Molecular hydrogen: prospective treatment strategy of kidney damage after cardiac surgery.

Cardiac surgery-associated acute kidney injury is a common post-operative complication, mostly due to increasing oxidative stress. Recently, molecular hydrogen (H2 gas) has also been applied to cardiac surgery due to its ability to reduce oxidative stress. We evaluated the potential effect of H2 application on the kidney in an in vivo model of simulated heart transplantation. Pigs underwent cardiac surgery within 3 h while connected to extracorporeal circulation (ECC) and subsequent 60 min of spontaneous reperfusion of the heart. We used two experimental groups: T-pigs after transplantation and TH-pigs after transplantation treated with 4% H2 mixed with air during inhalation of anesthesia and throughout oxygenation of blood in ECC. The levels of creatinine, urea and phosphorus were measured in plasma. Renal tissue samples were analyzed by Western blot method for protein levels of nuclear factor erythroid 2-related factor 2 (Nrf2), Kelch-like ECH-associated protein 1 (Keap-1), and superoxide dismutase (SOD1). After cardiac surgery, selected plasma biomarkers were elevated. However, H2 therapy was followed by the normalization of all these parameters. Our results suggest activation of Nrf2/Keap1 pathway as well as increased SOD1 protein expression in the group treated with H2. The administration of H2 had a protective effect on the kidneys of pigs after cardiac surgery, especially in terms of normalization of plasma biomarkers to control levels.

Effect of handling on ATP utilization of cerebral Na,K-ATPase in rats with trimethyltin-induced neurodegeneration.

Previously it was shown that for reduction of anxiety and stress of experimental animals, preventive handling seems to be one of the most effective methods. The present study was oriented on Na,K-ATPase, a key enzyme for maintaining proper concentrations of intracellular sodium and potassium ions. Malfunction of this enzyme has an essential role in the development of neurodegenerative diseases. It is known that this enzyme requires approximately 50% of the energy available to the brain. Therefore in the present study utilization of the energy source ATP by Na,K-ATPase in the frontal cerebral cortex, using the method of enzyme kinetics was investigated. As a model of neurodegeneration treatment with trimethyltin (TMT) was applied. Daily handling (10 min/day) of healthy rats and rats suffering neurodegeneration induced by administration of TMT in a dose of (7.5 mg/kg), at postnatal days 60-102 altered the expression of catalytic subunits of Na,K-ATPase as well as kinetic properties of this enzyme in the frontal cerebral cortex of adult male Wistar rats. In addition to the previously published beneficial effect on spatial memory, daily treatment of rats was accompanied by improved maintenance of sodium homeostasis in the frontal cortex. The key system responsible for this process, Na,K-ATPase, was able to utilize better the energy substrate ATP. In rats, manipulation of TMT-induced neurodegeneration promoted the expression of the α2 isoform of the enzyme, which is typical for glial cells. In healthy rats, manipulation was followed by increased expression of the α3 subunit, which is typical of neurons.

Erythrocyte Deformability and Na,K-ATPase Activity in Various Pathophysiological Situations and Their Protection by Selected Nutritional Antioxidants in Humans.

The physicochemical and functional properties of erythrocytes are worsened in a variety of diseases. Erythrocyte deformability refers to their ability to adjust their shape according to external forces exerted against them in the circulation. It is influenced by the functionality of the Na,K-ATPase enzyme, which is localized in their membranes. The proposed review is focused on knowledge regarding changes in erythrocyte Na,K-ATPase activity, and their impact on erythrocyte deformability in various pathophysiological situations observed exclusively in human studies, as well as on the potential erytroprotective effects of selected natural nutritional antioxidants. A clear link between the erythrocyte properties and the parameters of oxidative stress was observed. The undesirable consequences of oxidative stress on erythrocyte quality and hemorheology could be at least partially prevented by intake of diverse antioxidants occurring naturally in foodstuffs. Despite intensive research concerning the effect of antioxidants, only a small number of investigations on erythrocyte properties in humans is available in databases. It is worth shifting attention from animal and in vitro experiments and focusing more on antioxidant administration in human studies in order to establish what type of antioxidant, in what concentration, and in which individuals it may provide a beneficial effect on the human organism, by protecting erythrocyte properties.

