Can we use erythrocytes for the study of the activity of the ubiquitous Na+/H+ exchanger (NHE-1) in essential hypertension?

Both Na+/Li+ countertransport and electrochemical proton gradient (delta mu(H+))-induced Na+ and H+ fluxes are increased in erythrocytes from patients with essential hypertension. It was assumed that these abnormalities are related to ubiquitous (housekeeping) forms of the Na+/H+ exchanger (NHE-1). To examine this hypothesis, we compared kinetic and regulatory properties of erythrocyte Na+/Li+ countertransport and delta mu(H+)-induced Na+ and H+ fluxes with data obtained for cloned isoforms of the Na+/H+ exchanger.

Na+/H+ exchange in vascular smooth muscle cells is controlled by GTP-binding proteins.

This study examines the involvement of GTP-binding proteins (Gps) in the regulation of Na+/H+ exchange and Ca2+ influx, which are increased in vascular smooth muscle cells from spontaneously hypertensive rats. Gp activity was modulated by fluoride, GTPgammaS, GDPbetaS, and antisense oligodeoxynucleotides complementary to conserved regions of the alpha- and beta-subunits of Gps (alpha-comm and beta-comm, respectively). Beta-adrenergic-induced Gs-mediated cAMP production was used as a positive control to estimate the efficiency of these compounds.

Volume-dependent regulation of the respiratory burst of activated human neutrophils.

The effect of incubation medium osmolality on the respiratory burst of human neutrophils was studied using luminol-dependent chemiluminescence (CL) as an indicator of burst activity. Neutrophils were stimulated with N-formyl-Met-Leu-Phe (FMLP), phorbol-12-myristate-13-acetate (PMA), the calcium ionophore A23187, thermoaggregated IgG (IgGn), and opsonized zymosan (OZ). It was shown that increasing the osmolality of the incubation medium from 320 up to 420 mosM decreased the A23187- and OZ-induced CL responses by 90%.

[Transport of ions into human erythrocytes in various forms of hemolytic anemia: a correlation analysis].

The activity of Na+, K(+)-ATPase (ouabain-inhibited 86Rb influx), Na+, K+ cotransport (ouabain-insensitive furosemide-inhibited 86Rb or 22Na influx), Na+/Na+ exchange (ouabain-insensitive phloretin-inhibited 22Na influx) and Na+/Li+ exchange (ouabain-insensitive Na0(+)-depended Li+ efflux) as well as the passive permeability of the erythrocyte membrane for Na+, K+ and Li+ have been studied in patients with primary (microspherocytosis, hemoglobinopathy) and secondary (autoimmune) hemolytic anemia. The activities of the Na+, K(+)-pump and Na+, K(+)-cotransport were increased in patients with microspherocytosis-by 45% and 70%, respectively. In patients with hemoglobinopathy the Na+/Li+ exchange and passive permeability for K+ were increased 2-3-fold in comparison with the control with the control group.

[Effect of osmolarity of the medium on the chemiluminescence of human neutrophils].

The effect of osmolality of the incubation medium on the luminol-amplified chemiluminescence (CL) of human neutrophils stimulated by N-formyl-Met-Len-Phe (FMLP), phorbol-12-myristate-13-acetate (PMA), calcium ionophore A-23187, thermoaggregated IgG (aggIgG) and opsonized zymosan has been studied. It has been shown that increase of osmolality from 320 up to 420 mosM decreased the A-23187--and opsonized zymosan-induced CL responses by 90%. Under the same conditions PMA-, FMLP- and aggIgG-induced CL responses were decreased by 40-60%.

[Effects of ultraviolet irradiation on the Na/H exchange rate in erythrocytes of healthy subjects and patients with atherosclerosis of lower limb arteries].

Na+/H+ exchange rate in erythrocytes of patients with atherosclerosis of lower limb arteries is less than in erythrocytes of healthy subjects. Ultraviolet exposure of the patients blood in vitro activates Na/H exchange in erythrocytes.

Cation transport and adenosine triphosphatase activity in rat erythrocytes: a comparison of spontaneously hypertensive rats with the normotensive Brown-Norway strain.

