Therapy with human recombinant erythropoietin (EPO) has been accepted as effective for renal anemia in dialysis patients. However, studies in rats have shown that correcting anemia with EPO may affect the progression of renal dysfunction. In humans, however, the effect of EPO on residual renal function is a matter of controversy. We, therefore, investigated whether the long-term administration of EPO to predialysis patients influences residual renal function. Anemic patients at the predialysis stage with a serum creatinine (Cr) concentration ranging from 2 to 4 (average 2.9) mg/dl and a hematocrit (Ht) of less than 30% were randomly assigned to two groups which consisted of anemic patients not treated with EPO (group I, untreated anemic controls, n = 31) and anemic patients treated with EPO (group II, treated anemics, n = 42). Patients with nonsevere or moderate anemia (Ht > 30%) with a Cr ranging from 2 to 4 (average 2.6) mg/dl were also recruited as nonanemic controls (group III, untreated nonanemic controls, n = 35). Blood pressure was controlled to the same degree among the three groups by combined treatment with calcium antagonists and angiotensin-converting enzyme inhibitors. All patients were kept strictly on a low-protein (0.6 g/kg/day) and a low-salt (7 g/day) diet. The degree of control of dietary protein and blood pressure and the frequency of angiotensin-converting enzyme inhibitor administration were comparable among the three groups. The primary end point for each patient was a doubling of the baseline Cr which yielded cumulative renal survival rates which were plotted against time. Ht rose significantly from 27.0 ± 2.3 to 32.1 ± 3.2% in group II (n = 42, p < 0.001) with a rate of increase of 0.4 ± 0.06%/week. However, it declined from 27.9 ± 1.8 to 25.3 ± 1.9% in group I (n = 31, p < 0.001) and from 35.9 ± 3.5 to 32.2 ± 3.9% in group III (n = 35, p < 0.001). Cr doubled in 26 patients (84%) in group I as compared with 22 (52%) in group II and 21 (60%) in group III. The cumulative renal survival rates in groups II and III were significantly better than that in group I: p = 0.0003 (group I vs. group II) and p = 0.0024 (group I vs. group III). However, there was no difference in the renal survival rate between groups II and III (p = 0.3111). The better survival rate obtained in group II was attributable to the better survival rate for the nondiabetic patients in this group. The present study suggests that anemia, per se, is a factor in the progression of end-stage renal failure and that reversal of anemia by EPO can retard the progression of renal failure, especially in nondiabetic patiens, provided that blood pressure control, rate of increase in Ht, and dietary protein restriction are appropriate.

A total of 168 patients with non-insulin dependent diabetes (NIDDM) followed over 10 years were recruited in this study. The patients were divided into two groups: Group 1 patients had a stable renal function (N = 96) and Group 2 had a declining renal function (N = 72). Group 1 included those whose serum creatinine was normal five years ago but had increased to > or = 2 mg/dl or those who has reached end-stage renal failure (requiring dialysis) by the time of study. All patients were genotyped for the insertion/deletion (I/D) polymorphism of the ACE gene, the M235T polymorphism of the angiotensinogen (Atg) gene and the A1166C polymorphism of the angiotensin II type 1 receptor (AT1) gene. The genotype frequency distributions of M235T Atg and the A116C AT1 gene polymorphisms were not different between Group 1 versus Group 2. While the frequency of the ACE DD genotype in Group 1 (7.3%) was comparable to that of the general population, the DD frequency was significantly higher in Group 2 (26.4%) than in Group 1 (odds ratio, 4.56; 95% confidence interval, 1.80 approximately 11.56, P < 0.001). Among all 168 patients studied, the renal survival rate was significantly lower among DD than ID (P < 0.005) or II patients (P < 0.001). In patients with a declining renal function (Group 2), those with the DD genotype had a significantly shorter time interval from onset of diabetes to the initiation of dialysis (13.4 +/- 1.4 years) than those with ID (20.7 +/- 1.2 years, P < 0.01) or II genotypes (17.5 +/- 1.1 year, P < 0.01). Analysis of the clinical course of the three ACE genotypes revealed that the majority (95%) of patients with the DD genotype who had albuminuria progressed to end-stage renal disease within 10 years of diagnosis of diabetes. Our analysis also revealed that initiation and continuation of dialysis are associated with a progressive decrease in the frequency of the DD genotype. These results indicate that, in NIDDM, the ACE DD genotype has a high prognostic value for progressive deterioration of renal function. Moreover, the DD genotype appears to increase the mortality once dialysis is initiated.

