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Direct renin inhibition prevents cardiac dysfunction in a diabetic mouse model: comparison with an angiotensin receptor antagonist and angiotensin-converting enzyme inhibitor.

ABSTRACT: Hyperglycaemia up-regulates intracellular AngII (angiotensin II) production in cardiac myocytes, effects of which are blocked more effectively by renin inhibition than ARBs (angiotensin receptor blockers) or ACEis (angiotensin-converting enzyme inhibitors). In the present study, we determined whether renin inhibition is more effective at preventing diabetic cardiomyopathy than an ARB or ACEi. Diabetes was induced in adult mice for 10 weeks by STZ (streptozotocin). Diabetic mice were treated with insulin, aliskiren (a renin inhibitor), benazeprilat (an ACEi) or valsartan (an ARB) via subcutaneous mini-pumps. Significant impairment in diastolic and systolic cardiac functions was observed in diabetic mice, which was completely prevented by all three RAS (renin-angiotensin system) inhibitors. Hyperglycaemia significantly increased cardiac oxidative stress and circulating inflammatory cytokines, which were blocked by aliskiren and benazeprilat, whereas valsartan was partially effective. Diabetes increased cardiac PRR (prorenin receptor) expression and nuclear translocation of PLZF (promyelocytic zinc finger protein), which was completely prevented by aliskiren and valsartan, and partially by benazeprilat. Renin inhibition provided similar protection of cardiac function to ARBs and ACEis. Activation of PLZF by PRR represented a novel mechanism in diabetic cardiomyopathy. Differential effects of the three agents on oxidative stress, cytokines and PRR expression suggested subtle differences in their mechanisms of action.

SUBMITTER: Thomas CM

PROVIDER: S-EPMC3982397 | biostudies-literature | 2013 Apr

REPOSITORIES: biostudies-literature

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Direct renin inhibition prevents cardiac dysfunction in a diabetic mouse model: comparison with an angiotensin receptor antagonist and angiotensin-converting enzyme inhibitor.

Thomas Candice M CM Yong Qian Chen QC Seqqat Rachid R Chandel Niketa N Feldman David L DL Baker Kenneth M KM Kumar Rajesh R

Clinical science (London, England : 1979) 20130401 8

Hyperglycaemia up-regulates intracellular AngII (angiotensin II) production in cardiac myocytes, effects of which are blocked more effectively by renin inhibition than ARBs (angiotensin receptor blockers) or ACEis (angiotensin-converting enzyme inhibitors). In the present study, we determined whether renin inhibition is more effective at preventing diabetic cardiomyopathy than an ARB or ACEi. Diabetes was induced in adult mice for 10 weeks by STZ (streptozotocin). Diabetic mice were treated with ...[more]

PMID: 23116220

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Project description:Rationale: Smoking is a major risk factor for the development of cardiovascular and pulmonary diseases. The importance of the renin–angiotensin system in the development of cardiovascular and pulmonary disease is well established. Angiotensin-II, by means of its type 1 receptor (angiotensin type 1 receptor, AT1R), promotes increased sympathetic activity, salt and water reabsorption, vasoconstriction, inflammation, and aldosterone and vasopressin release, contributing to tissue fibrosis, endothelium dysfunction, and hypertension. Angiotensin-converting enzyme 2 cleaves angiotensin-II into the vasodilator peptide, angiotensin-(1–7), hence playing a pivotal role in the angiotensin-converting enzyme 2/angiotensin-(1–7) compensatory axis of the renin–angiotensin system. Angiotensin type 2 receptor (AT2R), another receptor for angiotensin-II, opposes the deleterious effects of AT1R activation, and angiotensin-converting enzyme 2–formed angiotensin-(1–7) has been shown to activate AT2R. Objectives: The goal of the present study was to examine how nicotine, the addictive component of cigarette smoke, alters the homeostasis of the renin–angiotensin system. Methods: Quantitative real-time polymerase chain reaction was performed to examine the expression of the components of the renin–angiotensin system after cigarette smoke exposure or direct nicotine inhalation. Radio telemetry was used for continuous blood pressure recording in conscious, unrestrained mice. Results: Our study showed that cigarette smoke or direct nicotine inhalation inhibits the expression of angiotensin-converting enzyme 2/AT2R in multiple organs and cell types. In the lung, cigarette smoke (6 cigarettes/d, 12 wk) inhibited the expression of both angiotensin-converting enzyme 2 and AT2R. In cardiac fibroblasts, nicotine exposure resulted in near complete suppression of angiotensin-converting enzyme 2 and AT2R. In the brain, nicotine vapor inhalation inhibited angiotensin-converting enzyme 2 expression in the hypothalamus, a region involved in central regulation of cardiopulmonary function. In addition, cultured Neuro2A cells exposed to nicotine showed a dose-dependent reduction of enzymatic activity of angiotensin-converting enzyme 2. Functionally, mice exposed to nicotine vapor (12 h/d, 4 wk) exhibited significantly increased mean arterial blood pressure, which was more pronounced during the night active cycle (mean?±?SE, 124?±?0.6 mm Hg in nicotine vapor–exposed mice vs. 107?±?0.4 mm Hg in air control mice; P <?0.0001). Conclusions: Our findings suggest that, by downregulating the compensatory angiotensin-converting enzyme 2/AT2R elements, nicotine disrupts the homeostasis of the renin–angiotensin system in multiple organs, which is likely an important mechanism leading to the development of cardiovascular and pulmonary disease.

Dataset Information

Direct renin inhibition prevents cardiac dysfunction in a diabetic mouse model: comparison with an angiotensin receptor antagonist and angiotensin-converting enzyme inhibitor.

Publications

Direct renin inhibition prevents cardiac dysfunction in a diabetic mouse model: comparison with an angiotensin receptor antagonist and angiotensin-converting enzyme inhibitor.

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