Loss of cardioprotective effects of preinfarction angina in elderly but not in adult patients.
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Biomedical subjects
Publications and source records attributed to P Abete.
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OBJECTIVES: To investigate the effects of ischemic preconditioning in hearts from adult and both sedentary and trained senescent rats. BACKGROUND: Ischemic preconditioning does not prevent postischemic dysfunction in the aging heart, probably because of reduction of cardiac norepinephrine release. Exercise training can reverse the age-related decrease of norepinephrine production. METHODS: We investigated the effects on mechanical parameters of ischemic preconditioning against 20 min of global ischemia followed by 40 min of reperfusion in isolated perfused hearts from adult (six months) and sedentary or trained (six weeks of graduated swim training) senescent (24 months) rats. Norepinephrine release in coronary effluent was determined by high-performance liquid chromatography. RESULTS: Final recovery of percent-developed pressure was significantly improved after preconditioning in adult hearts (91.6+/-9.6%) versus unconditioned controls (54.2+/-5.1%, p<0.01). The effect of preconditioning on developed pressure recovery was absent in sedentary but present in trained senescent hearts (39.6+/-4.1% vs. 64.3+/-7.1%, p<0.05). Norepinephrine release significantly increased after preconditioning in adult and in trained but not in sedentary senescent hearts. The depletion of myocardial norepinephrine stores by reserpine abolished preconditioning effects in adult and trained senescent hearts. CONCLUSIONS: In adult and trained but not in sedentary senescent hearts, preconditioning reduces postischemic dysfunction and is associated with an increase in norepinephrine release. Preconditioning was blocked by reserpine in both adult and trained senescent hearts. Thus, exercise training may restore preconditioning in the senescent heart through an increase of norepinephrine release.
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BACKGROUND: A reduction of exercise-induced ischemia in patients with coronary artery disease by means of brief period of exercise followed by resting is called the "warm-up" phenomenon. This phenomenon may represent a clinical counterpart of "ischemic preconditioning." We studied the warm-up phenomenon in both adult and elderly patients with similar angiographic evidence of coronary artery disease, using three exercise tests after excluding the "training effect." METHODS: In order to verify the presence of "training effect," three exercise tests were performed in days 1, 2, and 3 ("training" tests). The third test was used as baseline for a successive test, performed after a recovery period of 10 minutes to reestablish baseline electrocardiographic conditions. A third exercise test was performed 30 minutes later ("warm-up" tests). RESULTS: "Training" tests did not differ in all parameters in both adult and elderly patients. "Warm-up" tests showed that time to onset 1-mm ST depression was significantly higher (p < .001). whereas ST depression and time to recovery was significantly lower in the second and third test in adult but not in elderly patients (p < .001 ). Difference (in seconds) in the time at which 1-mm ST depression occurred on first warm-up exercise compared with the second was inversely correlated with age (p < .001 ). CONCLUSIONS: Previous exercise followed by resting is able to reduce the successive exercise-induced ischemia ("warm-up" phenomenon) in adult but not in elderly patients with coronary artery disease. This is independent of a greater age-related severity of coronary disease and of "training effect." These results confirm the hypothetical age-related reduction of "ischemic preconditioning" in aging heart.
Apoptosis of arterial cells induced by oxidized low density lipoproteins (OxLDL) is thought to contribute to the progression of atherosclerosis. However, most data on apoptotic effects and mechanisms of OxLDL were obtained with extensively oxidized LDL unlikely to occur in early stages of atherosclerotic lesions. We now demonstrate that mildly oxidized LDL generated by incubation with oxygen radical-producing xanthine/xanthine oxidase (X/XO) induces apoptosis in primary cultures of human coronary endothelial and SMC, as determined by TUNEL technique, DNA laddering, and FACS analysis. Apoptosis was markedly reduced when X/XO-LDL was generated in the presence of different oxygen radical scavengers. Apoptotic signals were mediated by intramembrane domains of both Fas and tumor necrosis factor (TNF) receptors I and II. Blocking of Fas ligand (FasL) reduced apoptosis by 50% and simultaneous blocking of FasL and TNF receptors by 70%. Activation of apoptotic receptors was accompanied by an increase of proapoptotic and a decrease in antiapoptotic proteins of the Bcl-2 family and resulted in marked activation of class I and II caspases. Mildly oxidized LDL also activated MAP and Jun kinases and increased p53 and other transcription factors (ATF-2, ELK-1, CREB, AP-1). Inhibitors of Map and Jun kinase significantly reduced apoptosis. Our results provide the first evidence that OxLDL-induced apoptosis involves TNF receptors and Jun activation. More important, they demonstrate that even mildly oxidized LDL formed in atherosclerotic lesions may activate a broad cascade of oxygen radical-sensitive signaling pathways affecting apoptosis and other processes influencing the evolution of plaques. Thus, we suggest that extensive oxidative modifications of LDL are not necessary to influence signal transduction and transcription in vivo.
