Under normal physiology, insulin exerts vasodilatory and pro-survival actions via the phosphatidylinositol 3-kinase (PI3-kinase) pathway and vasoconstrictive and mitogenic actions via the mitogen-activated protein kinase (MAPK) pathway in the vasculature. In the insulin resistant states, insulin signals through the PI3-kinase pathway are blunted but its signals through the MAPK cascade remain intact. This imbalance predisposes insulin resistant patients to hypertension and atherosclerosis. The renin-angiotensin system (RAS) is expressed both systemically and locally in the cardiovascular system. Insulin resistance up-regulates the local RAS which contributes to the pathogenesis of hypertension, heart failure, and atherosclerosis. Angiotensin II impairs insulin signaling, induces inflammation via the NF-kappaB pathway, reduces nitric oxide availability and facilitates vasoconstriction, leading to insulin resistance and endothelial dysfunction. Thus the RAS, insulin resistance and inflammation perpetuate each other and coordinately contribute to endothelial dysfunction, vascular injury and atherosclerosis. RAS inhibition decreases cardiovascular and renal morbidity and mortality and the incidence of new onset Type 2 diabetes.
Angiotensin II ; metabolism ; physiology ; Cardiovascular System ; metabolism ; Humans ; Insulin ; metabolism ; physiology

Angiotensin II ; metabolism ; Cisplatin ; adverse effects ; Humans ; Kidney ; drug effects ; Kidney Diseases ; chemically induced ; metabolism

Angiotensin II ; metabolism ; Animals ; Male ; Muscle, Skeletal ; Muscular Atrophy ; etiology ; metabolism ; pathology ; Rats ; Rats, Sprague-Dawley

OBJECTIVETo investigate the changes of angiotensin II (Ang II) and its receptors in male rats with diabetic erectile dysfunction (DED) so as to study its effects.

METHODSOut of 40 male SD rats, 30 were taken at random for diabetic models. After 8 weeks, the rats with erectile dysfunction were selected from these models. All the rats were divided into 3 groups: control ( n = 10), diabetes mellitus( DM, n = 9) and DED (n = 8). For each rat, the Ang II levels in the blood and homogenate prepared from part of the isolated penile tissues were determined respectively, and the Ang II receptors of the rest of the penile tissues were analyzed through immunohistochemical (IHC) assay.

RESULTSCompared with the control group, Ang II levels in the blood and penile tissues in the DM group, and that in the blood of the DED group were very high and the differences were statistically significant (P < 0.05). Ang II in the penile tissues of the DED increased sharply (P < 0.01). The receptors of Ang II changed contrariwise to the level of Ang ll.

CONCLUSIONAng II may play an important role in the pathogenesis of DED, and the Ang II antagonist or inhibitor of the angiotensin-converting enzyme (ACEI) may become a therapeutic method for DED in the future.

Angiotensin II ; blood ; metabolism ; Animals ; Diabetes Complications ; blood ; metabolism ; Erectile Dysfunction ; blood ; etiology ; metabolism ; Immunohistochemistry ; Male ; Penis ; metabolism ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Receptors, Angiotensin ; blood ; metabolism

Captopril can have nephrotoxic effects, which are largely attributed to accumulated renin and "escaped" angiotensin II (Ang II). Here we test whether angiotensin converting enzyme-1 (ACE1) inhibition damages kidneys via alteration of renal afferent arteriolar responses to Ang II and inflammatory signaling. C57Bl/6 mice were given vehicle or captopril (60 mg/kg per day) for four weeks. Hypertension was obtained by minipump supplying Ang II (400 ng/kg per min) during the second 2 weeks. We assessed kidney histology by periodic acid-Schiff (PAS) and Masson staining, glomerular filtration rate (GFR) by FITC-labeled inulin clearance, and responses to Ang II assessed in afferent arterioles in vitro. Moreover, arteriolar H₂O₂ and catalase, plasma renin were assayed by commercial kits, and mRNAs of renin receptor, transforming growth factor-β (TGF-β) and cyclooxygenase-2 (COX-2) in the renal cortex, mRNAs of angiotensin receptor-1 (AT₁R) and AT₂R in the preglomerular arterioles were detected by RT-qPCR. The results showed that, compared to vehicle, mice given captopril showed lowered blood pressure, reduced GFR, increased plasma renin, renal interstitial fibrosis and tubular epithelial vacuolar degeneration, increased expression of mRNAs of renal TGF-β and COX-2, decreased production of H₂O₂ and increased catalase activity in preglomerular arterioles and enhanced afferent arteriolar Ang II contractions. The latter were blunted by incubation with H₂O₂. The mRNAs of renal microvascular AT₁R and AT₂R remained unaffected by captopril. Ang II-infused mice showed increased blood pressure and reduced afferent arteriolar Ang II responses. Administration of captopril to the Ang II-infused mice normalized blood pressure, but not arteriolar Ang II responses. We conclude that inhibition of ACE1 enhances renal microvascular reactivity to Ang II and may enhance important inflammatory pathways.
Angiotensin II/pharmacology* ; Animals ; Arterioles/metabolism* ; Captopril/pharmacology* ; Hydrogen Peroxide/pharmacology* ; Kidney ; Mice

