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Query: UMLS:C0004135 (ATM)
 13,001 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Intracerebroventricular (ICV) angiotensin (AIl) administration stimulates central AII receptors to induce water consumption in rats. The aim of this study was to determine the role of brain AT1 and AT2 receptors in mediating chronic ICV AII-induced drinking in rats raised on normal or high sodium chloride diets from weaning. Rats were weaned at 21 days of age and placed on normal or high sodium chloride diet for 10-12 weeks. At adulthood, the animals were instrumented with brain lateral ventricular cannulas and femoral arterial catheters. Low dose chronic central AII infusion (20 ng min(-1)) significantly (P < 0.05) increased water intake in both groups of rats when compared with their respective controls of 24 h artificial cerebrospinal fluid infusions. In a separate group of high sodium fed rats, coinfusion of AII with the AT1 receptor antagonist, losartan (0.25 microg min(-1)) or the AT2 receptor blocker, PD 123319 (0.50 microg min(-1)) blocked chronic ICV AII-induced drinking. Upon reinfusion of AII water intake increased above control. Following the cessation of AII infusions, water intake returned to values not significantly different from control (P > 0.05). In contrast, in the normal sodium fed rats losartan, but not PD 123319, blocked the AII-mediated water intake. The data demonstrate that in high sodium chloride fed rats AII stimulates both central AT1 and AT2 receptors to induce drinking, while in the normal sodium chloride fed rats the peptide activates the drinking response primarily by stimulation of central AT1 receptors.
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PMID:Central AT1 and AT2 receptors mediate chronic intracerebroventricular angiotensin II-induced drinking in rats fed high sodium chloride diet from weaning. 1135 Feb 80

The aim of this study was to analyze if the upregulation of angiotensin-converting enzyme and AT1 receptors observed in a model of neointima formation results in increased contractions to angiotensin I (AI) and AII. Endothelial denudation was performed in left common carotid arteries of 3-month-old male Sprague-Dawley rats. Rats were killed at days 0, 4, 8 and 14 after injury and vascular reactivity was assessed in an organ bath. Responses were always compared with their contralateral vessels as a control. Contractile responses to 75 mM KCl were similar between groups. Noradrenaline (0.1 microM) induced significantly higher contractions at days 0 and 4. Relaxation to acetylcholine (Ach) (1 nM to 0.1 mM) was suppressed at day 0 and increased with time after injury. Relaxations to sodium nitroprusside (0.1 nM to 0.1 mM) were similar at all time points studied. Responses to AI and AII were increased at early steps of neointima formation and decreased with time after injury correlating with increased responses to Ach. Concentration-response curves to AI and AII had similar EC50 or Emax values at the same time points. These results indicate that in the rat i) neointima formation does not impair contractile responses to KCl nor relaxation to SNP, ii) a functional endothelium seems to regenerate with time after injury, and iii) the increase in ACE activity and AT1 receptor number does not have functional consequences.
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PMID:The upregulation of angiotensin-converting enzyme during neointima formation does not have functional consequences. 1169 65

In the present study we used the isolated rat aorta as a model to characterize the modulation of contractile effects of extra- and intracellularly administered angiotensin II by dithiothreitol (DTT) and hyperosmotic sucrose. DTT inactivation of AT1 receptor as well as disruption of the clathrin-coated pits by hyperosmotic sucrose significantly inhibited the contraction induced by intracellularly administered AII. We suggest that these intracellular effects of angiotensin peptides are associated with AT1 receptor activation/internalization and may thus be part of the mechanism of angiotensin peptides direct contractile effects in the vascular smooth muscle.
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PMID:Contractile effects of intracellularly administered angiotensin II are partially dependent on membrane receptors internalization in isolated rat aorta. 1209 24

The marmoset adrenal is interesting as it is developmentally similar to humans and other primates, but in adulthood 17,20-lyase activity is very low. One possible explanation is an altered regulation of P450c17 expression by AT1-R. We investigated the expression and zonal distribution of the AT1-R in marmoset adrenal glands and adrenocortical cells in culture since it is known that AT1-R is a regulator of P450c17 expression and activity. AT1-R was expressed strongly in the ZG and to diminishing degrees through the remainder of the cortex. There was negative expression in a putative ZI. Dispersed adrenocortical cells retained AT1-R protein as detected by ICC. Cells cultured for several days and treated in serum-free media for 48 h maintained AT1-R expression, as measured by western. However, at that 48 h time point, treatment with Forsk, AII, TPA, or the combination of A+F or T+F did not appear to effect AT1-R expression. We conclude that marmoset adrenals express AT1-R similarly to humans and other higher mammals, adrenocortical cells retain AT1-R expression in culture, and consistent with other adrenal cell culture models, AT1-R expression is not lost in response to agonists long term.
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PMID:Expression of AT1-R in marmoset whole adrenal glands and adrenocortical cells in culture. 1566 21

Angiotensin II antagonists (AIIAs) were introduced to treat hypertension about 10 years ago. During this period they were evaluated not only in terms of efficacy and safety but also in several large studies with clinical outcomes. They are efficacious in all clinical forms of hypertension and are effective also in all ethnic groups. Cardiovascular and renal protection in proteinuric diabetic nephropathy beyond blood pressure reduction was proved in major clinical studies: Losartan Intervention For Endpoint reduction in hypertension study (LIFE), Reduction of Endpoint in Non-Insulin dependent Diabetes Mellitus with the AII Antagonist Losartan (RENAAL) and Irbesartan Type 2 Diabetic Nephropathy Trial (IDNT). Their blood pressure independent protective effect is also mentioned by the blockade of AT1 receptor. As a class AIIs have a tolerability profile similar to placebo.
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PMID:Angiotensin II antagonists: clinical experience in the treatment of hypertension, prevention of cardiovascular outcomes and renal protection in diabetic nephropathy and proteinuria. 1676 99

AII (angiotensin II) is a vasoactive peptide that plays an important role in the development of liver fibrosis mainly by regulating profibrotic cytokine expression such as TGF-beta (transforming growth factor-beta). Activated HSCs (hepatic stellate cells) are the major cell type responsible for ECM (extracellular matrix) deposition during liver fibrosis and are also a target for AII and TGF-beta actions. Here, we studied the effect of AII on the mRNA levels of TGF-beta isoforms in primary cultures of rat HSCs. Both quiescent and activated HSCs were stimulated with AII for different time periods, and mRNA levels of TGF-beta1, TGF-beta2 and TGF-beta3 isoforms were evaluated using RNaseI protection assay. The mRNA levels of all TGF-beta isoforms, particularly TGF-beta2and TGF-beta3, were increased after AII treatment in activated HSCs. In addition, activated HSCs were able to produce active TGF-beta protein after AII treatment. The mRNA expression of TGF-beta isoforms induced by AII required both ERK1/2 and Nox (NADPH oxidase) activation but not PKC (protein kinase C) participation. ERK1/2 activation induced by AII occurs via AT1 receptors, but independently of either PKC and Nox activation or EGFR (epidermal growth factor receptor) transactivation. Interestingly, AII has a similar effect on TGF-beta expression in quiescent HSCs, although it has a smaller but significant effect on ERK1/2 activation in these cells.
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PMID:Angiotensin II increases mRNA levels of all TGF-beta isoforms in quiescent and activated rat hepatic stellate cells. 2055 91


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