow in humans. Blood viscosity is a well-known determinant of shear stress and vascular resistance; however, accurate quantitative assessments of shear rate-specific blood viscosity in the macrovasculature in conditions of elevated blood flow are inherently difficult, owing to the shear-thinning behaviour of blood. Herein, 12 men performed graded rhythmic handgrip exercise at 20, 40, 60 and 80% of their maximal workload. Brachial artery shear rate and diameter were measured via high-resolution Duplex ultrasound. Blood was sampled serially from an i.v. cannula in the exercising arm for the assessment of blood viscosity (cone-plates viscometer). We measured ex vivo blood viscosity at 10 discrete shear rates within the physiological range documented for the brachial artery in basal and exercise conditions. Subsequently, the blood viscosity data were fitted with a two-phase exponential decay, facilitating interpolation of blood viscosity values corresponding to the ultrasound-derived shear rate. Brachial artery shear rate and shear stress increased in a stepwise manner with increasing exercise intensity, reaching peak values of 940±245s-1 and 3.68±0.92Pa, respectively. Conversely, brachial artery shear rate-specific blood viscosity decreased with respect to baseline values throughout all exercise intensities by ∼6-11%, reaching a minimal value of 3.92±0.35mPas, despite concomitant haemoconcentration. This shear-thinning behaviour of blood, secondary to increased erythrocyte deformability, blunted the expected increase in shear stress based on shear rate prediction. Consequently, the use of shear stress yielded a higher slope for the brachial artery stimulus versus dilatation relationship than shear rate. Collectively, our data refute the use of shear rate to infer arterial shear stress-mediated processes.

Timolol effects on erythrocyte deformability and nitric oxide metabolism.

Timolol maleate is a compound used in treatment for reducing increased intra-ocular pressure by limiting aqueous humor production. Decreased erythrocyte deformability (ED), increased activity of erythrocyte acetylcholinesterase (AChE), increased values of nitrosoglutathione (GSNO) and nitic oxide (NO) and decreased plasma levels of NO metabolites, were described in primary open angle glaucoma patients. In healthy human red blood cells (RBCs), timolol is an inhibitor of AChE and induces NO efflux and GSNO efflux from that blood component in lower concentration than those obtained in presence of the natural AChE substrate, acetylcholine (ACh). The signal transduction pathway in RBCs described for NO in dependence of AChE-ACh active complex involves Gi protein, protein tyrosine kinase (PTK like Syk and p53/56Lyn), protein tyrosine phosphatase (PTP) and adenylyl cyclase (AC).The aim of this in vitro study was to verify the effect of timolol maleate in ED, NO efflux and NO derivatives molecules (NOx) like nitrite (NO2-), nitrate (NO3-, peroxynitrite (-ONOO) and GSNO under the presence of PTK, PTP, AC and guanylyl cyclase (GC) enzyme proteins inhibitors.Blood samples from healthy donors were each one divided and were performed aliquots in absence (control aliquots) and presence of timolol or timolol plus each inhibitor and Gi protein uncoupling. No significant differences in erythrocyte NO efflux, GSNO, peroxynitrite, nitrite and nitrate concentrations in response to timolol when compared with the untreated blood samples aliquots were obtained.It was observed an increase in erythrocyte deformability at high shear stresses induced by the simultaneous presence of timolol and band 3 protein dephosphorylation by PTK syk inhibitor. No significant differences where verified in peroxynitrite levels in the blood aliquots in presence of timolol plus each enzyme inhibitor and Gi protein uncoupling in relation to the control aliquots. No variation of GSNO concentration occurs under the presence of timolol and AMGT (PTK lyn inhibitor) besides the significant higher values observed with each one of the other inhibitors. Nitrate concentration increases significantly in all aliquots with timolol plus each one of the inhibitors. The same was observe with nitrite levels with exception of the aliquots with timolol plus AMGT or timolol plus Gi protein uncoupling showing no significant values in relation to the control aliquots.Besides the changes in NO derivative molecules and NO efflux from RBCs obtained in this study with blood samples of healthy donors under the effect of timolol plus each inhibitor of the proteins participants in NO signal transduction mechanism, further analogue studies must be promoted with blood samples of patients with glaucoma or any other inflammatory vascular disease.

