Thesis (Ph.D.)--Kent State University, 2006. / Title from PDF t.p. (viewed Jan. 11, 2007 ) Advisor: J Gary Meszaros. Keywords: cardiac fibroblast, angiotensin II, fibrosis, MAPK Includes bibliographical references (p. 150-168).

Thesis (Ph. D.)--University of Texas at Austin, 2006. / Vita. Includes bibliographical references.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / A doenÃa renal crÃnica (DRC) à caracterizada pela perda normalmente lenta, progressiva e irreversÃvel da funÃÃo renal. Sugere-se que, nesta patologia, a resposta natriurÃtica do organismo à ingestÃo de sal e a expansÃo de volume encontra-se reduzida em consequÃncia da lesÃo dos nÃfrons. Nesse contexto, mostram-se necessÃrios estudos que estabeleÃam uma relaÃÃo entre a DRC e a regulaÃÃo de peptÃdeos natriurÃticos, como guanilina (Gn), uroguanilina (UGn) e peptÃdeo natriurÃtico atrial (PNA), e o efeito da angiotensina II (AngII) sobre a regulaÃÃo destes peptÃdeos. Assim, buscou-se avaliar uma possÃvel modulaÃÃo da via das guanilinas pelo enalapril no modelo de nefrectomia 5/6 (nx5/6). Utilizou-se ratos Wistar, machos, com peso entre 250-300g. Os animais foram divididos em 4 grupos (n=8): grupos controle sem tratamento ou tratado com enalapril (10mg/kg v.o.) (SHAM e SHAM+E) e grupos submetidos à nx 5/6 sem tratamento ou tratado com enalapril (10 mg/kg v.o.) (Nx e Nx+E). Ao final da 10 semana apÃs a cirurgia, foram determinados alguns marcadores de funÃÃo renal. As amostras de rim foram encaminhadas para anÃlise histolÃgica e avaliaÃÃo expressÃo de RNAm para Gn, UGn, PNA e dos receptores da guanilato ciclase de membrana, GC-A e GC-C e do receptor de clearence (NPR-C). No intestino, determinou-se a expressÃo de RNAm para Gn, UGn e G-C. Nx apresentou os nÃveis sÃricos de creatinina (Nx= 1.28  0.07; SHAM= 0.67  0.02 mg/dL), urÃia (Nx=108.0  5.57; SHAM=96.83  4.08 mg/dL), proteinÃria (Nx=129.10  13.87 SHAM=96.83  4.07; mg/24hrs) e FENa+ (Nx=3.552  0.56; SHAM=1.43  0.16) aumentados, e a TFG (Nx=0.44  0.10  0.04; SHAM=0.97  0.07 mL/min) diminuÃda. Nx+E, quando comparado a Nx, apresentou nÃveis reduzidos de creatinina (Nx+E= 0.97  0.08; Nx=1.28  0.07 mg/dL), de proteinÃria (Nx+E=31.94  6.46 Nx= 129.10  13.87 mg/24hrs) e da FENa+ (Nx+E= 2.02  0.28; Nx=3.55  0.56), alÃm elevar a TFG (Nx+E=0.70  0.08; Nx=0.44  0.10 mL/min). Nx apresentou aumento da expressÃo gÃnica intra-renal de Gn (Nx=13.92  5.13; SHAM=1.08  0.20), UGn (Nx=12.77  7.00; SHAM=1.04  0.13), GC-A (Nx=5.91  1.36; SHAM=1.06  0.17) e NPR-C (Nx=7.835  1.72; SHAM=1.15  0.27), e Nx+E teve genes reduzidos para UGn (Nx+E=0.10  0.03; Nx=1.75  0.96), GC-A (Nx+E=0.031  0.01; Nx=1.18  0.27) e NPR-C (Nx+E=0.03  0.01; Nx=1.08  0.24) quando comparados a Nx. No intestino, houve uma reduÃÃo da transcriÃÃo de GC-C (Nx=0,22Â0,04; SHAM=1.12  0.22) em Nx, e o enalapril aumentou os nÃveis de expressÃo deste gene (Nx+E=3.94  0.57; Nx=1.15  0.22). Em conjunto, estes dados sugerem uma hiperativaÃÃo na via das guanilinas na DRC, alÃm de modulaÃÃo dessa classe de peptÃdeos por parte da AngII.

