Functionally abnormal Na+-K+ pump in erythrocytes of a morbidly obese patient

The Oxidative Status and Na+/K+-ATPase Activity in Obsessive-Compulsive Disorder: A Case Control Study

Background

Oxidative stress is involved in pathogenesis of some psychiatric disorders. To examine the role of oxidative stress in the etiopathogenesis of obsessive-compulsive disorder (OCD), we aimed to determine oxidative stress indices, including malondialdehyde (MDA) levels in serum and red blood cells (RBC) membrane, total antioxidant capacity (TAC), serum glutathione (GSH) levels, serum antioxidant vitamins (A and E), and Na+/K+-ATPase activity, in patients with the mentioned disorder vs. healthy controls.

Method

39 OCD patients diagnosed based on Diagnostic and Statistical Manual of Mental Disorders (DSM-V) and 39 volunteer healthy subjects were included in this study. MDA levels in serum and RBC membrane were measured using fluorometric method. Serum TAC level, serum GSH level, and Na+/K+-ATPase activity were also measured using spectrophotometric methods. Serum levels of vitamins were calculated by reversed-phase high-performance liquid chromatography (RP-HPLC).

Result

There was a significantly higher MDA level in serum (p < 0.0001) and RBC membrane (p = 0.002) of OCD patients compared with those in controls. A significant reduction in vitamin A (p = 0.001) and vitamin E (p = 0.024) levels was found in OCD patients vs. controls. There was significantly lower activity of erythrocyte membrane Na+/K+-ATPase in RBC membrane of OCD patients vs. controls (p < 0.0001).

Conclusion

Our findings indicate significantly higher levels MDA in both serum and RBC membrane, lower levels of serum vitamins A and E, and lower activity of membrane Na+/K+-ATPase in OCD patients compared to controls. These suggest an imbalance between oxidant and antioxidant factors in OCD patients that might play a fundamental role in the etiopathogenesis of OCD.

Relationship Between Red Cell Distribution Width and Oxidative Stress Indexes in Patients with Coronary Artery Disease

Background

Red blood cell distribution (RDW), an index of the size variability of erythrocytes, is significantly associated with coronary stenosis and can strongly predict the mortality risk in coronary artery disease (CAD). The biological mechanisms involved are not fully understood but may include oxidative stress. We sought to investigate the relationship between RDW and markers of oxidative stress in patients with CAD.

Methods

Participants were 112 consecutive patients referred to department of cardiac surgery for evaluation of chest pain. 32 patients had stable CAD, 40 patients had unstable CAD and 40 subjects were diagnosed as non-CAD. The levels of lipid peroxidation (TBARS) were measured in plasma and membrane samples by a fluorometric method. The plasma levels of glutathione (GSH) and total antioxidant capacity (TAC) were determined using spectrophotometric methods.

Results

Lipid peroxidation levels were significantly higher in the erythrocyte membrane of stable CAD patients than non-CAD patients. The levels of TAC were significantly lower in both stable and unstable groups when compared to that of the control group (P< 0.019 and P< 0.001, respectively), but did not differ between stable and unstable CAD. In addition, there was no significant difference in the serum GSH levels among the study groups. Membrane TBARS was directly associated with RDW in three groups of study.

Conclusions

We found an independent association between RDW levels and membrane lipid peroxidation in patients with CAD. This finding suggests that oxidative stress may be a potential underlying biological mechanism for increased RDW in CAD patients.

Investigation of membrane fatty acid profiles in erythrocytes of patients with stable coronary artery disease

BACKGROUND

The association between the erythrocyte membrane fatty acids and the severity of coronary stenosis has not been studied in patients with stable coronary artery disease (CAD).

OBJECTIVE

We sought to investigate whether the fatty acid profile of erythrocyte membranes is significantly different in patients with stable CAD compared with patients with nonsignificant coronary stenosis and evaluate a possible relationship between fatty acid profile and the severity of coronary stenosis.

METHODS

The population included 144 patients, undergoing clinically indicated coronary angiography. The severity of coronary stenosis was scored after coronary angiography, and patients were divided into 2 groups; the S-stenosis group (CAD patients, n = 82) had a significant stenosis indicated by coronary angiography and the second group, S-stenosis (n = 62), had nonsignificant coronary stenosis.

RESULTS

The erythrocyte membranes linoleic acid (LA) levels were lower (P < .001) and the arachidonic acid (AA)-to-LA ratio, a marker of desaturase activity, were higher (P < .001) in CAD patients compared with S-stenosis patients. The CAD scores were correlated negatively with the membrane LA levels (r = -0.338; P < .001) and positively with the AA-to-LA ratio (r = 0.306; P < .001).

