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Endogenous and exogenous circulating ANG II acts at one of the central circumventricular organs (CVOs), the subfornical organ (SFO), to modulate chronic blood pressure regulation. However, at the forebrain, another important CVO is the organum vasculosum of the lamina terminalis (OVLT). In the present study, we tested the hypothesis that the OVLT mediates the hypertension or the hypotension produced by chronic infusion of ANG II or losartan (ATl antagonist), respectively. Six days after sham or OVLT electrolytic lesion, male Sprague-Dawley rats (280-320 g, n = 6 per group) were instrumented with intravenous catheters and radiotelemetric blood pressure transducers. Following another week of recovery, rats were given 3 days of saline control infusion (7 ml/day) and were then infused with ANG II (10 ng x [kg.sup.-1] x [min.sup.-1]) or losartan (10 mg x [kg.sup.-1] x [day.sup.-1]) for l0 days, followed by 3 recovery days. Twenty-four hour average measurements of mean arterial pressure (MAP) and heart rate (HR) were made during this protocol. Hydromineral balance (HB) responses were measured during the experimental protocol. By clay 9 of ANG II treatment, MAP had increased 16 [+ or -] 4 mmHg in sham rats but only 4 [+ or -] 1 mmHg in OVLT lesioned rats without changes in HR or HB. However, the hypotension produced by 10 days of losartan infusion was not modified in OVLT lesioned rats. These results suggest that the OVLT might play an important role during elevation of plasma ANG II, facilitating increases of blood pressure but is not involved with baseline effects of endogenous ANG II. hypertension; angiotensin II; losartan doi: 10.1152/ajpregu.00034.2010.

Angiotensin II (ANG II) contributes to hypertension, cardiac hypertrophy, fibrosis, and dysfunction; however, it is difficult to separate the cardiac effect of ANG II from its hemodynamic action in vivo. To overcome the limitations, we used transgenic mice with cardiac-specific expression of a transgene fusion protein that releases ANG II from cardiomyocytes (Tg-ANG II) and treated them with deoxycorticosterone acetate (DOCA)-salt to suppress their systemic renin-angiotensin system. Using this unique model, we tested the hypothesis that cardiac ANG II, acting on the angiotensin type 1 receptor ([AT.sub.1]R), increases inflammation, oxidative stress, and apoptosis, accelerating cardiac hypertrophy and fibrosis. Male Tg-ANG II mice and their non-transgenic littermates (n-Tg) were uninephrectomized and divided into the following three groups: 1) vehicle-treated normotensive controls; 2) DOCA-salt; and 3) DOCA-salt + valsartan ([AT.sub.1]R blocker). Under basal conditions, systolic blood pressure (SBP) and cardiac phenotypes were similar between strains. In DOCA-salt hypertension, SBP increased similarly in both n-Tg and Tg-ANG II, and cardiac function did not differ between strains; however, Tg-ANG II had 1) greater ventricular hypertrophy as well as interstitial and perivascular fibrosis; 2) a higher number of deoxynucleotidyl-transferase-mediated dUTP nick end labeling-positive cells and infiltrating macrophages; 3) increased protein expression of NADPH oxidase 2 and transforming growth factor-[[beta].sub.1]; and 4) downregulation of phosphatidylinositol 3-kinase (PI 3-kinase) and protein kinase B (Akt) phosphorylation. Valsartan partially reversed these effects in Tg-ANG II but not in n-Tg. We conclude that, when hemodynamic loading conditions remain unchanged, cardiac ANG II does not alter heart size or cardiac functions. However, in animals with hypertension, cardiac ANG II, acting via [AT.sub.1]R, enhances inflammation, oxidative stress, and cell death (most likely via downregulation of PI 3-kinase and Akt), contributing to cardiac hypertrophy and fibrosis. inflammation; oxidative stress; cardiac hypertrophy; fibrosis doi: 10.1152/ajpheart.00538.2010.

It has been shown that angiotensin (ANG)-(1-7) activates nitric oxide synthase (NOS) in isolated ventricular myocytes from normotensive rats. Since many ANG-(1-7) actions are enhanced in situations of increased ANG II activity, as in hypertension, in this study we investigated the in vivo effect of ANG-(1-7) on NOS activity and expression of endothelial (eNOS), neuronal (nNOS), and inducible NOS (iNOS) in ventricles from spontaneously hypertensive rats (SHR). Rats were subjected to a 60-min ANG-(1-7) infusion (0.35 nmol/min); controls received saline. NOS activity was measured using the NADPH diaphorase histochemical method and by the conversion of L-[[sup.14]C]arginine to citrulline, and NOS phosphorylation and expression were determined using Western blotting. In SHR, ANG-(1-7) infusion diminished mean arterial pressure from 180 [+ or -] 9 to 146 [+ or -] 9 mmHg (P < 0.05), and this effect was prevented by nitro-L-arginine methyl ester (L-NAME), a NOS inhibitor. In addition, NOS activity and eNOS phosphorylation were increased by ANG-(1-7) infusion. Ventricular eNOS and nNOS expression were increased 67.4 [+ or -] 6.4 and 51 [+ or -] 10%, respectively, by ANG-(1-7), whereas iNOS was not changed. In another set of experiments, we evaluated the mechanism by which ANG-(1-7) modifies NOS activity. Isolated ventricle slices preincubated with ANG-(1-7) showed an increase in NOS activity and eNOS phosphorylation, which was blocked by an [AT.sub.2] and a bradykinin [B.sub.2] receptor antagonist, but not by the Mas receptor antagonist. Our results show that in rats in a hypertensive state, ANG-(1-7) infusion upregulates cardiac NOS expression and activity through an [AT.sub.2]- and bradykinin-dependent mechanism. In this way ANG-(1-7) may eficit its cardioprotective action and contribute to some of the counterregulatory [AT.sub.2] receptor effects that oppose the [AT.sub.1] receptor-mediated effects. receptors; hypertension; heart; bradykinin doi: 10.1152/ajpheart.00850.2009.

The study was undertaken to examine the potential cross talk between vasopressin and angiotensin II (ANG II) intracellular signaling pathways. We investigated in vivo and in vitro whether vasopressin-induced water reabsorption could be attenuated by ANG II AT1 receptor blockade (losartan). On a low-sodium diet (0.5 meq/day) dDAVP-treated animals with or without losartan exhibited comparable renal function [creatinine clearance 1.2 [+ or -] 0.1 in dDAVP + losartan (LSDL) vs. 1.1 [+ or -] 0.1 ml x 100 [g.sup.-1] x [day.sup.-1] in dDAVP alone (LSD), P > 0.05] and renal blood flow (6.3 [+ or -] 0.5 in LSDL vs. 6.8 [+ or -] 0.5 ml/min in LSD, P > 0.05). The urine output, however, was significantly increased in LSDL (2.5 [+ or -] 0.2 vs. 1.8 [+ or -] 0.2 ml x 100 [g.sup.-l] x [day.sup.-1], P < 0.05) in association with decreased urine osmolality (2,600 [+ or -] 83 vs. 3,256 [+ or -] 110 mosmol/kg[H.sub.2]O, P < 0.001) compared with rats in LSD. Immunoblotting revealed significantly decreased expression of medullary AQP2 (46 [+ or -] 6 vs. 176 [+ or -] 10% in LSD, P < 0.01), p-AQP2 (177 [+ or -] 13 vs. 214 [+ or -] 12% in LSD, P < 0.05), and AQP3 (134 [+ or -] 14 vs. 177 [+ or -] 11% in LSD, P < 0.05) in LSDL compared with LSD. The expressions of AQP1, the [[alpha].sub.1]- and [gamma]-subunits of Na-K-ATPase, and the Na-K-2Cl cotransporter were not different among groups. In vitro studies showed that ANG II or dDAVP treatment was associated with increased AQP2 expression and cAMP levels, which were potentiated by cotreatment with ANG II and dDAVP and were inhibited by AT1 blockade. In conclusion, ANG II AT1 receptor blockade in dDAVP-treated rats on a low-salt diet was associated with decreased urine concentration and decreased inner medullary AQP2, p-AQP2, and AQP3 expression, suggesting that AT1 receptor activation plays a significant role in regulating aquaporin expression and modulating urine concentration in vivo. Studies in collecting duct cells were confirmatory. aquaporin; urine concentration; cAMP doi: 10.1152/ajprenal.00168.2010.