The activity of transport adenosine triphosphatases (ATPases) in saponin-treated erythrocytes as well as the passive membrane permeability for 86Rb+ (K+), 45Ca2+ uptake (in the presence of orthovanadate) and the rate of Na(+)-H+ exchange in intact erythrocytes were studied in spontaneously hypertensive rats (SHR), Wistar-Kyoto (WKY) and Brown-Norway (BN.lx) rats. Higher Na+,K(+)-ATPase activity, lower Ca(2+)-ATPase activity, increased passive K+ permeability and greater 45Ca2+ uptake were observed in erythrocytes from SHR compared with BN.

[Erythrocyte Na+/Li+ countertransport and arterial hypertension: data of a cross-sectional population study].

The relation of red blood cell Na+/Li+ countertransport rate to the prevalence of arterial hypertension (AH) and blood pressure was evaluated in 720 individuals aged 23-60 years. In all age groups, the rate of red blood cell Na+/Li+ countertransport was significantly higher in males than in females. Age, alcohol use, obesity in males and age, obesity, and Na+/Li+ countertransport rate in females are factors that predispose to AH, as evidenced by multivariate logistic analysis.

On the mechanism of shrinkage-induced potassium influx in rat and human erythrocytes.

The rates of 86Rb influx into human and rat erythrocytes were studied in media of various tonicity. At sucrose concentrations below 0.3 mol/l, the ouabain-insensitive, furosemide-inhibited component of influx increased in rat but not in human erythrocytes; this may be explained by a rise in the rate of Na+, K+, Cl-- and/or K+, Cl-cotransport.

[Erythrocyte sodium-lithium countertransporter level as a risk factor of hypertension (prospective study data)].

A 3-year prospective study was undertaken to evaluate the relation of red blood cell Na+/Li+ countertransport rates to the incidence of arterial hypertension. A total of 227 subjects (males and females aged 24-54 years)--a 20% representative sample of organized population--was followed up. The annual incidence of arterial hypertension was 4.

[The transport of monovalent ions and calcium in the erythrocytes of patients with bronchial asthma].

The intracellular levels of sodium, potassium, and free calcium, as well as red blood cell transport of 86Rb (a radioactive potassium analogue) and 45Ca were measured in patients with bronchial asthma (BA). The intracellular content of sodium was 10-20% higher in patients with BA, though the differences in the present sample (7 controls and 18 BA patients) failed to be significant (p less than 0.05).

[The role of the rate of sodium-lithium countertransport of the erythrocytes in arterial hypertension].

The present work is concerned with the role of the velocity of Na+/Li(+)-countertransport of red blood cells (as an indicator of the function of cellular membranes) in the development of arterial hypertension under conditions of a populational study. A relationship is demonstrated between the velocity of Na+/Li(+)-countertransport and the sex, arterial pressure, body mass index, and blood serum triglycerides. The high velocity of Na+/Li(+)-countertransport is encountered in 25% of the population, being responsible for about 30% of all cases of arterial hypertension.

Ion transport systems in erythrocyte membrane of spontaneously hypertensive rats (SHR) as compared with normotensive rats of the Brown Norway (BN.lx) strain.

The activity of Na+, K(+)-ATPase in SHR erythrocytes treated with saponin is increased by 30-40% as compared to the Brown Norway (BN.lx) strain whereas the activity of Ca(2+)-ATPase is decreased by 20-30%. Passive permeability of SHR erythrocytes determined by 86Rb influx is increased by 20-30%.

Na+/H+ exchange in erythrocytes of spontaneously hypertensive rats: a study in F2 SHR x WKY hybrids.

The rate of proton gradient-induced Na+/H+ exchange in the erythrocytes of SHR was increased by 50-60% as compared to WKY animals. No significant correlation between Na+/H+ exchange and blood pressure was revealed in F2 hybrids of SHR and WKY rats. Na+/H+ exchange rate in the erythrocytes of F2 SHR x WKY hybrids was twice as high as in SHR and three times higher than in WKY rats.

Thermal inactivation of membrane proteins, volume-dependent Na+, K(+)-cotransport, and protein kinase C activator-induced changes of the shape of human and rat erythrocytes.

