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)

Neonatal treatment with angiotensin-converting enzyme (ACE) inhibitors or the angiotensin II type-1 receptor antagonist losartan in rats induces irreversible renal histological abnormalities, mainly papillary atrophy, in association with an impairment in urinary concentrating ability. The aim of the present study was to assess proximal tubular function in adult rats treated neonatally with enalapril. Male Wistar rats received daily, intraperitoneal injections of either enalapril (10 mg kg-1) or isotonic saline vehicle from 3 to 24 days of age. In 15-week-old, hydropenic rats we analysed: (i) proximal tubular iso-osmotic fluid reabsorption using the method of lithium clearance; and (ii) maximal tubular D-glucose reabsorption (TmG), under pentobarbital anaesthesia. The main findings were that neonatally enalapril-treated rats showed: (i) reductions in absolute (APRH2O) and fractional (FPRH2O) iso-osmotic fluid reabsorption in the proximal tubules (APRH2O: 0.50 +/- 0.02 vs. 0.64 +/- 0.03 mL min-1 g KW-1, P < 0.05; FPRH2O: 58 +/- 3 vs. 68 +/- 2%, P < 0.05); and (ii) a normal TmG. In addition, during baseline clearance measurements neonatally enalapril-treated rats showed increases in urine volume and fractional excretion rates of sodium and potassium, a reduction in urine osmolality, whereas glomerular filtration rate and effective renal plasma flow were unaltered. These results suggest that neonatal ACE inhibition produces an irreversible, but differentiated, abnormality in proximal tubular function. Thus, the development of a normal proximal tubular function in the rat seems to be dependent on an intact renin-angiotensin system, (RAS) neonatally.
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PMID:Proximal tubular function in adult rats treated neonatally with enalapril. 977 30

Angiotensin II receptors are essential components of the renin-angiotensin system transducing angiotensin II mediated signals across the plasma membrane of many cell types in the cardiovascular system. To date, three subtypes of angiotensin II receptors have been identified by molecular cloning, termed angiotensin II type 1 (AT1A, AT1B) and type 2 (AT2) receptors. This review focuses on recent transgenic animal models which have been generated to study the in vivo significance of angiotensin receptor diversity. AT1A receptors are the major blood pressure regulators and have a potent growth-stimulatory effect on cardiac myocytes in vivo. The AT1B receptor subtype may participate in the control of vascular tone if AT1A receptors are absent. AT2 receptors are abundantly expressed during embryonic development and may also play a role in blood pressure regulation by influencing vascular development and differentiation.
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PMID:Genetic deletion and overexpression of angiotensin II receptors. 982 20

The classically recognized functions of the renin-angiotensin system are mediated by type 1 (AT1) angiotensin receptors. Whereas man possesses a single AT1 receptor, there are two AT1 receptor isoforms in rodents (AT1A and AT1B) that are products of separate genes (Agtr1a and Agtr1b). We have generated mice lacking AT1B (Agtr1b -/-) and both AT1A and AT1B receptors (Agtr1a -/-Agtr1b -/-). Agtr1b -/- mice are healthy, without an abnormal phenotype. In contrast, Agtr1a -/-Agtr1b -/- mice have diminished growth, vascular thickening within the kidney, and atrophy of the inner renal medulla. This phenotype is virtually identical to that seen in angiotensinogen-deficient (Agt-/-) and angiotensin-converting enzyme-deficient (Ace -/-) mice that are unable to synthesize angiotensin II. Agtr1a -/-Agtr1b -/- mice have no systemic pressor response to infusions of angiotensin II, but they respond normally to another vasoconstrictor, epinephrine. Blood pressure is reduced substantially in the Agtr1a -/- Agtr1b -/- mice and following administration of an angiotensin converting enzyme inhibitor, their blood pressure increases paradoxically. We suggest that this is a result of interruption of AT2-receptor signaling. In summary, our studies suggest that both AT1 receptors promote somatic growth and maintenance of normal kidney structure. The absence of either of the AT1 receptor isoforms alone can be compensated in varying degrees by the other isoform. These studies reaffirm and extend the importance of AT1 receptors to mediate physiological functions of the renin-angiotensin system.
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PMID:Reduced growth, abnormal kidney structure, and type 2 (AT2) angiotensin receptor-mediated blood pressure regulation in mice lacking both AT1A and AT1B receptors for angiotensin II. 986 Sep 97

