UMLS:C0011881 - FACTA Search

Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Target Concepts:

Query: UMLS:C0011881 (diabetic nephropathy)
10,836 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

We have previously reported increased activity of Na+/H+ and Na+/Li+ exchanges in red blood cells (RBC) of patients with hypertension and diabetic nephropathy. The presence in human red blood cells (RBC) of insulin receptors has led us to examine the effects of this hormone on the kinetic parameters of Na+/H+ exchange as a first approach to define its mechanism of action. The antiporter activity was measured as net Na+ influx driven by an outward H+ gradient in acid-loaded, Na-depleted RBCs preincubated with or without (w/wo) insulin (0 to 100 microU/ml) for different time periods. The effects of insulin on the H+ and Na+ activation kinetics of Na+/H+ exchange were examined in RBCs of normal subjects fasted for 12 hours. Insulin (50 microU/ml for 1 hr) increased the Vmax from 28 +/- 6 to 49 +/- 8 mmol/liter cell x hr (N = 10, P < 0.0005) and the Km for Na+ from 72 +/- 10 to 142 +/- 19 mM (N = 4, P < 0.05) but did not change the Km for intracellular H+. Insulin also increased the Vmax of Na+/Li+ exchange at pHi 7.4 (0.34 +/- 0.03 to 0.45 +/- 0.04 mmol/liter cell x hr, N = 9, P < 0.005) as well as the Km for Na+ (31 +/- 3 to 6 +/- 10 mM, P < 0.0003). Therefore, insulin can modulate Na+ sites of Na+/Li+ or Na+/H+ exchanges independent of the occupancy of H+ sites to favor the release of bound Na+ into the cytoplasm. Insulin stimulation of Na+/H+ exchange required endogenous cytosolic Ca2+ levels. The kinetic effects of insulin on Na+/H+ and Na+/Li+ exchanges were imitated by okadaic acid (300 microM), an inhibitor of protein phosphatases which dephosphorylate serine-threonine residues. Okadaic acid increased the Vmax of Na+/H+ and Na+/Li+ exchanges and the Km for Na+ as insulin did. In conclusion, insulin stimulation of the Na+/H+ antiporter occurs by a novel kinetic mechanism leading to a decreased affinity for external Na+ without changes in the affinity for Hi. On the basis that insulin effects were imitated by okadaic acid, we hypothesize that this hormone may increase the phosphorylated state of serine-threonine residues of this antiporter protein.
...
PMID:Insulin activation of red blood cell Na+/H+ exchange decreases the affinity of sodium sites. 796 48

Combined kidney-pancreas transplantation has become the treatment of choice for many patients with end-stage diabetic nephropathy. Pancreas transplantation (PTx) alone is an option for type I diabetic patients without end-stage diabetic nephropathy. Knowledge of factors contributing to or predicting the rate of renal deterioration (including the effect of CsA on the patient's renal function before transplantation) is necessary to determine candidacy for either kidney-pancreas transplantation or PTx alone. To address this issue, we selected 12 pre-uremic patients with creatinine clearances (CrCl) above 40 ml/min and less than 100 ml/min to participate in a 6-week oral CsA challenge test. Serum chemistries, including serum creatinine (SCr) and CsA level, were measured weekly. Urinary protein and CrCl were measured at 0, 2, 4, and 6 weeks. Glomerular filtration rate (GFR) (by 125I-sodium iothalamate clearance) was measured at 0, 3, and 6 weeks. All patients initially received oral CsA at 10 mg/kg/day in 2 divided doses. Doses were adjusted to maintain a 12-hr trough level of 500-1000 ng/ml using a whole blood polyclonal TDX assay. Data are presented as mean +/- SEM and as box-plot graphs. One patient was a CsA challenge test failure because SCr exceeded 3.0 mg/dl despite a reduction in CsA dose and level. Therefore, this patient was not a candidate for PTx alone and was excluded from further analysis. Among the 11 nonfailures, the mean CsA level at 6 weeks was 640 +/- 76 ng/ml. SCr increased from 1.2 +/- 0.1 mg/dl to 1.6 +/- 0.1 mg/dl (33% increase) (P = 0.0001). CrCl decreased from 82 +/- 9 ml/min to 63 +/- 8 ml/min (24% decrease) (P = 0.03). GFR decreased from 95 +/- 15 ml/min to 70 +/- 10 ml/min (26% decrease) (P = 0.009). CrCl and GFR did not differ from one another at 0 and 6 weeks (r = 0.77 and 0.98; P = 0.3 and 0.7, respectively). Urinary protein decreased from 1.0 +/- 0.3 g/day to 0.7 +/- 0.3 g/day at both 4 and 6 weeks (P = 0.03 and 0.06, respectively). Three of the 11 patients have not yet received transplants. Eight patients subsequently received PTx alone and were followed prospectively. Two allografts were lost early to rejection. Six were followed from 5 to 19 months after PTx alone. Serum creatinine and CrCL measurements during the CsA challenge test predicted post-PTx levels: SCr 1.6 +/- 0.1 vs. 1.7 +/- 0.3 mg/dl, P = 0.48, and CrCl 68 +/- 10 vs. 53 +/- 3 ml/min, P = 0.17, respectively.
...
PMID:Cyclosporine challenge in the decision of combined kidney-pancreas versus solitary pancreas transplantation. 800 95