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Combined antihypertensive therapy plays a crucial role in achieving targeted blood pressure reductions and renoprotection. We therefore compared the antihypertensive and antiproteinuric effects of combined therapy with either a calcium channel blocker (CCB) plus an angiotensin II receptor blocker (ARB) or an angiotensin converting enzyme inhibitor (ACE-I) plus an ARB in patients with type 2 diabetes mellitus complicated by overt nephropathy and mild to moderate hypertension. After a 12-week dietary control period, diabetic patients with mildly to moderately impaired renal function were randomly assigned to either a CCB (amlodipine 5 mg once daily) or an ACE-I (temocapril 2 mg once daily) for 12 weeks (monotherapy period). Both groups then received add-on therapy with an ARB (candesartan 4 mg once daily) for an additional 12 weeks. During the monotherapy period, blood pressure was decreased equally well in both groups. Daily urinary protein excretion remained unchanged in the CCB-treated group (control period, 4.0 +/- 1.8 g/day vs. CCB period, 4.1 +/- 1.9 g/day; ns; n = 8), but decreased in the ACE-I-treated group (control period, 4.3 +/- 1.8 g/day vs. ACE-I period, 3.5 +/- 1.7 g/day; p < 0.05; n = 9). After the combined therapy period, blood pressure was decreased to the same degree in both groups. Although ARB plus CCB significantly reduced urinary protein excretion (to 3.5 +/- 1.5 g/day; p < 0.05 vs. control period; n = 8), a more profound reduction was achieved with ARB plus ACE-I (to 2.6 +/- 1.3 g/day; p < 0.01 vs. control period; n = 9). Monotherapy with the ACE-I increased the serum potassium concentration, and this elevation was sustained after addition of the ARB. In contrast, the serum potassium concentration was not influenced by monotherapy with the CCB, but was significantly increased after addition of the ARB. A decreased hematocrit was observed in the ARB plus ACE-I group. The present study suggests that combined antihypertensive therapy with either a CCB plus an ARB or an ACE-I plus an ARB exerts an antiproteinuric effect in patients with type 2 diabetic nephropathy with mildly impaired renal function. Although the latter combination had a more profound effect, it was associated with an increased serum potassium concentration and worsening of renal anemia. Thus, the combination of a CCB and an ARB should be the first line antihypertensive therapy in those with overt diabetic nephropathy. The long-term efficacy of these combined antihypertensive therapies will need to be further addressed in a future study.

The effects of endothelin-1 (ET) on the cytosolic free Ca (Cai) and cytosolic pH (pHi) were examined in primary cultures of human umbilical artery (HUA) vascular smooth muscle cells (VSMCs), respectively, loaded with fura-2 and 2',7'-bis(carboxyethyl)-5(6)-carboxyfluorescein. In 1 mM Ca, ET produced a dose-dependent, biphasic increase in the signal with a maximal effect at 400 nM ET. At this concentration, ET produced a Cai transient (mean +/- SE; a rise from basal Cai of 86 +/- 16 to 216 +/- 33 nM) that lasted for approximately 50-60 s. The Cai transient was followed by a slow but sustained increase in Cai. Both ET-induced Cai transient and posttransient Cai were attenuated in Ca deficient medium or by verapamil and nicardipine. In contrast to ET, thrombin elicited only a monophasic Cai response in HUA VSMCs. This response was also partially sensitive to Ca removal or verapamil. KCl (45 mM) depolarization did not elicit a Cai response. However, the presence of voltage sensitive Ca channels in HUA VSMCs was demonstrated by enhanced Mn uptake in cells depolarized with KCl. Both ET and thrombin treatment did not alter pHi. HUA VSMCs demonstrated a single class of ET receptors (approximately 13,000 sites/cell) with an equilibrium dissociation constant of 0.34 nM. Nicardipine did not alter ET binding. These observations suggest a dual effect of ET on the Cai profile in HUA VSMCs that is mediated by Ca mobilization and Ca entry through Ca channels. The Ca entry could include influx through receptor-operated Ca channels, voltage-sensitive Ca channels, or both, but without a direct interaction between ET and these channels.