In 22 patients with stable myocardial ischemia, we prospectively studied the short- and long-term effects of isosorbide-5-mononitrate (5-ISMN) on dipyridamole-induced myocardial ischemia, the ability of dipyridamole-stress echocardiography to evaluate nitrate tolerance, and the role of activation of the neurohumoral system in nitrate tolerance development, assessed by modifications of catecholamines plasma levels and heart rate variability. After brief treatment with 5-ISMN, dipyridamole-stress echocardiography was negative in 19 of 22 patients (p < 0.001 vs. placebo). During the sustained phase, dipyridamole-stress echocardiography was positive after both placebo and active drug (p = NS vs. placebo). Heart rate variability showed significantly higher values in power of the low frequency (LF) band and low- to high-frequency ratio (L/H), as well as significantly lower values of the power of the high-frequency (HF) band (all p < 0.001) during brief but not during sustained administration of 5-ISMN. Norepinephrine plasma levels were significantly higher (p < 0.001) during short-term 5-ISMN administration but not during the sustained phase. Our results indicate that short-term administration of 5-ISMN antagonizes dipyridamole-induced myocardial ischemia and show the loss of antiischemic efficacy in 95% of patients during sustained treatment, demonstrating that dipyridamole-stress echocardiography is a useful tool to assess the presence of nitrate tolerance. Spectral analysis of heart rate variability and norepinephrine values confirm that brief nitrate administration increases sympathetic activity, a possible crucial trigger event in the development of nitrate tolerance, whereas prolonged nitrate treatment is not associated with prolonged neurohumoral activation.
Oxygen radical-mediated injury has been implicated in the process of cardiac aging. We investigated the tolerance to oxidative stress of hearts from rats of different age. Langendorff-perfused hearts from 3-12-month-old rats received a 30 min infusion of the reactive oxygen specie hydrogen peroxide (H2O2, 60 microM), followed by a 15 min wash-out. H2O2 infusion resulted in a significantly larger increase in end-diastolic pressure in hearts of 6- and 12-month-old rats than 3 months (P<0.01). In addition, developed pressure and rate-pressure product decreased more evidently in 12-month-old hearts (P<0.01 vs 3 and 6 months). Arrhythmia analysis showed higher score in hearts of 12- and 6-month-old rats with respect to 3-month-old animals (P<0.05). Cardiac release of oxidized glutathione (an index of the ability of the heart to inactivate oxygen metabolites) was significantly lower in hearts from rats of 6 and 12 months than in younger animals (P<0.001). Finally, cardiac concentrations of the scavenger enzymes glutathione peroxidase and Mn-superoxide dismutase also significantly decreased with age. In conclusion, in rat heart metabolic and functional tolerance toward oxidative stress decreases with age. This phenomenon may contribute to the development of cardiovascular alterations with increasing age.
