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      Call for Papers: Green Renal Replacement Therapy: Caring for the Environment

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      About Blood Purification: 3.0 Impact Factor I 5.6 CiteScore I 0.83 Scimago Journal & Country Rank (SJR)

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      Aldosterone antagonism ameliorates proteinuria and nephrosclerosis independent of glomerular dynamics in L-NAME/SHR model.

      American journal of nephrology
      Animals, Hemodynamics, drug effects, Kidney Glomerulus, pathology, physiopathology, Male, Mineralocorticoid Receptor Antagonists, therapeutic use, NG-Nitroarginine Methyl Ester, pharmacology, Nephrosclerosis, drug therapy, Proteinuria, Rats, Rats, Inbred SHR, Spironolactone, analogs & derivatives

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          Abstract

          The renin-angiotensin-aldosterone system participates importantly in the progression of hypertensive renal disease. Angiotensin-converting enzyme inhibitors or angiotensin II receptor antagonists have been demonstrated to afford renoprotection in L-NAME-exacerbated nephrosclerosis in SHR rats. This study was designed to examine the effects of the aldosterone antagonist eplerenone on systemic and renal hemodynamics, glomerular dynamics, renal function and histopathology in L-NAME/SHR, and determine whether aldosterone antagonism would enhance the effectiveness of ACE inhibition. Six groups of 20-week-old SHR were studied using renal micropuncture and histopathological techniques after 3 weeks of treatment: SHR control (tapwater, n = 10); SHR + eplerenone (101 +/- 8.3 mg/kg/day, n = 10); SHR + L-NAME (5.0 +/- 0.12 mg/kg/day, n = 9); SHR + L-NAME + eplerenone (n = 8); SHR + L-NAME + lisinopril (3 mg/kg/day, n = 9), and SHR + L-NAME + eplerenone + lisinopril (n = 9). L-NAME-treated SHR developed massive proteinuria, severe hypertensive nephrosclerosis, and tubulointerstitial damage. Eplerenone significantly reduced proteinuria (127.4 +/- 26.5 vs. 51.9 +/- 16.7 mg/24 h, p < 0.01), improved glomerular and arteriolar injuries (65 +/- 9 vs. 29 +/- 9 score/100 glomeruli, p < 0.01; 116 +/- 18 vs. 41 +/- 13 score/100 arterioles, p < 0.01, respectively), and decreased tubulointerstitial damage index (1.43 +/- 0.07 vs. 0.39 +/- 0.07, p < 0.01) without altering mean arterial pressure or glomerular dynamics. Combined therapy of eplerenone with lisinopril produced no further benefits than lisinopril alone. The aldosterone antagonist eplerenone significantly ameliorated proteinuria and nephrosclerosis in the L-NAME/SHR model, independent of hemodynamic effects. Copyright 2004 S. Karger AG, Basel

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          Effects of the selective aldosterone blocker eplerenone versus the calcium antagonist amlodipine in systolic hypertension.

          Eplerenone is a highly selective aldosterone blocker, which is under development for the treatment of hypertension and heart failure. To assess its usefulness in older patients with systolic hypertension and widened pulse pressure, we compared the effects of eplerenone with amlodipine, on clinic blood pressure (BP) and pulse pressure and in a subset of the patients, ambulatory BP, vascular compliance, and urinary albumin excretion. The study involved 269 patients > or =50 years of age who were randomly assigned to either eplerenone (50 to 200 mg daily) or amlodipine (2.5 to 10 mg daily) in a double-blind titration to effect design. After 24 weeks of therapy, reductions in clinic systolic BP were similar for both treatments (eplerenone, -20.5+/-1.1 mm Hg; amlodipine, -20.1+/-1.1 mm Hg). Reductions in clinic diastolic BP were modestly larger on amlodipine (-6.9+/-0.7 mm Hg) compared with eplerenone (-4.5+/-0.7 mm Hg) (P=0.014). Pulse pressure was also reduced similarly from baseline by the 2 treatment groups (eplerenone, -15.9 mm Hg versus amlodipine, -13.4 mm Hg, P=0.07). Changes from baseline in pulse wave velocity after 24 weeks of therapy were statistically similar for eplerenone and amlodipine. In patients with microalbuminuria at baseline (>30 mg albumin/g creatinine), eplerenone reduced the urinary albumin/creatinine ratio by 52% compared with a reduction of 10% by amlodipine (P=0.04). Thus, eplerenone was as effective as amlodipine in lowering systolic BP and pulse pressure as well as pulse wave velocity in older patients with widened pulse pressure hypertension. Furthermore, eplerenone reduced microalbuminuria to a greater extent than amlodipine in this older patient group.
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            Effectiveness of Aldosterone Blockade in Patients With Diabetic Nephropathy

            It has been reported that continuous ACE inhibitor therapy does not necessarily produce a maintained decrease in plasma aldosterone levels, which may remain high or increase eventually during long-term use (aldosterone escape). We have examined the role of aldosterone escape in 45 patients with type 2 diabetes and early nephropathy treated with an ACE inhibitor for 40 weeks. With treatment, there was a 40% reduction in average urinary albumin excretion, although urinary albumin excretion in patients with aldosterone escape (18 patients) was significantly higher than that in patients without escape (27 patients). In the 18 patients with escape, spironolactone (25 mg/d) was added to ACE inhibitor treatment in 13. After a 24-week study period, urinary albumin excretion and left ventricular mass index were significantly reduced without blood pressure change. In conclusion, the present study demonstrates that aldosterone escape is observed in 40% of patients with type 2 diabetes with early nephropathy despite the use of ACE inhibitors. Our study suggests the possibility that aldosterone blockade may represent optimal therapy for patients with early diabetic nephropathy who show aldosterone escape during ACE inhibitor treatment and who no longer show maximal antiproteinuric effects of ACE inhibition. Additional, larger, prospectively randomized, double-blind studies will be needed before adaptation of this strategy.
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              Regulation of aldosterone secretion.

              Regulation of aldosterone secretion is complex both in terms of the number of secretagogues that can influence its biosynthesis and the number of second messengers utilized by these secretagogues (Table 1, Figure 1). ACTH primarily acts via the adenylate cyclase system through a stimulatory G protein; however, there is evidence that at low concentration it may also activate calcium influx and phospholipase C in some species. The primary effect of AII is activation of phospholipase C, which increases both calcium release from intracellular stores and calcium flux across the cell membrane and activates protein kinase C. Potassium depolarizes the membrane, thereby activating calcium flow through voltage-dependent calcium channels. It also directly or indirectly causes release of calcium from intracellular binding sites. A small change in cAMP levels may also be involved in the sustained secretory response to potassium. Species variation in the regulation of aldosterone secretion probably exists; the control mechanisms in the human appear to be closer to those in the rat than to those in cow and sheep. How changes in dietary sodium and potassium modify aldosterone secretion and the adrenal's responsiveness to secretagogues remains unclear. Yet these effects may be of considerable importance, both in terms of understanding the overall regulation of aldosterone secretion and in resolving the discrepancies in the results obtained under different experimental conditions.
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