Diabetic nephropathy is the main cause of increased mortality and morbidity in IDDM patients. The effect of antihypertensive treatment on the progression of the nephropathy is highly variable. The aim of this study was to evaluate putative predictors of the progression in diabetic nephropathy during long-term antihypertensive treatment. Eighteen hypertensive IDDM patients with diabetic nephropathy, who had not been treated previously, were followed during 3 years of treatment with captopril and frusemide or bendrofluazide. Glomerular filtration rate, arterial blood pressure, albuminuria and adjusted albuminuria were used as putative predictors of rate of decline in glomerular filtration. Fall rate in glomerular filtration rate was 4.6 (4.0) ml.min-1.year-1 (mean (SD)) during treatment. Relative change in albuminuria (ratio of first year of treatment/baseline) and albuminuria during first year of treatment were significantly correlated to fall rate in glomerular filtration rate during 3 years of treatment (r = 0.73, p < 0.001) and (r = 0.60, p < 0.01), respectively. Arterial blood pressure and glomerular filtration rate measured at baseline, during first year of treatment or relative changes in these variables did not correlate with fall rate in glomerular filtration rate during 3 years of treatment. Haemoglobin A1c, serum-cholesterol, protein intake and sodium excretion remained unchanged during treatment, and were not correlated with loss of kidney function. Reduction in albuminuria during captopril treatment predicts an attenuated rate of decline in glomerular filtration rate in early diabetic nephropathy (glomerular filtration rate > 70 ml.min-1.1.73 m-2). The finding suggests a clinical application in monitoring the efficacy of antihypertensive treatment in early diabetic nephropathy.
...
PMID:Reduction in albuminuria predicts a beneficial effect on diminishing the progression of human diabetic nephropathy during antihypertensive treatment. 805 90

Sodium-lithium countertransport (SLC) activity at a standard physiological sodium concentration is raised in uncomplicated IDDM, for which the kinetic mechanism is a raised maximum velocity (Vmax). Diabetic patients with nephropathy do not have raised values for Vmax but a low Michaelis constant (km). Transporter activity could be influenced by its membrane lipid environment. This was assessed in 21 control subjects, 32 uncomplicated diabetic patients, 17 patients with diabetic nephropathy and 11 patients with non-diabetic nephropathy by measuring the fluorescence anisotropy of DPH and TMA-DPH to assess different membrane regions. Standard SLC was higher in all the patient groups compared to the control subjects: 0.307 +/- 0.020 mmol Li/h x 1 cells in uncomplicated IDDM; 0.300 +/- 0.032 in diabetic nephropathy patients and 0.276 +/- 0.019 in non-diabetic nephropathy patients vs 0.216 +/- 0.011 mmol Li/h x 1 cells in control subjects (p < 0.001, p < 0.05, p < 0.05, respectively). This was due to raised Vmax values in the uncomplicated group: 0.528 +/- 0.035 vs 0.385 +/- 0.022 mmol Li/h x 1 cells in control subjects (p = 0.001) and low values for km in the diabetic nephropathy group: 58 (27-170) vs 106 (81-161) mmol/l in control subjects (p < 0.001). Raised SLC in the non-diabetic nephropathy group was largely due to raised Vmax: 0.460 +/- 0.030 mmol Li/h x 1 cells; p = 0.053, with no difference in km: 99.5 (74-137).(ABSTRACT TRUNCATED AT 250 WORDS)
...
PMID:Erythrocyte sodium-lithium countertransport activity is related to membrane fluidity in IDDM patients. 806 41