The aging heart appears to be more susceptible to ischemia-reperfusion injury than the adult heart. There is no evidence of an age-related difference in the threshold of myocardial ischemia and myocardial stunning. We studied the effects on mechanical, hemodynamic, and metabolic parameters of graded reduction of coronary perfusion pressure from 66 to 29 mmHg in isolated and perfused hearts from adult and senescent rats. Cardiac function was also assessed during recovery following ischemic period. In both adult and senescent hearts developed pressure and +dP/dt linearly decreased and end-diastolic pressure linearly increased with decreasing perfusion pressure. However, all mechanical parameters were more severely impaired in senescent than in adult hearts at 37 mmHg and 29 mmHg perfusion pressure, respectively (p < 0.01 vs. adult). At 29 mmHg, in both adult and senescent hearts lactate production similarly increased whereas creatine kinase leakage did not differ from controls. Developed pressure recovered more slowly in senescent than in adult hearts (p < 0.001) in the absence of cellular damage and in the presence of restoration of coronary flow. Lactate production observed at the same step of coronary perfusion pressure suggests that the ischemic threshold is similar in adult and senescent hearts. The slow recovery of myocardial contractility after the ischemic period observed in senescent hearts suggests an age-related increase in myocardial stunning.
The aim of this study was to evaluate the effects of verapamil administration on dipyridamole-induced transient wall-motion abnormalities as detected by two-dimensional echocardiographic monitoring in patients with coronary artery disease. Twenty-eight patients (16 men and 12 women; mean age, 60+/-7 years) with angiographic evidence of significant coronary artery disease, positive dipyridamole echocardiography test results at basal condition on two consecutive days, were prospectively studied. Patients were randomized to verapamil (360 mg/day) or placebo treatments, given in three divided doses daily for 7 days; at the end of this time, each patient crossed over to the alternate regimen. Dipyridamole echocardiographic testing was repeated at the end of each treatment period. Our data demonstrate that verapamil significantly reduces the dipyridamole-induced wall-motion score index, a quantitative marker of acute myocardial ischemia (1.7+/-0.4 vs. 1.3+/-0.2; p<0.001). Hemodynamic data show that the drug reduces heart rate and rate-pressure product at basal condition (heart rate from 75+/-8 to 67+/-9 beats/min; p<0.001; rate-pressure product from 99+/-13 to 86+/-13 U x 10(-2); p<0.001) and at peak dipyridamole infusion (heart rate from 96+/-8 to 89+/-6 beats/min; p<0.001; rate pressure product from 127+/-21 to 118+/-13 U x 10(-2); p<0.05) with respect to placebo treatment. We conclude that verapamil is able to reduce dipyridamole-induced ischemia, as detected by two-dimensional echocardiographic monitoring, in patients with coronary artery disease by reducing, at least partially, myocardial oxygen consumption. Moreover, its beneficial action could be related to the effects of the drug on coronary collateral circulation and on sympathetic modulation.
OBJECTIVE: Inducing tolerance to myocardial ischemia by repeated brief episodes of ischemia has been called "ischemic preconditioning." "Warm-up" phenomenon refers to patients with coronary heart disease improving performance after a first exertion and may represent a clinical counterpart to ischemic preconditioning. The goal of this study was to assess whether the severity of myocardial ischemia would be attenuated by two repeated walking-induced ischemic episodes in adult and older patients. SUBJECTS: Thirty-eight adults (51 +/- 5 years) and 39 older patients (76 +/- 4 years) with stable angina and angiographic evidence of coronary stenosis. MEASUREMENTS: Holter monitoring was performed in adult and older patients walking on two consecutive occasions, with a 5-minute rest between walks, a distance known to have previously caused myocardial ischemia. RESULTS: Computer-assisted analysis recorded by ambulatory Holter monitoring revealed that the mean maximal ST-segment depression (P < .001) and ischemia duration decreased (P < .001), whereas the ischemic threshold increased (P < .001), from the first to the second walk in the adult but not in the older group. CONCLUSIONS: Myocardial ischemia is attenuated and ischemic threshold is increased between two brief ischemic episodes in adult but not in older patients. These results indicate that the "warm-up" phenomenon, involved in increasing myocardial ischemic tolerance, is absent in the aging heart.
