Increased sodium-lithium countertransport activity in red cells of IgA nephropathy patients.

The aim of this work was to analyze Na,Li countertransport activity in the erythrocytes from patients with IgA nephropathy, in relationship with their blood pressure status and lipid profile. Forty-nine patients (32 males, 17 females) with biopsy-proven IgA nephropathy and without significant impairment of renal function (serum creatinine less than or equal to 1.4 mg/dl) and 36 normal subjects (21 males, 15 females) were evaluated. Twenty-nine patients with IgA nephropathy were normotensive and 20 hypertensive (diastolic pressure greater than or equal to 95 mm Hg or treated by antihypertensive drugs). Na,Li countertransport was significantly higher in red cells from hypertensive than from normotensive patients (P = 0.002) and normal subjects (P = 0.0001), (values respectively 309 +/- 17; 241 +/- 12 and 211 +/- 11 mumol/liter RBC/hr); normotensive patients with IgA nephropathy did not differ from controls regarding the Na,Li countertransport rate. A multiple stepwise logistic regression analysis with blood pressure status as the dependent variable and Na,Li countertransport activity, age, serum creatinine, proteinuria, cholesterol, triglycerides, plasma potassium and time from onset as independent variables, indicated an independent significant association for Na,Li countertransport (P = 0.002) proteinuria (P = 0.006), plasma potassium (P = 0.006) and age (P = 0.029). Other tested variables were not independently related to blood pressure status. Hyperlipidemic patients (plasma total cholesterol concentration greater than 200 mg/dl and/or plasma triglycerides greater than 172 mg/dl) had an erythrocyte Na,Li countertransport activity significantly higher than normolipidemic (P = 0.005) and controls (P = 0.001) (values respectively 295 +/- 14; 226 +/- 12 and 211 +/- 11 mumol/liter RBC/hr).(ABSTRACT TRUNCATED AT 250 WORDS)     

Intracellular pH and Na+/H+ antiport activity of cultured skin fibroblasts from diabetics.

Increased leucocyte Na+/H+ antiport activity has previously been demonstrated in both hypertensive subjects and Type 1 diabetic patients with nephropathy and may indicate a predisposition to hypertension in such diabetic patients. We have studied intracellular pH and Na+/H+ antiport activity in cultured skin fibroblasts from diabetic patients with and without nephropathy, together with non-diabetic controls to assess if such differences persisted in cultured cells. Fibroblasts from diabetic patients with nephropathy were significantly more alkaline [median (range): 6.90 (6.82 to 7.07)] compared to both normoalbuminuric diabetic patients [6.81 (6.75 to 6.89)] or normal controls [6.82 (6.77 to 6.93)] (P < 0.001 for both). This was associated with a raised Na+/H+ antiport activity in cells from patients with nephropathy when intracellular pH (pHi) was clamped to pH 6.5, without any differences in the maximal transport capacity of the antiport at pHi 6.2. Using both intracellular pH and Na+/H+ antiport activity at pHi 6.5, patients with nephropathy were separated from uncomplicated subjects with a sensitivity of 92% and a specificity of 100%. In conclusion, the raised Na+/H+ antiport activity in cells from patients with diabetic nephropathy persists despite passaging in vitro, thus indicating a heritable component, and results mainly from an increased apparent affinity of the antiport for intracellular H+.     

Clustering of risk factors in hypertensive insulin-dependent diabetics with high sodium-lithium countertransport.

Diabetic nephropathy is more common in patients with a positive family history of hypertension and with elevated red blood cell sodium-lithium countertransport, a marker of risk for essential hypertension. To evaluate whether there is a relationship between this cation transport system and indicators of risk of renal and cardiovascular complications in diabetic patients before the development of clinical proteinuria, we studied 31 type 1 (insulin-dependent) diabetic patients with arterial hypertension, without clinical proteinuria and 12 normotensive normoalbuminuric diabetic patients. Sodium-lithium countertransport activity was significantly higher in hypertensive patients (0.43 +/- 0.03 mmol/l RBC x hr) than in normotensive patients (0.23 +/- 0.03; P less than 0.001). To better explore the nature of the association between this transport system and arterial hypertension, hypertensive patients were divided in two groups, with high (greater than 0.41 mmol/l RBC x hr) or normal (less than 0.41) sodium-lithium countertransport activity. The two groups of hypertensive diabetics were similar in age, sex, body mass index and blood pressure levels.(ABSTRACT TRUNCATED AT 250 WORDS)     

Predisposition to hypertension: risk factor for nephropathy and hypertension in IDDM.