Promotion of whole blood rheology after vitamin C supplementation: focus on red blood cells 1.

Hemorheological properties represent significant contributors in the pathogenesis of cardiovascular diseases. As plasma vitamin C is inversely associated with blood viscosity in humans, we aimed to characterize the effect of vitamin C supplementation on hemorheology with an emphasis on erythrocyte functions. Twenty young healthy volunteers were asked to take vitamin C (1000 mg per day) for 3 weeks. We observed beneficial effect of intervention on multiple hemorheological parameters: whole blood viscosity in the range of medium to high shear rates, Casson yield stress, complex viscosity, and storage and loss moduli. As erythrocyte properties play a significant role in hemorheology, we characterized their deformability, nitric oxide production, and sodium pump activity in erythrocyte membranes. We can conclude that observed promotion in whole blood rheology may be consequence of improved erythrocyte functionality as concerns their ability to pass through narrow capillaries of the microcirculation, nitric oxide production, and sodium pump activity. Parameters reflecting oxidative stress and antioxidant status in plasma were not affected by our intervention. As improvement in hemorheology may play an important role in cardioprotection, it would be challenging to investigate the vitamin C supplementation to patients suffering from microcirculatory disturbances and worsened organ perfusion in the case of cardiovascular diseases.

Potential markers and metabolic processes involved in the mechanism of radiation-induced heart injury.

Irradiation of normal tissues leads to acute increase in reactive oxygen/nitrogen species that serve as intra- and inter-cellular signaling to alter cell and tissue function. In the case of chest irradiation, it can affect the heart, blood vessels, and lungs, with consequent tissue remodelation and adverse side effects and symptoms. This complex process is orchestrated by a large number of interacting molecular signals, including cytokines, chemokines, and growth factors. Inflammation, endothelial cell dysfunction, thrombogenesis, organ dysfunction, and ultimate failing of the heart occur as a pathological entity - "radiation-induced heart disease" (RIHD) that is major source of morbidity and mortality. The purpose of this review is to bring insights into the basic mechanisms of RIHD that may lead to the identification of targets for intervention in the radiotherapy side effect. Studies of authors also provide knowledge about how to select targeted drugs or biological molecules to modify the progression of radiation damage in the heart. New prospective studies are needed to validate that assessed factors and changes are useful as early markers of cardiac damage.

Oxidative Stress Markers and Na,K-ATPase Enzyme Kinetics Are Altered in the Cerebellum of Zucker Diabetic Fatty fa/fa Rats: A Comparison with Lean fa/+ and Wistar Rats.

Type 2 diabetes mellitus has been referred to as being closely related to oxidative stress, which may affect brain functions and brain glucose metabolism due to its high metabolic activity and lipid-rich content. Na,K-ATPase is an essential enzyme maintaining intracellular homeostasis, with properties that can sensitively mirror various pathophysiological conditions such as diabetes. The goal of this study was to determine oxidative stress markers as well as Na,K-ATPase activities in the cerebellum of Zucker diabetic fatty (ZDF) rats depending on diabetes severity. The following groups of male rats were used: Wistar, ZDF Lean (fa/+), and ZDF (fa/fa) rats, arbitrarily divided according to glycemia into ZDF obese (ZO, less severe diabetes) and ZDF diabetic (ZOD, advanced diabetes) groups. In addition to basic biometry and biochemistry, oxidative stress markers were assessed in plasma and cerebellar tissues. The Na, K-ATPase enzyme activity was measured at varying ATP substrate concentrations. The results indicate significant differences in basic biometric and biochemical parameters within all the studied groups. Furthermore, oxidative damage was greater in the cerebellum of both ZDF (fa/fa) groups compared with the controls. Interestingly, Na,K-ATPase enzyme activity was highest to lowest in the following order: ZOD > ZO > Wistar > ZDF lean rats. In conclusion, an increase in systemic oxidative stress resulting from diabetic conditions has a significant impact on the cerebellar tissue independently of diabetes severity. The increased cerebellar Na,K-ATPase activity may reflect compensatory mechanisms in aged ZDF (fa/fa) animals, rather than indicating cerebellar neurodegeneration: a phenomenon that warrants further investigation.

