Seminal levels of angiotensin II and angiotensin II type 2 receptor expression on spermatozoa in varicocele patients: Relation to fertility status.

Several theories were proposed to explain the pathophysiology of varicocele-related infertility seen in some patients. Our aim was to study the levels of angiotensin II in semen and angiotensin II type 2 receptor expression on spermatozoa in varicocele patients in relation to their fertility status and to evaluate the influence of varicocelectomy on their levels in infertile varicocele patients. Thirty fertile and 30 infertile varicocele patients and 30 healthy controls were subjected to measurement of reproductive hormones, semen analysis, measurement of seminal angiotensin II and evaluation of angiotensin II type 2 receptor expression on spermatozoa. Infertile varicocele patients underwent varicocelectomy and were re-evaluated for the same parameters after the operation. Sperm concentration, morphology, progressive motility, seminal angiotensin II and angiotensin II type 2 receptor expression were significantly lower in infertile varicocele patients compared with the other groups. Post-operative values showed significant increase in the studied parameters compared with the pre-operative values but not to other two groups. A significant positive correlation between angiotensin II type 2 receptor expression and progressive motility was detected in all studied groups. In conclusion, dysregulation of angiotensin II and angiotensin II type 2 receptor in varicocele patients may be involved in varicocele-related infertility.

Cutaneous inflammation differentially regulates the expression and function of Angiotensin-II types 1 and 2 receptors in rat primary sensory neurons.

Neuropathic and inflammatory pain results from cellular and molecular changes in dorsal root ganglion (DRG) neurons. The type-2 receptor for Angiotensin-II (AT2R) has been involved in this type of pain. However, the underlying mechanisms are poorly understood, including the role of the type-1 receptor for Angiotensin-II (AT1R). Here, we used a combination of immunohistochemistry and immunocytochemistry, RT-PCR and in vitro and in vivo pharmacological manipulation to examine how cutaneous inflammation affected the expression of AT1R and AT2R in subpopulations of rat DRG neurons and studied their impact on inflammation-induced neuritogenesis. We demonstrated that AT2R-neurons express C- or A-neuron markers, primarily IB4, trkA, and substance-P. AT1R expression was highest in small neurons and co-localized significantly with AT2R. In vitro, an inflammatory soup caused significant elevation of AT2R mRNA, whereas AT1R mRNA levels remained unchanged. In vivo, we found a unique pattern of change in the expression of AT1R and AT2R after cutaneous inflammation. AT2R increased in small neurons at 1 day and in medium size neurons at 4 days. Interestingly, cutaneous inflammation increased AT1R levels only in large neurons at 4 days. We found that in vitro and in vivo AT1R and AT2R acted co-operatively to regulate DRG neurite outgrowth. In vivo, AT2R inhibition impacted more on non-peptidergic C-neurons neuritogenesis, whereas AT1R blockade affected primarily peptidergic nerve terminals. Thus, cutaneous-induced inflammation regulated AT1R and AT2R expression and function in different DRG neuronal subpopulations at different times. These findings must be considered when targeting AT1R and AT2R to treat chronic inflammatory pain. Cover Image for this issue: doi: 10.1111/jnc.14737.

The angiotensin II type 2 receptors protect renal tubule mitochondria in early stages of diabetes mellitus.

Diabetic nephropathy correlates more closely to defective mitochondria and increased oxidative stress in the kidney than to hyperglycemia. A key driving factor of diabetic nephropathy is angiotensin II acting via the G-protein-coupled cell membrane type 1 receptor. The present study aimed to investigate the role of the angiotensin II type 2 receptor (AT2R) at the early stages of diabetic nephropathy. Using receptor binding studies and immunohistochemistry we found that the mitochondria in renal tubules contain high-affinity AT2Rs. Increased renal mitochondrial AT2R density by transgenic overexpression was associated with reduced superoxide production of isolated mitochondria from non-diabetic rats. Streptozotocin-induced diabetes (28 days) caused a drop in the ATP/oxygen ratio and an increase in the superoxide production of isolated renal mitochondria from wild-type diabetic rats. This correlated with changes in the renal expression profile and increased tubular epithelial cell proliferation. AT2R overexpression in tubular epithelial cells inhibited all diabetes-induced renal changes including a drop in mitochondrial bioenergetics efficiency, a rise in mitochondrial superoxide production, metabolic reprogramming, and increased proliferation. Thus, AT2Rs translocate to mitochondria and can contribute to reno-protective effects at early stages of diabetes. Hence, targeted AT2R overexpression in renal cells may open new avenues to develop novel types of drugs preventing diabetic nephropathy.