It has been clearly established that increased circulating angiotensin II (ANG II) with concurrent upregulation of brain and peripheral ANG II type 1 receptors ([AT.sub.1]R) are important mediators in the pathophysiology of several diseases characterized by sympatho-excitation. In an effort to further understand the regulation of [AT.sub.1]R expression in neurons, we determined the role of sequential activation of the transcription factors nuclear factor-[kappa]B (NF-[kappa]B) and Ets-like protein 1 (Elk-1) in [AT.sub.1]R upregulation. We used CATH.a neurons as our neuronal cell model. Cells were treated with ANG II (100 nM) over a preset time course. Following ANG II activation, there was a temporal increase in the p65 subunit of NF-[kappa]B that was observed at 30 min, peaked at 1 h, and was sustained up to 24 h. There was a concomitant decrease of I[kappa]B and increased I[kappa]K expression. We also observed an increase in [AT.sub.1]R expression which followed the temporal increase of NF-[kappa]B. The activation of NF-[kappa]B was blocked by using the inhibitors parthenolide or p65 small interfering RNA (siRNA) which both led to a decrease in [AT.sub.1]R expression. The expression of Elk-1 was upregulated over a time period following ANG II activation and was decreased following NF-[kappa]B inhibition, p65-DNA binding was assessed using electrophoretic mobility shift assay, and it was shown that there was a time-dependent increased binding that was inhibited by means of parthenolide pretreatment or siRNA-mediated p65 gene silencing. Therefore, our results suggest a combined role for the transcription factors NF-[kappa]B and Elk-1 in the upregulation of [AT.sub.1]R in the CATH.a cell neuronal model. These data imply a positive feedback mechanism that may impact neuronal discharge sensitivity in response to ANG II. CATH.a; cell culture; G protein-coupled receptors; small interfering RNA; angiotensin II type 1 receptor doi: 10.1152/ajpcell.00127.2010.

An increase in plasma ANG II causes neuronal activation in hypothalamic nuclei and a slow pressor response, presumably by increasing sympathetic drive. We evaluated whether the activation of a neuromodulatory pathway, involving aldosterone and 'ouabain,' is involved in these responses. In Wistar rats, the subcutaneous infusion of ANG II at 150 and 500 ng x [kg.sup.-1] x [min.sup.-1] gradually increased blood pressure up to 60 mmHg at the highest dose. ANG II at 500 ng x [kg.sup.-1] x min increased plasma ANG II by 4-fold, plasma aldosterone by 25-fold, and hypothalamic aldosterone by 3-fold. The intracerebroventricular infusion of an aldosterone synthase (AS) inhibitor prevented the ANG II-induced increase in hypothalamic aldosterone without affecting the increase in plasma aldosterone. Neuronal activity, as assessed by Fra-like immunoreactivity, increased transiently in the subfornical organ (SFO) but progressively in the paraventricular nucleus (PVN) and supraoptic nucleus (SON). The central infusion of the AS inhibitor or a mineralocorticoid receptor blocker markedly attenuated the ANG II-induced neuronal activation in the PVN but not in the SON. Pressor responses to ANG II at 150 ng x [kg-] x [min.sup.-1] were abolished by an intracerebroventricular infusion of the AS inhibitor. Pressor responses to ANG II at 500 ng x [kg.sup.-1] x [min.sup.-1 were attenuated by the central infusion of the AS inhibitor or the mineralocorticoid receptor blocker by 70-80% and by Digibind (to bind 'ouabain') by 50%. These results suggest a novel central nervous system mechanism for the ANG II-induced slow pressor response, i.e., circulating ANG II activates the SFO, leading to the direct activation of the PVN and SON, and, in addition, via aldosterone-dependent amplifying mechanisms, causes sustained activation of the PVN and thereby hypertension. Fra-like immunoreactivity; aldosterone synthase inhibitor; eplerenone; telemetry; angiotensin II doi: 10.1152/ajpheart.00256.2010.

Podocytes are an integral and important constituent of the glomerular filtration barrier (GFB) and are exposed to a higher concentrations of ANG II in diseased states; consequently, podocytes may accumulate oxidized proteins and damaged mitochondria. In the present study, we evaluated the effect of ANG II on the podocyte autophagic process, which is likely to be triggered in order to degrade unwanted proteins and damaged organelles. To quantitate the occurrence of autophagy, electron microscopic studies were carried out on control and ANG II-treated conditionally immortalized mouse podocytes (CIMPs). ANG II-treated cells showed a fivefold greater number of autophagosomes/field compared with control cells. This proautophagic effect of ANG II was inhibited by pretreatment with 3-methyladenine, an inhibitor of autophagy. ANG II also enhanced podocyte expression of autophagic genes such as LC3-2 and beclin-1. Since oxidative stress is often associated with the induction of autophagy, we examined the effect of ANG II on podocyte reactive oxygen species (ROS) generation. ANG II enhanced podocyte ROS generation in a time-dependent manner. To determine whether there is a causal relationship between ANG II-induced oxidative stress and induction of autophagy, we evaluated the effect of antioxidants on ANG II-induced autophagy. As expected, the proautophagic effect of ANG II was inhibited by antioxidants. We conclude that ANG II promotes podocyte autophagy through the generation of ROS. oxidative stress; angiotensin II doi: 10.1152/ajpcell.00424.2009.

Placental insufficiency results in intrauterine growth restriction (IUGR) and hypertension in adult male growth-restricted rats. Although renal ANG II and plasma renin activity do not differ between growth-restricted and control rats, blockade of the renin-angiotensin system (RAS) abolishes hypertension in growth-restricted rats, suggesting that the RAS contributes to IUGR-induced hypertension. Moreover, castration abolishes hypertension in growth-restricted rats, indicating an important role for testosterone. Therefore, we hypothesized that enhanced responsiveness to ANG II contributes to hypertension in this model of IUGR and that androgens may play a pivotal role in this enhanced response. Physiological parameters were determined at 16 wk of age in male rats pretreated with enalapril (40 mg x [kg.sup.-1] x [day.sup.-1]) for 1 wk. Baseline blood pressures were similar between growthrestricted (112 [+ or -] 3 mmHg) and control (110 [+ or -] 2 mmHg) rats; however, an enhanced pressor response to acute ANG II (100 ng x [kg.sup.-1] x [min.sup.-1] for 30 min) was observed in growth-restricted (160 [+ or -] 2 mmHg) vs. control (136 [+ or -] 2 mmHg; P < 0.05) rats. Castration abolished the enhanced pressor response to acute ANG II in growth-restricted (130 [+ or -] 2 mmHg) rats with no significant effect on blood pressure in controls (130 [+ or -] 2 mmHg). Blood pressure was increased to a similar extent above baseline in response to acute phenylephrine (100 [micro]g/min) in control (184 [+ or -] 5 mmHg) and growth-restricted (184 [+ or -] 8 mmHg) rats, suggesting the enhanced pressor response in growth-restricted rats is ANG II specific. Thus, these results suggest that growth-restricted rats exhibit an enhanced responsiveness to ANG II that is testosterone dependent and indicate that the RAS may serve as an underlying mechanism in mediating hypertension programmed in response to IUGR. sex steroids; blood pressure; developmental programming doi: 10.1152/ajpregu.00096.2010.