We investigated both sodium-lithium countertransport (Na-Li CT) and ouabain-sensitive sodium transport (Na pump) of erythrocytes in healthy subjects (group A), patients with non-insulin-dependent diabetes (NIDDM) without nephropathy (group B), patients in the proteinuric stage (group C), and those in the renal insufficiency stage (group D). Erythrocytes from all four groups had a similar initial water and ionic content and were loaded with similar degrees of Li and Na for efflux studies. There were no significant differences in erythrocyte Na-Li CT or Na pump among the four groups. However, the maximal rate of Na-Li CT was significantly higher in a group of subjects with essential hypertension when compared with groups A, B and C, consistent with the view that there is a genetic marker for essential hypertension. Ouabain-insensitive Na efflux (Na leak) of erythrocytes was found to be significantly higher in group D than in groups A or B. Also, a significant positive correlation existed between Na leak and urine protein levels of the subjects studied. Our results thus indicate that in contrast with insulin-dependent diabetic patients (IDDM) where an elevated Na-Li CT is observed, with diabetic nephropathy, Na-Li CT in NIDDM is apparently not associated with nephropathy; rather the ouabain-insensitive Na efflux appears to be correlated with the stages of nephropathy in NIDDM. The association suggests that the rate of ouabain-insensitive Na efflux may provide an index for assessing the degree of nephropathy in NIDDM patients.
...
PMID:Abnormalities of sodium transport in non-insulin-dependent diabetes: association with renal disease. 810 99

In order to elucidate the causal relationship between (Na(+)-K+)ATPase and diabetic nephropathy, we studied the erythrocyte (Na(+)-K+)ATPase activity in Type 2 diabetic patients, 20 with microalbuminuria and 27 without microalbuminuria and in 16 control subjects. (Na(+)-K+)ATPase activities in microalbuminuric patients (0.273 +/- 0.012 mumol Pi/mg protein/h, mean +/- SE) were significantly reduced compared with those without microalbuminuric patients (0.308 +/- 0.011 mumol Pi/mg protein/h, p < 0.05) and control subjects (0.330 +/- 0.011 mumol Pi/mg protein/h, p < 0.01). Microalbuminuric patients had higher systolic blood pressure (133 +/- 3 vs 124 +/- 3 mmHg, p < 0.05) and greater frequency of parental hypertension (50% vs 19%, p < 0.05) than those without microalbuminuria. (Na(+)-K+)ATPase activities in diabetic patients with hypertension were significantly reduced compared with those in diabetic patients without hypertension. Moreover, (Na(+)-K+)ATPase activities in diabetic patients with parental hypertension were significantly reduced compared with those in patients without parental hypertension. There was no difference in erythrocyte Na+ content between with and without microalbuminuria or hypertension or parental hypertension in diabetic patients. Erythrocyte Na+ content was significantly negatively correlated with (Na(+)-K+)ATPase activity in control subjects (r = -0.619, p < 0.05), but not in diabetic patients (r = -0.194). Plasma digitalis-like substances showed no correlation with (Na(+)-K+)ATPase activities in diabetic patients with microalbuminuria or hypertension or parental hypertension. We concluded that the reduction of erythrocyte (Na(+)-K+)ATPase activity may be related to a familial predisposition to arterial hypertension and may partly be responsible for the development of diabetic nephropathy in Type 2 diabetic patients.
...
PMID:Reduction of erythrocyte (Na(+)-K+)ATPase activity in type 2 (non-insulin-dependent) diabetic patients with microalbuminuria. 815 Apr 21

Previous studies of erythrocyte sodium-lithium countertransport activity, a putative genetic marker of essential hypertension, in Type I and Type II diabetic patients with nephropathy have given conflicting results. We have found changes in the maximum velocity (Vmax) and sodium-affinity constant (Km) of sodium-lithium countertransport in Type I diabetic patients with diabetic nephropathy. In this study, sodium-lithium countertransport kinetics were measured in Type II diabetic patients with established diabetic nephropathy, matched uncomplicated Type II diabetic patients, non-diabetic patients with nephropathy and healthy control subjects. Mean standard sodium-lithium countertransport activity was not significantly increased in either of the groups of diabetic patients compared with the non-diabetic control groups. The Type II diabetic patients with nephropathy had a significantly reduced km and Vmax compared with the uncomplicated diabetic patients and non-diabetic control group. These kinetic changes are identical to those observed in Type I diabetic nephropathy patients. There are similar underlying changes in the erythrocyte plasma membrane with the development of nephropathy in both Type I and Type II diabetes.
...
PMID:Nephropathy and changes in sodium-lithium countertransport kinetics in type 2 (non-insulin-dependent) diabetes mellitus. 815 3