Expression of Angiotensin II Types 1 and 2 Receptors in Endometriotic Lesions.

BACKGROUND/AIM: The aim of this study was to evaluate the gene and protein expression of angiotensin type (AT) 1, AT2 receptors in endometriotic lesions and its relation to prostaglandin (PG) synthases. MATERIALS AND METHODS: Endometriosis samples were obtained from 32 patients with endometriotic cysts. Endometrial tissues were obtained during operations for benign gynecological conditions. The expression of the AT1 and AT2 receptor mRNA and that of PG-endoperoxide synthase 2 and microsomal PGE2 synthase-1 (mPGES-1) was examined by quantitative RT-PCR. Immunohistochemical staining was performed for these receptors. RESULTS: AT1 and AT2 receptor proteins were mostly located in endometrial glandular epithelium and some stromal cells. Immunoreactivity of the receptor proteins was observed in both the eutopic endometrium and endometriotic lesions. The AT1/AT2 ratio in endometriotic cysts (median 7.29, range 1.88-187.60) was significantly increased compared with that in the eutopic endometrium in the proliferative-phase in controls (median 1.01, range 0.37-2.09, p < 0.001). There was a relationship between the AT1 mRNA expression and that of mPGES-1 mRNA in the endometriotic cysts (r = 0.394089, p < 0.05). There was a significant relationship between the mRNA expression of the AT2 receptor and that of mPGES-1 in eutopic endometrium of non-endometriotic control (r = 0.610714, p < 0.05). CONCLUSION: Renin-angiotensin system may play an important role in the pathophysiology of endometriosis.

Localization of angiotensin receptor type 2 in fetal bovine ovaries.

In the ovary, angiotensin II (ANGII) acts through the type 2 receptor (AGTR2) to induce ovulation and may play a role in follicle atresia. In this study, we determined the expression of AGTR2 mRNA and protein during follicle formation in the bovine ovary. Female fetuses at different gestational ages (60, 75, 90, 120, 150 and 210 days) were used for immunolocalization of AGTR2. At day 60, AGTR2 was localized to the cytoplasm of oogonia; from days 75 to 150, during follicle formation and development to secondary stage, AGTR2 immunostaining was weak and irregular, but from day 210 staining became evident in granulosa cells of preantral follicles and in both granulosa and theca cells of small antral follicles. These data differ from those in pigs, in which AGTR2 protein is detected in preantral follicles throughout gestation. Abundance of AGTR2 mRNA in whole ovaries did not change with fetal age. In conclusion, AGTR2 protein is expressed in ovigerous cords in fetal bovine ovaries but not in preantal follicles until the formation of antral follicles. These data suggest important species-specific differences in the expression of AGTR2 in fetal ovaries from polyovulatory and monovulatory animals.

[Role of angiotensin II receptor type 2 in predicting biochemical recurrence in the treatment of prostate cancer].

AIM: To identify markers for predicting aggressive forms of prostate cancer. MATERIALS AND METHODS: The study retrospectively evaluated expression of angiotensin II type 2 receptors (AT2-R) in prostate needle biopsy tissue from patients with and without biochemical recurrence after combined hormone and radiation therapy. RESULTS: The study findings showed that low expression of AT2-R in prostate tissue was associated with a high risk of biochemical recurrence. The data on the nature of AT2-R expression in prostate tissue of prostate cancer patients may be considered as a tool for predicting biochemical recurrence after combined hormone and radiation therapy. The test has a sensitivity of 87.5% and specificity of 85.71%.

Angiotensin II type 1 and 2 receptors and lymphatic vessels modulate lung remodeling and fibrosis in systemic sclerosis and idiopathic pulmonary fibrosis.