Araujo M, Welch WJ. Tubuloglomerular feedback is decreased in COX-1 knockout mice after chronic angiotensin II infusion. Am J Physiol Renal Physiol 298: F1059-F1063, 2010. First published January 27, 2010; doi: 10.1152/ajprenal.00547.2009.--Prostaglandins (PGs), produced by two isoforms of cyclooxygenase (COX), COX-1 and COX-2, are important modulators of renal hemodynamics. COX-1 and COX-2 are expressed in the kidney often at distinct sites. Thromboxane ([TxA.sub.2]), [PGE.sub.2], and prostacyclin (PGI2) are the major PGs in the renal cortex of mice. Acute infusion of the vasoconstrictor ANG II increases COX-2-dependent [PGE.sub.2] and [PGI.sub.2]. COX-2 is primarily expressed in the macula densa (MD), where several PG synthases are also expressed. We previously showed that MD COX-2 products modulate tubuloglomerular feedback (TGF) in the rat. Genetic deletion of COX-1 enhances COX-2 production of PGs, decreases renal and urinary PGs, and attenuates ANG II-induced hypertension. The present study tested the effects of chronic ANG II infusion on TGF in COX-1 knockout (KO) mice. Basal TGF was similar in COX-1 KO and wild-type (WT) mice. Chronic ANG II infusion increased TGF in WT mice (WT: 9.3 [+ or -] 0.7 vs. WT + ANG II: 12.2 [+ or -] 1.6 mmHg, P < 0.02). However, chronic ANG II decreased TGF in COX-1 KO mice (KO: 11.4 [+ or -] 1.1 vs. KO + ANG II: 8.3 [+ or -] 0.6 mmhg, P < 0.01). Pretreatment with the COX-2 inhibitor SC58,236 in COX-1 KO mice prevented the ANG II-associated reduction in TGF (11.4 [+ or -] 1.0 vs. 11.5 [+ or -] 0.28 mmHg, not significant). Excretion of 6-keto-[PGF.sub.2[alpha]], the metabolite of PGI2, was increased by ANG II infusion, whereas excretion of TxB2, the stable metabolite of [TxA.sub.2], was not changed. ANG II infusion increased mean arterial pressure similarly in both WT and KO mice (WT: 93 [+ or -] 2 vs. KO: 92 [+ or -] 3 mmHg), but not in KO mice pretreated with SC-58,236 (85 [+ or -] 2 mmHg). This study shows that COX-l-generated PGs partially mediate ANG II increases in TGF and that COX-2 PGs offset that effect. cyclooxygenase; prostaglandins; hypertension doi: 10.1152/ajprenal.00547.2009.

Crowley SD, Song Y, Lin EE, Griffiths R, Kim H, Ruiz P. Lymphocyte responses exacerbate angiotensin H-dependent hypertension. Am J Physiol Regul Integr Comp Physiol 298: R1089-R1097, 2010. First published February 10, 2010; doi:10.1152/ajpregu.00373.2009.--Activation of the immune system by ANG II contributes to the pathogenesis of hypertension, and pharmacological suppression of lymphocyte responses can ameliorate hypertensive end-organ damage. Therefore, to examine the mechanisms through which lymphocytes mediate blood pressure elevation, we studied ANG II-dependent hypertension in scid mice lacking lymphocyte responses and wild-type controls. Scid mice had a blunted hypertensive response to chronic ANG II infusion and accordingly developed less cardiac hypertrophy. Moreover, lymphocyte deficiency led to significant reductions in heart and kidney injury following 4 wk of angiotensin. The muted hypertensive response in the scid mice was associated with increased sodium excretion, urine volumes, and weight loss beginning on day 5 of angiotensin infusion. To explore the mechanisms underlying alterations in blood pressure and renal sodium handling, we measured gene expression for vasoactive mediators in the kidney after 4 wk of ANG II administration. Scid mice and controls had similar renal expression for interferon-[gamma], interleukin-1[beta], and interleukin-6. By contrast, lymphocyte deficiency (i.e., scid mice) during ANG II infusion led to upregulation of tumor necrosis factor-[alpha], endothelial nitric oxide synthase (eNOS), and cyclooxygenase-2 (COX-2) in the kidney. In turn, this enhanced eNOS and COX-2 expression in the scid kidneys was associated with exaggerated renal generation of nitric oxide, prostaglandin [E.sub.2], and prostacyclin, all of which promote natriuresis. Thus, the absence of lymphocyte activity protects from hypertension by allowing blood pressure-induced sodium excretion, possibly via stimulation of eNOSand COX-2-dependent pathways. inflammation; kidney diseases; T lymphocytes doi: 10.1152/ajpregu.00373.2009.

Mizushima T, Sasaki M, Ando T, Wada T, Tanaka M, Okamoto Y, Ebi M, Hirata Y, Murakami K, Mizoshita T, Shimura T, Kubota E, Ogasawara N, Tanida S, Kataoka H, Kamiya T, Alexander JS, Joh T. Blockage of angiotensin II type 1 receptor regulates TNF-[alpha]-induced MAdCAM-1 expression via inhibition of NF-[kappa]B translocation to the nucleus and ameliorates colitis. Am J Physiol Gastrointest Liver Physiol 298: G255-G266, 2010. First published November 25, 2009; doi: 10.1152/ajpgi.00264.2009.-- Mucosal vascular addressin cell adhesion molecule 1 (MAdCAM-1) is an important target in the treatment of inflammatory bowel disease (1BD). Recently, treatment of IBD with an antibody to [alpha]4137-integrin, a ligand for MAdCAM-1, has been an intense focus of research. Our aim was to clarify the mechanism by which MAdCAM-1 is regulated via angiotensin II type 1 receptor (AT1R), and to verify if AT1R might be a novel target for IBD treatment. The role of AT1R in the expression of MAdCAM-1 in SVEC (a murine high endothelial venule cell) and MJC-1 (a mouse colonic endothelial cell) was examined following cytokine stimulation. We further evaluated the effect of AT1R on the pathogenesis of immunemediated colitis using AT1R-deficient (AT1R-/-) mice and a selective AT1R blocker. AT1R blocker significantly suppressed MAdCAM-1 expression induced by TNF-[alpha], but did not inhibit phosphorylation of p38 MAPK or of I[kappa]B that modulate MAdCAM-1 expression. However, NF-[kappa]B translocation into the nucleus was inhibited by these treatments. In a murine colitis model induced by dextran sulfate sodium, the degree of colitis, judged by body weight loss, histological damage, and the disease activity index, was much milder in AT1R-/- than in wild-type mice. The expression of MAdCAM-I was also significantly lower in AT1R-/- than in wild-type mice. These results suggest that AT1R regulates the expression of MAdCAM-1 under colonic inflammatory conditions through regulation of the translocation of NF-[kappa]B into the nucleus. Furthermore, inhibition of ATIR ameliorates colitis in a mouse colitis model. Therefore, AT1R might be one of new therapeutic target of IBD via regulation of MAdCAM-1. mucosal addressin cell adhesion molecule-l; inflammatory bowel disease; nuclear factor-[kappa]B doi: 10.1152/ajpgi.00264.2009

