Jean-Paul Henry

Improvement of Endothelial Function by Chronic Angiotensin-Converting Enzyme Inhibition in Heart Failure Role of Nitric Oxide, Prostanoids, Oxidant Stress, and Bradykinin

BACKGROUND-Chronic heart failure (CHF) impairs the endothelium-dependent, flow-mediated dilation (FMD) of small arteries. However, whether chronic angiotensin-converting enzyme (ACE) inhibition affects the impairment of FMD in CHF is unknown. We investigated the effects of long-term ACE inhibition on the FMD of peripheral arteries in rats with CHF and the mechanism(s) involved. METHODS AND RESULTS-FMD was assessed in isolated, perfused gracilis muscle arteries from sham-operated, and untreated or ACE inhibitor-treated (perindopril 2 mg. kg(-1). day(-1) for 10 weeks) rats with CHF (coronary artery ligation). The role of nitric oxide (NO), prostaglandins, and free radicals was assessed by pretreating the vessels with the NO synthase inhibitor N(W)-nitro-L-arginine, the cyclooxygenase inhibitor diclofenac, or the free radical scavenger N-2-mercaptopropionyl-glycine (MPG). Endothelial NO synthase mRNA expression was determined by reverse transcriptase polymerase chain reaction. In animals with hemodynamic and echographic signs of CHF, FMD was converted into vasoconstriction, and this was prevented by ACE inhibition. FMD of arteries from sham-operated or ACE inhibitor-treated CHF rats was abolished by N(W)-nitro-L-arginine. In untreated CHF rats, FMD was increased by diclofenac and MPG. In contrast, in arteries from ACE inhibitor-treated rats, neither diclofenac nor MPG affected FMD. In parallel, ACE inhibition prevented the reduction of endothelial NO synthase mRNA by CHF. CONCLUSIONS-In CHF, ACE inhibition normalized NO-dependent dilatation and suppressed the production of vasoconstrictor prostanoid(s), resulting in improved FMD. The improvement of FMD might contribute to the beneficial effects of ACE inhibition during CHF.

Tissue Doppler Imaging Differentiates Physiological From Pathological Pressure-Overload Left Ventricular Hypertrophy in Rats

Background—The myocardial velocity gradient (MVG) is a recent index of regional myocardial function derived from endocardial and epicardial velocities obtained by tissue Doppler imaging (TDI). This index might be useful for discriminating between physiological and pathological left ventricular hypertrophy (LVH) and for documenting the early transition from compensated LVH to heart failure. We sought to compare MVG measured across the left ventricular posterior wall between normal rats and rats with physiological (exercise) and pathological (pressure-overload) LVH. Methods and Results—Wistar rats were assigned to one of the following groups: sedentary, exercise (swimming), and 2-month or 9-month abdominal aortic banding. Compared with sedentary rats, exercise and 2-month banding led to similar and significant LVH. After 2-month banding, conventional parameters of systolic function (left ventricular fractional shortening and dP/dtmax) were not affected. However, systolic and diastolic MVG were similar in exercise and sedentary rats but were significantly lower in rats with aortic banding. Aortic debanding after 2 months led to a full recovery of MVG, whereas MVG remained decreased when debanding was performed after 9 months. Conclusions—Myocardial contraction and relaxation assessed by TDI were impaired in pressure-overload LVH but not in exercise LVH. Therefore, TDI is more sensitive than conventional echocardiography for assessing myocardial dysfunction in pressure-overload LVH and for predicting early recovery in myocardial function after loading conditions normalization.

Exercise Improves Flow-Mediated Vasodilatation of Skeletal Muscle Arteries in Rats With Chronic Heart Failure Role of Nitric Oxide, Prostanoids, and Oxidant Stress