OBJECTIVE: To validate the importance of the angiotensin II receptor isotypes and the lymphatic vessels in systemic sclerosis and idiopathic pulmonary fibrosis. METHODS: We examined angiotensin II type 1 and 2 receptors and lymphatic vessels in the pulmonary tissues obtained from open lung biopsies of 30 patients with systemic sclerosis and 28 patients with idiopathic pulmonary fibrosis. Their histologic patterns included cellular and fibrotic non-specific interstitial pneumonia for systemic sclerosis and usual interstitial pneumonia for idiopathic pulmonary fibrosis. We used immunohistochemistry and histomorphometry to evaluate the number of cells in the alveolar septae and the vessels stained by these markers. Survival curves were also used. RESULTS: We found a significantly increased percentage of septal and vessel cells immunostained for the angiotensin type 1 and 2 receptors in the systemic sclerosis and idiopathic pulmonary fibrosis patients compared with the controls. A similar percentage of angiotensin 2 receptor positive vessel cells was observed in fibrotic non-specific interstitial pneumonia and usual interstitial pneumonia. A significantly increased percentage of lymphatic vessels was present in the usual interstitial pneumonia group compared with the non-specific interstitial pneumonia and control groups. A Cox regression analysis showed a high risk of death for the patients with usual interstitial pneumonia and a high percentage of vessel cells immunostained for the angiotensin 2 receptor in the lymphatic vessels. CONCLUSION: We concluded that angiotensin II receptor expression in the lung parenchyma can potentially control organ remodeling and fibrosis, which suggests that strategies aimed at preventing high angiotensin 2 receptor expression may be used as potential therapeutic target in patients with pulmonary systemic sclerosis and idiopathic pulmonary fibrosis.

Maternal high-fat diet programs rat offspring hypertension and activates the adipose renin-angiotensin system.

OBJECTIVE: A maternal high-fat diet creates an increased risk of offspring obesity and systemic hypertension. Although the renal renin-angiotensin system (RAS) is known to regulate blood pressure, it is now recognized that the RAS is also activated in adipose tissue during obesity. We hypothesized that programmed offspring hypertension is associated with the activation of the adipose tissue RAS in the offspring of obese rat dams. STUDY DESIGN: At 3 weeks of age, female rats were weaned to a high-fat diet (60% k/cal; n = 6) or control diet (10% k/cal; n = 6). At 11 weeks of age, these rats were mated and continued on their respective diets during pregnancy. After birth, at 1 day of age, subcutaneous adipose tissue was collected; litter size was standardized, and pups were cross-fostered to either control or high-fat diet dams, which created 4 study groups. At 21 days of age, offspring were weaned to control or high-fat diet. At 6 months of age, body fat and blood pressure were measured. Thereafter, subcutaneous and retroperitoneal adipose tissue was harvested from male offspring. Protein expression of adipose tissue RAS components were determined by Western blotting. RESULTS: The maternal high-fat diet induced early and persistent alterations in offspring adipose RAS components. These changes were dependent on the period of exposure to the maternal high-fat diet, were adipose tissue specific (subcutaneous and retroperitoneal), and were exacerbated by a postnatal high-fat diet. Maternal high-fat diet increased adiposity and blood pressure in offspring, regardless of the period of exposure. CONCLUSION: These findings suggest that programmed adiposity and the activation of the adipose tissue RAS are associated with hypertension in offspring of obese dams.

Immunohistochemical detection of angiotensin II receptors in mouse cerebellum and adrenal gland using "in vivo cryotechnique".

Angiotensin II (AT) receptors, including AT receptor type 1 (AT1R) and type 2 (AT2R), are expressed in the rodent central nervous system, but their distributions and activation states are still unclear. In this study, we have performed immunohistochemical analyses of AT receptors in mouse cerebellum and adrenal gland using our "in vivo cryotechnique" (IVCT). We used antibodies against amino-terminal domains of AT receptors, which are considered to undergo conformational changes upon the binding of AT. Immunoreactivity of AT1R was detected in mouse cerebellum, and was highest in the outer tissue areas of molecular layers using IVCT. The AT1R immunostaining largely overlapped with glial fibrillary acidic protein (GFAP), a marker of Bergmann glia. Surprisingly, the AT1R immunoreactivity in the cerebellar cortex was remarkably reduced following 5 and 10 min of hypoxia or direct administration of an AT1R antagonist, losartan. By contrast, in the adrenal cortex, such AT1R immunoreactivity detected at the zona glomerulosa did not change even after 15 min of hypoxia. The correlation of localization with GFAP and also hypoxia-induced decrease of its immunoreactivity were similarly observed by immunostaining of AT2R in the cerebellar specimens. These findings demonstrated that IVCT is useful to reveal dynamically changing immunoreactivities usually affected by receptor-ligand binding as well as hypoxia, and also suggested that functional activities of AT receptors are time-dependently modulated under hypoxia in the central nervous system in comparison with the adrenal glands.