Less than a quarter of the patients with juvenile-onset IDDM develop diabetic nephropathy during the first 20 years of diabetes. To study the determinants of this complication, we selected patients who had come with newly diagnosed IDDM to the Joslin Clinic between 1967 to 1972, and we examined them in 1986 to 1988, that is, 15 to 21 years after onset of diabetes. Using a case control design we compared three groups of cases, that is, advanced nephropathy (N = 43), only microalbuminuria (N = 41), and hypertension alone (N = 17), with a group of controls who remained normoalbuminuric and normotensive despite the long duration of IDDM (N = 61). In comparison with controls, patients with advanced nephropathy had more parents with hypertension (odds ratio 3.8), higher Vmax values of Na/Li countertransport in red blood cells (odds ratio 10.0 for the highest tertile), and higher mean arterial pressure during adolescence and early adulthood (odds ratio 3.1 for those above the median). They also had significantly poorer glycemic control during their first 12 years of diabetes. Patients with hypertension alone were similar to those with advanced nephropathy with regard to markers of predisposition to hypertension but differed from them with regard to glycemic control, having the best glycemic control of all the study groups. Patients who developed only microalbuminuria during 15 to 21 years of IDDM (some of whom will progress to overt proteinuria later) did not differ significantly from controls with regard to predisposition to hypertension. In conclusion, predisposition to hypertension is a major risk factor for the development of advanced diabetic nephropathy and essential hypertension during the first 20 years of IDDM.     

Abnormalities of erythrocyte sodium transport systems in Bartter's syndrome.

The basic tubular alteration present in Bartter's syndrome is still a subject of controversy. The possibility that a generalized defect in the transmembrane ion transport underlies the disease has been extensively investigated. Previous evaluations of cellular sodium metabolism in Bartter patients showed extremely variable findings. We have examined in the red blood cells of two patients with Bartter's syndrome the intracellular Na+ and K+ concentrations, the activity of the ouabain-sensitive Na+/K+ pump, furosemide-sensitive Na+/K+ cotransport, Na+/Li+ countertransport and the rate constant of Na+ and K+ passive permeability. We have compared these values with those of healthy subjects and patients with chronic hypokalemia produced by conditions other than Bartter's syndrome. Ouabain-sensitive Na+/K+ pump activity was decreased in both patients, whereas Na+/Li+ countertransport was activated. One of the patients also exhibited markedly decreased intraerythrocyte K+ concentration and decreased furosemide-sensitive Na+/K+ cotransport. The other had increased Na+/K+ cotransport activity and Na+ passive permeability. Intracellular Na+ and passive permeability to K+ were normal in both subjects. Neither oral potassium supplementation (100 mEq/day) nor indomethacin treatment (150 mg/day) could correct these abnormalities. Our results are partially consistent with previous observations and indicate the existence of heterogenous abnormalities of erythrocyte sodium transport systems in patients with Bartter's syndrome which are not a consequence of chronic hypokalemia.     

Polymorphic genes for kinin receptors,nephropathy and blood pressure in type 2 diabetic patients

BACKGROUND/AIMS: There is evidence that hereditary predisposition contributes to the development of diabetic nephropathy and hypertension. Polymorphisms in the genes for bradykinin receptors (B(1)R and B(2)R) were found to be associated with decreased risk of the development of end-stage renal disease. This study examines whether B(1)R G(-699)C and B(2)R C(181)T polymorphisms are associated with microalbuminuria or overt nephropathy, or blood pressure variation in type 2 diabetic subjects. METHODS: B(1)R and B(2)R polymorphisms were determined in 153 type 2 diabetic patients with microalbuminuria, 132 with overt nephropathy (macroalbuminuria or chronic renal failure), and 161 patients with normoalbuminuria despite diabetes duration longer than 10 years. RESULTS: Distributions of the examined polymorphisms did not differ between patients with microalbuminuria or overt nephropathy, compared to normoalbuminuric control subjects. Patients carrying the B(2)R T allele had lower DBP, compared with non-carriers: 83.6 +/- 12.0 vs. 87.4 +/- 12.1 mm Hg, p < 0.05. Among patients not receiving ACEI, both SBP and DBP was significantly lower in B(2)R T allele carriers, compared to non-carriers (137.2 +/- 20.3 vs. 146.5 +/- 21.7 mm Hg, and 80.3 +/- 11.9 vs. 85.8 +/- 11.6 mm Hg, p < 0.05). CONCLUSIONS: Examined polymorphisms are not associated with the increased risk of incipient or overt nephropathy in type 2 diabetic patients. B(2)R C(181)T polymorphism may contribute to blood pressure variation in these subjects.     

