Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

To examine and characterize the vascular renin--angiotensin system in low-renin models of renal hypertension with and without the presence of overt renal insufficiency, we studied the formation and metabolism of angiotensin in isolated perfused rat hindquarter preparations. Rats with 5/6 nephrectomy (5/6NX) and rats with one-kidney, one clip (1K1C) hypertension were compared to sham operated (sham) animals. Angiotensin peptides in plasma or perfusate were characterized by high-performance liquid chromatography and radioimmunoassay (RIA). Plasma angiotensin II was lower, and blood pressure was higher in both experimental groups, compared to sham animals. Plasma angiotensinogen, measured by both direct and indirect RIA, was increased in both experimental groups. The spontaneous release of angiotensin I and angiotensin II from perfused hindquarters did not differ between the groups. Angiotensin I conversion was not different in 5/6NX or 1K1C groups compared with controls. Furthermore, angiotensin conversion was completely inhibited by captopril (1 mumol/l) in all groups. Renin-induced angiotensin release was significantly increased in 5/6NX as compared with sham rats, whereas there was no difference in renin-induced angiotensin release between 1K1C and sham animals. Angiotensin II degradation was significantly attenuated in 5/6NX rats when compared with sham rats (27.6% versus 53.9%, respectively, P less than 0.05) but was unaltered in 1K1C rats. Thus, in chronic uremic hypertension, renin-induced angiotensin formation was increased in the face of decreased angiotensin II degradation. These data suggest that vascular angiotensin may contribute to the elevated blood pressure observed in chronic renal failure. In 1K1C rats, vascular angiotensin formation and metabolism was unchanged despite suppressed plasma angiotensin II.
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PMID:Local angiotensin formation in hindlimbs of uremic hypertensive and renovascular hypertensive rats. 184 58

Renin-angiotensin-aldosterone++ system was investigated in 60 patients suffering from rheumatoid arthritis. Forty-four of them (group 1) had arterial hypertension (144 +/- 4/94 +/- 2 mm Hg), sixteen were free of hypertension (120 +/- 3/80 +/- 1 mm Hg). Twenty-nine control subjects comparable by AH standing and demographic parameters had essential hypertension stage IB-IIA by A. L. Myasnikov classification (141 +/- 3/89 +/- 1 mm Hg). A tendency to renin suppression was dominating in 72% of group 1 patients (plasma renin activity less than 1.0 ng/ml/h). In this group there appeared high concentrations of A II (14.2 +/- 3.1 pg/ml) and plasma aldosterone++ (238 +/- 94 ng/ml). Rheumatoid vasculitis manifested in 86% of patients. Control subjects exhibited plasma renin activity greater than 3.0 ng/ml/hin 48%, average A II concentration was similar to that of group 1 (12.4 +/- 2.7 ng/ml/h, p greater than 0.05), plasma aldosterone++ level was significantly lower (176 +/- 29 ng/ml, p less than 0.05). Correlations were established between A II concentration and ESR (r = 0.39, p less than 0.05), A II and rheumatoid factor titers (r = 0.40, p less than 0.05). These indicate that immunopathological reactions are responsible for shifts in renin-angiotensin-aldosteron system in hypertensive rheumatoid arthritis subjects.
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PMID:[The renin-angiotensin-aldosterone system and arterial hypertension in patients with rheumatoid arthritis]. 187 68

Renin-secreting tumors are a rare cause of severe hypertension accompanied by hypokalemia. Typically, these tumors have been difficult to diagnose preoperatively by standard radiographic and hormonal studies. We describe a 44-year-old man who was hospitalized for paroxysmal hypertension and who had a 2.3 cm. mid upper pole renal mass on sonography. Computerized tomography-directed needle biopsy revealed a juxtaglomerular tumor and surgical excision of the tumor was curative. We discuss the unique diagnostic aspects of this case.
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PMID:Renin-secreting juxtaglomerular tumor causing severe hypertension: diagnosis by computerized tomography-directed needle biopsy. 194 53

The renin-angiotensin system (RAS) is an important modulator of blood pressure and fluid balance. The clinical success of angiotensin converting enzyme inhibitors (ACEIs) in the treatment of hypertension has stimulated the search for antagonists of renin. Because renin is highly specific for its substrate, angiotensinogen, renin inhibitors may emerge as clinically preferable alternatives to ACEIs, which affect multiple biological systems, including bradykinin and prostaglandin metabolism. Recent advances in renin inhibitor chemistry have produced highly specific and potent, transition-state analogs of angiotensinogen. Several compounds (e.g., enalkiren, ditekiren, CGP 38560A, and RO 42-5892) have been tested in man. These renin inhibitors produce dose-dependent decreases in plasma renin activity (PRA) which are dissociated from the dose-dependent decreases in blood pressure (BP). Potential explanations for this dissociation include methodologic errors in PRA assays and alternate sites or mechanisms of drug action, including inhibition of noncirculating tissue renin. A prolonged hypotensive effect is seen following single doses of enalkiren and RO 42-5892, and repeated dosing with enalkiren results in sustained hypotensive effect without tachyphylaxis. Renin inhibitors can reduce blood pressure irrespective of baseline renin status and sodium balance. However, high-renin patients generally respond more vigorously, and the hypotensive response is enhanced by sodium depletion. In general, renin inhibitors have been safe and well tolerated in limited clinical studies. New generation renin inhibitors with higher potency and greater oral bioavailability may join the antihypertensive armamentarium.
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PMID:Renin inhibitors in hypertension. 195 44