BACKGROUND: Primary aldosteronism (PA) is a disease associated with hypersecretion of aldosterone caused by an aldosterone-producing adrenal adenoma, bilateral adrenal hyperplasia, and, although rarely, by adrenal carcinoma. Arterial hypertension induces several cardiovascular alterations that yield a high cardiovascular risk. It has been shown that reduced myocardial perfusion at rest, assessed by thallium-201 myocardial scintigraphy, was greater in PA than in essential hypertension (EH). However, it is still unknown whether reduced myocardial perfusion at rest and/or regional function abnormalities are present during exercise-induced myocardial stress. PURPOSE: We addressed the impact of PA on myocardial ischemia and sought to identify signs of exercise-induced myocardial ischemia (assessed by MIBI-SPECT and echocardiography) in patients with PA compared to patients with EH. Patients with consistent signs of myocardial ischemia on all of the tests were studied by coronary arteriography. PATIENTS: We studied 72 patients with PA and an age/sex-matched group of 72 patients with EH enrolled in the cross-sectional Primary Aldosteronism and Heart Italian Multicenter Study (PAHIMS). METHODS: Regional function was detected from echocardiographic measurement of wall motion done at baseline and immediately after exercise. Myocardial perfusion was evaluated by SPECT imaging after injecting 99mTc-MIBI with the same-day protocol using the rest-stress sequence. RESULTS: Although the conditions of arterial pressure, duration of hypertension, and target organ damage were equivalent, the patients with PA had greater incidence of both reversible perfusion defects and abnormalities of regional function. Moreover, multiple regression analysis showed that the high plasma aldosterone level was highly predictive for SPECT ischemic score and wall motion index, suggesting that PA contributes to cardiovascular risk over and above that associated with ventricular hypertrophy. Exercise-induced myocardial ischemia in PA was not segmental but widely distributed suggesting that this phenomenon was not related to abnormal coronary perfusion. Accordingly, of the 38 patients with PA who underwent coronarography, there was no presence of significant coronary atherosclerotic lesions in 30 (78.9%) of the patients. CONCLUSIONS: The PAHIMS observed more exercise-induced moderate myocardial ischemic defects (co-detected by SPECT and echocardiograms and not segmental but widely allocated) in patients with PA than in patients with EH. This phenomenon occurred in a greater percentage of patients with PA without significant coronary lesions (78.95%, n = 38), which supports the possible presence of small-vessel intramyocardial disease.
Acidosis is associated with myocardial ischemia and several reports indicate the greater vulnerability of the aged heart to ischemic dysfunction. We investigated the effects of hypercapnic acidosis on isolated heart (n = 14) and papillary muscle (n = 10) from adult and senescent rats. Acidosis (pH from 7.36 to 6.91) induced a decrease in left ventricular developed pressure together with an increase in left ventricular end-diastolic pressure, but was significantly more evident in senescent than in adult hearts (p < .01). The return to normal pH induced a further increase in the end-diastolic pressure parallel to the development of arrhythmias that were greater in senescent than in adult hearts. In isolated papillary muscle, acidosis confirmed its greater negative inotropic effect on senescent than adult muscles (p < .01), while intracellular sodium activity (aNai) increased to a similar extent in both adult and senescent papillary muscles (p = NS). 5-(N,N-dimethyl)-amiloride hydrochloride (DMA), a specific inhibitor of Na+/H+ exchanger, produced similar modification of tension and aNai in both adult and senescent muscles. When DMA was superfused in acidotic solution, the contractility was markedly compromised in senescent than in adult muscles (p < .01), but the aNai modifications were similar in adult and senescent muscles (p = NS). Our results show that acidosis induced a greater reduction of contractility in senescent than in adult hearts. The similarity of contractility during DMA administration between adult and senescent muscle and of modifications of aNai suggests that depression of contractility with acidosis may be related to pathophysiologic mechanisms other than the Na+/H+ exchanger.