CONCLUSIONS

This study shows that LA levels of the erythrocyte membrane and AA-to-LA ratio are correlated with the severity of CAD.

The change in thyroid hormone signaling by altered training intensity in male rat skeletal muscle

Aerobic (sub lactate threshold; sub-LT) exercise training facilitates oxidative phosphorylation and glycolysis of skeletal muscle. Thyroid hormone (TH) also facilitates such metabolic events. Thus, we studied whether TH signaling pathway is activated by treadmill training. Male adult rats received 30 min/day treadmill training with different exercise intensity for 12 days. Then plasma lactate and thyrotropin (TSH) levels were measured. By lactate levels, rats were divided into stationary control (SC, 0 m/min), sub-LT (15 m/min) and supra lactate threshold (supra-LT; 25 m/min) training groups. Immediately after the last training, the soleus muscles were dissected out to measure TH receptor (TR) mRNA and protein expressions. Other rats received intraperitoneal injection of T3, 24 h after the last training and sacrificed 6 h after the injection to measure TH target gene expression. TSH level was suppressed in both sub-LT and supra-LT groups during the exercise. TRβ1 mRNA and protein levels were increased in sub-LT group. Sensitivity to T3 was altered in several TH-target genes by training. Particularly, induction of Na(+)/K(+)-ATPase β1 expression by T3 was significantly augmented in sub-LT group. These results indicate that sub-LT training alters TH signaling at least in part by increasing TRβ1 expression. Such TH signaling alteration may contribute metabolic adaptation in skeletal muscle during physical training.

Increased membrane lipid peroxidation and decreased Na+/K+-ATPase activity in erythrocytes of patients with stable coronary artery disease

OBJECTIVES

We aimed to determine erythrocyte membrane lipid peroxidation levels and Na/K-ATPase activity in patients with and without coronary artery disease (CAD) documented by coronary angiography.

DESIGN AND METHODS

A total of 144 patients who had undergone coronary angiography were divided into a CAD group (n=82) and a non-CAD group (control group, n=62) according to the results of coronary angiography. Lipid peroxide levels in plasma and the erythrocyte membrane were measured using a fluorimetric method. Total antioxidant status and Na/K-ATPase activity in plasma were determined using spectrophotometric methods.

RESULTS

Lipid peroxidation levels were significantly higher in the erythrocyte membrane of CAD patients compared with controls, whereas Na/K-ATPase activity was significantly lower in the erythrocyte membrane of CAD patients compared with controls. The coronary artery scores were correlated positively with membrane lipid peroxidation (r=0.324, P<0.001) and negatively with Na/K-ATPase activity (r=-0.302, P<0.001).

CONCLUSION

This study shows that the levels of membrane lipid peroxidation and Na/K-ATPase activity are correlated with the severity of CAD.

Biochemical changes in blood of type 2 diabetes with and without metabolic syndrome and their association with metabolic syndrome components

Background:

Multiple factors are involved in the development and progression of type 2 diabetes mellitus (DMII) to DMII with metabolic syndrome (MetS) and cardiovascular complications. To identify some of these factors, we aim to investigate the changes in erythrocyte membrane Na⁺/K⁺-ATPase activity, serum glucose, insulin, lipid profile, hemoglobin A1C (HbA1c), high-sensitivity C-reactive protein (hs-CRP), anthropometric measurements, and blood pressure in DMII with and without MetS.

Materials and Methods:

This cross-sectional study comprised 155 male subjects distributed into three groups as healthy controls (50 non-DMII volunteers), Group I (50 DMII without MetS), and Group II (55 DMII with MetS). Fasting blood samples were taken for the measurement of glucose, insulin, HbA1c, hs-CRP and lipid profile. Na⁺/K⁺-ATPase activity was determined in erythrocyte ghost.

Results:

Na⁺/K⁺-ATPase activity was significantly decreased in DMII groups compared with controls. No significant difference was shown in Na⁺/K⁺-ATPase activity between DMII groups. Total ATPase activity, total cholesterol and low-density lipoprotein-cholesterol levels were similar in the three groups. Levels of insulin, hs-CRP, triacylglycerols, systolic blood pressure, weight, waist and hip circumference, waist/hip ratio, and body mass index were significantly elevated and high-density lipoprotein-cholesterol significantly decreased only in Group II. Significant differences in serum glucose and hip circumference were seen between the groups. No significant differences in HbA1c levels were observed between DMII groups.

Conclusion:

Changes in many of the measured risk factors that occurred only in Group II compared with controls and Group I may provide an explanation of how DMII progresses to DMII with MetS and future cardiovascular complications.