A prospective study was conducted to compare the frequency of renin gene polymorphisms in normotensive and hypertensive subjects. Hypertensive (n = 102, blood pressure 168 +/- 17/103 +/- 9 mm Hg) and normotensive (n = 120, blood pressure 122 +/- 10/75 +/- 9 mm Hg) subjects were white, had similar age and sex distributions (hypertensive group, 45 +/- 10 years old and 52% female; normotensive group, 44 +/- 9 years old and 55% female) and similar body mass index (hypertensive group, 23.2 +/- 2.6; normotensive group, 22.5 +/- 2.4 kg/m2, p = 0.048). The familial susceptibility to hypertension was defined as at least one parent and one sibling who were hypertensive before age 65; subjects in the normotensive group had no familial history of hypertension. Renin gene polymorphisms located throughout the renin gene were identified by using three restriction enzymes (Taq I, HinfI, HindIII). For each polymorphic restriction site, allele frequencies were similar in the hypertensive and the normotensive groups. In the absence of parental genotypes, the haplotype frequencies combining the three restriction fragment length polymorphisms were estimated by using maximum likelihood techniques and were similar in both groups (hypertensive group, 0.429, 0.277, and 0.177; normotensive group, 0.453, 0.245, and 0.195 for the three most common haplotypes). A rare haplotype detected by Taq I/Hind III was apparently more frequent in the hypertensive than in the normotensive group (hypertensive group, tH 0.086, th 0.022; normotensive group, tH 0.038, th 0.050), but the difference was not statistically significant. In conclusion, no association between renin gene polymorphisms and essential hypertension was demonstrated in the present study.
Hypertension 1990 Dec
PMID:Similar frequencies of renin gene restriction fragment length polymorphisms in hypertensive and normotensive subjects. 197 31

Clinical research has defined the criteria for identifying "curable" renovascular hypertension. The prediction is based on the measurement of plasma renin activity in peripheral veins, renal veins, and the aorta. Renin profiles can be examined with the method of Laragh and coworkers (the so-called incremental method), in which values for plasma renin activity are incorporated into formulas to compute indexed parameters. A score is attributed to each index and the prediction is based on the final score. Because the identification of curable renovascular hypertension is made according to numerical rules, the method is easily transformed into a computer-assisted process. The program is written in BASIC, and it is short enough to run on a personal computer.
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PMID:Preoperative selection for curable renovascular hypertension. 201 Oct 54

Recent advances in molecular biological techniques provide us with genetic approaches for studying the renin-angiotensin system. Renin and angiotensinogen cDNAs have been cloned in several species, and the sequences are highly conserved between the species. The 5'-flanking region of the human renin gene indicated putative regulatory sequences of glucocorticoid, estrogen, progesterone, and cAMP. The 5'-flanking region of the human angiotensinogen gene also had putative regulatory sequences of glucocorticoid, estrogen, acute phase protein, and cAMP. These structures may be related to the tissue specific expression of the renin and angiotensinogen genes. In this review, expression of rat renin and angiotensinogen genes in various tissues in the following conditions are described: a) different sodium intake in the liver, kidney, and brain; b) angiotensin II and converting enzyme inhibition in the liver, kidney and brain; c) renovascular hypertension in the kidney and liver; d) aging in the liver and kidney; e) adrenal steroids in the liver, kidney and brain; f) gonadotropin and testosterone in the testes, liver and kidney; g) triiodothyronine in the liver, kidney and brain; h) nephrectomy in the liver and brain; i) high potassium, angiotensin II, sodium intake and nephrectomy in the adrenal gland; j) transgenic animal. Our results suggest that the expression of the renin and angiotensinogen genes are regulated in a tissue-specific manner.
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PMID:[Expression of the renin and angiotensinogen genes]. 204 11