As espécies reativas de oxigênio (EROs) são intermediários de vias de sinalização que regulam eventos celulares relevantes na função de células musculares lisas vasculares como migração, proliferação e contração. A NADPH oxidase é a principal fonte enzimática de EROs com finalidade sinalizadora no sistema cardiovascular. Estudos do nosso grupo demonstraram que a proteína dissulfeto isomerase (PDI), uma chaperona redox do retículo endoplasmåtico é capaz de modular a geração de EROs e a ativação de vias de sinalização redox dependentes pela Ang II. Apesar dos recentes avanços na compreensão dos mecanismos que regulam a interação entre a PDI e NADPH oxidase, o papel desta chaperona nos efeitos biológicos relacionados a EROs, como a contração vascular, não estão esclarecidos. A inibição da resposta contrátil pelo DTNB, um oxidante de tióis sugere o envolvimento de proteínas contendo tióis como a PDI e a NADPH oxidase na contração de aortas isoladas estimuladas com Ang II. Estes resultados foram confirmados por experimentos que demonstraram a expressão de PDI em todas as camadas vasculares da aorta de ratos Wistar e uma co-localização desta proteína com a isoforma NOX-1. A inibição da PDI diminuiu a geração de EROs e a reatividade vascular induzida por Ang II e NOR independente da presença do endotélio. A investigação dos mecanismos envolvidos sugere um papel da PDI na mobilização de cálcio dos estoques intracelulares via NADPH oxidase. A ativação de MAP quinases contribuiu para aumentar a mobilização de cálcio intracelular em aortas estimuladas com Ang II e NOR. No entanto, a inibição da PDI reduziu a fosforilação da ERK 1/2 em aortas estimuladas com Ang II, mas não com NOR. A análise conjunta dos nossos resultados sugere que mecanismos redox dependentes e independentes estariam envolvidos na regulação da resposta contrátil à Ang II e NOR pela PDI. / The reactive oxygen species (ROS) are intermediates of signaling pathways which regulates cellular events relevant for the vascular smooth cells function as migration, proliferation and contraction.The NADPH oxidase is the main enzimatic source of ROS with the signaling purpose on the cardiovascular system. We previously demonstrated that the protein disulfide isomerase (PDI), a redox chaperone of endoplasmic reticulum, is able to modulate the ROS generation and the activation of signaling redox ways dependent of Ang II. Although the recent advances in the understanding of mechanisms that regulate the interaction of PDI and NADPH oxidase, the role of this chaperone in the biological effects related to ROS, as vascular contraction, are not well clarified. The inhibition of the contractile response by DTNB, an oxidant thiol, suggest the involvement of proteins containing thiols as the PDI and NADPH oxidase in the contraction of isolated aortas stimulated with Ang II. These results were confirmed by experiments that demonstrated the PDI expression in Wistar rats vascular layers and a co-localization of this protein with the NOX-1 isoform. The PDI inhibition decreased ROS generation and the Ang II and NOR induced vascular reactivity endothelium independent. The investigation of involved mechanisms suggest that one PDI role is the calcium mobilization from the intracellular storage by NADPH oxidase way. The MAPkinases activation contributed to increase de intracellualar calcium in stimulated aortas with AngII and NOR. However, the PDI inhibition reduced the ERK ½ fosforilation in AngII- stimulated aorta, but not with NOR. The analyses of all of our results suggests that dependent and independent redox mechanims were involved in the regulation of contractile response to Ang II and NOR by PDI.

CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / A Angiotensina II (Ang II) exerce suas aÃÃes via receptores AT1 e AT2. Estudos recentes demonstraram que o sistema-renina-angiotensina (SRA) participa da inflamaÃÃo. O objetivo desse estudo foi avaliar o efeito da Ang II em modelos de inflamaÃÃo aguda. Ratos Wistar foram separados nos grupos: salina (Sal), Ang II (1 Âg), losartan (LOS, antagonista de AT1, 62,5 Âg) e CGP42112A (agonista de AT2, 142,5 Âg). O edema de pata foi induzido pela injeÃÃo subplantar (sp) de carragenina (Cg, 100 Âg) ou dextran (DXT, 100 Âg) e foi medido com pletismÃmetro em 0, 1, 2, 3 e 4h. Nos grupos Sal e Ang II, foi colhido tecido da pata para se determinar os nÃveis de mieloperoxidase (MPO), IL-1e TNF-α . Tecidos subcutÃneo e mesentÃrico foram removidos para avaliaÃÃo da degranulaÃÃo de mastÃcitos atravÃs da coloraÃÃo com azul de toluidina. Os grupos Sal e Ang II do edema de pata induzido por DXT foram tratados com mepiramina (MEP, anti-histamÃnico, 10mg/kg) ou metisergida (MET, anti-serotonÃnico, 1,5mg/kg) 1h antes da injeÃÃo de DXT. Ang II (0,5Âg/cavidade, ip) foi injetada 1h antes da injeÃÃo ip de Cg para analisar a migraÃÃo de neutrÃfilos para a cavidade peritoneal. Ang II, LOS e CGP amplificaram o edema de pata induzido por Cg e DXT e essa amplificaÃÃo foi significativa jà na primeira hora. A administraÃÃo de Ang II nÃo alterou a dosagem tecidual de MPO, TNF-α e IL-1 e nÃo induziu ou preveniu a migraÃÃo de neutrÃfilos para a cavidade peritoneal, mas induziu amplificaÃÃo significativa da degranulaÃÃo de mastÃcitos. MEP e MET reduziram a potenciaÃÃo do edema do DXT pela Ang II. Nossos resultados sugerem que a Ang II potenciou a resposta inflamatÃria provavelmente atravÃs de receptores AT2, jà que o antagonista de AT1, o agonista de AT2 e a Ang II amplificaram o edema de pata. Os dados apresentados aqui sugerem que Ang II aumentou a permeabilidade vascular atravÃs da induÃÃo da degranulaÃÃo de mastÃcitos, uma vez que houve amplificaÃÃo precoce do edema de pata da Cg e do edema vascular do DXT, e os antagonistas de serotonina e de histamina inibiram significativamente o aumento do edema de pata. / Angiotensin II (Ang II) exerts its actions via AT1 and AT2 receptors. Recent studies have demonstrated that the renin-angiotensin system (RAS) participates in inflammation. The aim of this study was to evaluate the effect of Ang II on models of acute inflammation. Wistar rats were separated in the groups: saline (Sal), Ang II (1Âg), losartan (LOS, AT1 antagonist, 62.5Âg) and CGP42112A (AT2 agonist, 142.5Âg). Paw edema was induced by subplantar injection of carrageenan (Cg, 100Âg) or dextran (DXT, 100Âg) and was measured with a plethysmometer at 0, 1, 2, 3 and 4h. In the Sal and Ang II groups, paw tissue was taken to determine myeloperoxidase (MPO), IL-1 and TNF-α levels. Subcutaneus and mesenterium tissue were taken to evaluate mast cell degranulation through the toluidine blue staining. Sal and Ang II groups of DXT-induced paw edema were treated i.p. with mepyramine (MEP, anti-histamine, 10mg/kg) or metisergyde (MET, anti-serotonin, 1.5mg/kg) 1h prior to the injection of DXT. Ang II (0.5Âg/cavity, ip) was injected i.p. 1h before the i.p. injection of Cg to analyse the leukocytes migration to the peritoneal cavity. Ang II, LOS and CGP enhanced the Cg and DXT-induced paw edema and this enhancement was already significant at 1h. The administration of Ang II did not change the tissue content of MPO, TNF-α and IL-1 and did not induced or prevented neutrophil migration to peritoneal cavity, but induced significant enhancement of mast cell degranulation. MEP and MET reduced the Ang II-facilitated DXT-induced edema. Our results suggest that Ang II enhances the inflammatory response probably through the AT2 receptors since the AT1 antagonist, AT2 agonist and Ang II potentiated the paw edema. The data presented here also suggest that Ang II increases the vascular permeability through induction of mast cells degranulation, since there was early amplification of Cg paw edema and DXT vascular edema, and antagonists of serotonin and histamine significantly inhibited the increase in paw edema.

