angiotensin-i and Necrosis

Recent evidence has shown that, in heart failure (HF), clinically relevant concentrations of angiotensin-(1-7) [Ang-(1-7)] counteracts angiotensin II induced cardiac depression and produces positive inotropic effects in both left ventricle (LV) and myocytes. However, the underlying electrophysiological mechanism is unclear. We investigated the role and mechanism of Ang-(1-7) on LV myocyte L-type calcium current (ICa,L) responses in normal state and in HF.. We compared the effect of Ang-(1-7) (10(-5) M) on ICa,L responses in isolated LV myocytes obtained from 11 rats with isoproterenol (ISO) induced HF (3 months after 170 mg/kg subcutaneous for 2 days) and from 8 age-matched normal control rats by patch clamp technique.. In normal myocytes, compared with baseline, superfusion of Ang-(1-7) caused no significant changes in ICa,L (8.2 ± 0.2 versus 8.0 ± 0.3 pA/pF, p= not significant). In HF myocytes, the baseline ICa,L was significantly reduced (5.3 ± 0.1 versus 8.0 ± 0.3 pA/pF, p < 0.01). Ang-(1-7) produced a 21% increase in ICa,L (6.4±0.1 versus 5.3±0.1 pA/pF, p < 0.01). Pretreatment of HF myocytes with a nitric oxide (NO) synthase inhibitor (L-NAME, 10(-5) M) resulted in a significantly greater increase in ICa,L (28%, 8.4 ± 0.1 versus 6.5 ± 0.1 pA/pF, p < 0.01) during Ang-(1-7) superfusion. In contrast, during incubation with the bradykinin (BK) inhibitor HOE 140 (10(-6) M), Ang-(1-7) induced increase in ICa,L was significantly decreased. The Ang-(1-7) induced increase in ICa,L was abolished by [D-Ala(7)]-Ang-(1-7) (A-779, 10(-5) M).. HF alters the response of ICa,L to Ang-(1-7). In normal myocytes, Ang-(1-7) has no significant effect on ICa,L. However, in HF myocytes, Ang-(1-7) increases ICa,L. These effects are mediated by the Ang-(1-7) Mas receptors and involve activation of NO/BK pathways.

Topics: Angiotensin I; Animals; Bradykinin; Calcium Channels, L-Type; Calcium Signaling; Cardiotonic Agents; Disease Models, Animal; Heart Failure; Isoproterenol; Male; Membrane Potentials; Myocytes, Cardiac; Necrosis; Nitric Oxide; Peptide Fragments; Proto-Oncogene Mas; Proto-Oncogene Proteins; Rats, Sprague-Dawley; Receptors, G-Protein-Coupled; Time Factors; Ventricular Function, Left

Angiotensin-converting enzyme (ACE) and its effector peptide angiotensin II (Ang II) have been implicated in the pathogenesis of pancreatitis. Angiotensin-converting enzyme 2 (ACE2) degrades Ang II to angiotensin-(1-7) [Ang-(1-7)] and has recently been described to have an antagonistic effect on ACE signalling. However, the specific underlying role of ACE2 in the pathogenesis of severe acute pancreatitis (SAP) is unclear. In the present study, the local imbalance of ACE and ACE2, as well as Ang II and Ang-(1-7) expression, was compared in wild-type (WT) and ACE2 knock-out (KO) or ACE2 transgenic (TG) mice subjected to cerulein-induced SAP. Serum amylase, tumour necrosis factor-α, interleukin (IL)-1β, IL-6 and IL-10 levels and histological morphometry were used to determine the severity of pancreatitis. In WT mice, pancreatic ACE and Ang II and serum Ang II expression increased (P < 0.05), while pancreatic ACE2 and Ang-(1-7) and serum Ang-(1-7) levels were also significantly elevated (P < 0.05) from 2 to 72 h after the onset of SAP. However, the ratio of pancreatic ACE2 to ACE expression was significantly reduced (from 1.46 ± 0.09 to 0.27 ± 0.05, P < 0.001) and paralleled the severity of pancreatitis. The Ace2 KO mice exhibited increased levels of tumour necrosis factor-α, IL-1β, IL-6, multifocal coagulative necrosis and inflammatory infiltrate, and lower levels of serum IL-10 and pancreatic Ang-(1-7) (4.70 ± 2.13 versus 10.87 ± 2.51, P < 0.001) compared with cerulein-treated WT mice at the same time point. Conversely, Ace2 TG mice with normal ACE expression were more resistant to SAP challenge as evidenced by a decreased inflammatory response, attenuated pathological changes and increased survival rates. These data suggest that the ACE2-ACE imbalance plays an important role in the pathogenesis of SAP and that pancreatic ACE2 is an important factor in determining the severity of SAP.