Am J Physiol Cell Physiol 298: C98-C106, 2010. First published October 21, 2009; doi: 10.1152/ajpcell.00321.2009.--As an endogenous physiologically active peptide, angiotensin (ANG) II plays an important role in the maintenance of blood pressure. In the arterial baroreceptor reflex (a pivotal regulator of blood pressure), aortic baroreceptor (AB) neurons located in the nodose ganglia (NG) are a primary afferent limb of the baroreflex. Hyperpolarization-activated currents ([I.sub.h]) in the AB neurons contribute to the excitability of the AB neurons. Therefore, the present study was to measure the modulating effect of ANG II on the [I.sub.h] in the primary AB neurons isolated from rats. Data from immunofluorescent and Western blot analyses showed that protein of [AT.sub.1] and [AT.sub.2] receptors was expressed in the nodose neurons. In the whole cell patch-clamp recording, ANG II concentration dependently enhanced the [I.sub.h] density in the AB neurons (100 nM ANG II-induced 53.8 [+ or -] 3.8% increase for A-type AB neurons and 30.4 [+ or -] 7.7% increase for C-type AB neurons at test pulse -140 mV, P < 0.05). ANG II also decreased membrane excitability in the AB neurons. [AT.sub.1] receptor antagonist (1 [micro]M losartan) but not [AT.sub.2] receptor antagonist (1 [micro]M PD-123,319) totally abolished the effect of ANG II on the [I.sub.h] and neuronal excitability. In addition, NADPH oxidase inhibitor (100 [micro]M apocynin) and superoxide scavenger (1 mM tempol) also significantly blunted the ANG II-induced increase of the [I.sub.h] and decrease of the membrane excitability in the AB neurons. Furthermore, losartan, apocynin, or tempol significantly attenuated the superoxide overproduction in the NG tissues induced by ANG II. These results suggest that ANG II-NADPH oxidase-superoxide signaling can activate the [I.sub.h] and subsequently decrease the membrane excitability of rat AB neurons. baroreflex; ion channels; NADPH oxidase; superoxide

Bouley R, Palomino Z, Tang S-S, Nunes P, Kobori H, Lu HA, Shum WW, Sabolic I, Brown D, Ingelfinger JR, Jung FF. Angiotensin II and hypertonicity modulate proximal tubular aquaporin 1 expression. Am J Physiol Renal Physiol 297: F1575-F1586, 2009. First published September 23, 2009; doi: 10.1152/ajprenal.90762.2008.--Aquaporin 1 (AQP1) is the major water channel in the renal proximal tubule (PT) and thin descending limb of Henle, but its regulation remains elusive. Here, we investigated the effect of ANG II, a key mediator of body water homeostasis, on AQP1 expression in immortalized rat proximal tubule cells (IRPTC) and rat kidney. Real-time PCR on IRPTC exposed to ANG II for 12 h revealed a biphasic effect AQP1 mRNA increased dose dependently in response to [10.sup.-12] to [10.sup.-8] M ANG II but decreased by 50% with [10.sup.-7] M ANG II. The twofold increase of AQP1 mRNA in the presence of [10.sup.-8] M ANG II was abolished by the AT1 receptor blocker losartan. Hypertonicity due to either NaCl or mannitol also upregulated AQP1 mRNA by threeand twofold, respectively. Immunocytochemistry and Western blotting revealed a two- to threefold increase in AQP1 protein expression in IRPTC exposed concomitantly to ANG II ([10.sup.-8]M) and hypertonic medium (either NaCl or mannitol), indicating that these stimuli were not additive. Three-dimensional reconstruction of confocal images suggested that AQP1 expression was increased by ANG II in both the apical and basolateral poles of IRPTC. In vivo studies showed that short-term ANG II infusion had a diuretic effect, while this effect was attenuated after several days of ANG II infusion. After 10 days, we observed a twofold increase in AQPI expression in the PT and thin descending limb of Henle of ANG II-infused rats that was abolished when rats were treated with the selective [AT.sub.1]-receptor antagonist olmesartan. Thus ANG II increases AQP1 expression in vitro and in vivo via direct interaction with the [AT.sub.1] receptor, providing an important regulatory mechanism to link PT water reabsorption to body fluid homeostasis via the renin-angiotensin system. renin angiotensin system; proximal tubule doi: 10.1152/ajprenal.90762.2008

To understand how rapid changes in blood pressure can regulate Na-K-ATPase in the kidney cortex, we tested the hypothesis that a short-term (5 min) decrease in renal perfusion pressure will increase the amount of Na-K-ATPase in the plasma membranes by an angiotensin II-dependent mechanism. The abdominal aorta of anesthetized Sprague-Dawley rats was constricted with a ligature between the renal arteries, and pressure was monitored on either side during acute constriction. Left renal perfusion pressure was reduced to 70 [+ or -] 1 mmHg (n = 6), whereas right renal perfusion pressure was 112 [+ or -] 4 mmHg. In control (nonconstricted) rats (n = 5), pressure to both kidneys was similar at 119 [+ or -] 6 mmHg. After 5 min of reduced perfusion, femoral venous samples were taken for plasma renin activity (PRA) and the kidneys excised. The cortex was dissected, minced, sieved, and biotinylated. Lower perfusion left kidneys showed a 41% increase (P < 0.003) in the amount of Na-K-ATPase in the plasma membrane compared with right kidneys. In controls, there was no difference in cell surface Na-K-ATPase between left and right kidneys (P = 0.47). PRA was 57% higher in experimental animals compared with controls. To test the role of angiotensin II in mediating the increase in Na-K-ATPase, we repeated the experiments (n = 6) in rats treated with ramiprilat. When angiotensin-converting enzyme was inhibited, the cell surface Na-K-ATPase of the two kidneys was equal (P = 0.46). These results confirm our hypothesis: rapid changes in blood pressure regulate trafficking of Na-K-ATPase in the kidney cortex. ouabain; sodium; blood pressure; renin doi: 10.1152/ajprenal.90363.2008.

The effects of chronic mild hypoxemia on the binding of angiotensin receptors in selected brain stem nuclei and reflex responses were studied in fetal sheep. Fetal and maternal catheters were placed at 120 days' gestation, and animals received intratracheal maternal administration of nitrogen (n = 16) or compressed air in controls (n = 19). Nitrogen infusion was adjusted to reduce fetal brachial artery P[O.sub.2] by 25% during 5 days. Spontaneous baroreflex sensitivity and spectral analysis of the pulse interval were analyzed during the 5 days hypoxemia period using 90 min of daily recording. Brains of control and hypoxemic animals were collected, and brain stem angiotensin receptor binding was studied by in vitro autoradiography at 130 days of gestation. After 5 days of hypoxemia, some animals in each group were submitted to one complete umbilical cord occlusion during 5 min. [[sup.125]I]sarthran binding showed that chronic mild hypoxemia significantly increases angiotensin type 1 receptor, angiotensin type 2 receptor, and ANG-(1-7) angiotensin receptor binding sites in the nucleus tractus solitarius and dorsal motor nucleus of the vagus (P < 0.05). Hypoxemia induced lower baroreflex sensitivity and a higher low frequency-to-high frequency ratio in the fetus, consistent with a shift from vagal to sympathetic autonomic cardiac regulation. Cord occlusion to elicit a chemoreflex response induced a greater bradycardic response in hypoxemic fetuses (slope of the initial fall in heart rate; 11.3 [+ or -] 1.9 vs. 6.4 [+ or -] 1.2 beats x [min.sup.-1] x [s.sup.-1], P < 0.05). In summary, chronic mild hypoxemia increased binding of angiotensin receptors in brain stem nuclei, decreased spontaneous barorefex gain, and increased chemoreflex responses to asphyxia in the fetus. These results suggest hypoxemia-induced alterations in brain stem mechanisms for cardiovascular control. fetus; hypoxemia; baroreflex