BACKGROUND: The enzyme lecithin-cholesterol acyl transferase (LCAT) esterifies free cholesterol on high-density lipoprotein (HDL) and the cholesteryl ester transfer protein (CETP) transfers cholesteryl ester to very-low-density lipoprotein (VLDL) and low-density lipoproteins (LDL). Using statins, contradictory findings have been made regarding CETP activity in normolipidemic individuals and in those with familial dysbetalipoproteinemia. In contrast, LCAT activity appears to be unaffected by simvastatin. Antioxidants have also been proposed for the use of anti-atherosclerotic treatment, because the oxidation of LDL may have a key role in the pathophysiology of atherogenesis. OBJECTIVE: To investigate, in hypercholesterolemic patients, whether a combination of pravastatin with the antioxidant, vitamin E, has greater effects on the activity of CETP and of LCAT than does pravastatin alone. METHODS: This placebo-diet-controlled multicenter trial included 220 hypercholesterolemic patients who were assigned randomly to groups to receive: diet and 20-40 mg pravastatin (n = 52), diet and alpha-tocopherol (n = 60), or diet associated with placebo (n = 52). Plasma LCAT activity was determined using excess exogenous substrate, containing [3H]cholesterol. Plasma CETP activity was measured in the supernatant fraction after precipitation of endogenous apo B-containing lipoproteins with phosphotungstate-Mg2+. The exchange of cholesteryl esters between [14C]cholesteryl ester-labeled LDL and unlabeled HDL was measured during a 16-h incubation, while LCAT was inhibited. RESULTS: The addition of pravastatin to the diet induced a significant decrease in plasma CETP activity (P < 0.05); this effect was less evident in the group cotreated with vitamin E. For the first time, it was shown that CETP concentrations increased significantly after vitamin E alone (P < 0.05). No significant differences in the plasma activity of LCAT were observed among the groups. CONCLUSIONS: Pravastatin reduced CETP activity, but not that of LCAT. Addition of vitamin E prevented the decrease in CETP activity and had no effect on LCAT activity. The mechanism responsible for these effects is unknown, but could involve the prevention of radical-induced damage to CETP by vitamin E.
OBJECTIVE: Congestive heart failure (CHF) is potentially preventable, and the identification of modifiable risk factors for cognitive impairment (CI) for older persons is a very important issue. We examined the cross-sectional relationship between CHF and CI in an older population. DESIGN: A cross-sectional survey. SETTING AND PARTICIPANTS: A total of 1339 subjects aged 65 and older were selected from the electoral rolls of Campania, a region of southern Italy. MEASUREMENTS: Sociodemographic characteristics were recorded, as was the presence of cardiovascular diseases, including CHF classified according to the New York Heart Association (NYHA) guidelines for disease severity; CI evaluated by means of the Mini-Mental State Examination (MMSE), with a score of <24 indicating impairment; geriatric depression scale (GDS) rating; blood pressure (BP); and heart rate (HR). RESULTS: The final sample numbered 1075; 172 subjects were excluded because of neurological disorders and psychotropic therapy, and 92 were excluded because their BP, HR, or cognitive examination was not recorded. Prevalence of CHF was 8.2%, and 23.0% of subjects scored <24 on the MMSE. The prevalence of CHF in subjects with an MMSE score of <24 and > or =24 was 20.2% and 4.6%, respectively (P < .001). Logistic regression analysis showed that CHF was associated independently with CI by sex, age, educational level, GDS, diabetes, hypertension, alcohol consumption, smoking, atrial fibrillation, systolic and diastolic BP, and HR. The risk of CI was 1.96-fold greater in subjects with CHF (odds ratio: 1.96; 95% confidence interval: 1.07-3.58; P < .028). Systolic BP decrease was correlated negatively with NYHA classes only in subjects with CI (r = -0.981; P < .020), whereas HR increase was correlated positively with NYHA classes only in subjects without CI (r = 0.985; P < .015). CONCLUSIONS: In our population, CHF is associated with CI in subjects aged 65 years and older. Systolic BP reduction and the lack of HR increase, related to NYHA classes, might characterize cognitively impaired subjects with CHF.