To investigate the molecular mechanism of angiotensin II (Ang II) receptor activation in adult rat cardiac fibroblasts, the expressions of cell signal transduction-associated genes were studied by using cDNA microarray. Cardiac fibroblasts of adult Sprague-Dawley rats (230~250 g) were isolated and cultured. The cells were divided into 4 groups: Ang II, Ang II + losartan, Ang II + PD123319, Ang II + losartan + PD123319. The expressions of Ang II receptors were studied by immunohistochemical staining. Total RNA was extracted and purified. After cDNA synthesis and biotin-16-dUTP labeling, the probes were denatured and hybridized with GEArray Q Series mouse G Protein-coupled Receptors Signaling Pathway Finder Gene Array (MM-025) containing 96 genes associated with 11 pathways. The arrays were scanned with a Uniscand1000 scanner and further analyzed with GEArray Analyzer software. RT-PCR was used to further confirm the results of gene microarray. The results of immunohistochemical staining showed that the expression of Ang II type 2 (AT2) receptor was evidently induced by Ang II stimulation when Ang II type 1 (AT1) receptor was blocked. The results of gene array indicated that blocking AT1 receptor changed 34 genes (more than 2 folds), 30 were down-regulated and 4 were up-regulated. The maximum change was not beyond 20 folds. The following 9 pathways were activated: cAMP/PKA, Ca2+, PKC, PLC, MAPK, PI-3 kinase, NO-cGMP, Rho, NF-kappaB pathways. Blockade of AT2 receptor caused 64 genes changing more than 2 folds (48 were down-regulated and 16 were up-regulated). Eleven pathways were basically activated. The change of the following 7 genes was over 30 folds: Cyp19a1 (37 folds), Il1r2 (42 folds), Cflar (53 folds), Bcl21 (31 folds), Pik3cg (278 folds), Cdkn1a (90 folds), Agt (162 folds). According to the activated extent, the signal transduction pathways in turn were PI-3 kinase, NF-kappaB and JAK-STAT pathways. Blocking both AT1 and AT2 receptors changed 46 genes more than 2 folds (36 were down-regulated and 10 were up-regulated). Eleven pathways were basically activated. The results of RT-PCR of IL-1beta and TNF-alpha confirmed the observations in gene microarray. Our results show that Ang II can induce a high expression of AT2 receptor in adult rat cardiac fibroblasts when AT1 receptor is blocked, and the signal mechanism of AT2 receptor is clearly different from that of AT1 receptor.
Angiotensin II ; pharmacology ; Angiotensin Receptor Antagonists ; pharmacology ; Animals ; Fibroblasts ; metabolism ; Gene Expression ; Imidazoles ; pharmacology ; Losartan ; pharmacology ; Myocardium ; cytology ; Pyridines ; pharmacology ; Rats ; Rats, Sprague-Dawley ; Receptor, Angiotensin, Type 1 ; metabolism ; Receptor, Angiotensin, Type 2 ; metabolism ; Signal Transduction

OBJECTIVEThis study was undertaken to observe the change in the local level of angiotensin II (Ang II) and the expression of its corresponding receptors AT1 and AT2 during wound healing, and explore the possible role of Ang II in wound healing .