Red cell Na+/Li+ countertransport and Na+/H+ exchanger isoforms in human proximal tubules

BACKGROUND: Increased activity of the Na+/Li+ countertransporter (SLC) is a well-recognized intermediate phenotype of hypertension and diabetic nephropathy and may indicate a predisposition to hypertension. Previous work has attempted to link this membrane transport marker to altered Na+ reabsorption in the proximal tubule. Since the Na+/H+ exchanger (NHE) isoforms 1 and 3 are expressed in the basolateral and apical membranes of the proximal tubule, respectively, we investigated the relationship between these transport proteins and red cell SLC to examine whether the peripheral blood transport phenotype is associated with altered levels of transport proteins in the proximal tubule. METHODS: Proximal tubules were prepared from human nephrectomy specimens. NHE-1 and NHE-3 were detected on Western blots by specific antibodies. Red cell SLC was also measured. RESULTS: Both NHE-1 and NHE-3 proteins were demonstrated, with molecular weights of 97 and 85 kD, respectively. SLC was very strongly correlated with the level of NHE-3 protein (r = 0.78, P < 0.001) and was negatively related to NHE-1 protein (r = -0.32). In multiple regression analysis, only NHE-3 and NHE-1 protein levels were significant predictors of red cell SLC, accounting for up to about 70% of the variance of this parameter. CONCLUSIONS: We conclude that red cell SLC may be a marker of increased NHE-3 protein expression in the proximal tubule, which may account for the blunted pressure natriuresis and predisposition to hypertension.     

Prevalence of raised sodium-lithium countertransport activity in type 1 diabetic patients.

The prevalence of raised Na+/Li+ countertransport (CT) activity (greater than 0.41 mmol/liter RBC/hr) was assessed in 185 consecutive insulin-dependent diabetic patients attending an outpatient diabetic clinic. Normoalbuminuria was defined as an overnight albumin excretion rate (AER) of less than 20 micrograms/min (N = 121), microalbuminuria as AER between 20 and 150 micrograms/min (N = 35) and macroalbuminuria as AER greater than or equal to 150 micrograms/min (N = 29). The prevalence of elevated Na+/Li+CT (greater than 0.41 mmol/liter RBC/hr) was 21.5, 42.8 and 51.7% (P = 0.0005), in patients with normo-, micro- and macroalbuminuria, respectively. In the whole group, Na+/Li+CT was significantly related to mean blood pressure (MBP; rs = 0.37, P less than 0.001) and AER (rs = 0.38, P less than 0.001). In a multiple regression analysis the significant correlates of AER, as a continuous variable, or of proteinuria (micro + macroalbuminuria), as a categorical variable, were Na+/Li+CT, MBP, duration of diabetes and glycosylated hemoglobin (HbA1). The frequency of normoalbuminuric patients with high Na+/Li+CT activity fell with duration of diabetes. The risk of proteinuria was significantly greater in patients with raised Na+/Li+CT compared to those with Na+/Li+CT within the normal range (odds ratio 3.8, 95% CI, 1.9 and 7.8). A relative excess of patients with proteinuria (micro + macroalbuminuria) was found in the group with elevated Na+/Li+CT and HbA1 above the median value (8.05%) of the whole population (chi 2 = 9.7, P less than 0.002).(ABSTRACT TRUNCATED AT 250 WORDS)     

Sodium-hydrogen antiporter: its possible role in the genesis of diabetic nephropathy