BACKGROUND Flow-mediated dilatation (FMD) of the peripheral arteries may be impaired in chronic heart failure (CHF), and this could contribute to the increased peripheral resistance and exercise intolerance that occur with this disease. Physical exercise improves the FMD of large conduit arteries in CHF, but whether a similar impairment also occurs in smaller arteries is unknown. The mechanisms of the changes in FMD after CHF or exercise are also unknown. METHODS AND RESULTS FMD was assessed in isolated, perfused, and preconstricted gracilis muscle arteries from sham-operated rats or CHF rats (coronary artery ligation) who were either sedentary or exercised (30-minute swimming period twice a day for 10 weeks, starting 7 days after ligation). In animals with hemodynamic and echographic signs of CHF, FMD was abolished and converted into vasoconstriction (percent change in diameter after 370 microL/min flow: sham, 42+/-5%; CHF, -4+/-3%; P<0.05). Exercise partially restored FMD (18+/-3%; P<0.05 versus CHF). In sham rats, FMD was abolished by the nitric oxide-synthase inhibitor Nomega-nitro-L-arginine (L-NA) but unaffected by the cyclooxygenase inhibitor diclofenac or the free radical scavenger N-(2-mercaptopropionyl)-glycine (MPG). In arteries from sedentary CHF rats, FMD was not modified by L-NA, but it was partially restored by diclofenac or MPG. In exercised CHF rats, FMD was abolished by L-NA and only moderately improved by diclofenac or MPG. Likewise, endothelial nitric oxide synthase mRNA expression (determined by reverse transcription polymerase chain reaction at the level of the gracilis muscle) was reduced by CHF, and this was prevented by exercise. CONCLUSIONS CHF abolishes the FMD of small arteries by impairing the nitric oxide pathway, increasing oxidant stress, and releasing a prostanoid-contracting factor. Exercise partially restores FMD by increasing expression of endothelial nitric oxide synthase and preventing the production of vasoconstrictor prostanoids and free radicals. Such restoration of FMD might contribute to the increase in exercise capacity after physical exercise in CHF.

Toll-Like Receptors 2-Deficient Mice Are Protected Against Postischemic Coronary Endothelial Dysfunction

Objectives—Toll-like receptors (TLR) 2 are expressed in cardiac and inflammatory cells, and regulate leukocyte function. Because leukocyte adhesion is a critical event in endothelial injury induced by ischemia/reperfusion (I/R), we assessed whether TLR2 were involved in I/R - induced coronary endothelial injury. Methods and Results—Ischemia - reperfusion markedly decreased NO-mediated coronary relaxations to acetylcholine assessed ex vivo. In contrast, in TLR2 deficient mice, I/R paradoxically improved the NO-mediated responses to acetylcholine. To precise the cellular compartment expressing TLR2 which is involved in endothelial injury, we developed bone-marrow chimeric mice by transplanting TLR2−/− bone marrow to WT mice or WT bone marrow to TLR2−/− mice and submitted them to I/R 5 weeks after transplant. Both chimeric mice displayed similar protection as TLR2−/− mice against I/R-induced endothelial dysfunction, suggesting a role of TLR2 expressed on both non-bone marrow cells (in our case presumably endothelial cells and/or cardiomyocytes) and cells of bone marrow origin (presumably neutrophils). TLR2 deficiency was also associated with a smaller infarct size, and reduced reperfusion-induced production of reactive oxygen species and leukocyte infiltration. Conclusions—TLR2 contribute to coronary endothelial dysfunction after I/R, possibly through stimulation of neutrophil- (and free radical-) mediated endothelial injury.

Increased Survival After Long-Term Treatment With Mibefradil, a Selective T-Channel Calcium Antagonist, in Heart Failure

OBJECTIVES We sought to investigate the effects of mibefradil on survival, hemodynamic variables and cardiac remodeling in a rat model of chronic heart failure (HF) and to compare these effects with those of the angiotensin-converting enzyme (ACE) inhibitor cilazapril. BACKGROUND The use of calcium channel blocking agents in chronic HF has been disappointing. Most studies have shown that these drugs have either no or even detrimental effects due in part to the negative inotropic effects they induce. Mibefradil is a calcium channel blocker that selectively blocks T channels and displays moderately negative inotropic properties only at high doses. Because T channels are upregulated in the hypertrophied heart and could mediate hypertrophic signals and increase arrhythmogenicity, blockade of these channels might be beneficial in chronic HF. METHODS Rats were subjected to coronary artery ligation and 9 months of treatment with mibefradil (15 mg/kg body weight per day) or cilazapril (10 mg/kg per day) or no treatment. Survival and systolic blood pressure were assessed over the 9-month treatment period, after which cardiac hemodynamic variables and structure were determined. RESULTS Mibefradil increased survival rate to the same extent as cilazapril (71% for mibefradil vs. 75% for cilazapril and 44% for no treatment). Mibefradil decreased systolic blood pressure, although to a lesser extent than cilazapril. Both treatments decreased left ventricular (LV) end-diastolic and central venous pressures, without any change in the first derivative of LV pressure over time or heart rate. Mibefradil decreased LV weight (although less than cilazapril) without affecting right ventricular weight. Finally, both drugs normalized LV collagen density. CONCLUSIONS Mibefradil in a rat model improved survival to the same extent as an ACE inhibitor, without impairing LV function, and was associated with a reduction in LV weight and fibrosis. Thus, mibefradil might be beneficial in the treatment of chronic HF.