Expression of angiotensinogen and receptors for angiotensin and prorenin in the monkey and human substantia nigra: an intracellular renin-angiotensin system in the nigra.

We have previously obtained in rodents a considerable amount of data suggesting a major role for the brain renin-angiotensin system (RAS) in dopaminergic neuron degeneration and potentially in Parkinson's disease. However, the presence of a local RAS has not been demonstrated in the monkey or the human substantia nigra compacta (SNc). The present study demonstrates the presence of major RAS components in dopaminergic neurons, astrocytes and microglia in both the monkey and the human SNc. Angiotensin type 1 and 2 and renin-prorenin receptors were located at the surface of dopaminergic neurons and glial cells, as expected for a tissular RAS. However, angiotensinogen and receptors for angiotensin and renin-prorenin were also observed at the cytoplasm and nuclear level, which suggests the presence of an intracrine or intracellular RAS in monkey and human SNc. Although astrocytes and microglia were labeled for angiotensin and prorenin receptors in the normal SNc, most glial cells appeared less immunoreactive than the dopaminergic neurons. However, our previous studies in rodent models of PD and studies in other animal models of brain diseases suggest that the RAS activity is significantly upregulated in glial cells in pathological conditions. The present results together with our previous findings in rodents suggest a major role for the nigral RAS in the normal functioning of the dopaminergic neurons, and in the progression of the dopaminergic degeneration.

Activation of skin renin-angiotensin system in diabetic rats.

The renin-angiotensin system (RAS) is reportedly involved in chronic diabetic complications such as diabetic nephropathy, but changes of the RAS in diabetic skin remain unknown. The aim of this study was to investigate the expression of angiotensin (Ang) II and its type 1 (AT1) and type 2 (AT2) receptors in diabetic skin tissues, and explore the relationship between the local RAS and pathological changes of diabetic skin. Our results showed that thinning of epidermis, degeneration of collagen, fracture of dermal layer, and atrophy/disappearance of subcutaneous fat were observed in diabetic skin. The expression level of AngII was increased in diabetic skin tissues compared to that in controls. mRNA and protein expression of AT1 receptor were also increased while the level of AT2 receptor decreased; the relative expression of AT1 to AT2 receptors was approximately threefold higher in diabetes than in controls. Furthermore, in the culture medium of primary cultured fibroblasts from diabetic skin, the concentration of AngII was significantly higher than that of normal control. The mRNA and protein expression of AT1 receptor was also increased in fibroblasts of diabetic skin compared to controls, while the protein expression of AT2 receptor was decreased. Taken together, our results suggest that the local RAS system is activated in diabetic skin and AngII receptor is likely to mediate the pathological changes of diabetic skin.

(Pro)renin receptors and angiotensin converting enzyme 2/angiotensin-(1-7)/Mas receptor axis in human aortic valve stenosis.

BACKGROUND: There is increasing evidence that renin-angiotensin system (RAS) may play a major role in the actively regulated fibrocalcific process in aortic valve stenosis (AS), but the gene expression or function of (pro)renin receptor ((P)RR), prorenin and renin or angiotensin converting enzyme 2(ACE2)/angiotensin-(1-7)/Mas receptor axis in calcific aortic valve disease is not known. METHODS AND RESULTS: We characterized expression of (P)RR, ACE2 and Mas receptor as well as renin, prorenin and angiotensin II type 2 (AT(2)) receptors in human aortic valves, and compared normal control valves (n = 11) with valves obtained from patients with aortic regurgitation (AR, n = 14), AR with fibrosis (n = 20) and AS (n = 61). By immunohistochemistry (P)RR positive staining was seen in the valvular endothelial cells of control and in the neovessels of stenotic valves. By RT-PCR, renin mRNA levels were 72% (P = 0.001) and prorenin mRNA levels 64% lower (P = 0.002) in stenotic aortic valves compared to control valves. ACE2, Mas receptor and AT(2)-receptor mRNA levels were 69% (P < 0.001), 58% (P = 0.008) and 75% (P = 0.001) lower, respectively, in stenotic valves. ACE2 positive staining, existing to lesser extent in stenotic aortic valves, was localized mainly to stromal area in spongiosa layer in control valves. CONCLUSIONS: (P)RR, prorenin and renin are expressed in human aortic valves. We also report for the first time expression of ACE2/angiotensin-(1-7)/-Mas receptor axis in human aortic valve cusps. The downregulation of ACE2/angiotensin-(1-7)/-Mas receptor axis as well as AT(2)-receptors may promote fibrosis, proliferation and inflammation in patients with AS.