Breast cancer patients have benefited from the use of targeted therapies directed at specific molecular alterations. To identify additional opportunities for targeted therapy, we searched for genes with marked overexpression in subsets of tumors across a panel of breast cancer profiling studies comprising 3,200 microarray experiments. In addition to prioritizing ERBB2, we found AGTR1, the angiotensin II receptor type I, to be markedly overexpressed in 10-20% of breast cancer cases across multiple independent patient cohorts. Validation experiments confirmed that AGTR1 is highly overexpressed, in several cases more than 100-fold. AGTR1 overexpression was restricted to estrogen receptor-positive tumors and was mutually exclusive with ERBB2 overexpression across all samples. Ectopic overexpression of AGTR1 in primary mammary epithelial cells, combined with angiotensin II stimulation, led to a highly invasive phenotype that was attenuated by the AGTR1 antagonist losartan. Similarly, losartan reduced tumor growth by 30% in AGTR1-positive breast cancer xenografts. Taken together, these observations indicate that marked AGTR1 overexpression defines a subpopulation of ER-positive, ERBB2-negative breast cancer that may benefit from targeted therapy with AGTR1 antagonists, such as losartan.

The renin-angiotensin system (RAS) is a major mediator of renal injury in diabetic nephropathy. Our previous studies demonstrated that 1,25-dihydroxyvitamin [D.sub.3] [1,25[(OH).sub.2][D.sub.3]] plays a renoprotective role by suppressing the RAS, with renin and angiotensinogen (AGT) as the main targets. The mechanism whereby 1,25[(OH).sub.2][D.sub.3] transcriptionally suppresses renin gene expression has been elucidated; however, how vitamin D regulates AGT remains unknown. Exposure of mesangial cells or podocytes to high glucose (HG; 30 mM) markedly stimulated AGT expression. In mesangial cells, the stimulation was inhibited by 1,25[(OH).sub.2][D.sub.3] (20 nM) or NF-[kappa]B inhibitor BAY 11-7082, suggesting the involvement of NF-[kappa]B in HG-induced AGT expression and the interaction between 1,25[(OH).sub.2][D.sub.3] and NF-[kappa]B in the regulation. Plasmid pNF-[kappa]B-Luc luciferase reporter assays showed that 1,25[(OH).sub.2][D.sub.3] blocked HG-induced NF-[kappa]B activity. EMSA and ChIP assays demonstrated increased p65/p50 binding to a NF-[kappa]B binding site at--1734 in the AGT gene promoter upon high glucose stimulation, and the binding was disrupted by 1,25[(OH).sub.2][D.sub.3] treatment. Overexpression of p65/p50 overcame 1,25[(OH).sub.2][D.sub.3] suppression, and mutation of this NF-[kappa]B binding site blunted 1,25[(OH).sub.2][D.sub.3] suppression of the promoter activity. In mice lacking the vitamin D receptor, AGT mRNA expression in the kidney was markedly increased compared with wild-type mice, and AGT induction in diabetic mice was suppressed by treatment with a vitamin D analog. These data indicate that 1,25[(OH).sub.2][D.sub.3] suppresses hyperglycemia-induced AGT expression by blocking NF-[kappa]B-mediated pathway. vitamin D receptor; renin-angiotensin system; diabetic nephropathy

ANG II type 1 receptors ([AT.sub.1]R) mediate most of the central effects of ANG II on cardiovascular function, fluid homeostasis, and sympathetic drive. The mechanisms regulating [AT.sub.1]R expression in the brain are unknown. In some tissues, the [AT.sub.1]R can be upregulated by prolonged exposure to ANG II. We examined the hypothesis that ANG II upregulates the [AT.sub.1]R in the brain by stimulating the intracellular mitogen-activated protein kinase (MAPK) signaling pathway. Using molecular and immunochemical approaches, we examined expression of the [AT.sub.1]R and phosphorylated MAPK in the paraventricular nucleus of the hypothalamus (PVN) and the subfornical organ (SFO) of rats receiving a chronic (4-wk) subcutaneous infusion of ANG II (0.6 [micro]g/h) or saline (vehicle control), with or without concomitant (4-wk) intracerebroventricular (ICV) infusions of MAPK inhibitors or the [AT.sub.1]R blocker losartan. Subcutaneous infusion of ANG II markedly increased phosphorylation of MAPK and expression of [AT.sub.1]R mRNA and protein and [AT.sub.1]R-like immunoreactivity in the PVN and SFO. ANG II-induced [AT.sub.1]R expression was blocked by ICV infusion of the p44142 MAPK inhibitor PD-98059 (0.025 [micro]g/h) and the JNK inhibitor SP-600125 (0.125 [micro]g/h), but not by the p38 MAPK inhibitor SB203580 (0.125 [micro]g/h). Upregulation of the [AT.sub.1]R in the PVN and SFO by peripheral ANG II was abolished by ICV losartan (10 [micro]g/h). The data indicate that blood-borne ANG II upregulates brain [AT.sub.1]R by activating intracellular p44/42 MAPK and JNK signaling pathways. paraventricular nucleus; subfornical organ; angiotensin II type 1 receptor; autonomic regulation

Angiotensin II (Ang II) stimulation of the Ang type 1 receptor (A[T.sub.I]R) facilitates myocardial remodeling through NADPH oxidase-mediated generation of oxidative stress. Components of the renin-angiotensin system constitute an autocrine/paracrine unit in the myocardium, including renin, which is the rate-limiting step in the generation of Ang II. This investigation sought to determine whether cardiac oxidative stress and cellular remodeling could be attenuated by in vivo renin inhibition and/or A[T.sub.1]R blockade in a rodent model of chronically elevated tissue Ang II levels, the transgenic (mRen2)27 rat (Ren2). The Ren2 overexpresses the mouse renin transgene with resultant hypertension, insulin resistance, and cardiovascular damage. Young (6- to 7-wk-old) heterozygous (+/-) male Ren2 and age-matched Sprague-Dawley rats were treated with the renin inhibitor aliskiren, which has high preferential affinity for human and mouse renin, an A[T.sub.1]R blocker, irbesartan, or placebo for 3 wk. Myocardial NADPH oxidase activity and immunostaining for NADPH oxidase subunits and 3-nitrotyrosine were evaluated and remodeling changes assessed by light and transmission electron microscopy. Blood pressure, myocardial NADPH oxidase activity and subunit immunostaining, 3-nitrotyrosine, perivascular fibrosis, mitochondrial content, and markers of activity were significantly increased in Ren2 compared with SD littermates. Both renin inhibition and blockade of the A[T.sub.1]R significantly attenuated cardiac functional and structural alterations, although irbesartan treatment resulted in greater reductions of both blood pressure and markers of oxidative stress. Collectively, these data suggest that both reduce changes driven, in part, by Ang II-mediated increases in NADPH oxidase and, in part, increases in blood pressure. cardiac remodeling; reduced nicotinamide adenine dinucleotide phosphate oxidase; oxidative stress