Topics: Acute Disease; Amylases; Angiotensin I; Angiotensin II; Angiotensin-Converting Enzyme 2; Animals; Biomarkers; Ceruletide; Disease Models, Animal; Genotype; Inflammation Mediators; Male; Mice, Inbred C57BL; Mice, Knockout; Necrosis; Pancreas; Pancreatitis; Peptide Fragments; Peptidyl-Dipeptidase A; Phenotype; Severity of Illness Index; Time Factors

The purpose of this study was to reveal the effect of angiotensin (1-7) on survival of random pattern, nicotinized, ischemic flap model in rats.. We used female Sprague Dawley rats weighing between 250 and 300 g. The study was performed on 3 groups each of them was consisted of 30 rats (control [C], angiotensin (1-7) [A] and vehicle [V]).While group C was subjected to 1 mL saline subcutaneous injection once daily for 28 days, groups A and V were nicotinized by 2 mg/kg nicotine subcutaneous injection, twice a day. At the end of this period, McFarlane random flap was constructed in all rats. No drug was applied to the flap bed in the group C, whereas for group A angiotensin (1-7) (A [1-7]) was delivered and a vehicle without an active ingredient was applied to the group V.Following surgery, immediately, Na-fluorescein diffusion tests were performed on 10 subjects of every group and necrotic areas were determined by millimetric paper method. After this, for determining angiogenesis, 10 subjects were killed from each group on the second day and fourth day. Finally, on the seventh day, necrotic areas were measured in 10 subjects of each group. They were then killed after photographs were taken. Specimens were collected from distal and critical zones of flaps, in all the groups, for immunohistochemical and histopathologic analyses.. Macroscopic measurements revealed equal ischemic areas for groups A and V in 30 minutes which were both larger than those of the group C (P < 0.005). Measurements performed on the seventh day showed a significant decrease of ischemia, which advanced to necrosis in the group A (P < 0.005). Groups V and C showed a direct progress to necrosis without changes in ischemia levels. Microscopic analysis exhibited a statistically significant increase in the number of microvascular structures and diameters of mature vascular structures in the group A compared with those of groups C and V (P < 0.005).. A (1-7) increased vasodilatation in nicotinized flaps, triggered angiogenesis in the first 2 days, and contributed remarkably to the flap survival.

Topics: Angiogenesis Inducing Agents; Angiotensin I; Animals; Female; Graft Survival; Ischemia; Necrosis; Neovascularization, Physiologic; Nicotine; Peptide Fragments; Rats; Rats, Sprague-Dawley; Skin Transplantation; Surgical Flaps; Vasodilation; Vasodilator Agents

The aims were to determine: (1) if angiotensin converting enzyme (ACE) inhibition and angiotensin II receptor blockade can prevent angiotensin II induced coronary vascular damage; (2) if the cardioprotective properties of ACE inhibition are dose dependent; and (3) if the cardioprotective properties of ACE inhibition are independent of its ability to prevent the conversion of angiotensin I to angiotensin II.. Control rats and rats with either renovascular hypertension or continuous angiotensin II infusion (150 ng.min-1) for 14 d were subdivided into nine groups as follows: unoperated and untreated controls (n = 5); untreated renovascular hypertension (n = 8); untreated angiotensin II (n = 9); a renovascular hypertension group receiving one of the following doses of lisinopril 20 (n = 8), 2.5 (n = 4), and 0.6 (n = 6) mg.kg-1.d-1; a renovascular hypertension group receiving losartan (7.5 mg.d-1, n = 4); and an angiotensin II group receiving either the high dose of lisinopril (n = 6) or losartan (n = 4). Treatment was started one day before initiation of renovascular hypertension and angiotensin II infusion and continued throughout the study period. The number and size of necrotic areas and numbers of damaged coronary vessels were determined in sections of right and left ventricular tissue.. Both coronary vascular injury and myocyte injury induced by angiotensin II were prevented by losartan. In renovascular hypertension, the lowest dose of lisinopril prevented vascular and attenuated myocyte damage but to a lesser degree than the higher doses. The cardioprotective ability of ACE inhibition is primarily the result of its ability to prevent the conversion of angiotensin I to angiotensin II.. Angiotensin II related cardiomyocyte necrosis and coronary vascular damage are angiotensin type 1 receptor mediated and completely preventable with the receptor antagonist losartan. The ability of ACE inhibition to prevent this damage is dose dependent and primarily related to the degree to which the inhibitor can prevent the conversion of angiotensin I to angiotensin II.

Topics: Angiotensin I; Angiotensin II; Animals; Biphenyl Compounds; Coronary Vessels; Dose-Response Relationship, Drug; Heart; Hypertension, Renovascular; Imidazoles; Lisinopril; Losartan; Male; Necrosis; Rats; Rats, Sprague-Dawley; Tetrazoles

Ac3-Proteinase from the venom of Agkistrodon acutus was isolated in a homogeneous form by a previously published method. Ac3-Proteinase possessed lethal, hemorrhagic, caseinolytic, azocaseinolytic, dimethylcaseinolytic and hide powder azure hydrolytic activities. These activities were inhibited when Ac3-Proteinase was incubated with the metal chelators ethylenediaminetetraacetic acid (EDTA), ethyleneglycol-bis-(beta-aminoethyl ether)-N,N'-tetraacetic acid (EGTA), tetraethylenepentamine (TEP), 1,10-phenanthroline, phosphoramidon or beta-mercaptoethanol. The toxin also hydrolyzed the oxidized A and B chains of both insulin and fibrinogen. The cleavage sites in the oxidized B chain of insulin were identified as His(10)-Leu(11), Ala(14)-Leu(15), Tyr(16)-Leu(17) and Phe(24)-Phe(25). The A alpha chain of fibrinogen was digested first followed by hydrolysis of the B beta chain. Toxicological and biochemical properties of Ac3-Proteinase were investigated further and are reported in this paper.

Topics: Angiotensin I; Animals; Caseins; Creatine Kinase; Crotalid Venoms; Endopeptidases; Hemorrhage; Mice; Necrosis; Peptides; Substrate Specificity; Thrombin