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.

Alterations in Antioxidant Status and Erythrocyte Properties in Children with Autism Spectrum Disorder.

Erythrocytes are responsible for the transport of oxygen within the organism, which is particularly important for nerve tissues. Erythrocyte quality has been shown to be deteriorated in oxidative stress conditions. In this study, we measured the same series of oxidative stress markers in plasma and erythrocytes to compare the differences between neurotypical children (controls) and children with autism spectrum disorder (ASD). We also focused on erythrocyte properties including their deformability, osmotic resistance, Na,K-ATPase activity, nitric oxide levels and free radical levels in children with ASD and controls. Greater oxidative damage to proteins and lipids was observed in the erythrocytes than in the plasma of ASD subjects. Additionally, antioxidant enzymes were more active in plasma samples from ASD children than in their erythrocytes. Significantly higher nitric oxide level and Na,K-ATPase enzyme activity were detected in erythrocytes of ASD individuals in comparison with the controls. Changes in oxidative status could at least partially contribute to the deterioration of erythrocyte morphology, as more frequent echinocyte formation was detected in ASD individuals. These alterations are most probably responsible for worsening the erythrocyte deformability observed in children with ASD. We can conclude that abnormalities in antioxidant status and erythrocyte properties could be involved in the pathomechanisms of ASD and eventually contribute to its clinical manifestations.

Alterations in Oxidative Stress Markers and Na,K-ATPase Enzyme Properties in Kidney after Fructose Intake and Quercetin Intervention in Rats.

The study aimed to characterize the consequences of a 15-week intake of 10% fructose on the kidney, with the focus on oxidative stress markers and properties of the Na,K-ATPase enzyme. Various antioxidants naturally occurring in common food were demonstrated to be protective against fructose-induced deterioration of kidneys. Therefore, we also aimed to observe the effect of 6-week quercetin administration (20 mg/kg/day) that was initiated following the 9-week period of higher fructose intake, by determining the concentration of sodium, potassium, creatinine, urea, and glucose in blood plasma and oxidative status directly in the renal tissue. Kinetic studies of renal Na,K-ATPase were utilized for a deeper insight into the molecular principles of expected changes in this enzyme activity under conditions of presumed fructose-induced renal injury. Fructose intake led to increase in body weight gain, plasma glucose and sodium levels, and deterioration of kidney properties, although some compensatory mechanisms were observable. Quercetin administration improved glycemic control in rats exposed to fructose overload. However, an increase in plasma creatinine, a decrease in GSH/GSSG ratio in renal tissue homogenate, and a controversial effect on renal Na,K-ATPase enzyme suggest that quercetin treatment may not be beneficial in the condition of pre-existing renal pathology.

Antioxidant SMe1EC2 may attenuate the disbalance of sodium homeostasis in the organism induced by higher intake of cholesterol.

The study was focused to the influence of higher intake of cholesterol on properties of the renal Na,K-ATPase, a key system in maintaining the homeostasis of sodium in the organism. Feeding for 4 weeks with cholesterol-enriched food for rats afflicted with hereditary hypertriglyceridemia by itself enhanced the activity of Na,K-ATPase, probably as a consequence of higher number of active enzyme molecules as suggested by 32 % increase of V (max) value. This may be hypothesized as a reason for the increased retention of sodium. Three-week-lasting treatment of animals kept on high cholesterol diet with antioxidant SMe1EC2 in a dose of 10 mg kg(-1) day(-1) normalized the function of renal Na,K-ATPase to the level comparable in hypertriglyceridemic rats fed with the standard diet. Therefore, our results suggest that the antioxidant SMe1EC2 in the applied dose seems to be effective in the attenuation of cholesterol-induced retention of sodium. Treatment for 3 weeks with Fenofibrate in a dose of 100 mg kg(-1) day(-1) reversed the function of renal Na,K-ATPase only slightly.

Na,K-ATPase Kinetics and Oxidative Stress in Kidneys of Zucker Diabetic Fatty (fa/fa) Rats Depending on the Diabetes Severity-Comparison with Lean (fa/+) and Wistar Rats.