METHODSA model of full-thickness cutaneous wound was developed on the back of C57/BL6 mice. Specimens were taken from the wound of each mouse on the day 0, 1, 3, 5, 7, 9, 11, 13 and 15 after wounding. The change in the generation of Ang II in wounded tissue during the healing process was detected with ELISA. The proliferation and the apoptosis of cells were detected by bromodeoxyuridine (Brdu) and terminal deoxynucleotidyl transferase mediated deoxyuridine triphosphate nick end labeling (TUNEL) method in wounded skin during the healing process, respectively. The cellular localization and the mRNA level change of Ang II receptors in wounded tissue during healing were detected with immunostaining and RT-PCR.

RESULTSAng II produced in wounded skin was increased in the first 7 days to reach the peak, and then gradually decreased during wound healing. BrdU labeling index was increased gradually in the first 7 days to reach the peak, and then gradually decreased during wound healing. The number of TUNEL-positive cells was increased slowly in the first 7 days after wounding. The increase in the number of TUNEL-positive cells was more markedly after epithelization of the wound. In normal mice, AT1 and AT2 receptor were found positively expressed in the whole epidermal layer, while positive expression was only found in the endothelial cells of the capillary vessels within the dermal layer, and positive expression was also found in appendages of the skin, i. e. hair follicle, sweat gland and sebaceous gland respectively. Positive staining signal of both AT1 and AT2 receptors were increased in the first 7 days to reach the peak, then gradually decreased. Expression of AT2R was increased again following the epithelization of wound. The result of RT-PCR showed that the expression of both AT1 and AT2 receptors was detectable, and AT1 receptor was increased in the first 7 days to the peak, and then gradually decreased during wound healing, while AT2 receptor expression reached its peak value on day 7, then gradually decreased, and increased again following the epithelization of wound.

CONCLUSIONSThese results indicate that Ang II participate in wound repair and related to remolding in the late stage of wound healing through the change in production of angiotensin II and expression of AT1 and AT2 receptors. AT1 receptor might be closely associated with cell proliferation, while AT2 receptor might play a role in cell apoptosis and remolding during wound healing.

Angiotensin II ; genetics ; metabolism ; Animals ; Apoptosis ; Cell Proliferation ; Male ; Mice ; Mice, Inbred C57BL ; RNA, Messenger ; genetics ; Receptors, Angiotensin ; genetics ; metabolism ; Skin ; injuries ; metabolism ; pathology ; Wound Healing ; physiology

OBJECTIVETo explore expression changes of myocardial renin angiotensin system induced by prenatal exposure to lipopolysaccharide in offspring rats.

METHODSTwelve pregnant SD rats were randomly divided into three groups: LPS model group: intraperitoneal injection of LPS (0.79 mg/kg) at 8, 10, 12 days of pregnancy; control group: intraperitoneal injection of sterile saline (0.5 ml) at 8, 10, 12 days of pregnancy; LPS + PDTC group: intraperitoneal injection of LPS (0.79 mg/kg) at 8, 10, 12 days of pregnancy plus daily intraperitoneal injection of NF-κB inhibitor -pyrrolidine dithiocarbamate (PDTC, 100 mg/kg) on day 8 to 14 pregnancy day. Protein expression of AngiotensinII(AngII) in heart was detected by immunohistochemistry; myocardial ACE,ACE2 mRNA expression was detected by real-time PCR; protein expression of ACE and ACE2 in heart was detected by Western blot in offspring rats of various groups.

RESULTSCompared with control group (0.07 ± 0.02,0.11 ± 0.01), AngII protein levels (0.14 ± 0.04) were significantly increased at 6 weeks (P < 0.01) and 16 weeks (0.17 ± 0.04, P < 0.05) in offspring rats of LPS model group, which could be significantly attenuated by PDTC intervention (0.10 ± 0.01,0.13 ± 0.03, respectively, all P < 0.05).Similarly, myocardial ACE mRNA expression in 16 weeks offspring rats of LPS model group was significantly upregulated compared with control group (1.10 ± 0.26 vs.0.72 ± 0.22, P < 0.05), which was significantly attenuated by PDTC intervention (0.67 ± 0.01, P < 0.01 vs.LPS group). Myocardial protein expression ACE2 in 16 weeks offspring rats of LPS model group was significantly downregulated compared to control group, which was slightly upregulated by PDTC intervention (P > 0.05).

