Angiotensin-converting enzyme 2 (ACE2) is an important component of the renin-angiotensin system (RAS). ACE2 is thought to have a renoprotective effect in diabetic nephropathy because it is capable of degrading profibrotic angiotensin II to potentially protective angiotensin-(1-7). Podocyte death and detachment is a key component of diabetic nephropathy. ACE2 is localized in the podocyte and during a diabetic state, podocyte ACE2 expression is reduced. The purpose of this study was to determine the effects of podocyte-specific ACE2 overexpression on the course of diabetic nephropathy. Diabetes was induced using streptozotocin in transgenic mice with podocyte-specific overexpression of human ACE2. The following parameters were assessed: systolic blood pressure, glomerular filtration rate, urinary albumin excretion, mesangial and glomerular area, and podocyte number. Transgenic diabetic mice showed a significant transient attenuated increase in albuminuria, an attenuated increase in mesangial area, decreased glomerular area, and preserved podocyte number, compared to wildtype diabetic mice. This was independent of a change in blood pressure. This study showed that the podocyte-specific overexpression of human ACE2 attenuates the development of diabetic nephropathy.

Class of 2008 Abstract / Objectives: : The purpose of this paper is to provide greater understanding of ACE inhibitor cough and appropriate treatment options. Methods: A Medline search of key terms from 1975-2008 was conducted and all types of published material were included in this review. The articles were evaluated for relevance and appropriateness for inclusion in this review. Subjects considered appropriate included ACE inhibitor cough treatment, mechanism of action, incidence and prevalence, genetics, cough characteristics, onset and resolution of cough, and others. Whenever possible, original studies were obtained but several reviews were also used. Results: ACE inhibitor cough is typically a dry, non-productive, persistent but benign cough reportedly occurring in anywhere from 0.5%-50% of patients receiving ACE inhibitors, though most studies indicate less than 20%. The mechanism is not completely understood but seems to be related to a complicated mechanism involving pathways caused by ACE inhibition and including bradykinin, C fibers, and prostaglandins. Several treatment options have been successful in resolving or relieving cough, including NSAIDs, baclofen, cromolyn and others. Results, however, are inconsistent. Anti-tussive agents, switching to a different ACE inhibitor, or lowering the dose of the current ACE inhibitor do not seem to be effective. Conclusions: In spite of its benign nature, ACE inhibitor cough is usually bothersome enough to discontinue the medication and therefore can not be ignored. Several treatments have appeared effective, all of which carry the risk of drug interactions and additional side effects, and alternative therapy such as angiotensin receptor blockers seem to be reasonable in indicated patients.

We investigated the effects of angiotensinogen (Ang), angiotensin I (Ang I), and angiotensin II (Ang II) on the fluidity of phosphatidylcholine vesicles. Changes in fluidity were assessed by changes in anisotopy values calculated from fluorescence polarization measurements. All three compounds produced an increase in membrane fluidity when localized inside the phosphatidylcholine vesicles. When placed outside the vesicles. Ang II increased bilayer rigidity (decreased fluidity), whereas Ang and Ang I produced no effect. These results suggest the possibility that these peptides may alter the fluidity of cell membranes by a direct action on the phospholipid bilayer, which may in turn interfere with receptor-mediated effects.

No description available.

No description available.

Thesis (M.Sc.)--University of Alberta, 2009. / A thesis submitted to the Faculty of Graduate Studies and Research in partial fulfillment of the requirements for the degree of Master of Science, Department of Physiology. Title from pdf file main screen (viewed on October 11, 2009). Includes bibliographical references.