Chronic elevations of circulating angiotensin II (Ang II) cause sustained hypertension and enhanced accumulation of intrarenal Ang II by an AT1 receptor-dependent process. The present study tested the hypothesis that chronic elevations in circulating Ang II regulate AT1 mRNA and protein expression in a tissue-specific manner. Sprague-Dawley rats were infused with Ang II (80 ng/min) or vehicle subcutaneously for 13 days via osmotic minipump. On day 12, systolic blood pressure averaged 186+/-12 mm Hg in Ang II-infused rats compared with rats given vehicle (121+/-2 mm Hg). Plasma renin activity was markedly suppressed in the Ang II-infused rats compared with vehicle-infused rats (0.1+/-0.01 versus 4.9+/-0.9 ng of Ang I. mL-1. h-1; P<0.05). Semiquantitative reverse transcription polymerase chain reaction using rat AT1A- and glyceraldehyde-3-phosphate-dehydrogenase (GAPDH)-specific primers was followed by Southern blot hybridization using specific radiolabeled cDNA or oligonucleotide probes. The results showed that the ratios of AT1A/GAPDH mRNA in the kidney (0.19+/-0.05 versus 0. 26+/-0.03) and liver (2.8+/-0.9 versus 3.0+/-0.5) were comparable in Ang II- and vehicle-infused rats. In contrast, AT1A/GAPDH mRNA levels were increased in the adrenal glands of Ang II-infused rats (0.49+/-0.04 versus 0.36+/-0.02; P<0.05). Western blot analysis showed that AT1 protein levels in the kidney and liver were also similar in the two groups. Therefore, these results indicate that renal and liver AT1 receptor gene expression is maintained in Ang II-induced hypertension. The failure to downregulate AT1 receptor mRNA and protein levels thus allows the sustained effects of chronic elevations in Ang II to elicit progressive increases in arterial pressure.
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PMID:Regulation of angiotensin II type 1 receptor mRNA and protein in angiotensin II-induced hypertension. 993 Nov 27

The present study describes the differential rostro-caudal patterning of angiotensinogen (AoGen) and AT1A receptor mRNAs in the rat SFO using specific and validated oligodeoxynucleotide probes for in situ hybridization. Highest levels of AoGen-specific gene expression were observed in the rostral region of the SFO with gradually decreasing intensity towards the caudal region of this sensory circumventricular organ lacking blood-brain barrier function. AoGen-related hybridization signals proved to be specifically prominent above cells in lateral aspects of the SFO, surrounding septal venules. Maximal expression of the AT1A receptor-specific gene, on the other hand, could be detected in the neuron-enriched, ventro-medial core region and dorsal annulus of the SFO, with low-intensity hybridization signals in its rostral and caudal parts. Water deprivation for 48 h, leading to extracellular hypertonic hypovolemia with elevated circulating AngII concentrations within the physiological range, caused a significant increase in AoGen-specific hybridization signals in the rostral and medial SFO regions. AT1A receptor gene expression and AngII receptor binding were markedly stimulated in the medial and caudal regions of the SFO (core and annulus) as compared to euhydrated animals. These data indicate, that mild dehydration differentially up-regulates AoGen- and AT1A receptor-specific mRNA formation as well as AT1 receptor binding in distinct regions of the SFO, and supports the involvement of different cellular subgroups in the expression of two major components of the central nervous renin-angiotensin system in this sensory circumventricular organ.
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PMID:Differential regulation of angiotensinogen and AT1A receptor mRNA within the rat subfornical organ during dehydration. 993 78