For a better insight into relations between type 2 diabetes mellitus (T2DM) and Na,K-ATPase properties in kidneys, we aimed to characterize two subgroups of ZDF obese (fa/fa) rats, with more and less developed T2DM, and compare them with two controls: lean (fa/+) and Wistar. Na,K-ATPase enzyme kinetics were estimated by measuring the ATP hydrolysis in the range of NaCl and ATP levels. As Na,K-ATPase is sensitive to oxidative stress, we evaluated selected oxidative stress parameters in kidney homogenates. Our results suggest that thiol-disulfide redox balance in the renal medulla and Na,K-ATPase properties in the renal cortex differ between both controls, while observed measurements in lean (fa/+) rats showed deviation towards the values observed in ZDF (fa/fa) rats. In comparison with both controls, Na,K-ATPase enzyme activity was higher in the renal cortex of ZDF rats independent of diabetes severity. This might be a consequence of increased glucose load in tubular fluid. The increase in lipid peroxidation observed in the renal cortex of ZDF rats was not associated with Na,K-ATPase activity impairment. Regarding the differences between subgroups of ZDF animals, well-developed T2DM (glycemia higher than 10 mmol/L) was associated with a higher ability of Na,K-ATPase to utilize the ATP energy substrate.

Effects of Taxifolin in Spontaneously Hypertensive Rats with a Focus on Erythrocyte Quality.

Oxidative stress and multiple erythrocyte abnormalities have been observed in hypertension. We focused on the effects of angiotensin-converting enzyme 2 (ACE2) inhibition by MLN-4760 inhibitor on angiotensin peptides, oxidative stress parameters, and selected erythrocyte quality markers in spontaneously hypertensive rats (SHR). We also investigated the potential effects of polyphenolic antioxidant taxifolin when applied in vivo and in vitro following its incubation with erythrocytes. SHRs were divided into four groups: control, taxifolin-treated, MLN-4760-treated, and MLN-4760 with taxifolin. MLN-4760 administration increased the blood pressure rise independent of taxifolin treatment, whereas taxifolin decreased it in control SHRs. Body weight gain was also higher in ACE2-inhibited animals and normalized after taxifolin treatment. However, taxifolin did not induce any change in angiotensin peptide concentrations nor a clear antioxidant effect. We documented an increase in Na,K-ATPase enzyme activity in erythrocyte membranes of ACE2-inhibited SHRs after taxifolin treatment. In conclusion, ACE2 inhibition deteriorated some selected RBC properties in SHRs. Although taxifolin treatment did not improve oxidative stress markers, our data confirmed the blood pressure-lowering potential, anti-obesogenic effect, and some "erythroprotective" effects of this compound in both control and ACE2-inhibited SHRs. In vitro investigations documenting different effects of taxifolin on erythrocyte properties from control and ACE2-inhibited SHRs accentuated the irreplaceability of in vivo studies.

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.

Angiotensin System Modulations in Spontaneously Hypertensive Rats and Consequences on Erythrocyte Properties; Action of MLN-4760 and Zofenopril.

Various pathologies (COVID-19 including) are associated with abnormalities in erythrocyte properties. Hypertension represents an unfavorable condition for erythrocyte quality and is the most prevalent risk factor in COVID-19 patients. ACE2 downregulation that is typical of these patients can further deteriorate cardiovascular health; however, its consequences on erythrocyte properties are not known yet. The aim was to investigate the effect of ACE2 inhibition and the potential beneficial effect of zofenopril on erythrocytes in spontaneously hypertensive rats. ACE2 inhibition induced by MLN-4760 (1 mg/kg/day for 2 weeks) led to deterioration of erythrocyte morphology and osmotic resistance, but plasma markers of oxidative stress, erythrocyte deformability, nitric oxide production and Na,K-ATPase activity were not significantly affected. Zofenopril administration (10 mg/kg/day, initiated after 4-day-lasting ACE2 inhibition) resulted in unexpected increase in angiotensin II plasma levels in both control and ACE-inhibited spontaneously hypertensive rats, but in normalization of osmotic resistance in ACE2-inhibited rats. The overall effect of zofenopril on erythrocyte qualities could be evaluated as beneficial.

