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Biomedical subjects

R R Ruffolo

Publications and source records attributed to R R Ruffolo.

At least 19 recordsLinked to original sources
PubMed1997

Pharmacology of carvedilol: rationale for use in hypertension, coronary artery disease, and congestive heart failure.

Carvedilol is a novel, multiple-action cardiovascular drug that is currently approved in many countries for the treatment of hypertension. The reduction in blood pressure produced by carvedilol results primarily from beta-adrenoceptor blockade and vasodilation, the latter resulting from alpha 1-adrenoceptor blockade. These actions, as well as several of the other activities of carvedilol, are associated with cardioprotection in animal models that occurs to a degree that is greater than that observed with other drugs. The multiple actions of carvedilol may also provide the underlying rationale for the use of the drug in the treatment of coronary artery disease and congestive heart failure. By virtue of being both a beta-blocker and a vasodilator, carvedilol significantly decreases myocardial work by reducing all three components of myocardial oxygen demand, namely, heart rate, contractility, and wall tension. The vasodilatory effects of carvedilol reduce afterload, and the resulting decrease in impedance to left ventricular ejection offsets the negative inotropic effect that would normally result from beta-blockade. As a consequence, stroke volume and cardiac output are maintained or even increased in animals and in patients with congestive heart failure who are treated with carvedilol. Carvedilol and several of its metabolites are potent antioxidants, and this activity may account, in part, for the cardioprotective effects of the drug observed in animal models of acute myocardial ischemia and, in theory, could also serve to protect the myocardium of patients with hypertension, coronary artery disease, and congestive heart failure, in which oxidative stress is now recognized to occur. The antioxidant effects of carvedilol may both inhibit the direct cytotoxic actions of reactive oxygen radicals and prevent oxygen-radical induced activation of transcription factors and genes associated with inflammatory and remodeling processes. Accordingly, carvedilol inhibits the gene expression of the intracellular adhesion molecule-1 (ICAM-1), an adhesion molecule for polymorphonuclear leukocytes, which typically infiltrate the myocardium under conditions of ischemia and may exacerbate ischemic injury. The antioxidant activity of carvedilol has been shown to inhibit the oxidation of low density lipoprotein (LDL) in vitro, thereby preventing the formation of this cytotoxic and atherogenic form of LDL. It follows, therefore, that in animal models of hyperlipidemia, carvedilol attenuates aortic lipid accumulation and decreases the aortic content of monocytes and foam cells, and at the same time it has been shown to preserve endothelial integrity and function. These actions of carvedilol are not shared by other beta-blockers or by other drugs currently used in the management of hypertension, coronary artery disease, or congestive heart failure. The multiple actions of carvedilol may provide the underlying pharmacologic rationale for the use of this drug in the treatment of patients with coronary artery disease or congestive heart failure, and these actions may account, at least in part, for the reduction in mortality produced by carvedilol in clinical trials involving patients with congestive heart failure. Likewise, these actions of carvedilol may also provide protection, beyond that afforded from reduction in blood pressure, against secondary organ damage in hypertensive patients treated with the drug.

Adrenergic beta-Antagonists↗
PubMed1997

Carvedilol inhibits aortic lipid deposition in the hypercholesterolemic rat.

The effects of carvedilol, a vasodilating beta-blocker with antioxidant activity, and nifedipine, a calcium channel blocker, were investigated on aortic lipid deposition and the accumulation of monocytes and foam cells at the sites of atherosclerotic lesions in rats subjected to a hypercholesterolemic diet. Fifty rats were randomly assigned to the following experimental groups: (1) regular rat chow (n = 5); (2) regular rat chow supplemented with a high-cholesterol diet (1% cholesterol and 1% cholic acid; n = 15); (3) a high-cholesterol diet plus nifedipine (n = 15), and (4) a high-cholesterol diet plus carvedilol (n = 15). Animals were maintained on these diets for 12 weeks. None of the treatment groups had blood pressures that were outside the normotensive range, and no significant differences in plasma lipid levels were observed among the high-cholesterol diet and drug-treated groups. There was a significantly lower lipid content (p < 0.001) in the thoracic aortas of the nifedipine-treated (211 +/- 23 nmol/mm2) and carvedilol-treated (182 +/- 23 nmol/mm2) groups compared to cholesterol-fed controls (242 +/- 27 nmol/mm2). Furthermore, carvedilol-treated animals showed significantly less (p < 0.001) lipid accumulation than did the nifedipine-treated animals. The number of monocytes and foam cells were decreased in both drug-treated groups compared to animals receiving high-cholesterol diets without drug treatment. The results demonstrate that treatment with carvedilol or nifedipine can significantly inhibit lipid deposition in the aorta and reduce monocyte and foam cell accumulation, and that carvedilol is significantly more effective than nifedipine in inhibiting lipid deposition.