The epidemiological evidence that only a subset of diabetic patients are susceptible to renal damage and the demonstration of clear familiar clustering of diabetic nephropathy are consistent with the possibility that genetic factors may explain the liability to or protection from renal disease of diabetic patients. A predisposition to hypertension and cardiovascular disease may be an important determinant of susceptibility to renal disease and its cardiovascular complications in diabetes since raised blood pressure [1] and an increased frequency of cardiovascular disease [2] are more prevalent in parents of diabetic patients with nephropathy. These results have raised growing interest in the search for intermediate phenotypes significantly associated with diabetic nephropathy, poorly influenced by environment, stable with age, easy to quantify and possibly dependent upon a single major gene effect. Such intermediate phenotypes can be useful for early diagnosis and would help clarify the molecular mechanisms leading to diabetic nephropathy. An elevation of Na+/H+ antiporter activity has consistently been associated with diabetic renal disease both in insulin-dependent diabetes mellitus (IDDM) and non-insulin-dependent diabetes mellitus (NIDDM) patients, making this cell membrane exchanger system an ideal intermediate phenotype for the study of diabetic nephropathy.      

Abnormal albuminuria and blood pressure rise in incipient diabetic nephropathy induced by exercise

The aim of the study was to evaluate the influence of light to moderate dynamic work (450 kpm/min followed by 600 kpm/min during 20 min each) on the blood pressure and renal protein handling in insulin-dependent diabetic patients with incipient nephropathy (D3) (elevated baseline albumin excretion but without clinical proteinuria). Fifteen male diabetic patients (D3) with a mean age of 26.5 +/- 4.8 years (SD) and a diabetes duration of 15.6 +/- 3.4 years (SD), 11 comparable diabetic patients with normal urinary albumin excretion (D2), and ten non-diabetic subjects (C) were studied. In D3 baseline diastolic blood pressure was elevated [92.1 mm Hg +/- 6.0 (mean +/- SD)] compared to D2 (80.9 mm Hg +/- 4.8, 2P = 0.003%) and C (79.5 mm Hg +/- 12.4, 2P = 1.2%). Baseline systolic blood pressure was not significantly different in the three groups, but systolic blood pressure was more elevated at 600 kpm/min in D3 (193.0 mm Hg +/- 23.0) compared to D2 (170.5 +/- 17.3, 2P = 1.2%) and C (157.5 mm Hg +/- 20.9, 2P = 0.07%). Baseline albumin excretion in D3 was 82.6 micrograms/min X/ divided by 2.5 (geometric mean X/ divided by tolerance factor) and during exercise the maximal albumin excretion rose to 195.0 micrograms/min X/ divided by 2.6 (2P = 0.01%). In D2 albumin excretion rose from 3.3 micrograms/min X/ divided by 1.9 to 7.9 micrograms/min X/ divided by 1.5 (2P = 0.02%). The albumin excretion in C did not change during exercise. A highly significant correlation between maximal exercise induced systolic blood pressure and maximal exercise induced albumin excretion was demonstrable in D3.(ABSTRACT TRUNCATED AT 250 WORDS)     

Lipids and cellular Na+/H+ antiport activity in diabetic nephropathy.

Increased cellular Na+/H+ antiport activity has been documented in various cell types from hypertensive humans and rats. This membrane abnormality may be associated with the thickening of the vascular media of resistance vessels. Such an abnormality has also been demonstrated in cells from type I diabetic patients with nephropathy, and may indicate the predisposition to essential hypertension in such patients. We now demonstrate the importance of the rate-limiting enzyme for cholesterol and isoprenoid synthesis, 3-hydroxy-3-methyl-glutaryl coenzyme A reductase, in determining cellular Na+/H+ antiport activity. This finding may have application in the future treatment of diabetic patients with proteinuria.     

Sodium transport in red blood cells from dialyzed uremic patients

Studies on red blood cell (RBC) sodium (Na) transport in chronic renal failure have described abnormalities in the ouabain-sensitive Na, K pump. We now report Na transport in RBC using cation flux methodology, measuring both the ouabain-sensitive Na, K pump and the ouabain-insensitive Na, K cotransport (CoT) and Na, lithium (Li) countertransport (CTT) in 28 subjects on hemodialysis, eight subjects on chronic ambulatory peritoneal dialysis (CAPD) and 29 control subjects. Intracellular cation content and passive permeability of Na were also examined. Mean Na efflux through the ouabain-sensitive Na, K pump was not reduced in dialysis patients when compared to normal subjects, whether measured in fresh cells (1.41 +/- 0.05 vs. 1.30 +/- 0.03 mmole/liter RBC/hr; P less than 0.05) or in Na-loaded cells (7.10 +/- 0.24 vs. 6.90 +/- 0.22; NS). There was, however, a marked and uniform suppression of the CoT pathway in Na-loaded cells from dialysis patients versus controls (0.14 +/- 0.02 vs. 0.41 +/- 0.05 mmole/liter RBC/hr; P less than 0.001). Mean CTT activity, as measured by Li efflux, was not different between dialysis and normal subjects. Uremic and normal RBC had similar intracellular Na or K content as well as passive permeability for either ion. This indicates that intracellular cationic homeostasis is maintained, perhaps secondary to balanced changes in cationic flux activity through these transport pathways.     