Association of the total cholesterol content of erythrocyte membranes with the severity of disease in stable coronary artery disease

Increasing evidence suggests that erythrocytes may participate in atherogenesis. We sought to investigate whether the total cholesterol content of erythrocyte membranes (CEM) is significantly different in patients with stable coronary artery disease (CAD) compared to patients with nonsignificant coronary stenosis and determine the correlation between CEM and the severity of coronary stenosis. Methods. The population included 144 patients, undergoing clinically indicated coronary angiography. The severity of coronary stenosis was scored after coronary angiography and patients were divided into two groups; the S-stenosis group (CAD patients, n = 82) had a significant stenosis indicated by coronary angiography and the second group, N-stenosis (n = 62), had nonsignificant coronary stenosis. Lipid parameters were determined by routine laboratory methods. CEM was measured using an enzymatic assay, and protein content was assessed by the modified Lowry method. Results. The mean of CEM levels was higher (P < 0.001) in stable CAD patients (137.2 µg/mg of membrane protein) compared with N-stenosis patients (110.0 µg/mg of membrane protein). The coronary artery scores were correlated positively with CEM levels (r = 0.296, P < 0.001). Conclusion. CEM levels are positively associated with the severity of CAD, meaning that CEM might contribute to the development of CAD.

Activities of three erythrocyte enzymes of hyperglycemic rats (Rattus norvegicus) treated with Allium sativa extract

Background

The present study sought to investigate erythrocyte glutathione S-transferases (GST), NADH-Methaemoglobin reductase (NADH-MR) and Na⁺/K⁺-ATPase activities of hypoglycemic rats treated with ethanol/water (1:2 v/v) extract of A. sativa as agent of glycemic control.

Methods

Hyperglycemia was induced by a single intra-peritoneal injection of 0.1 mol/L alloxan monohydrate in phosphate buffer saline (PBS) solution (pH = 7.4); dosage = 140 mg/kg. At the end of the experimental time (t = 76 h), erythrocyte GST, NADH-MR and Na⁺/K⁺-ATPase activities as well as serum fasting blood sugar (FBS) levels were measured by spectrophotometric methods.

Results

Serum FBS levels of control/normal (C/N) rats ranged between 72.93 ± 0.82–95.12 ± 0.92 mg/dL, whereas experimental rats without glycemic control gave: 249.41 ± 1.03–256.11 ± 1.23 mg/dL. Hyperglycemic rats treated with ethanol/water (1:2 v/v) extract of A. sativa exhibited comparative reduced serum levels of FBS alongside with erythrocyte GST, NADH-MR and Na⁺/K⁺-ATPase activities. The average relative activities of the three enzymes and corresponding order of enzyme activity in hyperglycemic rats treated with ethanol/water (1:2 v/v) extract of A. sativa was: NADH-MR = 60.99% > GST = 47.81% > Na⁺/K⁺-ATPase = 46.81%. In the same order, relative activities of the three enzymes in rats without glycemic control were: NADH-MR = 49.65% > GST = 23.69% > Na⁺/K⁺-ATPase = 17.02%.

Conclusion

Erythrocyte GST, NADH-MR and Na⁺/K⁺-ATPase activities gave insights into the pathophysiology of diabetic state and served as biomarkers for ascertaining therapeutic control in Type 1 diabetes mellitus.

Association between erythrocyte Na+K+-ATPase activity and some blood lipids in type 1 diabetic patients from Lagos, Nigeria

BACKGROUND

Altered levels of erythrocyte Na+K+-ATPase, atherogenic and anti-atherogenic lipid metabolites have been implicated in diabetic complications but their pattern of interactions remains poorly understood.This study evaluated this relationship in Nigerian patients with Type 1 diabetes mellitus.

METHODS

A total of 34 consented Type 1 diabetic patients and age -matched 27 non-diabetic controls were enrolled. Fasting plasma levels of total cholesterol, triglycerides and HDL-cholesterol were determined spectrophotometrically and LDL-cholesterol estimated using Friedewald formula. Total protein content and Na+K+-ATPase activity were also determined spectrophotometrically from ghost erythrocyte membrane prepared by osmotic lysis.