The heat sorption curves for human and rat erythrocyte membranes in the temperature region from 40 degrees C to 90 degrees C have been compared resulting from thermal gel analysis of these membranes. The main heat sorption peaks are located within the temperature regions from 49 degrees C to 52 degrees C (A transition), from 56 degrees C to 59 degrees C (B transition), from 62 degrees C to 65 degrees C (C transition) and from 74 degrees C to 82 degrees C (D transition). Thermoinactivation temperatures for most of the membrane proteins in human and rat erythrocytes are rather different, which suggests essential differences in the arrangement of their membrane frameworks.

Protein kinase C activity in erythrocytes in primary hypertension: regulation of cell shape and cation transport.

Protein kinase C activity in the lysate of erythrocytes of patients with essential hypertension (EH) and spontaneously hypertensive rats (SHR) was found to be increased by 1.6-2.0 times as compared with normotensive controls.

Volume-dependent regulation of cation transport and polyphosphoinositide metabolism in human and rat erythrocytes: features revealed in primary hypertension.

The rate of delta mu H+ --induced erythrocyte Na+/H+ exchange is increased in both patients with essential hypertension (EH) and spontaneously hypertensive rats (SHR). The increase of Na+,K(+)-cotransport was revealed in erythrocytes of SHR only. This alteration as well as a decrease of mean cell volume were observed in both young and old erythrocytes of SHR.

Na+-H+ exchange and other ion-transport systems in erythrocytes of essential hypertensives and spontaneously hypertensive rats: a comparative analysis.

The activity of ion-transport systems and Ca2+-induced erythrocyte haemolysis were compared between patients with essential hypertension and two strains of spontaneously hypertensive rats. Previous data on the increased rate of Na+-Li+ countertransport in erythrocytes of essential hypertensives were confirmed in this study. However, identification of Na+-Li+ countertransport in rat erythrocytes remained a complicated person because of the high rate of sodium-independent efflux of Li+.

[Transport of monovalent cations and calcium in erythrocytes of rats with spontaneous hypertension: study with fractions enriched with young and old cells].

The erythrocytes from two spontaneously hypertensive rat strains (SHR and MHS) differ from those of control strains such as WKY and MNS in showing lower values of the mean volume and higher Na,K-cotransport rates. After 4-hour incubation in the presence of orthovanadate 45Ca levels in the erythrocytes from SHR was twice as high as in those from WKY. Under the same conditions, hemoglobin crystallization occurred, this process in SHR erythrocytes took place more intensively.

[Cation transport and calcium-induced hemolysis in the erythrocytes of patients with hypertension and in spontaneously hypertensive rats (comparative analysis)].

A comparison was made of the physicochemical characteristics of erythrocyte membranes in two strains of spontaneously hypertensive rats, namely SHR and MHS and in patients with essential hypertension (EH). The authors confirmed the results of the previously reported studies that Na+/Li+/H+ countertransport rates were higher in the erythrocytes of patients with EH. The high rate of L1+ sodium-independent efflux hindered identification of Na+/H+ turnover in the rat erythrocytes.

[Calcium transport in brain synaptosomes during depolarization. The role of potential-dependent channels and Na+/Ca2+ metabolism].

The contribution of Ca2+ channels and Na+/Ca2+ exchange to Ca2+ uptake in rat brain synaptosomes upon long- (t greater than or equal to 30 s) and short-term (t less than 30 s) depolarization by high K+ was studied by measuring the 45Ca content and free Ca2+ concentration (from Quin-2 fluorescence). At 37 degrees C, the system responsible for the K+-stimulated uptake of 45Ca (t greater than or equal to 30 s) and the Na+/Ca+ exchanger are characterized by a similar concentration dependence of external Ca2+ (Ca0(2+] and K0+ as well as by an equal sensitivity to verapamil (Ki = approximately 20-40 microM) and La2+ (Ki = approximately 50 microM). These data and the results from predepolarization suggest that the 45Ca entry into synaptosomes at t greater than or equal to 30 s is due to the activation of Na+/Ca+ exchange caused by its electrogenic component, while the insignificant contribution of Ca2+ channels can be accounted for by their inactivation.

Volume-dependent regulation of ion transport and membrane phosphorylation in human and rat erythrocytes.

Osmotic swelling of human and rat erythrocytes does not induce regulatory volume decrease. Regulatory volume increase was observed in shrunken erythrocytes of rats only. This reaction was blocked by the inhibitors of Na+/H+ exchange.