Adrenergic beta-Antagonists↗
PubMed1997

Hypercholesterolemia impairs a detoxification mechanism against peroxynitrite and renders the vascular tissue more susceptible to oxidative injury.

Previous studies have shown that glutathione (GSH) plays a central role in the protection against peroxynitrite (ONOO-) toxicity. The present study evaluated the changes of the GSH cytoprotective system against ONOO- in hypercholesterolemia and determined the effects of carvedilol, a beta-blocker with free radical-scavenging activity, on these hypercholesterol-induced changes. New Zealand White rabbits were fed either a normal diet, a high-cholesterol diet, or a high-cholesterol diet supplemented with either carvedilol or propranolol. Eight weeks later, the rabbits were killed, and the thoracic aortas were isolated. Total GSH content of aortic tissue, vasorelaxation response of aortic rings to exogenous ONOO-, No regeneration from ONOO- by aortic homogenate, and ONOO(-)-induced aortic tissue injury were examined. Hypercholesterolemia decreased tissue GSH content (0.52 +/- 0.08 versus 0.86 +/- 0.04 mumol/g in control, P < .01), attenuated the vasorelaxation response to ONOO- (40 +/- 4.1% versus 76 +/- 3.2%, P < .01), reduced NO regeneration from ONOO- (387 +/- 40 versus 662 +/- 51 pmol, P < .01), and potentiated ONOO(-)-induced vascular tissue injury (37 +/- 4.4% versus 14 +/- 2.6% of increase in lactate dehydrogenase release after 3-morpholinosydnonimine exposure, P < .01). Treatment of the hypercholesterolemic rabbits with carvedilol, but not propranolol, significantly preserved tissue GSH content (0.79 +/- 0.05 mumol/g, P < .01 versus nontreated hypercholesterolemic rabbits), restored the vasorelaxation to ONOO- (61 +/- 2%, P < .01), increased NO regeneration from ONOO- (583 +/- 39 pmol, P < .01), and attenuated ONOO(-)-induced tissue injury (19 +/- 1.8%, P < .01). These results suggest that hypercholesterolemia impairs the GSH-mediated detoxification mechanism against ONOO- and renders the vascular tissue more susceptible to oxidative injury. Carvedilol, a novel vasodilating beta-blocker with antioxidant activity, significantly preserved this self-defense system and protected tissue from oxidant injury.

Animals↗
PubMed1996

Endothelin receptors: receptor classification, novel receptor antagonists, and potential therapeutic targets.

The development of endothelin receptor antagonists has progressed rapidly since the initial discovery of endothelin. Highly potent, orally active nonpeptide endothelin receptor antagonists have been identified, and are being used as pharmacological tools to elucidate the role of endothelin in pathological disorders. Subtype selective endothelin receptor antagonists will also be useful in understanding the physiological and pathological roles of the different subtypes of the endothelin receptors. The selectivity profile for the ideal endothelin receptor antagonist is presently unknown, and it may actually be that the optimal profile for a compound may depend on the clinical indication. In the near future, data from clinical trials with endothelin receptor antagonists will become available and will help to establish the role of endothelin in the etiology of human disease, as well as to provide valuable information concerning the optimum endothelin receptor subtype selectivity for antagonists needed for therapeutic agents.

Amino Acid Sequence↗
PubMed1996

The use of alpha-adrenoceptor antagonists in the pharmacological management of benign prostatic hypertrophy: an overview.