The renin-angiotensin system plays a central role in the maintenance of blood pressure. Angiotensin II, the main effector of this system, results from the action of angiotensin-converting enzyme (ACE) on angiotensin I. Angiotensin II, maintains vasomotor tone via its vasoconstrictor action, and also increases salt and water retention by stimulating the release of aldosterone. ACE inhibitors, such as captopril, enalapril and lisinopril, are highly effective in the treatment of hypertension and congestive cardiac failure. Previous studies have suggested that angiotensin converting enzyme (ACE) production may be enhanced during pharmacological inhibition of the enzyme. Little is known, however about the mechanism of this induction. After demonstrating increases in circulating ACE protein in cardiac failure patients receiving the ACE inhibitor captopril, a rat model was used to study this effect. A sensitive enzyme linked immunosorbent assay for rat ACE was developed and a partial cDNA for rat ACE cloned to enable examination of ACE mRNA and protein expression during enzyme inhibition with enalapril. Rat lung ACE mRNA increased by 156% (p<0.05) and ACE protein doubled within 3 hours of administering a single dose of enalapril. Testicular ACE mRNA also increased by 300% (p<0.05) within 2 hours and returned to pretreatment levels by 6 hours. The angiotensin II antagonist saralasin similarly caused a significant (p<0.0001) 800% enhancement of mRNA expression. Aldosterone pretreatment of rats prior to enalapril administration was found to abolish this mRNA induction. These findings indicate that increased ACE expression during inhibition results from reduced levels of angiotensin II with consequent reduced stimulation of the angiotensin 11 receptor and its effects, such as aldosterone release. This suggests that ACE levels are regulated by a negative feedback loop involving the distal components of the renin-angiotensin system, namely angiotensin II and aldosterone. In situ hybridisation and immunohistochemical techniques were employed to localise the site of this inductive response in rat tissue sections. It was found that lung macrophages were markedly induced to produce ACE, as was ACE in seminiferous tubules. ACE induction was also noted in the expected sites of renal tubular epithelium and glomerular tissue. Interestingly, ACE expression was also enhanced in cardiac valves. In these studies it has been conclusively demonstrated that new ACE expression is induced by enzyme inhibitor therapy. A variety of techniques have been developed that will allow futher study of ACE in rat tissues.