AT2 receptor signaling and sympathetic regulation.

There is a growing consensus that the balance between Angiotensin Type 1 (AT1R) and Angiotensin Type 2 (AT2R) signaling in many tissues may determine the magnitude and, in some cases the direction, of the biological response. Sympatho-excitation in cardiovascular diseases is mediated by a variety of factors and is, in part, dependent on Angiotensin II signaling in the central nervous system. Recent data have provided evidence that the AT2R can modulate sympatho-excitation in animals with hypertension and heart failure. The evidence for this concept is reviewed and a model is put forward to support the rationale that therapeutic targeting of the central AT2R may be beneficial in the setting of chronic heart failure.

Angiotensin-2 receptors (AT1-R and AT2-R), new prognostic factors for renal clear-cell carcinoma?

BACKGROUND: The growth factor Angiotensin-2 signals through Angiotensin receptor type 1 (AT1-R) in a broad range of cell types and tumours and through the type-2 receptor (AT2-R) in a more restricted group of cell types. Although numerous forms of cancer have been shown to overexpress AT1-R, expression of AT1-R and AT2-R by human renal clear-cell carcinoma (RCCC) is not well understood. In this study, the expression of both angiotensin receptors was quantified in a retrospective series of RCCC and correlated with prognostic factors. METHODS: Angiotensin receptor type 1 and AT2-R expressions were quantified on tumour tissues by immunohistochemistry (IHC), western blot and quantitative reverse transcriptase PCR (qRT-PCR). IHC results were correlated to Fuhrman's grade and patient progression-free survival (PFS). RESULTS: A total of 84 RCCC were analysed. By IHC, AT1-R and AT2-R were expressed to a greater level in high-grade tumours (AT1-R: P<0.001, AT2-R: P<0.001). Univariate analysis showed a correlation between PFS and AT1-R or AT2-R expression (P=0.001). By multivariate analysis, only AT2-R expression correlated with PFS (HR 1.021, P=0.006) and cancer stage (P<0.001). By western blot, AT1-R and AT1-R were also found to be overexpressed in higher Fuhrman's grade (P<0.01 and P=0.001 respectively). By qRT-PCR, AT1-R but not AT2-R mRNA were downregulated (P=0.001 and P=0.118, respectively). CONCLUSION: Our results show that AT1-R and AT2-R proteins are overexpressed in the most aggressive forms of RCCC and that AT2-R expression correlates with PFS. AT1-R or AT2-R blockage could, therefore, offer novel directions for anti-RCCC therapy.

Ethanol-induced downregulation of the angiotensin AT2 receptor in murine fibroblasts is mediated by PARP-1.