Influence of sub-chronic diabetes mellitus on functional properties of renal Na(+),K(+)-ATPase in both genders of rats.

For characterization of Na(+),K(+)-ATPase, a key enzyme involved in maintenance of intracellular sodium homeostasis, expression of alpha1 subunit and the ATP- and Na(+)-binding properties were investigated by Western blot analysis and by enzyme kinetics, respectively. Previous studies documented time-dependent alteration of properties of renal Na(+),K(+)-ATPase from its mobilization after 8 days to serious deteriorations after 16 weeks of diabetes in rats. Characterizing the critical period during development of the disease, when mobilization of Na(+),K(+)-ATPase observed in the acute phase turns to its damage, we examined the enzyme properties after 8 weeks lasting diabetes which was induced by a single intraperitoneal administration of streptozotocin in a dose of 65 mg.kg(-1). The unchanged expression of Na(+),K(+)-ATPase alpha1-subunit in both genders indicates that 8 weeks represent the time when the mobilization of enzyme synthesis observed previously in acute diabetes is lost. In this time the renal Na(+),K(+)-ATPase undergoes structural changes in the vicinity of Na(+)-binding site resulting in worsened affinity to sodium in both genders as indicated by 13% and 18% increase of K(Na) value in female and male rats, respectively. However, gender specific was the diabetes-induced decrease in affinity to ATP by 18% which occurred in female rats only.

Dual effect of polyphenolic compounds on cardiac Na+/K+-ATPase during development and persistence of hypertension in rats.

The enzyme kinetics of cardiac Na(+)/K(+)-ATPase were used for characterizing the ATP- and Na(+)-binding sites after administration of red wine polyphenolic compounds (Provinol) during developing and sustained hypertension. Hypertension was induced in rats (LN group) by the nitric oxide synthase inhibitor N(G)-nitro-L-arginine methyl ester (L-NAME, 40 mg*kg(-1)*day(-1)). Provinol (40 mg*kg(-1)*day(-1)) was applied during developing hypertension (LNPF4 group) and sustained hypertension (LNPF7/3 group). Provinol reduced the number of active Na(+)/K(+)-ATPase molecules in cardiac tissue, as indicated by decreased V(max) values (by 33% in LNPF4 and 26% in LNPF7/3 compared with LN). Concerning qualitative properties of the enzyme, Provinol induced different effects on the ATP- and Na(+)-binding sites of Na(+)/K(+)-ATPase. The ATP-binding site was impaired by Provinol, as indicated by increased K(m) value (by 52% in LNPF4 vs. LN), suggesting worsened utilization of substrate by the enzyme. In sustained hypertension, however, Provinol had no effect on the ATP-binding site, as indicated by unchanged K(m) value (LNPF7/3 vs. LN). On the other hand, the Na(+)-binding site was protected by Provinol, as suggested by decreased K(Na) value (by 72% in LNPF4 and 69% in LNPF7/3 vs. LN), indicating an increased affinity of the enzyme for sodium. Thus, Provinol appeared to stimulate the extrusion of Na(+) from cardiac cells, especially in the physiologically important range of sodium concentrations (2-10 mmol*L(-1)), during both developing and sustained hypertension.

Acute diabetes mellitus and its influence on renal Na,K-ATPase in both genders.

Due to the importance of renal Na,K-ATPase in maintaining the sodium homeostasis in the organism, its activity and abundance is intensively studied in condition of diabetes mellitus. The main subject of this study was the investigation of properties of renal Na,K-ATPase and abundance of its alpha1 subunit in view of possible gender-dependent differences in male and female diabetic rats. Diabetes was induced by a single intraperitoneal dose of streptozotocin in a dose of 65 mg.kg(-1). The acute diabetes lasting 8 days induced a significant increase in Na,K-ATPase activity accompanied by significant gender specific increase in K(m) value indicating a worsened affinity of ATP-binding site in female rats. In addition, our present experiments, revealed a significantly higher abundance of renal Na,K-ATPase alpha1 subunit in diabetic rats of both genders amounting 94% increase in males and 107% in females. But, not all of the newly synthesized enzyme molecules are fully active, as the increase in the number of active molecules is smaller (representing 23% in males and 20% in females) as indicated by lower increase in V(max) values.