CONCLUSIONPregnancy exposure to lipopolysaccharide increases myocardial ACE and AngII expression while reduces myocardial ACE2 expression in offspring rats, which might be one of the pathomechanisms of offspring hypertension.

Angiotensin II ; metabolism ; Animals ; Female ; Lipopolysaccharides ; toxicity ; Myocardium ; metabolism ; Peptidyl-Dipeptidase A ; metabolism ; Pregnancy ; Prenatal Exposure Delayed Effects ; Rats ; Rats, Sprague-Dawley ; Renin-Angiotensin System

Increased arterial stiffness is an independent predictor of cardiovascular disease independent from blood pressure. Recent studies have shed new light on the importance of inflammation on the pathogenesis of arterial stiffness. Arterial stiffness is associated with the increased activity of angiotensin II, which results in increased NADPH oxidase activity, reduced NO bioavailability and increased production of reactive oxygen species. Angiotensin II signaling activates matrix metalloproteinases (MMPs) which degrade TGFbeta precursors to produce active TGFbeta, which then results in increased arterial fibrosis. Angiotensin II signaling also activates cytokines, including monocyte chemoattractant protein-1, TNF-alpha, interleukin-1, interleukin-17 and interleukin-6. There is also ample clinical evidence that demonstrates the association of inflammation with increased arterial stiffness. Recent studies have shown that reductions in inflammation can reduce arterial stiffness. In patients with rheumatoid arthritis, increased aortic pulse wave velocity in patients was significantly reduced by anti tumor necrosis factor-alpha therapy. Among the major classes of anti hypertensive drugs, drugs that block the activation of the RAS system may be more effective in reducing the progression of arterial stiffness. Thus, there is rationale for targeting specific inflammatory pathways involved in arterial stiffness in the development of future drugs. Understanding the role of inflammation in the pathogenesis of arterial stiffness is important to understanding the complex puzzle that is the pathophysiology of arterial stiffening and may be important for future development of novel treatments.
Angiotensin II/metabolism ; Humans ; Inflammation/drug therapy/metabolism/*physiopathology ; Matrix Metalloproteinases/metabolism ; Vascular Stiffness/drug effects/*physiology

OBJECTIVETo study the effect of angiotensin II on phosphoinositide-3 kinase/Akt cascade in cultured fibroblasts derived from patients with hypertrophic scars.

METHODSThe expression of AT1 and AT2 receptor was detected by immunofluorescence staining. Cultured human skin fibroblasts were treated with Ang II (10(-9) - 10(-7) mol/L), with or without an AT1 receptor blocker, valsartan or an AT2 receptor antagonist, PD123319. The phosphorylation of Akt was detected by western blotting, and PI3K activity was measured by Assay of PI3-K activity.

RESULTSImmunofluorescence staining showed that cultured fibroblasts derived from hypertrophic scars expressed both AT1 and AT2 receptors. Ang II increased Akt phosphorylation and PI3K activity in cultured hypertrophic scar fibroblasts in a dose- and time-dependent manner. Additionally, Ang II-induced Akt phosphorylation was blocked by wortmannin, a PI3-K inhibitor. This Ang II-activated PI3-K/Akt cascade was significantly inhibited by valsartan, an AT1 receptor specific blocker (P<0.05), whereas enhanced by PD123319, an AT2 receptor antagonist (P<0.05).

CONCLUSIONThese results indicate that Ang II receptors regulates PI3-K/Akt cascade of hypertrophic scars fibroblasts via AT1 and AT2.

Angiotensin II ; pharmacology ; Angiotensin II Type 1 Receptor Blockers ; pharmacology ; Angiotensin II Type 2 Receptor Blockers ; Cells, Cultured ; Cicatrix, Hypertrophic ; metabolism ; pathology ; Fibroblasts ; cytology ; drug effects ; metabolism ; Humans ; Imidazoles ; pharmacology ; Phosphatidylinositol 3-Kinases ; metabolism ; Proto-Oncogene Proteins c-akt ; metabolism ; Pyridines ; pharmacology ; Receptor, Angiotensin, Type 1 ; Signal Transduction ; Tetrazoles ; pharmacology ; Valine ; analogs & derivatives ; pharmacology ; Valsartan