[Ca.sup.+] influx across the plasma membrane is a major component of mesangial cell (MC) response to vasoconstrictors. Polycystin 2 (PC2), the protein product of the gene mutated in type 2 autosomal dominant polycystic kidney disease, has been shown to function as a nonselective cation channel in a variety of cell types. The present study was performed to test the hypothesis that PC2 and its binding partners constitute a [Ca.sup.2+]-permeable channel and contribute to ANG II-induced [Ca.sup.2+] signaling in MCs. Western blot and immunocy-to-chemistry showed PC2 expression in cultured human MCs. The existence of PC2 in MCs was further confirmed by immunohistochemsitry in rat kidney sections. Coimmunoprecipitation displayed a selective interaction of PC2 with canonical transient receptor potential (TRPC) proteins TRPC1 and TRPC4. Cell-attached patch-clamp experiments revealed that ANG II-induced membrane currents were enhanced by over-expression of pkd2 but significantly inhibited by knock down of pkd2, 30 [micro]M [Gd.sup.3+] (a PC2 channel blocker), and dominant-negative pkd2 mutant (pkd2-D511V). Corresponding to the increase in channel currents, ANG II stimulation increased expression of PC2 on the cell surface of MCs and interaction with TRPC1 and TRPC4. Furthermore, ANG H-induced MC contraction was significantly reduced in pkd2-knocked down MCs. These data suggest that PC2 selectively assembles with TRPC1 and TRPC4 to form channel complexes mediating ANG II-induced [Ca.sup.2+] responses in MCs. calcium channel

ADP-ribosyl cyclase (ADPR-cyclase) produces a [Ca.sup.2+]-mobilizing second messenger cyclic ADP-ribose (cADPR) from NA[D.sup.+]. In this study, we investigated the molecular basis of ADPR-cyclase activation and the following cellular events in angiotensin II (ANG II) signaling in mouse mesangial cells (MMCs). Treatment of MMCs with ANG II induced an increase in intracellular [Ca.sup.2+] concentrations through a transient [Ca.sup.2+] release via an inositol 1,4,5-trisphosphate receptor and a sustained [Ca.sup.2+] influx via L-type [Ca.sup.2+] channels. The sustained [Ca.sup.2+] signal, but not the transient [Ca.sup.2+] signal, was blocked by a cADPR antagonistic analog, 8-bromo-cADPR (8-Br-cADPR), and an ADPRcyclase inhibitor, 4,4'-dihydroxyazobenzene (DHAB). In support of the results, ANG II stimulated cADPR production in a time-dependent manner, and DHAB inhibited ANG II-induced cADPR production. Application of pharmacological inhibitors revealed that activation of ADPR-cyclase by ANG II involved ANG II type 1 receptor, phosphoinositide 3-kinase, protein tyrosine kinase, and phospolipase C-[gamma]1. Moreover, DHAB as well as 8-Br-cADPR abrogated ANG II-mediated Akt phosphorylation, nuclear translocation of nuclear factor of activated T cell, and uptake of [[sup.3]H]thymidine and [[sup.3]H]leucine in MMCs. These results demonstrate that ADPR-cyclase in MMCs plays a pivotal role in ANG II signaling for cell proliferation and protein synthesis. cyclic ADP-ribose; intracellular [Ca.sup.2+] concentration

Acidosis and angiotensin II stimulate ammonia production and transport by the proximal tubule. We examined the modulatory effect of the type 1 angiotensin II receptor blocker losartan on the ability of metabolic acidosis to stimulate ammonia production and secretion by mouse $2 proximal tubule segments. Mice given N[H.sub.4]Cl for 7 days developed metabolic acidosis (low serum bicarbonate concentration) and increased urinary excretion of ammonia. $2 tubule segments from acidotic mice displayed higher rates of ammonia production and secretion compared with those from control mice. However, when losartan was coadministered in vivo with N[H.sub.4]aCl, both the acidosisinduced increase in urinary ammonia excretion and the adaptive increase in ammonia production and secretion of microperfused S2 segments were largely blocked. In renal cortical tissue, losartan blocked the acid-induced increase in brush-border membrane NHE3 expression but had no effect on the acid-induced upregulation of phosphate-dependent glutaminase or phosphoenolpyruvate carboxykinase 1 in cortical homogenates. Addition of angiotensin II to the microperfusion solution enhanced ammonia secretion and production rates in tubules from N[H.sub.4]Cl-treated and control mice in a losartaninhibitable manner. These results demonstrate that a 7-day acid challenge induces an adaptive increase in ammonia production and secretion by the proximal tubule and suggest that during metabolic acidosis, angiotensin II signaling is necessary for adaptive enhancements of ammonia excretion by the kidney and ammonia production and secretion by S2 proximal tubule segments, as mediated, in part, by angiotensin receptor-dependent enhancement of NHE3 expression. ammonia transport; ammoniagenesis; acid-base physiology; losartan; sodium-hydrogen exchanger

Like humans, savannah baboons (Papiosp.) show heritable interindividual variation in complex physiological phenotypes. One prominent example of such variation involves production of the homeostatic regulator protein angiotensin converting enzyme (ACE), which shows heritable variation in both baboons and humans. In humans, this phenotypic variation is associated with an Alu insertion-deletion polymorphism in the ACE gene, which explains approximately half of the variation in serum ACE activity. We identified a similar Alu insertion-deletion polymorphism in the baboon ACE homologue and measured its frequency in a wild population and a captive population of baboons. We also analyzed the contribution of ACE genotype at this indel to variation in serum ACE activity in the captive population. When conditioned on weight, a known factor affect ing ACE activity in humans, age and ACE genotype both accounted for variance in ACE activity; in particular, we identified a significant nonadditive interaction between age and genotype. A model incorporating this interaction effect explained 21.6% of the variation in residual serum ACE activity. Individuals homozygous for the deletion mutation exhibited significantly higher levels of ACE activity than insertion-deletion heterozygotes at younger ages (10-14 years), but showed a trend towards lower levels of ACE activity compared with heterozygotes at older ages ([greater than or equal to]15 years). These results demonstrate an interesting parallel between the genetic architecture underlying ACE variation in humans and baboons, suggesting that further attention should be paid in humans to the relationship between ACE genetic variation and aging. KEY WORDS angiotensin converting enzyme; genotype-phenotype; Amboseli; parallel evolution

Byline: O. E. Mustafina (1), T. R. Nasibullin (1), E. K. Khusnutdinova (1) Keywords: human genomics; polymerase chain reaction; genetics of essential hypertension; T174M polymorphism; angiotensinogen gene; renin--angiotensin system Abstract: The alleles and genotypes of the T174M polymorphism of the angiotensinogen gene were PCR-analyzed in Russians and Tatars from Bashkortostan. The genotype frequency distribution observed in either ethnic group did not differ from that reported for other populations. The T174M polymorphism was tested for association with essential hypertension (EH). Genotypes TT, TM, and MM were found respectively in 82.56, 13.95, and 3.49% normotensive Russians and in 83.81, 16.19, and 0% normotensive Tatars. The frequency of genotype TM in patients with EH onset beyond 45 years of age was significantly higher than in controls of the same age without signs of cardiovascular disorders (51.72 vs. 11.11% in Russians and 45.45 vs. 16% in Tatars). Patients with EH onset under 45 did not differ in genotype frequency distribution from normotensive subjects of the same age. Genotype TM was associated with higher risk of EH in people over 45. Author Affiliation: (1) Institute of Biochemistry and Genetics, Ufa Research Center, Russian Academy of Sciences, Ufa, 450054, Russia Article History: Registration Date: 09/10/2004

