RESUMO
OBJECTIVE: Collateral artery growth (arteriogenesis) is an important adaptive response to hampered arterial perfusion. It is unknown whether preventive physical exercise before limb ischemia can improve arteriogenesis and modulate mononuclear cell function. This study aimed at investigating the effects of endurance exercise before arterial occlusion on MNC function and collateral artery growth. APPROACH AND RESULTS: After 3 weeks of voluntary treadmill exercise, ligation of the right femoral artery was performed in mice. Hindlimb perfusion immediately after surgery did not differ from sedentary mice. However, previous exercise improved perfusion restoration ≤7 days after femoral artery ligation, also when exercise was stopped at ligation. This was accompanied by an accumulation of peri-collateral macrophages and increased expression of endothelial nitric oxide synthase and inducible nitric oxide synthase (iNOS) in hindlimb collateral and in MNC of blood and spleen. Systemic monocyte and macrophage depletion by liposomal clodronate but not splenectomy attenuated exercise-induced perfusion restoration, collateral artery growth, peri-collateral macrophage accumulation, and upregulation of iNOS. iNOS-deficient mice did not show exercise-induced perfusion restoration. Transplantation of bone marrow-derived MNC from iNOS-deficient mice into wild-type animals inhibited exercise-induced collateral artery growth. In contrast to sedentary controls, thrice weekly aerobic exercise training for 6 months in humans increased peripheral blood MNC iNOS expression. CONCLUSIONS: Circulating mononuclear cell-derived inducible nitric oxide is an important mediator of exercise-induced collateral artery growth.
Assuntos
Circulação Colateral , Exercício Físico , Isquemia/terapia , Monócitos/metabolismo , Músculo Esquelético/irrigação sanguínea , Óxido Nítrico/metabolismo , Esforço Físico , Adulto , Animais , Transplante de Medula Óssea , Estudos de Casos e Controles , Linhagem Celular Tumoral , Quimiocina CCL2/sangue , Quimiocina CCL2/genética , Modelos Animais de Doenças , Feminino , Membro Posterior , Humanos , Isquemia/genética , Isquemia/metabolismo , Isquemia/fisiopatologia , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout , Pessoa de Meia-Idade , Monócitos/transplante , Neovascularização Fisiológica , Óxido Nítrico Sintase Tipo II/deficiência , Óxido Nítrico Sintase Tipo II/genética , Óxido Nítrico Sintase Tipo II/metabolismo , Óxido Nítrico Sintase Tipo III/metabolismo , Interferência de RNA , Fluxo Sanguíneo Regional , Corrida , Transdução de Sinais , Fatores de Tempo , TransfecçãoRESUMO
AIMS: Collateral arteries protect tissue from ischaemia. Heart rate correlates with vascular events in patients with arterial obstructive disease. Here, we tested the effect of heart-rate reduction (HRR) on collateral artery growth. METHODS AND RESULTS: The I(f)-channel inhibitor ivabradine reduced heart rate by 11% in wild-type and 15% in apolipoprotein E (ApoE)(-/-) mice and restored endothelium-dependent relaxation in aortic rings of ApoE(-/-) mice. Microsphere perfusion and angiographies demonstrated that ivabradine did not change hindlimb perfusion in wild-type mice but improved perfusion in ApoE(-/-) mice from 40.5 ± 15.8-60.2 ± 18.5% ligated/unligated hindlimb. Heart rate reduction (13%) with metoprolol failed to improve endothelial function and perfusion. Protein expression of endothelial nitric oxide synthase (eNOS), phosphorylated eNOS, and eNOS activity were increased in collateral tissue following ivabradine treatment of ApoE(-/-) mice. Co-treatment with nitric oxide-inhibitor N (G)-nitro-L-arginine methyl ester abolished the effects of ivabradine on arteriogenesis. Following ivabradine, classical inflammatory cytokine expression was lowered in ApoE(-/-) circulating mononuclear cells and in plasma, but unaltered in collateral-containing hindlimb tissue, where numbers of perivascular macrophages also remained unchanged. However, ivabradine reduced expression of anti-arteriogenic cytokines CXCL10and CXCL11 and of smooth muscle cell markers smoothelin and desmin in ApoE(-/-) hindlimb tissue. Endothelial nitric oxide synthase and inflammatory cytokine expression were unchanged in wild-type mice. Ivabradine did not affect cytokine production in HUVECs and THP1 mononuclear cells and had no effect on the membrane potential of HUVECs in patch-clamp experiments. CONCLUSION: Ivabradine-induced HRR stimulates adaptive collateral artery growth. Important contributing mechanisms include improved endothelial function, eNOS activity, and modulation of inflammatory cytokine gene expression.
Assuntos
Antiarrítmicos/farmacologia , Aterosclerose/fisiopatologia , Benzazepinas/farmacologia , Circulação Colateral/efeitos dos fármacos , Frequência Cardíaca/efeitos dos fármacos , Hipercolesterolemia/fisiopatologia , Animais , Apolipoproteínas E/metabolismo , Artérias/efeitos dos fármacos , Capilares/efeitos dos fármacos , Canais de Cátion Regulados por Nucleotídeos Cíclicos/antagonistas & inibidores , Citocinas/efeitos dos fármacos , Ivabradina , Ligadura , Camundongos , Óxido Nítrico Sintase Tipo III/metabolismo , Espécies Reativas de Oxigênio/metabolismo , Estresse FisiológicoRESUMO
Arteriogenesis as a way to restore blood flow after arterial occlusion has been under investigation for the treatment of coronary artery disease (CAD) for decades. Therapeutic approaches so far have included delivery of cytokines and growth factors as well as mechanical stimulation such as external counterpulsation. As knowledge on the mechanisms of arteriogenesis expanded, new therapeutic approaches have emerged. This review summarizes recent attempts to stimulate the growth of the coronary vasculature and discusses their potential in clinical application. This article also delivers an overview of current studies and trials on coronary arteriogenesis.