Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.4.23.15 (renin)
 35,795 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Endothelin is an important modulator of renal function via its binding to abundant receptors in renal tissue and by the ability of renal endothelial and epithelial cells to synthesize and release endothelin. In the kidney, endothelin may function as a paracrine-autocrine factor in the regulation of renal blood flow, glomerular hemodynamics, and sodium and water homeostasis. Recent evidence suggests that circulating endothelin may play an important role in renal regulation in cardiorenal states of endothelin activation. Endothelin is a potent renal vasconstrictor that has dual actions on glomerular filtration rate due to its ability to preferentially constrict efferent arterioles preserving glomerular filtration. Furthermore, endothelin modulates sodium excretion and water balance at the level of the proximal tubule and medullary collecting ducts, respectively, by mechanisms that are still unclear. In addition, endothelin stimulates the renin-angiotensin-aldosterone system and atrial natriuretic peptide release and inhibits arginine vasopressin-mediated water reabsorption in the inner medullary collecting duct. Recent studies using specific receptor antagonists have demonstrated a pathophysiologic role for endothelin during renal ischemia, cyclosporine-induced toxicity, and chronic renal failure. This review highlights recent research that supports an important role for endothelin as a locally produced vasoactive and natriuretic peptide in the regulation of renal hemodynamic and excretory functions.
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PMID:Physiologic and pathophysiologic roles of endothelin in the kidney. 785 Apr 14

The effect of chronic hypobaric hypoxia (CHH) on the development of 2k-2c Goldblatt renovascular hypertension has been analyzed in rats of both sexes. Results have shown lower values of blood pressure (BP) in all the animals exposed to CHH compared with their normoxic control (P < 0.001). Haematocrit was increased by adaptation to CHH (P < 0.001), and was larger in male than in female hypoxic rats, both normotensive (P < 0.05) and hypertensive (P < 0.01). Plasma renin activity was higher in normoxic and hypoxic hypertensive female rats than in their normotensive controls (P < 0.05). Plasma angiotensinogen concentration was higher in normoxic control male rats than in all the other groups. This difference disappeared after adaptation to CHH or development of hypertension. Plasma aldosterone concentration was lowest in normoxic control male rats and the difference also disappeared after CHH or renal ischemia. Present data indicate that CHH blunts the hypertensive response to bilateral renal ischemia in male and female rats. Sexual differences related to the mechanisms that could be involved in hypertension development have been observed. The renin-angiotensin-aldosterone system might be modulated by gonadal hormones during the development of hypertension.
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PMID:Changes in the renin-angiotensin-aldosterone system in 2 kidney -2 clip Goldblatt hypertensive rats of both sexes submitted to chronic hypobaric hypoxia. 800 44

The experimental discovery of the pathophysiological relationship between renal artery stenosis and arterial hypertension was historically reported (1934) before the clinical description of the disease in human patients (1950). The experimental model explains the relation between renal ischemia, renal endocrine activation, and morphological alterations of the homo and contralateral kidneys. In particular, the experimental model improves the understanding of the evolution of renovascular disease. In human patients, renal artery stenosis does not always lead to clinical disease. Because of the frequency of arterial hypertension, there is not always a clear relationship between hypertension and renal insufficiency or renal artery stenosis. Therefore a complete diagnosis of renal endocrine and exocrine function is needed to understand this relation before deciding on the therapeutic approach. This diagnosis is made by exploration of the renal renin-angiotensin axis, its pharmacological blockade and the response of the excretory function. This approach corresponds to the clinical description of the evolution of the disease; the peripheral and renal vein renin assays; the pressure and scintigraphic response to converting enzyme inhibition and renal morphological definition by echography and CT scan. This pathological approach permits a rational choice of the therapeutic indication: non-intervention, specific medical treatment, endovascular or surgical revascularization or nephrectomy.
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PMID:[Is in depth diagnosis important in renal artery stenosis?]. 815 92

We report a case of hyponatremia, polyuria-polydipsia, hypokalemia, nephrotic syndrome, and hypertension caused by unilateral renal ischemia, and the resolution after nephrectomy of the ischemic kidney. The renin-angiotensin-aldosterone axis seems to play an essential role in the pathogenesis of these features. Mechanisms by which angiotensin II, hypokalemia, and proteinuria can affect salt and water balances, and the role of angiotensin II as a cause of heavy proteinuria are discussed. Renovascular hypertension should be considered in the differential diagnosis of hyponatremia, hypokalemia, and polyuria-polydipsia.
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PMID:Multiple manifestations of renovascular hypertension. 820 70