O sistema renina-angiotensina (SRA) circulante é um sistema endócrino que promove a produção de angiotensina (Ang) II, a qual exerce seus efeitos pela interação com receptores específicos. O conceito clássico do SRA circulante está sendo modificado, pois tem sido demonstrada a existência de sistemas locais capazes de gerar angiotensinas de forma independente do SRA circulante em vários tecidos e órgãos. Trabalhos recentes sugerem a existência de alguns componentes do SRA em tecido gengival e fibroblastos gengivais de diferentes espécies. Porém, não são encontrados na literatura achados inequívocos sobre a presença de importantes componentes do SRA, tais como renina e angiotensinogênio, no tecido gengival de rato. Portanto, os objetivos do presente trabalho foram: 1) estudar a expressão e localização de componentes do SRA no tecido gengival de rato e 2) estudar in vitro a funcionalidade do SRA local em homogenato de tecido gengival de rato quanto à formação de Ang II e outros peptídeos vasoativos a partir de precursores de Ang II. Transcrição reversa seguida de reação em cadeia da polimerase (RTPCR) foi utilizada para avaliar a expressão de RNAm. Análise imunohistoquímica foi utilizada para detecção e localização de renina no tecido gengival de rato. Um método fluorimétrico padronizado com o tripeptídeo Hipuril-Histidina-Leucina (Hip-His-Leu) foi usado para medir a atividade da ECA em homogenatos de tecido gengival de rato. A técnica de cromatografia líqüida de alto desempenho (HPLC) foi usada para analisar os produtos formados após a incubação de homogenatos de tecido gengival de rato com Ang I ou tetradecapeptídeo substrato de renina (TDP). RT-PCR revelou a expressão de RNAm para renina, angiotensinogênio, ECA e receptores de Ang II (AT1a, AT1b e AT2) em tecido gengival; em fibroblastos cultivados de tecido gengival foi observada expressão de RNAm para renina, angiotensinogênio e receptor AT1a. A técnica de imunohistoquímica demonstrou a existência de renina em vasos de tecido gengival de rato. Atividade da ECA foi detectada por meio do ensaio fluorimétrico (4,95±0,89 nmol His-Leu/g.min). Quando Ang I foi usada como substrato, análises de HPLC mostraram a formação de Ang 1-9 (0,576±0,128 nmol/mg.min), Ang II (0,066±0,008 nmol/mg.min) e Ang 1-7 (0,111±0,017 nmol/mg.min), enquanto que os mesmos peptídeos (0,139±0,031; 0,206±0,046 e 0,039±0,007 nmol/mg.min, respectivamente) e Ang I (0,973±0,139 nmol/mg.min) foram formados quando TDP foi usado como substrato. Adicionalmente, análises de HPLC revelaram a ausência de enzimas que degradam Ang II em homogenatos de tecido gengival de rato. Em conclusão, os resultados apresentados neste trabalho mostram claramente a existência de um SRA local em tecido gengival de rato, que é capaz de gerar Ang II e outros peptídeos vasoativos in vitro. Estudos adicionais são necessários para elucidar o papel deste sistema local no tecido gengival de rato. / Systemic renin-angiotensin system (RAS) promotes the plasmatic production of angiotensin (Ang) II, which acts through the interaction with specific receptors. The concept of this classic circulating RAS has been modified since there is growing evidence that local systems in various tissues and organs are capable of generating angiotensins independently of the circulating RAS. Recent works suggest the existence of some RAS components in the gingival tissue and cultured gingival fibroblasts of different species, but there is paucity of data in the literature regarding the unequivocal existence of crucial RAS components, such as renin and angiotensinogen, in the rat gingival tissue. Therefore, the aims of the present work were to: 1) study the expression and localization of RAS components in the rat gingival tissue and 2) evaluate the in vitro production of Ang II and other peptides catalyzed by rat gingival tissue homogenates incubated with different precursors of Ang II. Reverse transcription-polymerase chain reaction (RT-PCR) was used to assess mRNA expression. Immunohistochemical (IHC) analysis aimed to detect and localize renin in the rat gingival tissue. A standardized fluorimetric method with the tripeptide Hippuryl-Histidyl-Leucine (Hip-His-Leu) was used to measure tissue ACE activity in rat gingival tissue homogenates. High performance liquid chromatography (HLPC) was used to analyze the products formed after the incubation of rat gingival tissue homogenates with Ang I or tetradecapeptide renin substrate (TDP). RT-PCR revealed the mRNA expression for renin, angiotensinogen, ACE and Ang II receptors (AT1a, AT1b and AT2) in the rat gingival tissue; cultured gingival fibroblasts expressed renin, angiotensinogen and AT1a receptor. IHC demonstrated the existence of renin in vessels of the rat gingival tissue. ACE activity was detected by the fluorimetric assay (4.95±0.89 nmol His-Leu/g.min). When Ang I was used as the substrate, HPLC analyses showed the formation of Ang 1-9 (0.576±0.128 nmol/mg.min), Ang II (0.066±0.008 nmol/mg.min) and Ang 1-7 (0.111±0.017 nmol/mg.min) whereas these same peptides (0.139±0.031; 0.206±0.046 and 0.039±0.007 nmol/mg.min, respectively) and Ang I (0.973±0.139 nmol/mg.min) were formed when TDP was the substrate. Additionally, HPLC revealed absence of Ang II degrading enzymes in rat gingival tissue homogenates. In conclusion, the results presented here clearly show the existence of a local RAS in the rat gingival tissue, which is capable of generating Ang II and other vasoactive peptides in vitro. Further studies are required to elucidate the role of this system in the rat gingival tissue.

Jiang, Lili. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 215-235). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