The Effects of HES 130/0.4 Application on Erythrocyte Deformability in Ureteral Obstructed Rats

Aim: The administration of plasma expanders is crucial for managing critically ill patients across a range of clinical conditions, including major surgery, hemorrhagic shock, and trauma. However, the effects of hydroxyethyl starch (HES) on erythrocyte aggregation remain controversial. For this reason, we aimed to investigate the effects of HES 130/0.4, performed renal insufficiency by experimentally unilateral ureteral obstruction, on erythrocyte deformability. Materials and Methods: A total of 24 rats were divided into 4 groups; Control, HES 130/0.4, Ureter Obstruction (UO) and UO-HES130/0.4. Urethral obstruction groups were treated with ketamine anesthesia with a low abdominal incision and reached to the distal of right ureter and sutured with 2.0 mersilen then waited for 3 weeks for late term renal insufficiency. 20 mL.kg-1 of HES 130/0.4 (Voluven) were infused intravenously to the HES 130/0.4 and UO-HES130/0.4 group. After 24-hour, rats were sacrificed. Deformability measurements were performed using 5% haematocrit in a phosphate-buffered saline (PBS) buffer. Results and Discussion: Relative resistance was increased in all groups compared to the control group (p<0.0001). In all groups, erythrocyte deformability index was found to be significantly higher than the control group (Group C-Group HES, p=0.023, Group C- Group UO, p<0.0001, Group C-Group UO-HES, p<0.0001). UO-HES group had significantly increased erythrocyte deformability index compared with the HES group (p=0.031, p=0.021, respectively). It was determined that HES 130/0.4 application did not change erythrocyte deformability in ureteral obstructed rats (p=0.785). Conclusion: The use of HES 130/0.4 has no negative effects on erythrocyte deformability in ureteral obstructed rats. We think that indications should be used correctly when using HES 130/0.4.

Effects of different rehabilitation models on erythrocyte deformability and nitrite plus nitrate as end-products of nitric oxide levels in elderly women.

The aim of the present study was to analyze the effects of two rehabilitation protocols, dance movement therapy exercises (DMT) and general rehabilitation exercises (GRE), on erythrocyte deformability and plasma levels of nitrite plus nitrate as end products of nitric oxide (NOx) in elderly women. The study included 39 women aged 61-82years, subjected to either GRE (n=20) or DMT (n=19). Women were subjected to 5-months programs of GRE and DMT, with each session lasting no longer than 45-50min, and the intensity of exercising corresponding to no more than 40-60% of heart rate reserve. Plasma levels of NOx were determined spectrophotometrically before and at the end of the intervention. A significant increase in the total nitrate/nitrite concentration from 1.341μmol/L to 1.590μmol/L (7.3%) was observed in women subjected to the DMT rehabilitation program. Furthermore, an increase in erythrocyte deformability was observed in this group at shear stress 0.30. No significant difference was found between the pre- and post-rehabilitation NOx levels of women participating in the GRE program. Participation in DMT rehabilitation program might be reflected by an increase in plasma NOx levels and an improvement of erythrocyte deformability at lesser shear stress, and thus could potentially result in better vascular function. DMT should be offered to older adults, especially to persons who do not find conventional forms of rehabilitation as attractive, as they might refrain from physical activity and suffer from a faster decline in nitric oxide production. Geriatr Gerontol Int 2017; 17: 2479-2484.

Acute dark chocolate ingestion is beneficial for hemodynamics via enhancement of erythrocyte deformability in healthy humans

Erythrocyte deformability is an important property of erythrocytes that considerably affects blood flow and hemodynamics. The high content of polyphenols present in dark chocolate has been reported to play a protective role in functionality of erythrocytes. We hypothesized that chocolate might influence erythrocytes not only after repeated chronic intake, but also immediately after its ingestion. Thus, we determined the acute effect of dark chocolate and milk (with lower content of biologically active substances) chocolate intake on erythrocyte deformability. We also focused on selected factors that may affect erythrocyte deformability, specifically nitric oxide production in erythrocytes and total antioxidant capacity of plasma. We determined posttreatment changes in the mentioned parameters 2hours after consumption of chocolate compared with their levels before consumption of chocolate. In contrast to milk chocolate intake, the dark chocolate led to a significantly higher increase in erythrocyte deformability. Nitric oxide production in erythrocytes was not changed after dark chocolate intake, but significantly decreased after milk chocolate. The plasma total antioxidant capacity remained unaffected after ingestion of both chocolates. We conclude that our hypothesis was confirmed. Single ingestion of dark chocolate improved erythrocyte deformability despite unchanged nitric oxide production and antioxidant capacity of plasma. Increased deformability of erythrocytes may considerably improve rheological properties of blood and thus hemodynamics in humans, resulting in better tissue oxygenation.

