Losartan increases NO release in afferent arterioles during regression of l-NAME-induced renal damage

Effect of Calcitriol on the Renal Microvasculature Differentiation Disturbances Induced by AT1 Blockade During Nephrogenesis in Rats

Alterations in the renal vasculature during fetal programming can cause disturbances in renal structure and function that persist into adulthood. Calcitriol can affect cellular differentiation and proliferation, and promote endothelial cell maintenance, each of which is a key event in nephrogenesis. Calcitriol is a negative endocrine regulator of the renin gene. Rats exposed to renin-angiotensin system (RAS) antagonists during lactation have been shown to develop renal disorders, which demonstrated that the RAS may play an important role in mammalian kidney development. We evaluated the effects of calcitriol administration on losartan [angiotensin II receptor antagonist (ANGII), AT₁]-induced changes in renal differentiation in rats during lactation. Rats treated with losartan showed alterations in renal function and structure that persisted into adulthood. These disruptions included hydronephrosis, papillary atrophy, endothelial dysfunction, and aberrant endothelial structure. These changes were mitigated by treatment with calcitriol. The results of our study showed that animals exposed to AT₁ blockade during lactation exhibited altered renal microvasculature differentiation in adulthood that was attenuated by treatment with calcitriol.

Extracorporeal shock wave therapy does not improve hypertensive nephropathy

Low-energy extracorporeal shock wave therapy (SWT) has been shown to improve myocardial dysfunction, hind limb ischemia, erectile function, and to facilitate cell therapy and healing process. These therapeutic effects were mainly due to promoting angiogenesis. Since chronic kidney diseases are characterized by renal fibrosis and capillaries rarefaction, they may benefit from a proangiogenic treatment. The objective of our study was to determine whether SWT could ameliorate renal repair and favor angiogenesis in L-NAME-induced hypertensive nephropathy in rats. SWT was started when proteinuria exceeded 1 g/mmol of creatinine and 1 week after L-NAME removal. SWT consisted of implying 0.09 mJ/mm(2) (400 shots), 3 times per week. After 4 weeks of SWT, blood pressure, renal function and urinary protein excretion did not differ between treated (LN + SWT) and untreated rats (LN). Histological lesions including glomerulosclerosis and arteriolosclerosis scores, tubular dilatation and interstitial fibrosis were similar in both groups. In addition, peritubular capillaries and eNOS, VEGF, VEGF-R, SDF-1 gene expressions did not increase in SWT-treated compared to untreated animals. No procedural complications or adverse effects were observed in control (C + SWT) and hypertensive rats (LN + SWT). These results suggest that extracorporeal kidney shock wave therapy does not induce angiogenesis and does not improve renal function and structure, at least in the model of hypertensive nephropathy although the treatment is well tolerated.

Renin inhibition reverses renal disease in transgenic mice by shifting the balance between profibrotic and antifibrotic agents

Aliskiren, a direct renin inhibitor, is a novel antihypertensive drug. To study whether aliskiren can reverse chronic kidney disease, we administered it to renin transgenic mice, a strain characterized by elevated blood pressure and a slow decline of renal function, mimicking well the progression of hypertensive chronic kidney disease. Ten-month-old transgenic mice were treated either with aliskiren or placebo for 28 days. Age-matched wild-type mice treated or not with aliskiren were considered as normotensive controls. Aliskiren reduced blood pressure to wild-type levels from as early as day 14. Proteinuria and cardiac hypertrophy and fibrosis were also normalized. Renal interstitial fibrosis and inflammation were significantly ameliorated in aliskiren-treated mice (shown by the decrease of proinflammatory and profibrotic markers), and the phenotypes of tubular epithelial cells and podocytes were restored as evidenced by the reappearance of cellular proteins characteristic of normal phenotype of these cells. Profibrotic p38 and Erk mitogen-activated protein kinases were highly activated in placebo-treated transgenic animals. Aliskiren treatment cancelled this activation. This nephroprotection was not attributed to the antihypertensive activity of aliskiren, because blood pressure normalization after treatment with hydralazine failed to induce the regression of renal fibrosis. Direct inhibition of renin can restore renal function and structure in aged hypertensive animals with existing proteinuria. This finding suggests that, in addition to antihypertensive action, aliskiren can be also used to treat chronic kidney disease.