Typical causes of renovascular hypertension include intramural atherosclerotic lesions of the main renal arteries or their branches and fibromuscular dysplasia of the renal arterial wall with luminal narrowing. We report a patient with new-onset, accelerated hypertension (blood pressure 220/140 mm Hg, status epilepticus, retinal hemorrhages) secondary to a dissection of the anterior division of the right renal artery that was accompanied by hyperreninemia, hyperaldosteronism, and hypokalemia. At presentation in the untreated state, unstimulated plasma renin activity and the serum aldosterone level were markedly elevated. Following right nephrectomy, blood pressure levels normalized without antihypertensive therapy, and plasma renin activity, serum aldosterone and potassium levels normalized. Histologic study of the right renal artery showed an isolated dissection of the anterior branch of the vessel between the muscularis and adventitia that created marked reduction in luminal diameter and renal ischemia. There was no evidence of any other vascular abnormalities, atherosclerosis, or fibromuscular dysplasia. These findings demonstrate that an isolated dissection of a branch of the renal artery may induce profound hyperreninemia and represents a rare, reversible etiology for accelerated hypertension associated with acute encephalopathy.
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PMID:Accelerated hypertension with encephalopathy due to an isolated dissection of a renal artery branch vessel. 820 71

Some reports have stated that central norepinephrine (NE) depletion inhibited the development of hypertension in the rat. On the other hand, this pharmacological treatment induces changes on the central renin-angiotensin system. The present study was designed to follow the development of 2 kidney-2 clip (2k-2c) renovascular hypertension in rats depleted of central NE and to analyze the central and peripheral renin-angiotensin system. Male Wistar rats (n = 40) were used. Half of the animals was injected, intracisternally, with 6-hydroxydopamine (6-OHDA), the remaining rats only received the vehicle. One week later a silver clip was placed on each renal artery on half of the 6-OHDA treated rats and on half of the vehicle treated animals. A sham operation was performed on the remaining rats. Blood pressure was measured weekly during 7 weeks. Then, blood and cerebrospinal fluid (CSF) samples were obtained. The brain was dissected in several areas. NE and angiotensinogen concentration (AoC) were determined in tissue samples. AoC was evaluated in plasma and CSF; plasma renin activity was also measured. Hypertension development was not prevented by central NE depletion, which was significant in all central areas (p < 0.001). Other significant results showed that renal ischemia and/or NE depletion induced a significant increase in angiotensinogen concentration in the hypothalamus (p < 0.01) and in CSF (p < 0.05). In summary: central NE depletion was not able to modify the development of 2 k - 2 c hypertension. Treatment and renal ischemia induced an increase of central AoC.
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PMID:Effect of central norepinephrine depletion on renovascular hypertension and on the renin system. 837 8

The purpose of this study was to elucidate the role of endogenous angiotensin II in mediating the renovascular effects of renal adrenergic stimulation. Six conscious dogs instrumented for monitoring of renal blood flow were subjected to step increases every 10 minutes in the rate of norepinephrine infusion into the renal artery. Under control conditions, infusion of norepinephrine (10-40 ng/min per milliliter per minute of control renal blood flow) increased plasma renin activity and decreased renal blood flow progressively by approximately 10-75%. When increments in angiotensin II during norepinephrine infusion were abolished by fixing plasma levels of angiotensin II at either normal or high concentrations by chronic infusion of captopril plus angiotensin II, renal blood flow responses to adrenergic stimulation were greatly attenuated at rates of norepinephrine infusion that decreased renal blood flow up to approximately 40% under control conditions. Thus, acutely generated angiotensin II appeared to contribute to the renovascular effects of norepinephrine. However, when endogenous levels of angiotensin II were suppressed to low levels by chronic infusion of captopril alone, norepinephrine induced severe renal ischemia at much lower rates of infusion than occurred when the renin-angiotensin system was intact. Since this enhanced sensitivity to norepinephrine did not occur during chronic captopril infusion when angiotensin II was given simultaneously at rates that restored mean arterial pressure to normotensive levels or higher, low arterial pressure during chronic captopril administration may predispose the kidneys to excessive renal vasoconstriction during renal adrenergic stimulation.
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PMID:Influence of endogenous angiotensin on the renovascular response to norepinephrine. 849 4