Sodium-lithium countertransport activity and insulin resistance in normotensive IDDM patients.

In insulin-dependent diabetes (IDDM), an overactivity of sodium-lithium countertransport (Na+/Li+ CT) has been associated with the risk of nephropathy and hypertension, two conditions of insulin resistance. We investigated the sensitivity to insulin with a hyperinsulinemic (approximately 719 pM [approximately 100 microU/ml]) euglycemic clamp in two groups of normotensive nonproteinuric IDDM patients; 12 (10 men, 2 women) had high Na+/Li+ CT activity (mean 0.47, range 0.42-0.68 mmol/L red blood cells [RBC]/h, group 1) and 12 (9 men, 3 women) had normal Na+/Li+ CT activity (mean 0.24, range 0.12-0.31 mmol/L RBC/h, group 2). The two groups were similar in age (mean +/- SE 36 +/- 2 vs. 33 +/- 1 yr), duration of diabetes (19 +/- 3 vs. 18 +/- 2 yr), body mass index (26 +/- 0.8 vs. 24 +/- 0.6 kg/m2), arterial blood pressure (systolic/diastolic 121 +/- 4/79 +/- 2 vs. 122 +/- 3/77 +/- 2 mmHg), and glycemic control (HbA1 8.5 +/- 0.4 vs. 8.0 +/- 0.4%). Albumin excretion rate (AER) ranged between 4.7 and 148 (geometric mean 14) micrograms/min in group 1 and between 2.7 and 93 (geometric mean 11) micrograms/min in group 2. There were four microalbuminuric patients (AER greater than 30 micrograms/min) in each group. Whole-body glucose uptake was significantly reduced on average in group 1 compared with group 2 (41.6 +/- 2.2 mumol.kg-1.min-1 [7.48 +/- 0.4 mg.kg-1.min-1] vs. 49.6 +/- 2.2 mumol.kg-1.min-1 [8.93 +/- 0.4 mg.kg-1.min-1, P = 0.03), but some overlap existed between the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)     

Is increased erythrocyte sodium-lithium countertransport a useful marker for diabetic nephropathy?

Genetic predisposition to essential hypertension has been proposed as a risk factor for the development of diabetic nephropathy in type 1 (insulin-dependent) diabetes mellitus. An increased sodium-lithium countertransport activity (NaLiCT) has been suggested as a genetic marker for essential hypertension. We therefore evaluated NaLiCT in diabetic patients with (N = 39) or without (N = 23) diabetic nephropathy (DNP), patients with non-diabetic renal diseases (N = 42) and in healthy controls (N = 24). The NaLiCT was elevated in both diabetic patient groups compared to healthy controls (median 244; range 134 to 390 mumol.liter cells-1.hr-1), but was not different in patients with DNP (median 314; range 162 to 676), without DNP (median 325; range 189 to 627) and patients with non-diabetic renal disease (median 300; range 142 to 655). The genetic predisposition to DNP is illustrated by the fact that diabetic sibs of probands with DNP showed a higher occurrence of DNP than diabetic sibs of patients without DNP. We analyzed whether familial DNP clustered with an increased NaLiCT. The NaLiCT in sibs concordant for the presence of DNP (N = 10; median 307; range 217 to 428 mumol.liter cells-1.hr-1) was not significantly different from that in sibs concordant for absence of DNP (N = 15; median 279; range 189 to 442). We conclude that erythrocyte sodium-lithium countertransport activity cannot be used as a marker to identify patients at risk for the development of diabetic nephropathy.     