RESULTS

Results indicate significant (P < 0.05) reduction in Na+K+-ATPase activity in the Type 1 diabetic patients (0.38 +/- 0.08 vs. 0.59 +/- 0.07 microM Pi/mgprotein/h) compared to the control but with greater reduction in the diabetic subgroup with poor glycemic control (n = 20) and in whom cases of hypercholesterolemia (8.8%), hypertriglyceridemia (2.9%) and elevated LDL-cholesterol (5.9% each) were found. Correlation analyses further revealed significant (P < 0.05) inverse correlations [r = -(0.708-0.797] between all the atherogenic lipid metabolites measured and Na+K+-ATPase in this subgroup contrary to group with good glycemic control or non-diabetic subjects in which significant (P < 0.05) Na+K+-ATPase and HDL-C association were found (r = 0.427 - 0.489). The Na+K+-ATPase from the diabetic patients also exhibited increased sensitivity to digoxin and alterations in kinetic constants Vmax and Km determined by glycemic status of the patients.

CONCLUSION

It can be concluded that poor glycemic control evokes greater reduction in erythrocyte Na+K+-ATPase activity and promote enzyme-blood atherogenic lipid relationships in Type 1 diabetic Nigerian patients.

Elevated tissue sodium concentration in malignant breast lesions detected with non-invasive 23Na MRI

BACKGROUND

The hypothesis that physiological and biochemical changes associated with proliferating malignant tumors may cause an increase in total tissue sodium concentration (TSC) was tested with non-invasive, quantitative sodium ((23)Na) magnetic resonance imaging (MRI) in patients with benign and malignant breast tumors.

METHODS

(23)Na and (1)H MRI of the breast was performed on 22 women with suspicious breast lesions (> or =1 cm) at 1.5 Tesla. A commercial proton ((1)H) phased array breast coil and custom solenoidal (23)Na coil were used to acquire (1)H and (23)Na images during the same MRI examination. Quantitative 3-dimensional (23)Na projection imaging was implemented with negligible signal loss from MRI relaxation, or from radio-frequency field inhomogeneity, in less than 15 min. Co-registered (1)H and (23)Na images permitted quantification of TSC in normal and suspicious tissues on the basis of (1)H MRI contrast enhancement and anatomy, with histology confirmed by biopsy.

RESULTS

Sodium concentrations were consistently elevated in (N = 19) histologically proven malignant breast lesions by an average of 63% compared to glandular tissue. The increase in sodium concentration in malignant tissue was highly significant compared to unaffected glandular tissue (P < 0.0001, paired t-test), adipose tissue, and TSC in three patients with benign lesions.

CONCLUSION

Elevated TSC in breast lesions measured by non-invasive (23)Na MRI appears to be a cellular-level indicator associated with malignancy. This method may have potential to improve the specificity of breast MRI with only a modest increase in scan time per patient.

Properties of the Na+-K+ pump in human red cells with increased number of pump sites

We studied the Na+/K+ pump in red cells from an obese human subject (MAJ) in which the number of pumps/cell was 10-20 times higher than normal. Through measurements of the kinetic properties of several modes of operation of the Na+/K+ pump we determined that the pumps in MAJ cells are kinetically normal. In the presence of adequate metabolic substrate the maximum rates of Na+ pumping and lactate production saturated at 60 and 12 nmol/1 cell per h, respectively. Under physiological conditions pump and "leak" Na+ fluxes were similar in MAJ and normal cells. Since internal Na+ was lower in MAJ than in normal cells (Nai+ approximately 2 and 8 mmol/1 cell, respectively), we conclude that the reduction in cell Na+ allows the Na+/K+ pump in MAJ cells to operate at lower fraction of maximum capacity and to compensate for the increased number of pumps.

Heterogeneity of the erythrocyte Na-K pump status in human obesity

The number of Na-K pump units, the Na-K-ATPase activity, the K transport turnover rate per pump unit and the intracellular Na and K concentrations were measured in the erythrocytes of 56 obese patients and 20 normal subjects. No differences were found between the two groups. In obese patients, we failed to observe any influence of dietary habits, age of onset, or family history of obesity on the Na pump status. On the other hand, we found that the number of pump units was not a close reflection of the membrane cation transport and in some patients with an abnormally high number of pump units, an inappropriately low Na-K-ATPase activity was observed. We also identified two small groups of obese patients with, respectively, abnormally high or low K transport turnover rate per pump unit. Our study seems to support the hypothesis that abnormalities in the erythrocyte Na-K pump system are not usual in the obese population but are probably present only in a limited number of selected patients.