Em roedores, a administração de Losartan (LO) durante a nefrogênese (primeiras duas semanas de vida) leva à insuficiência renal progressiva e, mais tardiamente, à hipertensão, indicando que a Angiotensina II (AII) é indispensável a uma nefrogênese adequada. Os mediadores intracelulares desse efeito são desconhecidos. Nós investigamos se o sistema NF-kB, que tem influência na embriogênese de outros tecidos, poderia ser um desses mediadores. Trinta e duas ratas Munich Wistar, cada uma amamentando 6 filhotes, foram divididas em dois grupos: C, sem tratamento, e PDTC, que receberam o inibidor do NF-kB Pirrolidina Ditiocarbamato (PDTC), 280 mg/kg/dia na água de beber durante 21 dias. A prole (C e PDTC), constituída de ratos machos, foi acompanhada até 10 meses de vida sem qualquer tratamento. Diferentemente do observado anteriormente com o LO, o PDTC não promoveu redução do número de néfrons nem albuminúria, indicando que o sistema NF-kB não participa crucialmente da nefrogênese. No entanto, os ratos que receberam o PDTC durante a lactação apresentaram hipertensão persistente, associada a hipertrofia de miócitos e a fibrose miocárdica. Para investigar a patogênese da hipertensão (que não se pode explicar por uma redução no número de néfrons), as expressões renais dos componentes do sistema renina-angiotensina (SRA) e dos transportadores tubulares foram determinadas por PCR em tempo real (qRT-PCR) aos 3 e 10 meses de vida. Aos 3 meses, a expressão de angiotensinogênio (AGT) e renina foram significativamente aumentadas no grupo PDTC vs C, indicando que uma ativação local do SRA pode explicar o desenvolvimento da hipertensão no grupo PDTC. No entanto, a expressão de todos os componentes do SRA examinados nos animais que receberam o PDTC durante a nefrogênese estava diminuída aos 10 meses, possivelmente devido a um mecanismo compensatório, sugerindo que a hipertensão foi mantida por outros mecanismos. No túbulo proximal, observou-se um aumento da expressão do transportador sódio/glicose isoforma 1 (SGLT1) (luminal) e sódio/bicarbonato (NBC) (basolateral), bem como um aumento numérico na expressão do trocador luminal sódio/hidrogênio isoforma 3 (NHE3), sugerindo que essas anormalidades podem estar envolvidas na patogênese da hipertensão nesses animais. Aos 10 meses, a expressão de todas as moléculas estava diminuída, sugerindo a participação de outros mecanismos na manutenção da hipertensão em longo prazo. A administração de PDTC pode representar um novo modelo de hipertensão essencial, possivelmente iniciada pela ativação local do SRA e por anormalidades no transporte de sódio no túbulo proximal e mantida em longo prazo por outros mecanismos. / Losartan treatment during late murine nephrogenesis (first 2 weeks of extrauterine life) causes progressive renal injury in adult life and, at more advanced stages, hypertension, indicating a physiologic action of angiotensin II on nephrogenesis. The possible intracellular pathways that might mediate this effect are unknown. We investigated the possibility that the NF-kB system, known to participate in the embryogenesis of other tissues, could be one of these mediators. Soon after delivery, thirty-two Munich-Wistar dams, each nursing 6 male pups, were divided in 2 groups: C, untreated, and PDTC, receiving the NF-kB inhibitor pyrrolidine dithiocarbamate (PDTC), 280 mg/kg/day in drinking water during 21 days. After weaning (at 25 days), the offspring (C and PDTC) were followed until 10 months of age with no further treatment. Unlike Losartan, neonatal PDTC treatment promoted no reduction in the number of nephrons and no abnormal albuminuria, indicating that the NF-kB system does not participate decisively in nephrogenesis. Nevertheless, rats that received PDTC during lactation exhibited stable hypertension associated with myocardial hypertrophy and fibrosis. To investigate the pathogenesis of hypertension, which cannot be ascribed to number of nephrons reduction, the renal expressions of the renin-angiotensin system (RAS) components and of several molecules involved in sodium transport were determined by qRT-PCR at 3 and 10 months of life. The renal expression of renin and angiotensinogen in PDTC-treated rats at 3 months of age was significantly higher in comparison with control, but lower than age-matched controls at 10 months of age, suggesting that, although hypertension may be initiated by a derangement in the RAS, it was maintained by other mechanisms in the long run. At 3 months of age, there was upregulation of the luminal sodium/glucose transporter and the basolateral sodium/bicarbonate transporter at the proximal tubule, as well as a numerically higher expression of the luminal sodium/hydrogen exchanger, suggesting that these abnormalities might also be related to the pathogenesis of hypertension in these rats. At 10 months of age, however, the expression of all these transporters was reduced, suggesting that none of them was responsible for the long-term maintenance of high blood pressure. Neonatal PDTC administration represents a new model of essential hypertension, possibly related to local renal activation of the RAS and to deranged sodium transport at the proximal tubule. In the long run, hypertension must be maintained by other mechanisms.