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Melatonin (N-acetyl-5-methoxytryptamine), the principal hormone of the vertebral pineal gland, elicits several neurobiological effects. However, the effects of melatonin on cardiac muscle are still unknown. The first goal of the study was to investigate the role of melatonin on myocardial contractility in isolated rat papillary muscle using dose-response curves to melatonin, to isoproterenol and calcium either in the presence or in the absence of melatonin (0.3 nM). Response curves to isoproterenol were additionally performed in the presence of melatonin plus the specific receptor antagonist N-acetyltryptamine (10 microM); the adenylate-cyclase stimulator forskolin (10 microM) was also used. Melatonin has no direct inotropic effect in isolated rat papillary muscle but counteracts isoproterenol but not [Ca2+] effects. In fact, the EC50 for isoproterenol was significantly higher in the presence than in the absence of melatonin (p < 0.001). This anti-adrenergic action occurs through an interaction to a specific cardiac receptor. Forskolin-stimulated adenylate cyclase induced an increase of contractile force (+118 +/- 25%) which was reduced in the presence of melatonin (+26 +/- 10%; p < 0.01). In conclusion, we found that melatonin possess anti-adrenergic effect in isolated rat papillary muscle. This phenomenon was abolished in the presence of its receptor antagonist N-acetyl-tryptamine demonstrating that melatonin operates through a specific cardiac receptor. The reduction of contractility increase, induced by forskolin-stimulated adenylate cyclase, shows that melatonin may act through a reduction of cyclic AMP accumulation.
In chronic heart failure substantial and characteristic changes occur in the function of the adrenergic nervous system. Studies in isolated left ventricular muscle and in single cardiomyocytes from experimental models of aging and, recently, from humans show an age-related reduced contractile response to beta-adrenoceptor stimulation. "beta-adrenoceptor desensitization" is thought to be a general and common mechanism to explain the age- and heart failure-related decrease in beta-adrenoceptor response. The aim of this review is to compare alterations in beta-adrenoceptor mechanisms in physiological cardiovascular aging and chronic heart failure. From an analysis of the overall data on the role of aging in beta-adrenoceptor regulation in human and animal hearts, it is possible to conclude that the reduced response to beta-agonists is common to all species and all cardiac tissues. Moreover, the age-related changes are limited to beta-adrenoceptor-G-protein (s)-adenylyl cyclase system abnormalities, while the type and level of abnormalities change with species and tissues. The modifications shown in the aging heart are not very different from some observed in heart failure. In particular, both in aged and failing hearts we may see that the decrease in beta-adrenoceptor responsiveness is related to changes in G-protein function.
OBJECTIVES: The present study examined whether angina 48 h before myocardial infarction provides protection in adult and elderly patients. BACKGROUND: The mortality rate for coronary artery disease is greater in elderly than in young patients. In experimental studies, ischemic preconditioning affords an endogenous form of protection against ischemia-reperfusion injury in adult but not in senescent hearts. Angina before myocardial infarction, a clinical equivalent of experimental ischemic preconditioning, has a protective effect in adult patients. It is not known whether angina before myocardial infarction is also protective in aged patients. METHODS: We retrospectively verified whether antecedent angina within 48 h of myocardial infarction exerts a beneficial effect on in-hospital outcomes in adult (< 65 years old, n = 293) and elderly (> or = 65 years old, n = 210) patients. RESULTS: In-hospital death was more frequent in adult patients without than in those with previous angina (10% vs. 2.6%, p < 0.01), as were congestive heart failure or shock (10.7% vs. 3.3%, p < 0.02) and the combined end points (in-hospital death and congestive heart failure or shock) (20.7% vs. 5.9%, p < 0.0003). In contrast, the presence or absence of previous angina before acute myocardial infarction in elderly patients seems not to influence the incidence of in-hospital death (14.4% vs. 15.2%, p = 0.97), congestive heart failure or shock (11.0% vs. 11.9%, p = 0.99) and the combined end points (25.4% vs. 27.1%, p = 0.89). Logistic regression analysis models for in-hospital end points show that previous angina is a positive predictor in adult but not in elderly patients. CONCLUSIONS: The presence of angina before acute myocardial infarction seems to confer protection against in-hospital outcomes in adults; this effect seemed to be less obvious in elderly patients. This study suggests that the protection afforded by angina in adult patients may involve the occurrence of ischemic preconditioning, which seems to be lost in senescent patients.