1. A 17 year old female presented with severe hypertension, hypokalaemia and elevated levels of plasma renin activity due to a renin-secreting tumour. 2. Renin was responsive to posture, low sodium diet, saline infusion and frusemide, but relatively unresponsive to raising or lowering circulating levels of angiotensin II. 3. Renal venous renin levels lateralized to the side of the tumour with good contralateral suppression when measured with control of posture and avoidance of prior stimulation, with and without angiotensin converting enzyme inhibition. 4. Levels of atrial natriuretic peptide were elevated and responsive to posture, saline infusion and angiotensin infusion. 5. The tumour was evident on computerized tomography, but not on intravenous pyelography or renal angiography. 6. Responsiveness of renin secretion to normal stimuli in reninoma may make diagnosis difficult, and renal vein sampling under controlled conditions is necessary.
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PMID:A renin-secreting tumour sensitive to changes in central blood volume (presumably via sympathetics) but not to circulating angiotensin II. 216 Mar 42

Spontaneously hypertensive Okamoto-strain rats (SHR) and normotensive Wistar-Kyoto (WKY) rats were actively immunized with mouse renin to investigate the effect on blood pressure of blocking the renin-angiotensinogen reaction. Ten male SHR and 10 male WKY rats were immunized with purified mouse submandibular gland renin. Control rats were immunized with bovine serum albumin. Antirenin antibodies were produced by both SHR and WKY rats, but renin-immunized SHR had higher titers of circulating renin antibodies after three injections. The increase in renin antibody in renin-immunized SHR was associated with a significant drop in blood pressure (tail-cuff method) that became similar to that of the WKY control rats after four injections. The blockade by antirenin immunoglobulins of the renin-angiotensinogen reaction also decreased the blood pressure of normotensive rats. Perfusion of renin-immunized rats with mouse submandibular renin (10 micrograms) in vivo caused no increase in blood pressure. Perfusion of renin-immunized, salt-depleted SHR with converting enzyme inhibitor caused no further decrease in blood pressure but significantly decreased blood pressure in salt-depleted control rats. The presence of circulating renin antibodies was associated with low plasma renin activity (0.31 +/- 0.23 ng angiotensin I [Ang I]/ml/hr). Plasma renin activity was unchanged in control animals (13.1 +/- 3.9 ng Ang I/ml/hr in control SHR, 13.9 +/- 3.2 ng Ang I/ml/hr in control WKY rats). Renin antibody-rich serum produced a dose-dependent inhibition of rat renin enzymatic activity in vitro. The chronic blockade of the renin-angiotensinogen reaction in renin-immunized SHR produced an almost-complete disappearance of Ang II (0.8 %/- 7 fmol/ml; control SHR, 30.6 +/- 15.7 fmol/ml) and a 50% reduction in urinary aldosterone. Renin immunization was never associated with a detectable loss of sodium after either 10 or 24 weeks. The glomerular filtration rate was not decreased 10 weeks after renin immunization, whereas blood pressure was significantly decreased, plasma renin activity was blocked, and renal plasma flow was increased. The ratio of left ventricular weight to body weight after 24 weeks was significantly below control levels in renin-immunized WKY rats and SHR. Histological examination of the kidney of renin-immunized SHR showed a chronic autoimmune interstitial nephritis characterized by the presence of immunoglobulins, mononuclear cell infiltration, and fibrosis around the juxtaglomerular apparatus. These experiments demonstrate that chronic specific blockade of renin decreases blood pressure in a genetic model of hypertension in which the renin-angiotensin system is not directly involved.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:Physiological and immunopathological consequences of active immunization of spontaneously hypertensive and normotensive rats against murine renin. 218 56

Diuretic therapy may enhance renin release by various mechanisms, principally contraction of extracellular fluid volume and its effects, including a fall in arterial pressure. Awake hydropenic or volume-expanded rats received diuretics (amiloride and hydrochlorothiazide) that are known inhibitors of NaCl transport beyond the macula densa; also the well-known Na(+)-K(+)-2 Cl- transport system inhibitor furosemide was administered. We also evaluated the effect of a dose of ethacrynic acid (a drug that shares the same mechanism of action as furosemide but is not diuretic in the rat). The direct action of the diuretics on renin-producing cells was examined in isolated glomeruli; a rise in renin release was observed with the calmodulin inhibitor trifluoperazine (10(-5) M). Renin release in intact hydropenic rats was not altered by diuretic therapy, but furosemide increased plasma renin activity in hydropenic as well as in volume-expanded rats. This demonstrates the importance of furosemide inhibition of transport in the macula densa for its renin secretory action. None of the diuretics (amiloride, hydrochlorothiazide, ethacrynic acid, or furosemide) elicited changes in renin release from glomeruli (10(-6) to 10(-3) M); amiloride and hydrochlorothiazide (10(-4) to 10(-3) M) did not change renin release from slices, but 10(-3) M ethacrynic acid and furosemide increased renin secretion in this preparation. This suggests that an effect on the macula densa is essential in loop diuretic-mediated renin release.(ABSTRACT TRUNCATED AT 250 WORDS)
Hypertension 1990 Sep
PMID:Role of macula densa in diuretics-induced renin release. 220 82


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