Molecular mechanisms accompanying ethanol-induced cytotoxicity remain to be defined. The renin-angiotensin system with its respective receptors, the angiotensin AT1 and AT2 receptor (AT1R and AT2R), has been implicated in these processes. The AT2R seems to counteract the pro-inflammatory, pro-hypertrophic, and pro-fibrotic actions of the AT1R and is involved in cellular differentiation and tissue repair. Recently, we identified poly(ADP-ribose) polymerase-1 (PARP-1) as a novel negative transcriptional regulator of the AT2R. However, the complex interactions between ethanol, PARP-1, and the AT2R are largely unknown. In this in vitro study, we aimed to clarify whether acute ethanol treatment modifies AT2R promoter activity or AT2R mRNA and protein levels and whether PARP-1 is involved in ethanol-mediated regulation of the AT2R. Murine fibroblasts of the R3T3 and MEF line (murine embryonic fibroblasts) were exposed to ethanol for 24h. AT2R promoter activity, mRNA and protein levels were analyzed with and without PARP-1 inhibition and in PARP-1 knockout MEF cells. Expression of PARP-1 was analyzed over course of time, and cell viability and DNA fragmentation were measured on single-cell level by flow cytometry. Ethanol exposition induced substantial downregulation of the AT2R on promoter, mRNA and protein levels in a dose-dependent manner. Pharmacological inhibition or ablation of PARP-1 completely abolished this effect. Ethanol treatment did not have any effect on AT1R mRNA and protein levels in MEF cells. Further, acute ethanol treatment promoted DNA fragmentation and caused transcriptional induction of PARP-1. Our findings reveal that PARP-1 is an upstream transcriptional regulator of the AT2 receptor in the context of ethanol exposure and represses the AT2R gene in fibroblasts in vitro. Variations in expression of the potentially tissue-protective AT2R might contribute to ethanol-mediated pathology.

Salt-induced cardiac hypertrophy and interstitial fibrosis are due to a blood pressure-independent mechanism in Wistar rats.

High salt intake is a known cardiovascular risk factor and is associated with cardiac alterations. To better understand this effect, male Wistar rats were fed a normal (NSD: 1.3% NaCl), high 4 (HSD4: 4%), or high 8 (HSD8: 8%) salt diet from weaning until 18 wk of age. The HSD8 group was subdivided into HSD8, HSD8+HZ (15 mg . kg(-1) . d(-1) hydralazine in the drinking water), and HSD8+LOS (20 mg . kg(-1) . d(-1) losartan in the drinking water) groups. The cardiomyocyte diameter was greater in the HSD4 and HSD8 groups than in the HSD8+LOS and NSD groups. Interstitial fibrosis was greater in the HSD4 and HSD8 groups than in the HSD8+HZ and NSD groups. Hydralazine prevented high blood pressure (BP) and fibrosis, but not cardiomyocyte hypertrophy. Losartan prevented high BP and cardiomyocyte hypertrophy, but not fibrosis. Angiotensin II type 1 receptor (AT(1)) protein expression in both ventricles was greater in the HSD8 group than in the NSD group. Losartan, but not hydralazine, prevented this effect. Compared with the NSD group, the binding of an AT(1) conformation-specific antibody that recognizes the activated form of the receptor was lower in both ventricles in all other groups. Losartan further lowered the binding of the anti-AT(1) antibody in both ventricles compared with all other experimental groups. Angiotensin II was greater in both ventricles in all groups compared with the NSD group. Myocardial structural alterations in response to HSD are independent of the effect on BP. Salt-induced cardiomyocyte hypertrophy and interstitial fibrosis possibly are due to different mechanisms. Evidence from the present study suggests that salt-induced AT(1) receptor internalization is probably due to angiotensin II binding.

Localization of type-2 angiotensin II receptor in adrenal gland.

The localization of the type-2 angiotensin II receptor (AT2) in the adrenal glands of rats, guinea pigs, bovines, and humans was examined at the mRNA and protein levels. PCR products for AT2 were detected in the adrenal cortices and adrenal medullae of all the mammals examined with an RT-PCR technique. Three different anti-AT2 antibodies (Abs), whose specificity was confirmed in our hands, recognized a 50-kDa protein in the adrenal glands of the four mammals, and this recognition was abolished by the preabsorption of an Ab with an antigen. Immunoblotting and immunohistochemistry revealed that the 50-kDa protein was expressed consistently and variably in the adrenal cortices and medullae of various mammals, respectively. We conclude that the 50-kDa AT2 is consistently expressed in the adrenal cortex in a wide variety of mammals.

Angiotensin II receptor type 1 is upregulated in atrial tissue of patients with rheumatic valvular disease with atrial fibrillation.