Mechanism Of Cytomegalovirus Penetration Through Erythrocyte Membrane

Objective: To study the effect of cytomegalovirus infection on histidine concentration in erythrocytes of peripheral blood in pregnant women at 27-28th week of gestation and virus penetration through the erythrocyte membrane and to demonstrate the morphofunctional alterations of the latter. The objective of this study is to demonstrate the mechanism of cytomegalovirus penetration through the erythrocyte membrane as well as to describe the process of its structure damage which leads to the accumulation in the peripheral blood of degenerative forms of erythrocytes that lose their ability to deformability. This creates the conditions for the formation of hemic anaemia in a pregnant woman. The research has been conducted on the basis of current data and our own studies. Materials and methods: 75 pregnant women at 27-28th weeks of gestation were examined, including 55 CMV-seropositive ones with CMV-infection exacerbation at 27th week of gestation. All the studies were carried out at the Federal State Budget Scientific Institution “Far Eastern Scientific Centre of Physiology and Pathology of Respiration” during one year time. Histidine activity in peripheral blood erythrocytes was found according to the method suggested by Lucenko Michael T and Andrievskaya Irina A.; fatty acid peroxides in erythrocyte membrane-by Winkler-Schultze method; erythrocyte membrane microviscosity was found by spectrofluorimetric method of lateral diffusion of pyrene. Erythrocyte deformability was also found in accordance with the method of Lucenko Michael T and Andrievskaya Irina A. The calculation of deformed erythrocytes was done using automated cytophotometric device “Mekos” (Russia). Erythrocyte membrane condensation was measured in pixels by means of cytophotometric camera “Pixera” (USA). Results: During the exacerbation of CMV infection at 27-28th weeks of gestation the amount of distal histidine was lower 2.13 times per one erythrocyte. The level of unsaturated fatty acids increased 2.9 times, of fatty acid peroxides in erythrocyte membranes increased 3.3 times, which resulted in 1.7 times increase in erythrocyte membrane microviscosity in the lipid bilayer and in 6.8 times increase in erythrocyte deformability. Conclusion: The exacerbation of chronic CMV infection at 27-28th weeks of gestation causes the virus intrusion into erythrocyte membrane damaging the distal histidine content, which promotes further penetration of proteins of viral envelope and tegument into the erythrocyte. That results in the disturbance of phospholipids bond with erythrocyte membrane proteins, increase in fatty acid peroxides in erythrocytes and decrease in the membrane microviscosity. This promotes the accumulation of deformable erythrocytes in peripheral blood thus causing the threat of anemia formation in pregnant woman at late gestation.

Exposure of Stored Packed Erythrocytes to Nitric Oxide Prevents Transfusion-associated Pulmonary Hypertension.

Transfusion of packed erythrocytes stored for a long duration is associated with increased pulmonary arterial pressure and vascular resistance. Prolonged storage decreases erythrocyte deformability, and older erythrocytes are rapidly removed from the circulation after transfusion. The authors studied whether treating stored packed ovine erythrocytes with NO before transfusion could prevent pulmonary vasoconstriction, enhance erythrocyte deformability, and prolong erythrocyte survival after transfusion. Ovine leukoreduced packed erythrocytes were treated before transfusion with either NO gas or a short-lived NO donor. Sheep were transfused with autologous packed erythrocytes, which were stored at 4°C for either 2 ("fresh blood") or 40 days ("stored blood"). Pulmonary and systemic hemodynamic parameters were monitored before, during, and after transfusion. Transfused erythrocytes were labeled with biotin to measure their circulating lifespan. Erythrocyte deformability was assessed before and after NO treatment using a microfluidic device. NO treatment improved the deformability of stored erythrocytes and increased the number of stored erythrocytes circulating at 1 and 24 h after transfusion. NO treatment prevented transfusion-associated pulmonary hypertension (mean pulmonary arterial pressure at 30 min of 21 ± 1 vs. 15 ± 1 mmHg in control and NO-treated packed erythrocytes, P < 0.0001). Washing stored packed erythrocytes before transfusion did not prevent pulmonary hypertension. NO treatment of stored packed erythrocytes before transfusion oxidizes cell-free oxyhemoglobin to methemoglobin, prevents subsequent NO scavenging in the pulmonary vasculature, and limits pulmonary hypertension. NO treatment increases erythrocyte deformability and erythrocyte survival after transfusion. NO treatment might provide a promising therapeutic approach to prevent pulmonary hypertension and extend erythrocyte survival.