Abstract Cardiac pathologies, including ventricular hypertrophy, are the primary cause of death in industrialized countries. Cardiac hypertrophy is often the consequence of work overload on the heart and characterizes several cardiovascular diseases, including atherosclerosis and hypertension. Cardiac hypertrophy is accompanied by genetic reprogramming characterized by the reexpression of several embryonic and growth response genes. Two of these genes encode A- and B-type natriuretic peptides (ANP and BNP), two cardiac-specific hormones secreted by myocytes, which play an important role in blood pressure regulation. The aim of the present study was to study the effect of acute pressure overload on BNP gene expression in the hearts of normal and hypertensive rats and then to examine the role of a passerine factor, angiotensin II (Ang II), on volume and pressure overload -induced ANP and BNP secretion and synthesis. Further, the aim was to characterize elements on the BNP promoter mediating hemodynamic stress in vivo. BNP gene expression was studied in conscious spontaneously hypertensive (SHR) rats and together with ANP in two hypertensive, ream Transgenic rat models. The increased workload of the heart was produced by the infusion of vasopressin (AVP), phenylephrine (PHE) or bolus saline infusion. The increased workload caused rapid increases in cardiac BNP mRNA levels. Daring both AVP and PHE infusions, substantial increases in ventricular BNP mRNA levels were already evident after I h, and peak levels of BNP mRNA were reached at 4 h. Transgenic rats carrying one extra mouse renin gene showed impaired secretion and synthesis of ANP and BNP, while double transgenic rats carrying both human angiotensinogen and human renin genes showed augmentation of left atrial, but not ventricular BNP gene expression in response ta acute pressure overload. To characterize the elements mediating hemodynamic stress, bi-lateral nephrectomy was performed. GATA motif transduced the hemodynamic stress stimulus 26–28 hrs postnephrectomy in BNP gene expression.In conclusion, these results show that pressure overload abruptly stimulates the cardiac expression of a noncontractile protein gene BNP, suggesting that it may be used as a myocyte-specific marker of mechanical loading. BNP gene expression was augmented in atria hut nut in ventricles in response to pressure overload in an experimental model of hypertension, suggesting that high local levels of Ang II may differentially regulate cardiac gene expression in atrial and ventricular myocytes in double transgenic rats. At the transcriptional level, acute hemodynamic stress produced by nephrectomy increases BNP reporter expression through a GATA-dependent pathway.