Early Versus Delayed Angiotensin-Converting Enzyme Inhibition in Experimental Chronic Heart Failure Effects on Survival, Hemodynamics, and Cardiovascular Remodeling

BACKGROUND The efficacy of ACE inhibitors in congestive heart failure (CHF) might be affected by the pathophysiological status present at the onset of treatment. We compared in a rat model the effects of ACE inhibition (lisinopril, 10 mg.kg-1.d-1) initiated early (1 week) or late (3 months) after myocardial infarction (i.e., at time points corresponding to moderate or severe CHF without or with established cardiac remodeling). METHODS AND RESULTS Survival was improved by early treatment at 3 months (from 76% to 95%) and by both early and delayed treatment at 9 months (placebo, 28%; early, 90%; delayed, 61%). Delayed treatment was initiated in a more severe pathophysiological context of CHF than early treatment, illustrated in untreated rats by higher left ventricular (LV) end-diastolic and central venous pressures and by increased LV weight and LV cavity circumference. After 9 months, early and delayed treatments reduced systolic, LV end-diastolic, and central venous pressures. Both treatments also similarly decreased LV weight, LV cavity circumference, and LV collagen density. CONCLUSIONS In this rat model of CHF, early and delayed ACE inhibitor treatments both increase survival and exert similar beneficial effects on cardiac hemodynamics and remodeling. Although early treatment prevents the development of ventricular dysfunction and remodeling, delayed treatment is capable of reversing cardiac hypertrophy and remodeling, as well as ventricular dysfunction. Thus, ACE inhibitors exert marked beneficial effects even when treatment is initiated late into the evolution of heart failure (ie, at a time of established ventricular dysfunction and remodeling).

Arteriogenic Therapy by Intramyocardial Sustained Delivery of a Novel Growth Factor Combination Prevents Chronic Heart Failure

Background— Therapeutic angiogenesis is a promising approach for the treatment of cardiovascular diseases, including myocardial infarction and chronic heart failure. We aimed to improve proangiogenic therapies by identifying novel arteriogenic growth factor combinations, developing injectable delivery systems for spatiotemporally controlled growth factor release, and evaluating functional consequences of targeted intramyocardial growth factor delivery in chronic heart failure. Methods and Results— First, we observed that fibroblast growth factor and hepatocyte growth factor synergistically stimulate vascular cell migration and proliferation in vitro. Using 2 in vivo angiogenesis assays (n=5 mice per group), we found that the growth factor combination results in a more potent and durable angiogenic response than either growth factor used alone. Furthermore, we determined that the molecular mechanisms involve potentiation of Akt and mitogen-activated protein kinase signal transduction pathways, as well as upregulation of angiogenic growth factor receptors. Next, we developed crosslinked albumin-alginate microcapsules that sequentially release fibroblast growth factor-2 and hepatocyte growth factor. Finally, in a rat model of chronic heart failure induced by coronary ligation (n=14 to 15 rats per group), we found that intramyocardial slow release of fibroblast growth factor-2 with hepatocyte growth factor potently stimulates angiogenesis and arteriogenesis and prevents cardiac hypertrophy and fibrosis, as determined by immunohistochemistry, leading to improved cardiac perfusion after 3 months, as shown by magnetic resonance imaging. These multiple beneficial effects resulted in reduced adverse cardiac remodeling and improved left ventricular function, as revealed by echocardiography. Conclusion— Our data showing the selective advantage of using fibroblast growth factor-2 together with hepatocyte growth factor suggest that this growth factor combination may constitute an efficient novel treatment for chronic heart failure.