(-)-Epicatechin Prevents Blood Pressure Increase and Reduces Locomotor Hyperactivity in Young Spontaneously Hypertensive Rats.

This study investigated the effects of subchronic (−)-epicatechin (Epi) treatment on locomotor activity and hypertension development in young spontaneously hypertensive rats (SHR). Epi was administered in drinking water (100 mg/kg/day) for 2 weeks. Epi significantly prevented the development of hypertension (138 ± 2 versus 169 ± 5 mmHg, p < 0.001) and reduced total distance traveled in the open-field test (22 ± 2 versus 35 ± 4 m, p < 0.01). In blood, Epi significantly enhanced erythrocyte deformability, increased total antioxidant capacity, and decreased nitrotyrosine concentration. In the aorta, Epi significantly increased nitric oxide (NO) synthase (NOS) activity and elevated the NO-dependent vasorelaxation. In the left heart ventricle, Epi increased NOS activity without altering gene expressions of nNOS, iNOS, and eNOS. Moreover, Epi reduced superoxide production in the left heart ventricle and the aorta. In the brain, Epi increased nNOS gene expression (in the brainstem and cerebellum) and eNOS expression (in the cerebellum) but had no effect on overall NOS activity. In conclusion, Epi prevented the development of hypertension and reduced locomotor hyperactivity in young SHR. These effects resulted from improved cardiovascular NO bioavailability concurrently with increased erythrocyte deformability, without changes in NO production in the brain.

New approach to treat an old problem: Mannitol for post-dural puncture headache.

Sir, In their comments on our article,[1,2] the readers are correct on the theories regarding the causation of post-dural puncture headache (PDPH, a low-pressure headache), either due to traction on pain-sensitive parietal duramater or veno-dilatation in keeping with the Monroe-Kellie doctrine. Their observations and arguments are essentially sound and astute; however, we offer the following clarifications regarding the relief of PDPH. Mannitol acts by the following means: ‘Acute increases in blood osmolality → decrease brain water content (occurs mainly in healthy brain tissue with intact blood brain barrier) → decreased brain bulk, intracranial pressure, increased intracranial compliance’.[3] It is this decreased brain bulk, the authors believe, cause the brain to re-float in a contracted cerebrospinal fluid (CSF) volume, the end result of continuous CSF leakage [Figures ​[Figures11 and ​and2].2]. We believe that re-floatation is an important factor that helps mannitol alleviate PDPH along with other factors, which are quoted in the following text. ‘Blood rheology is also improved because of decreased endothelial oedema and decreased erythrocyte oedema and increased erythrocyte deformability with augmentation of perfusion, especially through the microvasculature’.[3] Ergo, the effects of mannitol on brain circulation are beneficial and contributory to re-floatation, leading to mitigation of PDPH.[4] Figure 1 Brain floatation Figure 2 Re-floatation principle The rebound phenomena as pointed out by the readers, is also a true entity. But in a patient who underwent spinal anaesthesia or inadvertent dural puncture with a Tuohy needle, the disruption to the blood-brain barrier is extremely minimal and will not cause entry of sufficient mannitol into the brain parenchyma to cause a rebound effect. Rebound phenomena also effects the CSF pressure, making it higher and maybe beneficial in a low-pressure headache.[5] The arguments regarding dyselectrolytemia and dehydration are true as well, but as we all know, mannitol is a time-tested drug in the fields of neurology and neurosurgery (and in other clinical situations, where indicated).[6] However, it should be carefully used, like any other drug, keeping in mind the hydration and electrolyte status of the patient, as not to defeat its very purpose. Although mannitol has never been traditionally indicated to treat PDPH, the authors have used it successfully in numerous instances with rapid clinical gains. Our colleagues at the Department of Anaesthesia, at CMC Vellore, support these benefits of mannitol on PDPH. That's why the authors only suggest that a clinical trial may be taken up to establish this fact. Instead of just reassuring the patient that PDPH is self-limiting and will subside in a couple days, and giving hydration and analgesics, if there is a way to ‘fix the problem’, why not embrace it? The authors do not claim this as an established approach, but it is a step in the right direction and may be subjected to modifications and analysis, after the necessary clinical trials: Risk-benefit ratio needs to be analysed in depth. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