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/S0002-8703(00)90315-6 Byline: Tamas Szombathy, Livia Janoskuti, Csaba Szalai, Albert Csaszar, Miklos Miklosi, Zsuzsa Meszaros, Pal Kempler, Zoltan Laszlo, Tamas Fenyvesi, Laszlo Romics Abstract: Background Mitral valve prolapse syndrome (MVPS), a term applied to patients who have a variety of symptoms, has been associated with autonomic or neuroendocrine dysfunction. Recent evidence suggests that effects of angiotensin II mediated by the angiotensin II type 1 (AT.sub.1) receptor are involved in modulation of cardiovascular autonomic control in human beings. Association of a genetic polymorphism (A-C.sup.1166) of the AT.sub.1 gene with abnormal vasomotion and low blood pressure related to autonomic control has been reported recently. Because the role of this genetic variant in MVPS has not been studied, we performed a case-control study of the A-C.sup.1166 variant in a group of 76 white subjects with MVPS. Methods and Results All patients were genotyped by use of a mismatch polymerase chain reaction/Afl II restriction fragment length polymorphism analysis. Frequency of the C.sup.1166 allele was 0.4 in patients with MVPS and 0.26 in control patients. The difference in genotype (chi square = 6.5; P < .05) and allele (chi square = 5.9; P = .02) frequencies between the groups was significant. The odds ratio in favor of carrying the C allele was 4 times greater for patients with MVP than for control patients (95% confidence interval 1.4 to 12.1). Conclusions The current results indicate that the A-C.sup.1166 polymorphism of the angiotensin II type 1 receptor gene is associated with MVPS in the white population. (Am Heart J 2000;139:101-5.) Author Affiliation: Budapest, Hungary From the.sup.aThird Department of Medicine, the Division of Cardiology, and the.sup.bDepartment of Pharmacodynamics, Semmelweis University..sup.CHeim Pal's Hospital, Molecular Genetics Laboratory; and the.sup.dDepartment of Cardiology, Szent Margit's Hospital Article History: Received 17 June 1998; Accepted 7 October 1998 Article Note: (footnote) [star] Supported by grant OTKA T016750 from the National Scientific Research Fund., [star][star] Reprint requests: Tamas Szombathy, MD, Third Department of Medicine, Semmelweis University, 4 Kutvolgyi ut, Budapest, 1125, Hungary., a 0002-8703/2000/$12.00 + 0 4/1/95077

Byline: Bernhard R. Winkelmann, Andreas P. Russ, Markus Nauck, Barbel Klein, Bernhard O. Bohm, Volker Maier, Rainer Zotz, Georg Matheis, Andreas Wolf, Heinrich Wieland, Werner GroA, David J. Galton, Winfried Marz Abstract: Background Genes encoding components of the renin-angiotensin system have been associated with elevated blood pressure (BP) and an increased risk of coronary artery disease. To explore the role of the angiotensinogen (AGT) gene in coronary atherosclerosis and thrombosis, we studied the effect of the AGT M235T gene variant on plasma AGT levels and BP in patients with coronary artery disease and in the subgroup of survivors of myocardial infarction as compared with angiographically defined control subjects. Methods and Results This was a case-control study of 301 white male subjects examined at Frankfurt University medical center. Plasma AGT levels increased stepwise according to the number of T235 alleles present (no T235 allele, 14.8 [+ or -] 3.9 nmol/L; 1 allele, 15.7 [+ or -] 5.1 nmol/L; 2 alleles, 17.3 [+ or -] 4.7 nmol/L; P = .006). In a multivariate model, circulating AGT emerged as the most important predictor of diastolic pressure (P = .001). In addition, AGT M235T gene polymorphism remained a significant predictor of diastolic BP in a multivariate model adjusted for age, body mass index, fasting glucose, apolipoprotein B, presence of coronary artery disease, and treatment with antihypertensive agents (P < .05). Finally, homozygosity for T235 was associated with increased univariate risk of coronary artery disease and myocardial infarction (odds ratio estimates 1.5; 95% confidence intervals 1.1 to 2.1, P = .03, and 1.0 to 2.1, P = .05, respectively). Conclusions The significant relations observed between the AGT M235T variant, its protein product, and the cardiovascular disease phenotypes provide evidence for a possible role of elevated circulating AGT in the pathogenesis of coronary artery disease. (Am Heart J 1999;137:698-705.) Author Affiliation: Ludwigshafen, Frankfurt, Freiburg, Ulm, and Dusseldorf, Germany, and London, United Kingdom From the Department of Cardiology, Ludwigshafen Heart Center; the Departments of Medicine, Heart Surgery, and Biochemistry, Johann Wolfgang Goethe University, Frankfurt; the Division of Clinical Chemistry, Department of Medicine, Albert Ludwigs University, Freiburg; the Department of Medicine, University Ulm; Institute of Blood Transfusion and Hemostasiology, University Dusseldorf; and the Department of Metabolism and Genetics, St Bartholomew's Hospital, London Article History: Received 12 March 1998; Accepted 12 June 1998 Article Note: (footnote) [star] Supported by research grants from Bristol-Myers Squibb GmbH, Munich, Germany (W.M.), the Commission of the European Community (D.J.G. and W.M.) (EEC Biomed Program PL931211), and Forschungsschwerpunkt Land Baden-Wurttemberg (B.O.B.)., [star][star] Reprint requests: Bernhard R. Winkelmann, MD, Herzzentrum Ludwigshafen, Klinikum der Stadt Ludwigshafen, Bremserstr 79, 67063 Ludwigshafen, Germany., a 0002-8703/99/$8.00 + 0 4/1/92529

Byline: John E. Sanderson, Cheuk M. Yu, Robert P. Young, Irene O.L. Shum, Shan Wei, Mano Arumanayagam, Kam S. Woo Abstract: Background An association between the DD allele of the angiotensin-converting enzyme gene and a poorer outcome in patients with heart failure has been found in whites. The DD allele frequency is lower in Chinese, but the M235T variant of the angiotensinogen gene is more common in Chinese than whites; it is not known to what extent polymorphisms of the renin-angiotensin system affect clinical status or prognosis in Chinese patients with heart failure. Methods We assessed the relations among polymorphism of the angiotensin-converting enzyme gene, angiotensinogen M235T (AGT) gene, and angiotensin type I receptor A1166C gene with left ventricular systolic function, left and right ventricular diastolic function, serum angiotensin-converting enzyme, plasma aldosterone and atrial natriuretic peptide levels at presentation, and clinical outcome at 1 year (survival, hospital admissions) in a cohort of Chinese patients with typical systolic heart failure (n = 82). Results We confirmed the low prevalence of the angiotensin-converting DD and the angiotensin type I receptor CC genotypes, and high prevalence of the AGT TT genotype in Chinese subjects compared with whites. There was no relation between the various gene polymorphisms and survival at 1 year assessed by multiple regression or Cox regression survival analysis. The AC variant of the angiotensin type I receptor gene was associated with morbidity over a 1-year period (hospital admissions) and increased baseline aldosterone levels, but none of the other polymorphisms correlated with systolic or diastolic function, aldosterone or atrial natriuretic peptide levels. By multiple regression for effects on mortality rate, only atrial natriuretic peptide and age were significant. Conclusions In Chinese patients with heart failure, polymorphisms of the renin-angiotensin system do not appear to be related to survival or severity, probably because of the different prevalence of these genotypes in the Chinese. Thus this study illustrates that large interethnic differences in the frequencies of genotype polymorphisms of the renin-angiotensin system exist and results from one ethnic group cannot be extrapolated to another. (Am Heart J 1999;137:653-7.) Author Affiliation: Hong Kong, People's Republic of China From the departments of Medicine and Therapeutics and Chemical Pathology,* The Chinese University of Hong Kong, Prince of Wales Hospital Article History: Received 9 December 1997; Accepted 15 May 1998 Article Note: (footnote) [star] Supported by a grant from the Hong Kong Government Research Grant Council (Ref no. CUHK 427/95M)., [star][star] Reprint requests: John E. Sanderson, Department of Medicine & Therapeutics, The Chinese University of Hong Kong, 9/F Clinical Sciences Bldg, Prince of Wales Hospital, Shatin, N.T., Hong Kong.E-mail: jesanderson@cuhk.edu.hk , a 0002-8703/99/$8.00 + 0 4/1/93211