Proteinuric diabetic patients have an increased risk of cardiovascular disease and almost always have hypertension. In the early stages of diabetic renal disease (microalbuminuria) when renal function is well preserved, systemic arterial blood pressure is already elevated compared to insulin-dependent diabetic patients without microalbuminuria. Prospective studies have shown that normoalbuminuric patients who progress to microalbuminuria have higher blood pressures (albeit within the normal range) than those who persistently remain normoalbuminuric. Parents of insulin-dependent diabetic patients with nephropathy have a higher prevalence of hypertension and cardiovascular disease compared to those of patients without nephropathy. Moreover, diabetic nephropathy clusters within families. Erythrocyte sodium-lithium countertransport activity, the most consistent marker for essential hypertension and its cardiorenal complications, is elevated in diabetic patients with nephropathy and in their non-diabetic parents. These data suggest that a familial predisposition to arterial hypertension and cardiovascular disease increases the risk for the development of nephropathy and its associated cardiovascular complications in insulin-dependent diabetes. Arterial hypertension is a state of insulin resistance and diabetic patients susceptible to nephropathy have been found to be less insulin sensitive. Preventive strategies of diabetic kidney disease in the future will have to take into account its metabolic hemodynamic and familial basis.
...
PMID:Familial, hemodynamic and metabolic factors in the predisposition to diabetic kidney disease. 816 30

The effects of spirapril and isradipine on blood pressure, urinary albumin excretion and sodium-volume homeostasis in hypertensive insulin-dependent diabetic patients with nephropathy were assessed. Fifteen Type 1 diabetic patients aged 28-53 years with a diabetes duration of 19-37 years were studied. All had hypertension and diabetic nephropathy with a urinary albumin excretion of more than 300 mg/24 h. After a single blind placebo treatment period of 4 weeks the patients were randomly assigned to treatment with the calcium antagonist isradipine SRO 5 mg once daily or the ACE inhibitor spirapril 6 mg once daily for 6 months in a double-blind design. Isradipine lowered ambulatory systolic blood pressure from 152 +/- 12 to 141 +/- 11 mmHg (p < 0.05) and ambulatory diastolic pressure from 91 +/- 9 to 86 +/- 8 mmHg (p < 0.05). The blood pressure lowering effect of spirapril was similar: 156 +/- 13 vs 143 +/- 11 mmHg (p < 0.01) and 90 +/- 4 vs 84 +/- 4 mmHg (p < 0.05). The fractional albumin clearance was unchanged on isradipine but decreased after 6 months treatment with spirapril with on average 20% (p < 0.05). Total body exchangeable sodium decreased on spirapril treatment: 2994 +/- 296 vs 2636 +/- 194 meq/1.73 m2 (p < 0.05) and extracellular volume tended to do so (p = 0.12). On isradipine treatment these parameters remained unchanged. In conclusion both isradipine and spirapril lowered blood pressure in patients with diabetic nephropathy. Only the ACE inhibitor had demonstrable beneficial effects on urinary albumin excretion rate and the sodium-volume expansion seen in these patients.
...
PMID:A comparison of spirapril and isradipine in patients with diabetic nephropathy and hypertension. 817

Lithium is the best available marker of proximal tubular reabsorption of fluid. The first part of the present thesis reviews the background for the use of the lithium clearance (CLi) method. Micropuncture studies on proximal reabsorption of lithium, showed that CLi is a reasonably correct measure of end-proximal fluid delivery rate, even during osmotic diuresis. During severe salt restriction, distal reabsorption of lithium renders the CLi method inappropriate in animals, but this problem does probably not occur in humans. The major current issue is whether a quantitatively significant reabsorption of lithium occurs in the loop of Henle. Available evidence is in accord with the interpretation that it does not occur. The interpretation of results form CLi studies depends to a surprising degree on the investigators beliefs about renal physiology. In the evaluation of proximal tubular function, the relevant parameter is the absolute proximal reabsorption rate of fluid and sodium. In the evaluation of integrated distal tubular reabsorption of sodium, the relevant parameter is the fractional distal reabsorption rate of sodium. The fractional CLi does not give meaningful information, and calculated absolute distal reabsorption rate of sodium is inherently not suited to detect modest changes in distal reabsorption leading to large changes in sodium excretion. Results from the use of the CLi method in relation to diabetes are reviewed in the second section. Even in IDDM patients with early diabetic nephropathy, the proximal reabsorption rate is elevated, resulting in a normal CLi despite glomerular hyperfiltration. Overnight euglycemia did not change GFR in IDDM patients, but during maintained euglycemia, GFR was normalized. A few hours of hyperglycemia prevented the decline in GFR, whereas CLi was unchanged. Thus hyperglycemia produced changes in renal function similar to those observed previously, but the time-course of the effect of euglycemia on kidney function is delayed. Plasma levels of atrial natriuretic peptide, renin and glucagon were not importantly affected by plasma glucose. In NIDDM patients CLi was normal, despite slight hyperfiltration, although this observation must be confirmed in a study with larger sample size. Prompted by the clinical observation of a marked decline in the GFR induced by carbonic anhydrase inhibitors, we studied the renal effects of acetazolamide in a controlled study.(ABSTRACT TRUNCATED AT 400 WORDS)
...
PMID:Lithium clearance in the evaluation of segmental renal tubular reabsorption of sodium and water in diabetes mellitus. 818 64

<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>