O sistema renina-angiotensina (SRA) circulante é um sistema endócrino que promove a produção de angiotensina (Ang) II, a qual exerce seus efeitos pela interação com receptores específicos. O conceito clássico do SRA circulante está sendo modificado, pois tem sido demonstrada a existência de sistemas locais capazes de gerar angiotensinas de forma independente do SRA circulante em vários tecidos e órgãos. Trabalhos recentes sugerem a existência de alguns componentes do SRA em tecido gengival e fibroblastos gengivais de diferentes espécies. Porém, não são encontrados na literatura achados inequívocos sobre a presença de importantes componentes do SRA, tais como renina e angiotensinogênio, no tecido gengival de rato. Portanto, os objetivos do presente trabalho foram: 1) estudar a expressão e localização de componentes do SRA no tecido gengival de rato e 2) estudar in vitro a funcionalidade do SRA local em homogenato de tecido gengival de rato quanto à formação de Ang II e outros peptídeos vasoativos a partir de precursores de Ang II. Transcrição reversa seguida de reação em cadeia da polimerase (RTPCR) foi utilizada para avaliar a expressão de RNAm. Análise imunohistoquímica foi utilizada para detecção e localização de renina no tecido gengival de rato. Um método fluorimétrico padronizado com o tripeptídeo Hipuril-Histidina-Leucina (Hip-His-Leu) foi usado para medir a atividade da ECA em homogenatos de tecido gengival de rato. A técnica de cromatografia líqüida de alto desempenho (HPLC) foi usada para analisar os produtos formados após a incubação de homogenatos de tecido gengival de rato com Ang I ou tetradecapeptídeo substrato de renina (TDP). RT-PCR revelou a expressão de RNAm para renina, angiotensinogênio, ECA e receptores de Ang II (AT1a, AT1b e AT2) em tecido gengival; em fibroblastos cultivados de tecido gengival foi observada expressão de RNAm para renina, angiotensinogênio e receptor AT1a. A técnica de imunohistoquímica demonstrou a existência de renina em vasos de tecido gengival de rato. Atividade da ECA foi detectada por meio do ensaio fluorimétrico (4,95±0,89 nmol His-Leu/g.min). Quando Ang I foi usada como substrato, análises de HPLC mostraram a formação de Ang 1-9 (0,576±0,128 nmol/mg.min), Ang II (0,066±0,008 nmol/mg.min) e Ang 1-7 (0,111±0,017 nmol/mg.min), enquanto que os mesmos peptídeos (0,139±0,031; 0,206±0,046 e 0,039±0,007 nmol/mg.min, respectivamente) e Ang I (0,973±0,139 nmol/mg.min) foram formados quando TDP foi usado como substrato. Adicionalmente, análises de HPLC revelaram a ausência de enzimas que degradam Ang II em homogenatos de tecido gengival de rato. Em conclusão, os resultados apresentados neste trabalho mostram claramente a existência de um SRA local em tecido gengival de rato, que é capaz de gerar Ang II e outros peptídeos vasoativos in vitro. Estudos adicionais são necessários para elucidar o papel deste sistema local no tecido gengival de rato. / Systemic renin-angiotensin system (RAS) promotes the plasmatic production of angiotensin (Ang) II, which acts through the interaction with specific receptors. The concept of this classic circulating RAS has been modified since there is growing evidence that local systems in various tissues and organs are capable of generating angiotensins independently of the circulating RAS. Recent works suggest the existence of some RAS components in the gingival tissue and cultured gingival fibroblasts of different species, but there is paucity of data in the literature regarding the unequivocal existence of crucial RAS components, such as renin and angiotensinogen, in the rat gingival tissue. Therefore, the aims of the present work were to: 1) study the expression and localization of RAS components in the rat gingival tissue and 2) evaluate the in vitro production of Ang II and other peptides catalyzed by rat gingival tissue homogenates incubated with different precursors of Ang II. Reverse transcription-polymerase chain reaction (RT-PCR) was used to assess mRNA expression. Immunohistochemical (IHC) analysis aimed to detect and localize renin in the rat gingival tissue. A standardized fluorimetric method with the tripeptide Hippuryl-Histidyl-Leucine (Hip-His-Leu) was used to measure tissue ACE activity in rat gingival tissue homogenates. High performance liquid chromatography (HLPC) was used to analyze the products formed after the incubation of rat gingival tissue homogenates with Ang I or tetradecapeptide renin substrate (TDP). RT-PCR revealed the mRNA expression for renin, angiotensinogen, ACE and Ang II receptors (AT1a, AT1b and AT2) in the rat gingival tissue; cultured gingival fibroblasts expressed renin, angiotensinogen and AT1a receptor. IHC demonstrated the existence of renin in vessels of the rat gingival tissue. ACE activity was detected by the fluorimetric assay (4.95±0.89 nmol His-Leu/g.min). When Ang I was used as the substrate, HPLC analyses showed the formation of Ang 1-9 (0.576±0.128 nmol/mg.min), Ang II (0.066±0.008 nmol/mg.min) and Ang 1-7 (0.111±0.017 nmol/mg.min) whereas these same peptides (0.139±0.031; 0.206±0.046 and 0.039±0.007 nmol/mg.min, respectively) and Ang I (0.973±0.139 nmol/mg.min) were formed when TDP was the substrate. Additionally, HPLC revealed absence of Ang II degrading enzymes in rat gingival tissue homogenates. In conclusion, the results presented here clearly show the existence of a local RAS in the rat gingival tissue, which is capable of generating Ang II and other vasoactive peptides in vitro. Further studies are required to elucidate the role of this system in the rat gingival tissue.