Components of the renin-angiotensin system play an important role in the normal regulation of blood pressure. We carried out a comprehensive genetic linkage study of the genes involved in the renin-angiotensin cascade in Finnish hypertensive twins and their affected siblings. We found no evidence for linkage between essential hypertension and the genes coding for renin, angiotensinogen, angiotensin-converting enzyme, or kallikrein 1 in the 329 hypertensive individuals of 142 families studied. In contrast, two intragenic markers for the type 1 angiotensin II receptor (AT1) showed some evidence for linkage in the total sample. A closer examination of this gene locus was carried out using subgroups of nonobese sibpairs with early onset of hypertension and uniform geographical origin. These stratifications yielded suggestive evidence for linkage of hypertension to the genetic area containing the AT1 gene, with a maximal multipoint logarithm of the odds (LOD) score of 2.9. A genetic association study carried out in an independent series of 50 hypertensive cases and 122 normotensive controls showed an increase in the frequency of the A1166-->C allele of the AT1 gene in the hypertensive individuals. In a novel variant of model-free multipoint linkage analysis allowing linkage disequilibrium in the calculations, an LOD score of 5.13 was obtained. Sequence analyses of the entire coding region and 848 bp of promoter region in the DNA sample on 8 index samples did not reveal previously unpublished sequence variations. The data provide evidence that a common genetic variant of the AT1 gene locus influences the risk of essential hypertension in the Finnish population.
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PMID:Evidence for involvement of the type 1 angiotensin II receptor locus in essential hypertension. 1008 97

The effects of the angiotensin II receptor type 1 (AT1) antagonist losartan on pressure overload-induced left ventricular (LV) hypertrophy were studied in female Sprague-Dawley rats. Starting on the day of surgery, losartan (L, 12 mg/kg/day) was administered as continuous intraperitoneal infusion for 2 weeks by using alzet mini-osmotic-pumps (model 2002). This dose of losartan shifted the in vivo dose-response curve of the angiotensin II-induced elevation of left ventricular systolic pressure (LVSP) to the right. Pressure overload was achieved by placing a band around the aortic arch. This caused an aortic stenosis (AS) with an outer diameter of 1.0 mm. The hemodynamic effects were measured in the intact, anesthetized rats (n = 15). The hearts were excised, and the weights of the left (LV) and right ventricle (RV) were determined. Some of these hearts (n = 7) were perfused with collagenase to obtain isolated cardiac myocytes for the measurement of cell volume. Other hearts (n = 8) were examined for morphological changes. In the animals with AS, LVSP was markedly elevated. Furthermore, LV weight and LV myocyte cell volume were increased in this group, while RV weight and RV myocyte cell volume remained stable in all the groups. L had no significant effect on the AS-induced increase in LVSP and cell size parameters, nor on the weight gain of the LV. Histological analysis revealed that the AS-induced enlargement of the mean myocyte diameter was not affected by L. The interstitial collagen fraction was increased in the AS rats and became normalized by L. These data suggest that the renin-angiotensin system might not be involved in the development of pressure-induced cardiac hypertrophy within the time-frame of these experiments, but that it does play a major role in the genesis of the interstitial fibrosis which is a typical feature of this pathophysiological condition.
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PMID:Differential effects of angiotensin II receptor blockade on pressure-induced left ventricular hypertrophy and fibrosis in rats. 1009 56

Electrolytes and water are bidirectionally transported across the epithelial cells of mammalian small and large intestines. In animals with chronic renal failure, plasma levels of angiotensin II and specific 125I-angiotensin II binding sites increase and result in enhanced excretions of K+, Cl- and urate from distal colon, in an AT1-receptor sensitive manner. Angiotensin-converting enzyme activity and mRNA levels for renin-2 and AT1A-receptor are blunted or lowered transiently by gastric intake of low Na+ in rodent, suggesting that angiotensin II serves as a humoral mediator for "gastric Na+ monitor". Angiotensin II causes also very potent contractions of gastrointestinal smooth muscles as shown in vascular smooth muscles. This review is focused on understanding potential roles of angiotensin II in gastrointestinal functions.
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PMID:[Modulations by stimulation of angiotensin II type 1 receptor of gastrointestinal functions]. 1036 34