To explore the role of the Na-H antiport in essential hypertension, we studied the kinetics of cytosolic pH and external sodium activation of this transport system in platelets from 65 normotensive and essential hypertensive subjects on and off antlhypertensive medications. Subjects included both blacks and whites, as well as men and women. The fluorescent dye 2'7-bis(carboxyethyl)-5,6-carboxyfluorescein was used to monitor the cytosolic pH in these cells. Platelets from black (hypertensive and normotensive) men and hypertensive white men demonstrated a highly significant alkaline shift in the apparent cytosolic pH set point for activation of the Na-H antiport. For the hypertensive subgroups, the cytosolic pH set point values (mean±SEM) were: white men, 7.45 ±0.052; white women, 7.04 ±0.089; black men, 7.66±0.148; and black women, 7.20±0.082. For the normotensive subgroups, the cytosolic pH set point values were: white men, 7.13 ±0.034; white women, 7.05 ±0.036; black men, 7.50±0.110; and black women, 7.20±0.176 (p=0.0016 for race and/>=0.0001 for gender, using a three-way analysis of variance by race, gender, and hypertension). There were no race-, gender-, or blood pressure-related differences among the various cohorts in the kinetics of sodium activation of the Na-H antiport, the cellular buffering power, and basal pH. These results suggest that at basal pH the Na-H antiport is quiescent in platelets from both black and white women and normotensive white men. However, it can be active at basal pH in platelets from black men (normotensive and hypertensive) and in platelets from hypertensive white men. Our work demonstrates the heterogenous nature of the alterations in the Na-H antiport in essential hypertension and its dependence on gender and racial extraction. (Hypertension 1990;16:180-189) T he current consensus holds that alterations in the cellular regulation of cytosolic free calcium (Caj) and cytosolic sodium (Naj) participate in the pathophysiology of essential hypertension. This concept has emerged from numerous studies demonstrating that several ion transport systems are altered in this disease. Recently, the focus of a number of investigations has been on human platelets, inasmuch as these circulating cells are responsive to a variety of agonists that regulate Caj and Naj. Moreover, platelets share characteristics with vascular smooth muscle cells, which play an important role in the increased peripheral vascular resistance that occurs in essential hypertension. One

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To investigate whether angiotensin-converting enzyme inhibitor (ACE-I) potentially alleviates hyperdipsia, the effect of cilazapril on dialysis-associated excessive thirst was studied by evaluating various dipsogenic parameters in patients undergoing chronic hemodialysis (HD) who manifest an excessive interdialysis body weight gain of more than 5%, and show simultaneous severe-to-moderate hyperdipsia. An initial single dose of 1 mg of cilazapril given at the end of the HD session produced a marked improvement in the interdialysis thirst scores and a simultaneous reduction in plasma angiotensin II (All) concentration due to the inhibition of ACE activity. The interdialysis body weight gain in the cilazapril treatment period was significantly smaller than that in the nontreatment period. None of the other parameters including blood pressure, plasma osmolarity, and serum Na and K concentration were different in the treatment vs. the nontreatment period. The present data help to explain the potential pharmacological action of All in the physiology of thirst and suggest that cilazapril may effectively alleviate dialysis-associated hyperdipsia at least on some occasions. The mechanism by which ACE-I exerts an antidipsogenic action may, in part, be accounted for by the reduction in plasma concentration of All, as a result of the ACE inhibition.