Na+ sensitive hypertension in Dahl salt sensitive rats (Dahl S) or spontaneously hypertensive rats (SHR) is linked to intrinsic changes in the brain that favour increased Na+ entry into the cerebrospinal fluid (CSF) followed by increases in sympathetic hyperactivity and hypertension (Huang et al 2004). Similar responses are observed in salt resistant and Wistar rats that receive an intracerebroventricular (icv) infusion of Na+ rich artificial cerebrospinal fluid (aCSF) (Huang et al 2001, 2006). Downstream to increased CSF[Na+], a pathway has been described involving mineralocorticoid receptors (MRs), benzamil sensitive Na+ channels, “ouabain”, and angiotensin II type 1 receptors (AT1-R) (Huang et al 1998, Zhao et al 2001, Wang and Leenen 2003, Huang et al 2008). Blood pressure (BP) responses to increased CSF[Na+] may involve activation of AT1-R in the subfornical organ (SFO) as the BP response to injection of NaCl into a lateral ventricle can be blocked by AT1-R blockade in the SFO (Rohmeiss et al 1995a). The role of aldosterone and AT1-R in the SFO was investigated in mediating the BP and heart rate (HR) response to increases in CSF[Na+] and local [Na+]. Results show that infusion of 0.45M and 0.6M Na+ rich aCSF into the SFO increases BP but not HR. The BP is unchanged by infusion of a mannitol solution osmotically equivalent to 0.6M Na+ rich aCSF indicating that the SFO is Na+ sensitive. The BP response to a lower concentration of Na+ (0.45M) is enhanced by prior infusion of aldosterone while BP response to 0.6M is not further enhanced suggesting that the SFO may have maximal responsiveness to acute increases in [Na+] at 0.6M. The BP responses to Na+ rich aCSF in the SFO and the enhancement of those responses by aldosterone can be blocked by infusion of the AT1-R blocker Candesartan in the SFO. This response appears therefore to be mediated in the SFO through AT1-R activation, likely through Ang II release in the SFO. ICV infusion of Na+ rich aCSF increases BP but not HR and this response is partially blocked by infusion of the AT1-R blocker Candesartan in the SFO. This indicates that nearly half the BP responses to icv infusion of Na+ rich aCSF is mediated through AT1-R activation in the SFO. Lastly, contrary to icv, PVN and MnPO studies (Huang and Leenen 1996, Budzikowski and Leenen 2001, Gabor and Leenen 2009) ouabain in the SFO does not increase BP or HR. In conclusion, these results show that the SFO is Na+ sensitive and mediates half the BP responses to changes in CSF[Na+] through a mechanism that involves AT1-R activation. The SFO is further sensitized to Na+ by aldosterone presumably through its genomic effects. Lastly, ouabain in the SFO does not increase BP or HR suggesting that endogenous ouabain in the SFO is not involved in modulating BP or HR responses.

Angiotensin II (Ang II) is an important modulator for development of atherosclerosis from early stage foam cell formation to advanced stage plaque rupture. Recently, the importance of locally generated Ang II, especially in macrophages, has become more evident. Generation of Ang II by several enzymes other than ACE and renin has been shown mainly in vitro. Cathepsin G is one these enzymes which is expressed in neutrophils and macrophages. Macrophages are one of the primary and crucial cells in atherosclerotic lesions which become lipid-laden foam cells through lipoprotein uptake. We hypothesized that activation of nuclear factors in foam cells increases Ang II by modulation of the renin angiotensin system (RAS) genes and cathepsin G. We also hypothesized that cathepsin G, through its Ang II generating activity and its other catalytic functions, promotes atherosclerosis. The present study assessed the Ang I and II levels and expression of the RAS genes in THP-1 cells, a human acute monocytic leukemia cell line, and in peritoneal and bone marrow-derived macrophages after exposure to acetylated LDL (ac-LDL). I also evaluated how RAS blockade would affect foam cell formation in THP-1 cells. In parallel, I assessed the role of cathepsin G in Ang II generation and in the progression of atherosclerosis in cathepsin G heterozygous knockout mice on an Apoe-/- background (Ctsg+/-Apoe-/- mice). Ac-LDL treatment increased Ang I and Ang II levels in cell lysates and media from THP-1 cells but not in peritoneal or