We determined the relationship between the gene polymorphism of angiotensinogen (AGT), angiotensin-converting enzyme (ACE), or angiotensin II receptor (AT1R) and the progression of diabetic nephropathy in a multicenter trial of ethnically homogeneous Japanese patients with non-insulin-dependent diabetes (NIDDM). Gene polymorphism of ACE I/D, AGT M235T and AT1R A1166C was determined by polymerase chain reaction amplification using allele-specific primers. Japanese NIDDM patients (n = 1,152) were selected from several diabetic clinics. All patients were divided into three groups as follows: (1) group I (n = 407): normoalbuminuric patients; (2) group II (n = 327): microalbuminuric patients, and (3) group III (n = 418): overt albuminuric patients. Clinical factors for investigation in all patients were the date of birth, gender, levels of urinary albumin excretion, findings of the ocular fundus, duration of diabetes, hemoglobin A1c and blood pressure. It appears that genetic polymorphisms in the renin-angiotensin systems, i.e. ACE or AT1R, may affect the progression to renal failure of patients (especially females) with NIDDM.
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PMID:Relationship between polymorphism in the angiotensinogen, angiotensin-converting enzyme or angiotensin II receptor and renal progression in Japanese NIDDM patients. 1036 6

The intrarenal factors responsible for hypertension in double-transgenic rats (dTGR) harboring human renin and human angiotensinogen genes are unclear. The pressure-natriuresis and -diuresis relationships in response to chronic angiotensin-converting enzyme (ACE) inhibition and AT1 receptor blockade were evaluated. Renal renin-angiotensin and nitric oxide (NO) system gene expression was also investigated. Six-week-old dTGR were treated for 3 wk with submaximal doses of cilazapril (10 mg/kg, orally) or losartan (10 mg/kg, orally) or with the drug combination. In untreated dTGR, pressure-natriuresis relationships were maximally shifted rightward by approximately 70 to 80 mmHg, and both renal blood flow (RBF) and GFR were markedly decreased. Submaximal cilazapril and losartan dosages both decreased systolic BP by 30 mmHg and shifted the pressure-natriuresis curves leftward by 25 to 30 mmHg. Cilazapril increased RBF and GFR to values observed in normotensive control animals but did not significantly affect fractional sodium excretion (FENa) or fractional water excretion (FEH2O) curves. In contrast, losartan had no significant effect on RBF or GFR but shifted the FENa and FEH2O curves leftward. The cilazapril and losartan combination completely normalized BP and shifted the pressure-natriuresis curves leftward more than did either drug alone. When cilazapril and losartan were administered at higher doses (30 mg/kg, orally), the two drugs equally shifted the pressure-natriuresis curves leftward, by 50 mmHg. Both drugs increased RBF and GFR; however, only losartan shifted FENa and FEH2O curves leftward. Human and rat renin and angiotensinogen genes were downregulated in dTGR and were increased by losartan and cilazapril treatments, whereas no changes in the expression of rat ACE and AT1A receptor genes were observed. Endothelial NO synthase expression was increased by cilazapril but not by losartan. Neither inducible NO synthase nor neural NO synthase gene expression was affected by drug treatments. Therefore, submaximal ACE inhibition enhanced sodium excretion mainly by increasing RBF and GFR, whereas submaximal AT1 receptor blockade decreased tubular sodium and water reabsorption. The combination of the two drugs produced an additive effect. The ACE inhibitor effects may involve increased endothelial NO synthase expression, perhaps related to the inhibition of bradykinin degradation.
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PMID:Angiotensin-converting enzyme inhibition and AT1 receptor blockade modify the pressure-natriuresis relationship by additive mechanisms in rats with human renin and angiotensinogen genes. 1044 34


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