Abnormal kinetics of erythrocyte sodium lithium countertransport in renal transplant recipients

Cardiovascular disease is now the most common cause of death in renal transplantation. Cyclosporine (CsA)-associated hypertension might be a major cause of cardiovascular risk factors. There is evidence suggesting that one mechanism of CsA toxicity might be mediated through alteration of membrane lipid peroxidation, which can activate cellular pathways. Erythrocyte sodium lithium countertransport (Na/Li CT) is a sensitive membrane protein that is abnormal in several hypertensive-related diseases. We have studied the kinetics of erythrocyte Na/Li CT in 38 renal transplant recipients. Group 1 (15 patients) received CsA, azathioprine, and prednisolone (C+A+P), Group 2 (15 patients) CsA and prednisolone (C+P), and Group 3 (8 patients) azathioprine and prednisolone (A+P). Compared with the normal subjects, the Michaelis constant for extracellular sodium (Km) of erythrocyte Na/Li CT was lower among the CsA-based regimen groups (C+A+P and C+P), but not the A+P group. The maximum velocity (Vmax)/Km ratio was also higher among the C+A+P and C+P groups than the A+P group. These abnormalities of Na/Li CT kinetics might be due to abnormalities of cell membrane functions, caused by immunosuppressive drugs, particularly CsA. Further studies involving the effect of CsA on the physiological function of membrane thiol proteins are required.     

Cyclooxygenase-2 inhibitor blocks expression of mediators of renal injury in a model of diabetes and hypertension

BACKGROUND: We previously reported that renal cortical cyclooxygenase (COX-2) expression increased following subtotal nephrectomy, and chronic treatment with a selective COX-2 inhibitor, SC58236, reduced proteinuria and retarded the development of glomerulosclerosis. The present studies were designed to examine the effects of COX-2 inhibition in a model of diabetic nephropathy. METHODS: Rats were divided into three groups: control, diabetic (streptozotocin-induced diabetic animals with superimposed DOCA/salt hypertension; right nephrectomy and DOCA treatment), and treated (administration of the selective COX-2 inhibitor, SC58236, to a subset of diabetic/DOCA/salt rats). Insulin was administered to maintain blood glucose in the 200 to 300 mg/dL range. RESULTS: Systolic blood pressure in the two diabetic groups was elevated within one week and remained elevated until sacrifice at six weeks (control, 108 +/- 2 mm Hg; diabetic, 158 +/- 4 mm Hg; treated, 156 +/- 7 mm Hg). When measured at six weeks, immunoreactive COX-2 expression in the renal cortex of the diabetic rats was 2.5 +/- 0.3-fold of control animals (N = 7). Immunohistochemical localization indicated increased expression in macula densa and surrounding cortical thick ascending limb of Henle (cTALH). The COX-2 inhibitor decreased COX-2 expression in diabetic rats to 1.3 +/- 0.1-fold control. In addition, SC58236 decreased expression of PAI-1 (diabetic vs. treated, 3.2 +/- 0.5 vs. 1.7 +/- 0.2-fold control, N = 7, P < 0.05), vascular endothelial growth factor (VEGF; 2.0 +/- 0.2 vs. 1.2 +/- 0.2; N = 7, P < 0.05), fibronectin (2.4 +/- 0.3 to 1.3 +/- 0.1; N = 7, P < 0.05) and transforming growth factor-beta (TGF-beta; 2.1 +/- 0.2 vs. 1.3 +/- 0.2; N = 7, P < 0.05). Proteinuria at six weeks was decreased in the SC58236-treated rats (149 +/- 8 vs. 92 +/- 8 mg/24 h; N = 7, P < 0.01). The mesangial sclerosis index, defined as increases in extracellular matrix within the mesangial space, was determined at six weeks; the control group had an index of 0.06 +/- 0.01, the diabetic group was 2.7 +/- 0.04 and the treated group was 0.6 +/- 0.03 (P < 0.0001 compared to the diabetic group). CONCLUSIONS: These results suggest that in an experimental model of diabetes and hypertension, inhibition of COX-2 expression decreases potential mediators of glomerular and tubulointerstitial injury and also decreases biochemical, functional and structural markers of renal injury.     