Role of intracellular signaling systems in regulation of erythrocyte microrheology

Erythrocyte deformability and thus the efficiency of the oxygen delivery to tissues depends on three main factors: elasticity of cell membrane, viscosity of cytoplasm, and the erythrocyte surface/volume ratio. The membrane elasticity and stability most considerably contribute to the whole cell deformability. There are experimental data suggesting that erythrocyte deformability is regulated by intracellular signaling pathways. The aim of this work was to study the role of the adenylyl cyclase–cAMP systems and intracellular calcium signaling mechanism in the regulation of erythrocyte deformability. We found that stimulator of adenylyl cyclase (AC) forskolin (10–5 M) and cell-penetrating cAMP analog dB-cAMP (5 × 10–5 M) increased erythrocyte deformability. Inhibitors of the phosphodiesterase (PDE) activity, such as isobutyl methylxanthine, vinpocetine, and cilostazol (10–5 M), also increased the erythrocyte deformability, which provides another line of evidence of the cAMP involvement in the regulation of erythrocyte deformability. On the other hand, stimulation of Ca2+ entry into erythrocytes induced by Ca2+ ionophore A23187 (3 × 10–6 M), sodium fluoride, or sodium vanadate considerably decreased the cell deformability, while blockade of the Ca2+ entry into erythrocytes by verapamil (10–5 M) increased their deformability. Mechanical stress of the erythrocyte membrane in the absence of extracellular Ca2+ did not change the deformability, while the mechanical stress applied in the presence of Ca2+ (50–200 µM) decreased deformability by 4–18%. On the whole, the obtained results suggest that for the increase in the erythrocyte deformability the AC–cAMP–PKA cascade has to be activated, while the pathway triggered by the Ca2+ entry into the cells is required to lower the erythrocyte deformability (elasticity) and hence, to increase the whole cell membrane stability. It is possible that these pathways are coordinated at the PDE level.

The effects of short-term and long-term testosterone supplementation on blood viscosity and erythrocyte deformability in healthy adult mice.

Testosterone treatment induces erythrocytosis that could potentially affect blood viscosity and cardiovascular risk. We thus investigated the effects of testosterone administration on blood viscosity and erythrocyte deformability using mouse models. Blood viscosity, erythrocyte deformability, and hematocrits were measured in normal male and female mice, as well as in females and castrated males after short-term (2 wk) and long-term (5-7 mo) testosterone intervention (50 mg/kg, weekly). Castrated males for long-term intervention were studied in parallel with the normal males to assess the effect of long-term testosterone deprivation. An additional short-term intervention study was conducted in females with a lower testosterone dose (5 mg/kg). Our results indicate no rheological difference among normal males, females, and castrated males at steady-state. Short-term high-dose testosterone increased hematocrit and whole-blood viscosity in both females and castrated males. This effect diminished after long-term treatment, in association with increased erythrocyte deformability in the testosterone-treated mice, suggesting the presence of adaptive mechanism. Considering that cardiovascular events in human trials are seen early after intervention, rheological changes as potential mediator of vascular events warrant further investigation.

New approach to treat an old problem: Mannitol for post dural puncture headache!