Endothelial Estrogen Receptor α Plays an Essential Role in the Coronary and Myocardial Protective Effects of Estradiol in Ischemia/Reperfusion

Objective—To assess the coronary endothelial protective effects of 17&bgr;-estradiol (E2) and the role of estrogen receptor (ER) &agr; in ischemia/reperfusion (I/R). Methods and Results—E2 exerts protective effects in cardiac I/R. However, the implication in vivo of the endothelium and the cellular targets of the anti-ischemic effects of E2 are unknown. Mice were subjected to I/R (30 minutes of I and 1 hour of R) in vivo, after which acetylcholine-induced relaxation of isolated coronary segments was assessed ex vivo. I/R induced a coronary endothelial dysfunction in untreated ovariectomized mice that was prevented by long-term treatment with E2 in wild-type, but not in ER&agr;−/−, mice. Chimeric mice inactivated for ER&agr; in the hematopoietic compartment remained protected by E2. Further inactivation of endothelial ER&agr; abolished the protective action of E2 on coronary endothelial function in Tie2-Cre(+) ER&agr;f/f mice. More importantly, E2 significantly limited infarct size in wild-type mice but not in mice deficient in endothelial ER&agr;, even in the presence of hematopoietic ER&agr;. Conclusion—Endothelial ER&agr; plays a crucial role in the E2-induced prevention of endothelial dysfunction after I/R. To our knowledge, we demonstrate for the first time, by using unique genetically modified mice, that targeting endothelial protection per se can confer cardiomyocyte protection in I/R.

Improvement of Peripheral Endothelial Dysfunction by Protein Tyrosine Phosphatase Inhibitors in Heart Failure

Background— Chronic heart failure (CHF) induces endothelial dysfunction characterized by a decrease in nitric oxide (NO) production in response to flow (flow-mediated dilatation [FMD]). Because activation of endothelial NO synthase (eNOS) by flow requires tyrosine phosphorylation, we tested whether endothelial dysfunction could be corrected by increasing phosphotyrosine levels using protein tyrosine phosphatase (PTP) inhibitors and especially inhibitors of PTP1B. Methods and Results— CHF was induced by coronary ligation in mice, and FMD was assessed in isolated and cannulated mesenteric artery segments (2 mm in length and <300 &mgr;m in diameter). CHF almost abolished FMD but only moderately affected the response to acetylcholine. In mice with CHF, the PTP1B inhibitors AS279, AS098, and AS713 restored FMD to levels similar to those of normal mice. This restoration was reduced by inhibitors of eNOS and phosphatidylinositol-3 kinase. Polymerase chain reaction and Western blot showed that arteries express PTP1B, and this expression was not affected by CHF. Immunolocalization revealed the presence of PTP1B in the endothelium and the adventitia. Flow induced a transient eNOS phosphorylation that was absent in CHF. PTP1B inhibition stimulated early eNOS phosphorylation and increased phosphorylation of Akt. Conclusions— Our results demonstrate for the first time that PTP1B inhibitors may be potent treatments for endothelial dysfunction.

Long-Term Survival and Hemodynamics After Endothelin-A Receptor Antagonism and Angiotensin-Converting Enzyme Inhibition in Rats With Chronic Heart Failure Monotherapy Versus Combination Therapy

Background—In patients with congestive heart failure (CHF) receiving ACE inhibitors, acute administration of selective endothelin (ET) antagonists additionally improves systemic and cardiac hemodynamics. We investigated, in a rat model of CHF, whether such acute synergistic effects are sustained and accompanied, in the long term, by an additional limitation of left ventricular remodeling or an increase in survival. Methods and Results—Rats were subjected to coronary artery ligation and treated for 3 or 9 months with vehicle or with the ACE inhibitor trandolapril (Tr) (0.3 mg/kg−1 per day−1), the ETA antagonist LU 135252 (LU, 30 mg/kg−1 per day−1), or their combination starting 7 days after ligation. After 3 months, the combination decreased LV systolic- and end-diastolic pressures (−32% and −80%, respectively) more markedly than Tr (−21% and −61%, respectively) or LU alone (−14% and −48%, respectively). Echocardiographic studies revealed that all treatments limited LV dilatation and increased LV fractional shortening and cardiac index. All treatments equally reduced left ventricular collagen density, whereas only Tr or the combination reduced LV weight. Finally, although LU did not modify long-term survival, Tr and the combination of Tr with LU induced a similar improvement of survival. Conclusions—In this rat model, long-term combined administration of an ETA antagonist and an ACE inhibitor induces additional effects in terms of systemic and cardiac hemodynamics; however, this is not associated with an additional increase in long-term survival.