Alteration of renal Na,K-ATPase in rats following the mediastinal γ-irradiation.

Na,K-ATPase represents the key enzyme that maintains the homeostasis of sodium and potassium ions in the cells. It was documented that in directly irradiated organs the activity of this enzyme is decreased. The aim of present study was to clarify the remote effect of irradiation in mediastinal area on the activity of the Na,K-ATPase in kidneys in rats. Ionizing radiation in single dose 25 Gy resulted in consequent decrease of the body weight gain as well as the size of kidneys in Wistar rats. In addition, radiation induced alterations in the oxidative status of blood plasma. Irradiation also decreased the activity of renal Na,K-ATPase. Measurements of enzyme kinetics that were dependent on the concentration of energy substrate ATP or cofactor Na+ indicated that the lowered enzyme activity is probably a consequence of decreased number of active molecules of the enzyme, as suggested by lowered Vmax values. Immunoblot analysis confirmed the lowered expression of the catalytic alpha subunit together with decreased content of the glycosylated form of beta subunit in the renal tissue of irradiated rats. The ability of the enzyme to bind the substrate ATP, as well as Na+ was not affected, as shown by unaltered values of Km and KNa . Irradiation of the body in the mediastinal area despite protection of kidneys by lead plates during application of X-ray was followed by significant decline of activity of the renal Na,K-ATPase, what may result in deteriorated homeostasis in the organism.

Heart failure and role of circulating MMP-2 and MMP-9.

The myocardial extracellular matrix (ECM) is the dynamic environment that is fundamental for the structural and physiological homeostasis of the heart. Alterations in ECM homeostasis may lead to diastolic or systolic dysfunction and consequent development of heart failure (HF). For degradation of ECM, matrix metalloproteinases (MMPs) are responsible. To the most frequently analyzed MMPs in relation to HF syndrome belong MMP-2 and MMP-9. This review summarizes the recent knowledge concerning the role of circulating MMP-2 and MMP-9 (i.e. those that can be determined in blood plasma or serum) in HF, based primarily on papers from human studies. Majority of studies enrolling the higher count of participants suggested that the state of active myocardial remodeling is accompanied by enhanced activation of MMP-2 and MMP-9 and may be also represented by changes in their circulating concentrations. Their levels may be a useful marker for the identification of patients at risk for HF development and poor outcome by themselves, or at the very least as a components of multimarker approach. At the same time MMP-2 and MMP-9 circulating levels can serve as indicators of efficiency of the therapy provided to HF patients, as well as for identification of patients who could profit from particular therapeutic intervention via modification of MMP pathway.

Gender difference in functional properties of Na,K-ATPase in the heart of spontaneously hypertensive rats.

The aim of present study was the investigation of functional properties of the cardiac Na,K-ATPase in 16 weeks old male and female spontaneously hypertensive rats (SHR). The Na,K-ATPase activity in the presence of increasing concentrations of ATP, as well as Na(+) was lower in SHR of both genders, as compared to respective normotensive controls. Evaluation of kinetic parameters revealed a significant decrease of the maximum velocity (V(max)) in males (30% for ATP-activation, 40% for Na(+)-activation), as well as in females (24% for ATP, 29% for Na(+)), indicating a hypertension-induced diminution of the number of active enzyme molecules in cardiac sarcolemma. Insignificant changes were observed in the value of Michaelis-Menten constant (K(m)) in both cases. The concentration of sodium that gives half-maximal reaction velocity (K(Na)), increased by 38% in male and by 70% in female SHR. This impairment in the affinity of the Na(+)-binding site together with decreased number of active Na,K-ATPase molecules are probably responsible for the deteriorated enzyme-function in hearts of SHR. Direct comparison of SHR of both genders showed, that the enzyme from female hearts seems to be adapted better to hypertension as documented by its increased activity as a consequence of improved ability to bind and utilize ATP, as suggested by 32% decrease of K(m) value in females. In addition, the enzyme from female hearts is able to increase its activity (by 41%) in the presence of increasing sodium concentration even in the range where the enzyme from male hearts is already saturated.