OBJECTIVE: The purpose of this study was to examine the changes in expression of angiotensin II receptor type 1/2 in left or right atrial tissue from patients with rheumatic valvular disease with or without atrial fibrillation. METHODS: Atrial tissue samples were obtained from 39 patients with rheumatic mitral valve disease during cardiac surgery. Among these patients, there were 25 with atrial fibrillation and 14 with sinus rhythm. The level of angiotensin II receptor type 1 or type 2 mRNA transcription was measured by means of a semiquantitative reverse transcription-polymerase chain reaction technique. Expression of angiotensin II receptor type 1 or type 2 protein was detected by means of immunohistochemistry assay and Western blot analysis. RESULTS: The inner diameter of the left atrium was clearly enlarged in the atrial fibrillation group in comparison with that seen in the sinus rhythm group. The expression levels of both angiotensin II receptor type 1 mRNA and protein in the left atrial tissue were significantly increased in the patients with atrial fibrillation compared with those seen in patients with sinus rhythm (P < .05). Interestingly, the comparison of angiotensin II receptor type 2 expression levels in the left atrial tissue between these 2 groups is not statistically significant. In addition, the results of angiotensin II receptor type 1 or 2 expression in the right atrial tissue did not show any obvious change in the patients with atrial fibrillation versus those with sinus rhythm. CONCLUSIONS: Expression of angiotensin II receptor type 1 but not type 2 is highly upregulated only in the left atrial tissue of patients with rheumatic valvular disease with atrial fibrillation. This suggests that there is a possible pathophysiologic role of the renin-angiotensin system in patients with atrial fibrillation and that a series of effects mediated by the activation of angiotensin II receptor type 1 in the left atrial tissue might be one of the molecular mechanisms involved in the process of atrial remodeling in atrial fibrillation.

Angiotensin II receptor expression and relation to Helicobacter pylori-infection in the stomach of the Mongolian gerbil.

BACKGROUND: The role of the renin-angiotensin system in gastric physiology and disease has as yet been sparsely explored. The first aim of the study was to investigate the baseline presence and location of angiotensin II receptors (AT1R and AT2R) in the stomach of the Mongolian gerbil. A second aim was to elucidate whether the presence of H. pylori infection is associated with changes in the expression of these receptors. METHODS: H. pylori-negative and H. pylori-infected (strain SS1 or TN2GF4) male Mongolian gerbils were investigated. The stomachs were examined at six or 12 months after inoculation by the use of immunohistochemistry, western blot and microscopic morphometry. RESULTS: AT1R and AT2R were located in a variety of cells in the gerbil gastric wall, including a subpopulation of endocrine cells in the antral mucosa and inflammatory cells infiltrating H. pylori-infected stomachs. Gerbils infected with the SS1 strain showed a significantly increased antral AT1R protein expression and an increased number of infiltrating polymorphonuclear leucocytes (PMNs) at 12 months. The AT1R protein expression correlated with the number of PMNs and the antral expression of myeloperoxidase. CONCLUSIONS: Angiotensin II receptors are present in a variety of cells in the gastric wall of the Mongolian gerbil. The results indicate an influence dependent on the H. pylori strain on the gastric AT1R expression and a relationship between gastric AT1R expression and mucosal PMNs infiltration.

The ontogeny of components of the renin-angiotensin system in the porcine fetal ovary.

There is an autonomous renin-angiotensin system (RAS) in the adult ovary. Renin is present in the primitive kidney, and the fetal ovary develops from the nephrogenic ridge. We hypothesised that components of the ovarian RAS would be present from early gestation, with potential roles in ovarian development. We studied fetal pig ovaries from approximately day 45 (approximately 0.39 gestation) to term and measured mRNA (RT-PCR) for prorenin, angiotensinogen and the angiotensin II (AngII) Type 1 and 2 receptors (AT(1) and AT(2)), and protein expression (Western blot) and localization (immunohistochemistry) of the AT(1) and AT(2) receptors. mRNA for prorenin was present in relatively low abundance from at least day 45 and rose to approximately day 75 of gestation, whilst mRNA for angiotensinogen rose steadily. mRNA for the AT(1) receptor was present from approximately day 45 and did not alter significantly with increasing gestation but AT(2) receptor mRNA was initially high, falling sharply through pregnancy. The AT(1) receptor protein abundance fell steadily to term, whereas the AT(2) receptor protein did not change during gestation. Both receptors were localised in the surface epithelium and egg nests, the granulosa cells of primordial, primary and secondary follicles, and the oocytes of all except the secondary follicles. Collectively, our results support the hypothesis that there is a functional RAS in the fetal ovary from at least approximately day 45 of gestation until term and that it may have a paracrine role in ovarian growth and development.