Benign prostatic hypertrophy (BPH) produces symptomatic urethral obstruction in a significant percentage of older men. Since the incidence of BPH is age related, the clinical and economic impact of this disease will continue to progress as average lifespan increases. BPH is associated with growth of both glandular and stromal elements of the prostate gland. Glandular hyperplasia can be partially reversed by withdrawal of androgenic tone with androgen receptor antagonists or steroid-5-alpha-reductase inhibitors. However, the reduction in prostatic size produced by these agents has little effect on the dynamic tone induced by nerve mediated contraction of stromal smooth muscle. This tone is mediated by activation of alpha-adrenoceptors. Therefore the alpha-adrenoceptor antagonists represent a useful pharmacological approach to the treatment of BPH. Studies in isolated strips of human prostate show that either exogenous alpha-adrenoceptor agonists or electrical field stimulation will induce contraction. Studies with selective antagonists such as prazosin show that this response is mediated by the alpha 1-adrenoceptor, even though radioligand binding studies show the presence of alpha 1 and alpha 2 adrenoceptor subtypes in approximately equal density. Following the cloning of multiple alpha 1-adrenoceptors, the contractile response in human prostate has been assigned to the alpha 1A adrenoceptor. However, recent data would suggest a functional role for another subtype, which has not yet been cloned, and designated as alpha 1L based on a relatively low affinity for prazosin. Clinical trials have shown efficacy of a variety of alpha-adrenoceptor antagonists in BPH, including non-selective agents such as phenoxybenzamine, as well as a variety of selective alpha 1-adrenoceptor antagonists, most structurally related to prazosin. The agents most commonly employed at the present time include the prazosin analogs terazosin, doxazosin and alfuzosin, as well as the structurally unrelated indoramin and tamsulosin. The design of new alpha 1-antagonists for BPH has concentrated on agents producing preferential blockage of urogenital vis-á-vis vascular alpha 1-adrenoceptors, based either on selectivity for the alpha 1A-adrenoceptor subtype or on functional uroselectivity in animal models. While these newer agents offer the prospect of reducing the incidence of the cardiovascular side effects associated with current therapy their superiority over nonselective alpha 1-adrenoceptor antagonists remains to be demonstrated in the clinical setting.

Adrenergic alpha-Antagonists↗
PubMed1996

Carvedilol, a novel vasodilating beta-blocker with the potential for cardiovascular organ protection.

Carvedilol is a vasodilating beta-blocker currently marketed for the treatment of mild to moderate hypertension and application is being filed to the FDA for treatment of congestive heart failure. Carvedilol reduces peripheral vascular resistance by blocking arterial alpha 1-adrenoceptors, thereby producing vasodilation, while preventing reflex tachycardia by blocking cardiac beta 1- and beta 2-adrenoceptors. In addition to the safety and efficacy of carvedilol as an antihypertensive agent, experimental studies indicate that carvedilol also provides significant cardioprotection in animal models of acute myocardial infarction as well as protection against the vascular remodelling that occurs following injury of the vasculature. Recent pharmacological studies have uncovered several novel properties of carvedilol which may function to protect the heart and vasculature from chronic pathological processes, such as ischaemia, atherosclerosis and the remodelling that occurs in the heart and blood vessels as a consequence of pressure overload, injury or shear stress. Specifically, carvedilol, likely as a result of the carbazol moiety, is a potent anti-oxidant. In physicochemical, biochemical and cellular assays carvedilol and several of its metabolites inhibit lipid peroxidation, scavenge oxygen free radicals, inhibit the formation of reactive oxygen radicals and prevent the depletion of endogenous antioxidants, such as vitamin E and glutathione. Moreover, carvedilol blocks the oxidation of low-density lipoproteins (LDL), and thereby prevents the formation of oxidized-LDL which is believed to stimulate foam cell formation and augment the development of atherosclerotic plaque. The ability of carvedilol to prevent the formation of oxidized LDL, in addition to the general anti-oxidant properties of the compound, results in the protection of the endothelium from oxygen free radical injury, and thereby prevents the subsequent events triggered by endothelial damage. Recently, carvedilol has also been shown to inhibit vascular smooth muscle cell proliferation and migration. Because carvedilol can inhibit vascular smooth muscle cell proliferation induced by a wide variety of mitogens (e.g. growth factors, angiotensin II, endothelin, thrombin), it is likely that the site of inhibition occurs at some point beyond the specific mitogen receptors, possibly at a distal common pathway that affects the smooth muscle cell cycle. These unique activities of carvedilol have also been confirmed in vivo in a rat model of neointimal formation following vascular injury by balloon angioplasty, where vascular smooth muscle cell migration and proliferation are the key processes involved in the formation of neointima leading to vascular stenosis. In this model, carvedilol suppressed neointimal growth to a remarkable extent ( > 85% inhibition of neointimal formation) at a dose that is similar to the antihypertensive dose used clinically in hypertensive patients. Taken together, these unique multiple actions of carvedilol provide not only for adequate control of elevated blood pressure, but may also provide for protection of the heart and vasculature from secondary damage due to hypertension itself, as well as from other causes, such as ischaemia, pressure overload, shear stress, vascular injury and atherosclerosis.

