Heart rate reduction by ivabradine reduces oxidative stress, improves endothelial function, and prevents atherosclerosis in apolipoprotein E-deficient mice.
ABSTRACT Elevated heart rate is associated with increased cardiovascular morbidity. We hypothesized that selective heart rate reduction may influence endothelial function and atherogenesis and tested the effects of the I(f) current inhibitor ivabradine in apolipoprotein E-deficient mice.
Male apolipoprotein E-deficient mice fed a high-cholesterol diet were treated with ivabradine (10 mg . kg(-1) . d(-1)) or vehicle for 6 weeks (n=10 per group). Ivabradine reduced heart rate by 13.4% (472+/-9 versus 545+/-11 bpm; P<0.01) but did not alter blood pressure or lipid levels. Endothelium-dependent relaxation of aortic rings was significantly improved in ivabradine-fed animals (P<0.01). Ivabradine decreased atherosclerotic plaque size in the aortic root by >40% and in the ascending aorta by >70% (P<0.05). Heart rate reduction by ivabradine had no effect on the number of endothelial progenitor cells and did not alter aortic endothelial nitric oxide synthase, phosphorylated Akt, vascular cell adhesion molecule-1, or intercellular adhesion molecule-1 expression but decreased monocyte chemotactic protein-1 mRNA and exerted potent antioxidative effects. Ivabradine reduced vascular NADPH oxidase activity to 48+/-6% and decreased markers of superoxide production and lipid peroxidation in the aortic wall (P<0.05). The in vivo effects of ivabradine were absent at a dose that did not lower heart rate, in aortic rings treated ex vivo, and in cultured vascular cells. In contrast to ivabradine, treatment with hydralazine (25 mg . kg(-1) . d(-1) for 6 weeks) reduced blood pressure (-15%) but increased heart rate (37%) and did not improve endothelial function, atherosclerosis, or oxidative stress.
Selective heart rate reduction with ivabradine decreases markers of vascular oxidative stress, improves endothelial function, and reduces atherosclerotic plaque formation in apolipoprotein E-deficient mice.
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ABSTRACT: A large number of studies in healthy and asymptomatic subjects, as well as patients with already established cardiovascular disease (CAD) have demonstrated that heart rate (HR) is a very important and major independent cardiovascular risk factor for prognosis. Lowering heart rate reduces cardiac work, thereby diminishing myocardial oxygen demand. Several experimental studies in animals, including dogs and pigs, have clarified the beneficial effects of ivabradine associated with HR lowering. Ivabradine is a selective inhibitor of the hyperpolarisation activated cyclic-nucleotide-gated funny current (If) involved in pacemaker generation and responsiveness of the sino-atrial node (SAN), which result in HR reduction with no other apparent direct cardiovascular effects. Several studies show that ivabradine substantially and significantly reduces major risks associated with heart failure when added to guideline-based and evidence-based treatment. However the biological effect of ivabradine have yet to be studied. This effects can appear directly on myocardium or on a systemic level improving endothelial function and modulating immune cell migration. Indeed ivabradine is an 'open-channel' blocker of human hyperpolarization-activated cyclic nucleotide gated channels of type-4 (hHCN4), and a 'closed-channel' blocker of mouse HCN1 channels in a dose-dependent manner. At endothelial level ivabradine decreased monocyte chemotactin protein-1 mRNA expression and exerted a potent anti-oxidative effect through reduction of vascular NADPH oxidase activity. Finally, on an immune level, ivabradine inhibits the chemokine-induced migration of CD4-positive lymphocytes. In this review, we discuss the biological effects of ivabradine and highlight its effects on CAD.Molecules 01/2012; 17(5):4924-35. · 2.39 Impact Factor
Article: The Apoe-/- Mouse PhysioLab(R) Platform: A Validated Physiologically-based Mathematical Model of Atherosclerotic Plaque Progression in the Apoe-/- Mouse[show abstract] [hide abstract]
ABSTRACT: Motivation:Atherosclerosis is a complex multi-pathway inflammatory disease where accumulation of oxidatively modified lipids and leukocytes in the arterial intima leads to plaque formation over time. Translating Apoe-/- mouse results to the clinical setting is complicated by uncertainty around (a) mechanisms underlying disease etiology, (b) relative importance of these mechanisms as drivers of progression, and (c) how these roles change in response to perturbation by therapeutic intervention or lifestyle changes. Results: We describe a large-scale mechanistic, mathematical model of atherosclerosis in the Apoe-/- mouse and its validation with in vivo Apoe -/- data. Major physiological components include cholesterol/macrophage trafficking, inflammation, endothelial function, oxidative stress, and thrombosis. Heterogeneity in disease progression, observed despite genetic uniformity and experimentally controlled conditions, was captured through “virtual mice”. This model may be used to optimize in vivo experiments and paves the way for a similar modeling approach for human disease. Availability: The model is available by remote desktop client at Apoe.entelos.com.BioDiscovery. 09/2012; 3(2).