bone marrow-derived macrophages from wild type C57BL/6 mice. In ac-LDL-treated THP-1 cells, ACE and cathepsin G mRNA levels and activities were elevated. Angiotensinogen mRNA is increased but not the angiotensinogen protein concentration. Renin mRNA level and activity were not altered by ac-LDL treatment. Blocking RAS by an AT1 receptor blocker, ACE inhibitors or a renin inhibitor decreased cholesteryl ester content of THP-1 cells after exposure to ac-LDL. To confirm that the Ang II effect on foam cell formation was not unique to ac-LDL, we treated the THP-1 macrophages with a renin inhibitor or an AT1 receptor inhibitor after exposure to oxidized LDL (ox-LDL). RAS blockade in ox-LDL-treated cells also abolished cholesteryl ester formation. To see how Ang II plays a role in foam cell formation we assessed the effect of RAS inhibitors on SR-A, the principal receptor for mediating ac-LDL entry into the cells and on acyl-CoA:cholesterol acyl transferase (ACAT-1), the enzyme responsible for intracellular cholesterol esterification. RAS blockade in both ac-LDL- and ox-LDL-treated cells decreased SR-A and ACAT-1 protein levels. Cathepsin G partial deficiency on an Apoe-/- background did not change Ang II levels in peritoneal or bone marrow-derived macrophage cell lysates or media. This deficiency also did not affect immunoreactive angiotensin peptide levels in atherosclerotic lesions. After 8 weeks on a high fat diet Ctsg+/-Apoe-/- mice were similar to Ctsg+/+Apoe-/- mice in terms of lesion size and serum cholesterol levels but the Ctsg+/+Apoe-/- mice had more advanced lesions with more collagen and smooth muscle cells and fewer macrophages. Moreover, Ctsg+/+Apoe-/- mice had more apoptotic cells than their Ctsg+/-Apoe-/- littermates. Overall, our findings indicate that Ang II is increased in foam cells and this endogenous Ang II is involved in cholesteryl ester formation, possibly by regulating the levels of ACAT-1 and SR-A. We did not find any role for cathepsin G in generation of Ang II in mice but cathepsin G does, nevertheless, promote the progression of atherosclerotic lesions to a more advanced stage.

Abstract Statement of problem Plasma angiotensin II (Ang II) increases blood pressure (BP) through the activation of brain angiotensinergic pathways and the aldosterone-mineralocorticoid receptors (MR)- epithelial Na+ channel (ENaC)-endogenous ouabain (EO) pathway. The response of BP to circulating Ang II is enhanced by high salt intake, but the central mechanisms mediating this elevated response are not known. Methods of investigation Study 1) Male Wistar rats were divided into 4 groups and treated with regular salt diet (0.4% NaCl), high salt diet (2% NaCl), sc Ang II infusion (150 ng/kg/min), or sc Ang II infusion together with 2% salt diet for 14 days; plasma aldosterone and corticosterone levels, CYP11B2 mRNA in adrenal cortex and the mRNA levels of Ang II type 1 receptors (AT1R), CYP11B1 (11-β hydroxylase), CYP11B2 (aldosterone synthase), MR, 11βHSD2, ENaC α, ENaC β and ENaC γ in the subfornical organ (SFO), paraventricular nucleus (PVN), supraoptic nucleus (SON) and rostral ventrolateral medulla (RVLM) were measured. Study 2) MR blockers (eplerenone, spironolactone), ENaC blocker (benzamil), AT1R blocker (losartan) or vehicles were centrally infused in rats treated with Ang II plus high salt, and BP and heart rate (HR) were recorded by telemetry; plasma aldosterone and corticosterone levels and CYP11B2 mRNA expression in adrenal cortex were measured. Major findings Ang II alone caused a small increase in BP. Ang II together with 2% salt diet markedly increased the BP and plasma aldosterone level. Sc Ang II decreased 11βHSD2 and MR mRNA expression in the PVN, increased AT1R and ENaC γ expression in the PVN, and increased AT1R mRNA expression in the RVLM. Other genes tested in the four brain nuclei were not affected by sc Ang II or high salt diet. BP and plasma aldosterone increases in response to Ang II and salt, as well as CYP11B2 mRNA expression in adrenal cortex, were largely prevented by central infusion of eplerenone, spironolactone, benzamil or losartan. Main conclusion BP and plasma aldosterone responses to Ang II-salt are under the control of central mechanisms, and MR-AT1R activation in the brain plays a critical role in Ang II-salt induced hypertension.