Effects of aggressive blood pressure control in normotensive type 2 diabetic patients on albuminuria, retinopathy and strokes

BACKGROUND: Although several important studies have been performed in hypertensive type 2 diabetic patients, it is not known whether lowering blood pressure in normotensive (BP <140/90 mm Hg) patients offers any beneficial results on vascular complications. The current study evaluated the effect of intensive versus moderate diastolic blood pressure (DBP) control on diabetic vascular complications in 480 normotensive type 2 diabetic patients. METHODS: The current study was a prospective, randomized controlled trial in normotensive type 2 diabetic subjects. The subjects were randomized to intensive (10 mm Hg below the baseline DBP) versus moderate (80 to 89 mm Hg) DBP control. Patients in the moderate therapy group were given placebo, while the patients randomized to intensive therapy received either nisoldipine or enalapril in a blinded manner as the initial antihypertensive medication. The primary end point evaluated was the change in creatinine clearance with the secondary endpoints consisting of change in urinary albumin excretion, progression of retinopathy and neuropathy and the incidence of cardiovascular disease. RESULTS: The mean follow-up was 5.3 years. Mean BP in the intensive group was 128 +/- 0.8/75 +/- 0.3 mm Hg versus 137 +/- 0.7/81 +/- 0.3 mm Hg in the moderate group, P < 0.0001. Although no difference was demonstrated in creatinine clearance (P = 0.43), a lower percentage of patients in the intensive group progressed from normoalbuminuria to microalbuminuria (P = 0.012) and microalbuminuria to overt albuminuria (P = 0.028). The intensive BP control group also demonstrated less progression of diabetic retinopathy (P = 0.019) and a lower incidence of strokes (P = 0.03). The results were the same whether enalapril or nisoldipine was used as the initial antihypertensive agent. CONCLUSION: Over a five-year follow-up period, intensive (approximately 128/75 mm Hg) BP control in normotensive type 2 diabetic patients: (1) slowed the progression to incipient and overt diabetic nephropathy; (2) decreased the progression of diabetic retinopathy; and (3) diminished the incidence of stroke.     

Hypertension, proteinuria and azotaemia in diabetes

The prevalence of hypertension was evaluated in 479 white subjects with diabetes, according to the type of diabetes and the presence of persistent proteinuria as a marker for diabetic nephropathy. Hypertension was uncommon in 178 insulin dependent diabetic subjects without proteinuria (5%) (mean age 25.0 +/- 12.5 years), but occurred in 23% of 58 patients with proteinuria (mean age 28.9 +/- 14.1 years) and in 90% with azotaemia (P less than 0.00001). Among patients with non-insulin-dependent diabetes hypertension was found in 25% of 170 without renal disease (mean age 48.0 +/- 10.3 years) and in 53% of 53 (mean age 51.4 +/- 13.0 years) with proteinuria (P = 0.0002). We conclude that the prevalence of hypertension among subjects with diabetes depends on the type of diabetes, age, and the presence and severity of diabetic renal involvement.     

Prediction of clinical diabetic nephropathy in IDDM patients. Alternatives to microalbuminuria?

This perspective deals with prediction of overt diabetic nephropathy in patients with insulin-dependent diabetes mellitus (IDDM). The role of elevated urinary albumin excretion rate (microalbuminuria) in predicting diabetic nephropathy has been emphasized by new follow-up studies. Development of severe kidney impairment was seen in a large percentage of patients with microalbuminuria, but with more intensive care for diabetic patients, this percentage may be falling. Herein, I analyzed alternatives to microalbuminuria in predicting kidney disease in diabetes. 1) Parental predisposition to hypertension is not seen in all studies and therefore may not be a decisive factor, and it cannot be used in prediction of nephropathy. 2) Prediabetic blood pressure may predict nephropathy in certain non-insulin-dependent diabetic patients, but elevated blood pressure seems to develop after early microalbuminuria and is likely to be an aggravating factor in established microalbuminuria in IDDM patients. 3) At the clinical diagnosis of IDDM, diabetic nephropathy cannot be predicted. 4) Glycemic control is poor in normoalbuminuric patients with later development of microalbuminuria, and multiple glycosylated hemoglobin measurements are therefore important. 5) In diabetes, glomerular hyperfiltration is associated with late nephropathy, but it alone cannot be the decisive factor, because hyperfiltration in nondiabetic individuals does not produce kidney disease, according to new long-term follow-up studies. 6) Studies of glomerular structure and ultrastructure have not yet documented predictive values for overt nephropathy, but further studies are in progress. 7) Isolated blood pressure elevation without microabuminuria (probably representing essential hypertension in diabetes) has not been predictive. 8) It is clear that elevation of serum creatinine is a very late and insensitive parameter, occurring only with pronounced proteinuria.(ABSTRACT TRUNCATED AT 250 WORDS)