[3H]ouabain binding and sodium content in lymphocyte sub-populations and the demonstration of increased binding in type 2 diabetes mellitus

The number of specific [3H]ouabain binding sites in T-lymphocytes was determined and linear Scatchard plots were obtained. The number of sites was 30088 +/- 3039 (mean +/- SD) per lymphocyte in 14 healthy males and 33939 +/- 3185 in 11 males with type 2 diabetes (P less than 0.01). No difference between the dissociation constants were found (Kd = 3.91 and 3.86 mmol/l). The number of binding sites in lymphocytes from 15 healthy males with normal glucose tolerance but with a strong family history of type 2 diabetes did not differ from the controls. In T-lymphocytes a significantly higher number of specific ouabain binding sites was found than in non-T-lymphocytes (P less than 0.01). There was no difference between the dissociation constants. (Kd = 3.69 and 3.97 mmol/l). Intra-lymphocytic sodium was measured in 18 healthy individuals and the mean content was 8.1 +/- 2.3 mmol/kg lymphocytes. A lower content of sodium in T- compared to non-T-lymphocytes was also found (5.9 +/- 0.8 mmol/kg vs 15.5 +/- 0.8 mmol/kg, P less than 0.001). There was no correlation between lymphocytes and erythrocytes concerning [3H]ouabain binding sites or sodium concentration.

Elevated skeletal muscle sodium-potassium-ATPase in human obesity

To determine whether muscle sodium-potassium-ATPase activity, an expression of energy turnover, is increased in obesity, we studied a group of nine non-obese and seven obese subjects undergoing elective cholecystectomy. The muscle ATPase activity was 87 per cent higher (p less than 0.001) in obese subjects compared with non-obese subjects. The increase in the ATPase activity positively correlated with both the body mass index (r = 0.81) and excess body weight (r = 0.75). No relationship was found between erythrocyte and muscle sodium-potassium-ATPase activities (r = 0.25). These findings demonstrate an increased ATPase activity in skeletal muscle obtained from obese subjects and that the erythrocyte is an inaccurate marker of this enzyme with respect to other body tissue.

Changes in cell membrane Na,K-ATPase activity associated with induction of dietary obesity in the rat

The effect of diet-induced obesity on tissue Na, K-ATPase activity ("sodium pump") has been determined in the intact rat exposed to a cafeteria diet. Mature female Charles River rats showed significant increases in carcass lipid on this regimen (P less than 0.01), whereas male rats exposed to cafeteria diet and control male and female animals on laboratory chow showed no increase in carcass lipid over the 54 to 103 days that the animals were studied. In the female cafeteria-diet group, red blood cell membrane Na, K-ATPase activity and carcass lipid were highly correlated (r = 0.847, P less than 0.001). Significant trends in Na, K-ATPase activity as a function of carcass lipid did not occur in either kidney or liver crude membrane preparations from cafeteria-diet females. No correlation was seen in red cell, liver, or kidney membrane Na, K-ATPase with carcass lipid in male cafeteria-diet animals or in the control males and females. In this animal model of nongenetic obesity, changes in tissue Na, K-ATPase activity can be induced by dietary manipulation and are sex-specific and organ-specific.

Sodium-potassium-ATPase activity is influenced by ethnic origin and not by obesity

Previous investigations have suggested that red-cell ouabain binding (an indirect measure of sodium-potassium-ATPase activity) is lower in severely obese patients than in normal controls. We now confirm that ouabain binding measures sodium-potassium-ATPase activity, and we demonstrate that the level of this activity is genetically determined. The activity of this enzyme differs in various ethnic and racial groups, relatively high levels being encountered in non-Jewish white subjects, particularly those with some Scandinavian ancestry. On the other hand, black, Asian, and Jewish white subjects have lower sodium-potassium-ATPase activity. In contrast, no difference was found in red-cell sodium-potassium-ATPase activity between severely obese and normal persons, nor could we confirm a putative effect of food intake on the level of the red-cell enzyme. We suggest that in most earlier studies in which differences were found between normal and severely obese persons, those differences could have been due to differences in the ethnic origins of the obese and control populations.

Achievements in hypertension: a 25 year overview

Only 25 years ago, the field of hypertension was challenged by retrospective clinical data and epidemiologic information suggesting that an elevated arterial pressure is a major risk factor for enhanced cardiovascular morbidity and mortality. Not only was antihypertensive therapy looked on by many as dangerous and fraught with severe and undesirable side effects, but its validity in reversing the course of disease was not yet demonstrated. This review discusses the dramatic new information amassed over the past 25 years that points to the new physiologic and clinical concepts concerning hypertension. It considers impressive new diagnostic techniques and methods designed to identify secondary forms of hypertension and target organ involvement. In summary, it outlines the feasibility of reversing overall (and cardiovascular) morbidity and mortality with an array of antihypertensive agents that provide the therapeutic ability to suppress most pathophysiologic pressor mechanisms of hypertensive disease. The lesson is clear: hypertension provides the greatest available challenge to the new era of preventive cardiology in the 21st century.