Sir, In their comments on our article,[1,2] the readers are correct on the theories regarding the causation of post-dural puncture headache (PDPH, a low-pressure headache), either due to traction on pain-sensitive parietal duramater or veno-dilatation in keeping with the Monroe-Kellie doctrine. Their observations and arguments are essentially sound and astute; however, we offer the following clarifications regarding the relief of PDPH. Mannitol acts by the following means: ‘Acute increases in blood osmolality → decrease brain water content (occurs mainly in healthy brain tissue with intact blood brain barrier) → decreased brain bulk, intracranial pressure, increased intracranial compliance’.[3] It is this decreased brain bulk, the authors believe, cause the brain to re-float in a contracted cerebrospinal fluid (CSF) volume, the end result of continuous CSF leakage [Figures ​[Figures11 and ​and2].2]. We believe that re-floatation is an important factor that helps mannitol alleviate PDPH along with other factors, which are quoted in the following text. ‘Blood rheology is also improved because of decreased endothelial oedema and decreased erythrocyte oedema and increased erythrocyte deformability with augmentation of perfusion, especially through the microvasculature’.[3] Ergo, the effects of mannitol on brain circulation are beneficial and contributory to re-floatation, leading to mitigation of PDPH.[4] Figure 1 Brain floatation Figure 2 Re-floatation principle The rebound phenomena as pointed out by the readers, is also a true entity. But in a patient who underwent spinal anaesthesia or inadvertent dural puncture with a Tuohy needle, the disruption to the blood-brain barrier is extremely minimal and will not cause entry of sufficient mannitol into the brain parenchyma to cause a rebound effect. Rebound phenomena also effects the CSF pressure, making it higher and maybe beneficial in a low-pressure headache.[5] The arguments regarding dyselectrolytemia and dehydration are true as well, but as we all know, mannitol is a time-tested drug in the fields of neurology and neurosurgery (and in other clinical situations, where indicated).[6] However, it should be carefully used, like any other drug, keeping in mind the hydration and electrolyte status of the patient, as not to defeat its very purpose. Although mannitol has never been traditionally indicated to treat PDPH, the authors have used it successfully in numerous instances with rapid clinical gains. Our colleagues at the Department of Anaesthesia, at CMC Vellore, support these benefits of mannitol on PDPH. That's why the authors only suggest that a clinical trial may be taken up to establish this fact. Instead of just reassuring the patient that PDPH is self-limiting and will subside in a couple days, and giving hydration and analgesics, if there is a way to ‘fix the problem’, why not embrace it? The authors do not claim this as an established approach, but it is a step in the right direction and may be subjected to modifications and analysis, after the necessary clinical trials: Risk-benefit ratio needs to be analysed in depth. Financial support and sponsorship Nil. Conflicts of interest There are no conflicts of interest.

The influence of winter swimming on the rheological properties of blood

The aim of this study was to analyze the changes in blood rheology resulting from regular winter swimming. The study was carried out on 12 male winter swimmers. Venous blood for morphological, biochemical and rheological analysis was sampled twice from each winter swimmer - at the beginning of the season and after its completion. There were no significant changes detected in the median values of most blood morphological parameters. The only exception pertained to MCHC which was significantly lower after the season. Winter swimming entailed significant decrease in median elongation index values at shear stress levels of 0.30 Pa and 0.58 Pa, and significant increase in median values of this parameter at shear stress levels ≥1.13 Pa. No significant changes were observed in winter swimmers' median values of aggregation indices and plasma viscosity. The median level of glucose was lower post winter swimming in comparison to the pre-seasonal values. In contrast, one season of winter swimming did not influence swimmers' median value of fibrinogen concentration. In summary, this study revealed positive effects of winter swimming on the rheological properties of blood, manifested by an increase in erythrocyte deformability without accompanying changes in erythrocyte aggregation.

Mechanism of endurance training-induced erythrocyte deformability in rats involves erythropoiesis

Higher erythrocyte deformability may reduce the risk of circulatory diseases by enhancing oxygen delivery and reducing the load on the cardiovascular system. The effect of endurance training on erythrocyte deformability is not clear. This study explored the impact of endurance training on erythrocyte deformation and shape and investigated the underlying mechanisms of hemorheological alterations. Forty male Wistar rats were randomly divided into two groups: sedentary (S; n = 21) and exercised (E; n = 19). Hematological indices and erythrocyte shape were measured at the end of the 11th week. The gene expression of erythropoietin (Epo) and the Epo receptor (EpoR) was quantified using reverse transcription-PCR (RT-PCR), and Epo protein expression was analyzed using Western blotting. Endurance training significantly decreased the abnormality ratio of erythrocyte shape (P < 0.01). The deformability indicator (DI) of red blood cells was lower in the E group than in the S group (P < 0.01). Eleven weeks of endurance training increased Epo mRNA and protein expression in the kidney (P < 0.01), EpoR mRNA expression in the bone marrow (P < 0.05), and relative circulating Epo (P < 0.01) compared to the sedentary group. The decrease in the erythrocyte morphological index and the maximum of deformability indicator were associated with an increase in relative circulating Epo. In conclusion, 11 weeks of endurance training increased erythrocyte deformability. Epo and EpoR may contribute to the decreased morphological index and deformability indicator in erythrocytes during endurance training in rats.