In an effort to further evaluate the potential application of laparoscopy to urologic surgery, we explored the feasibility of using this minimally invasive approach for performing a partial nephrectomy. Nine female pigs underwent laparoscopic partial nephrectomy (LPN) utilizing a plastic cable tie (15 mm. x 4 mm. x 1 mm.) to achieve renal ischemia and an Argon Beam Coagulator probe (ABC) (Birtcher Medical Systems) to fulgurate the transected surface. Six weeks after LPN, 6 pigs underwent creatinine clearance, renin level, arteriography, BP samples and were then killed. The renal remnants were weighed and sectioned for histological studies. These studies revealed excellent function of the renal remnant, no AV fistula, and no evidence of renovascular hypertension. LPN is a feasible, repeatable procedure in the pig. Control of the renal hilum, transient parenchymal compression with a plastic cable, and use of the argon beam coagulator are key elements in performing this procedure.
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PMID:Laparoscopic partial nephrectomy in the pig model. 1143 70

Chronic activation of the circulating renin-angiotensin-aldosterone system (RAAS), as can occur with unilateral renal ischemia (URI), is associated with an adverse structural remodeling of the right and left ventricles characterized by reparative (i.e., microscopic scars) and reactive (i.e., perivascular/interstitial) fibrosis. The time course and cells involved in fibroplastic and fibrogenic phases of these events are unclear. Hearts were examined over the course of 8 weeks in rats infused with either angiotensin II or aldosterone, and compared to rats with URI. Tissue sections from the same heart were stained with hematoxylin and eosin, collagen specific picrosirius red, or immunolabeled with PCNA or alpha smooth muscle actin antibody. With angiotensin II or renal ischemia, fibroblast proliferation, presenting as focal accumulations at both sites of myocyte necrosis and widespread perivascular locations, was present in each ventricle on days 2 and 4, but not thereafter, alpha-Smooth muscle actin containing cells (myofibroblasts) appeared at day 2 and persisted through week 2 with renal ischemia and week 6 with angiotensin II. Macrophages, neutrophils and lymphocytes were transiently found at sites of necrosis between day 2-4 of renal ischemia. AngII-induced necrotic sites were characterized by macrophages and lymphocytes from day 2 through week 6, and neutrophils at day 2-4. Increased collagen volume fraction, presenting as immature scars associated with fibroblast clusters and interstitial/perivascular fibrosis, was evident on day 14 in both ventricles. In contrast, fibroblast proliferation during aldosterone infusion did not appear in both ventricles until week 3 and was associated with a subsequent reparative and reactive fibrosis as early as 4 weeks. Myofibroblasts became evident between 3-6 weeks; macrophages and lymphocytes were seen between 3-8 weeks. Neutrophils were not seen at any time point with aldosterone. Thus, the temporal cellular response and appearance of myocardial fibrosis associated with chronic elevations in angiotensin II and/or aldosterone differ. We conclude that separate pathogenic mechanisms are operative with these effector hormones of the RAAS.
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PMID:Temporal differences in fibroblast proliferation and phenotype expression in response to chronic administration of angiotensin II or aldosterone. 852 18

A case of thrombotic microangiopathy presenting as a hemolytic uremic syndrome complicated by untreatable hypertension and ultimately requiring bilateral nephrectomy is discussed. Severe hypertension and renal failure may complicate the course of vascular diseases of the kidney, including thrombotic microangiopathy, chronic hypertension, and scleroderma. Toxins, pressure stress, and immune material may trigger the initial injury to vascular endothelium. The malignant course of these renal vascular diseases seems linked to the severity of vascular injury. Endothelial injury manifests with swelling and detachment of endothelial cells from the basement membrane, expansion of the subendothelial space, and newly formed basement membrane-like material. In arterioles, endothelial injury precedes myointimal swelling and proliferation, leading to vascular lumina narrowing or obliteration and secondary glomerular ischemia, with glomerular tuft collapse and garland-like wrinkling and thickening of the capillary wall. Endothelial cell injury is very likely the common determinant of a cascade of events that lead to irreversible renal failure. When the initial insult (toxins, mechanical stress, antibodies) is promptly removed, lesions are self-limiting and the patient usually recovers. However, a severe insult persisting for some time can lead to chronic and irreversible vascular lesions that, through renal ischemia, trigger maximal activation of the renin angiotensin system with a brisk elevation in arterial blood pressure that may combine to further vascular injury and renal ischemia. Moreover, enhanced shear stress in the severely narrowed microcirculation, through abnormal von Willebrand factor processing, can also favor endothelial injury and platelet aggregation, which may further worsen the vascular lesions and sustain the microangiopathic process. Plasma manipulation, arteriolar vasodilators, and angiotensin-converting enzyme inhibitors normally control the vicious circle, but in few severe cases bilateral nephrectomy remains the last chance to save the patient's life.
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PMID:Malignant vascular disease of the kidney: nature of the lesions, mediators of disease progression, and the case for bilateral nephrectomy. 867 55


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