Byline: Wayne H-H Sheu, W-J Lee, C-Y Jeng, Mason S. Young, Y-A Ding, Y-T Chen Abstract: Background Variants of the angiotensinogen gene may increase the risk of having arterial hypertension and coronary heart disease (CHD), but their effect on insulin resistance remains unknown. Methods We determined M235 and T174 allele status and fasting plasma glucose, insulin, and lipids values in nondiabetic men with CHD documented on angiography (n = 102) and in a control group (n = 145). Plasma glucose and insulin responses to 75 gm oral glucose tolerant test and insulin resistance as measured by an insulin suppression test were also carried out in 46 (45%) patients with CHD and in 73 (50%) members of a control group. Results We found no association between M235T status and blood pressure, fasting plasma glucose, insulin, most of the lipids values, and insulin resistance in patients with CHD and normal subjects. Nevertheless, compared with individuals with homozygotes T174, subjects with heterozygotes T174M were associated with greater glucose and insulin response to the oral glucose tolerance test and insulin resistance indicated by higher steady state plasma glucose concentrations in patients with CHD (14.7 [+ or -] 0.9 vs 11.3 [+ or -] 0.7 mmol/L, p < 0.04). Similar findings were found in the control group, with higher steady-state plasma glucose values in individuals with heterozygotes T174M than in those with homozygotes T174 (10.1 [+ or -] 1.4 vs 7.7 [+ or -] 0.4 mmol/L, p < 0.05). Conclusion We suggest that the angiotensinogen T174M allele might be associated with insulin resistance in nondiabetic men with and without CHD. (Am Heart J 1998;136:125-31.) Author Affiliation: Taichung and Taipei, Taiwan, Republic of China Article History: Received 20 August 1997; Accepted 16 January 1998 Article Note: (footnote) [star] From the Divisons of aEndocrinology and Metabolism and dCardiology, Department of Medicine, Taichung Veterans General Hospital, Taichung; the Divisions of bEndocrinology and Metabolism cCardiology, Tri-Service General Hospital, Taipei; National Defense Medical Center and National Yang-Ming University., [star][star] Supported by grants from National Science Council, Taiwan (NSC 86-2314-B075A-024) and from Taichung Veterans General Hospital, Taiwan (TCVGH 86-3501C and VGHTH 86-025-3)., a Reprint requests: Wayne H-H Sheu, MD, Division of Endocrinology and Metabolism, Taichung Veterans General Hospital, No. 160, Section 3, Taichung, Taiwan 407, ROC., aa 4/1/89190

Transgenic mice having the human angiotensinogen (HAGT) gene were used to examine the developmental regulation of HAGT expression. HAGT expression was first observed at embryonic day 8.5 (E8.5) and was present in large quantities from E9.5 onward. There were moderate amounts of HAGT mRNA in liver and kidney and small amounts in heart and brain from E16.5 onward. Data showed that sequences found in the transgene can confer the proper developmental expression profile.

The tissue-specific regulation of angiotensinogen gene expression in Wistar fatty rats (WFRs) and control Wistar lean rats (WLRs) was analyzed during the development of obesity. WLRs and WFRs exhibited age-related changes in body weight including higher levels of systolic blood pressure in WFRs. Angiotensinogen messenger RNA expression was also controlled in a tissue- and development-specific manner in WFRs and WLRs. Furthermore, adipogenic differentiation in the preadipocyte culture system induced angiotensinogen gene expression.

Gene targeting experiments were conducted on the murine angiotensin type 1B (AT1B) receptor gene (Agtr1B) to determine the role of selective Agrt1b gene inactivation on the renal and adrenal gland morphological defects. Interruption of the exon3 of murine Agtr1B via gene targeting of embryonic stem cells failed to induce abnormal morphological development in murine adrenal gland and kidneys. The development of normal organs after Agtr1b deletion indicated the presence of an angiotensin-independent mechanism that induces hyperaldosteronism.

Byline: Alisher Ishanov, Hiroshi Okamoto, Keiji Yoneya, Masashi Watanabe, Izumi Nakagawa, Masaharu Machida, Hisao Onozuka, Taisei Mikami, Hideaki Kawaguchi, Akira Hata, Kiyotaro Kondo, Akira Kitabatake Abstract: To examine the contribution of the renin-angiotensin system to hypertrophic cardiomyopathy (HCM), we studied 96 patients with HCM (mean age 50 years, 55% male), 105 of their unaffected siblings and offspring, and 160 healthy subjects without known hypertension and left ventricular hypertrophy (LVH) who were frequency matched to cases by age and sex. Patients were divided into familial or sporadic HCM (FHCM or SHCM) groups with or without affected members of their family. The region of interest in the angiotensinogen (AGT) gene, the missense mutation with methione-to-threonine amino acid substitution at codon 235 in angiotensinogen (M235T), was amplified by polymerase chain reaction with the use of allele-specific oligonucleotide primers flanking the polymorphic region of the AGT gene to amplify template deoxyribonucleic acid prepared from peripheral leukocytes. The T allele frequency was higher in the SHCM group than in unaffected siblings and offspring (88% vs 78%, I.sup.2 = 4.6, p < 0.05). The M allele frequency was higher in unaffected siblings and offspring than in patients with SHCM (23% vs 12%, I.sup.2 = 4.6, p < 0.05). The T allele frequency among unaffected siblings and offspring was similar to that observed in healthy subjects (78% vs 78%). We conclude that HCM, especially in sporadic cases, is partially determined by genetic disposition. The molecular variant of angiotensinogen T235 seems to be a predisposing factor for cardiac hypertrophy in HCM and carries an approximately twofold increased risk. (Am Heart J 1997;133:184-9.) Author Affiliation: Sapporo, Japan Article History: Received 1 May 1996; Accepted 15 July 1996 Article Note: (footnote) [star] Supported in part by research grants on cardiomyopathy from the Ministry of Health and Welfare of Japan, the Hokkaido Heart Foundation, and Grants-in-Aid for Scientific Research from the Ministry of Education, Science and Culture of Japan, Grant Nos. 06404033, 06454283, 06670684, 07557342, and 07670743., [star][star] Reprint requests: Hiroshi Okamoto, MD, PhD, Department of Cardiovascular Medicine, Hokkaido University School of Medicine, Kita-15, Nishi-7, Kita-ku, Sapporo 060, Japan., a 4/1/77767