Adrenergic beta-Antagonists↗
PubMed1996

Carvedilol, a new beta adrenoreceptor blocker and free radical scavenger, attenuates myocardial ischemia-reperfusion injury in hypercholesterolemic rabbits.

Oxygen-derived free radicals play a critical role in atherogenesis and reperfusion injury. The present experiment evaluated the effects of carvedilol, a new beta adrenoreceptor blocker with potent free radical-scavenging activity, on myocardial ischemia and reperfusion injury in a hypercholesterolemic rabbit model. New Zealand rabbits were fed a normal diet, a high-cholesterol diet, or a high-cholesterol diet supplemented with 1200 ppm carvedilol or propranolol. Eight weeks later, the rabbits were subjected to 60 min of myocardial ischemia followed by 60 min of reperfusion. The nontreated cholesterol-fed animals experienced greater cardiac damage after ischemia and reperfusion than rabbits fed a normal diet (necrosis 51% +/- 4% vs. 28% +/- 3% in the normal-diet group, P < .01). In addition, nontreated cholesterol-fed rabbits showed a significantly decreased vasorelaxant response to ACh in U-46619-precontracted aortic rings (56% +/- 5% vs 90% +/- 3% in the control group, P < .001). Treatment with propranolol neither preserved endothelial function after cholesterol feeding nor reduced neutrophil accumulation in ischemic-reperfused myocardial tissue. Propranolol treatment did significantly decrease HR, pressure-rate index and infarct size (necrosis 33% +/- 4%). Despite their having essentially identical effects on HR and pressure-rate index, carvedilol exerted more profound cardiac protective effects than propranolol (necrosis 19% +/- 3%). Moreover, carvedilol treatment significantly preserved aortic endothelial function and markedly reduced neutrophil accumulation in ischemic-reperfused myocardial tissue. These results indicate that in addition to its beta blocking activity, the antioxidant and endothelial protective activities of carvedilol contributed significantly to its cardiac protective effects after ischemia and reperfusion.

Adrenergic beta-Antagonists↗
PubMed1996

The selectivity in vitro of the stereoisomers of the beta-3 adrenoceptor agonist BRL 37344.

The stimulation by BRL 37344 of lipolysis in rat adipose tissues, and of relaxation of the rat distal colon, is mediated by the beta-3 adrenoceptor. The stereochemical requirements of the beta-3 adrenoceptor are poorly understood. The activities of the four stereoisomers of BRL 37344 (i.e., two pairs of diastereoisomers) on three beta-3 adrenoceptor-mediated responses (brown and white adipose tissue lipolysis and relaxation of distal colon) have been determined and compared with those responses mediated by beta-1 adrenoceptors (increase in atrial rate) and beta-2 adrenoceptors (uterine relaxation). The potency order for the stereoisomers (RR>RS=SR>>SS) was the same for all tissues, regardless of whether the response was mediated by beta-1, beta-2 or beta-3 adrenoceptors. These results indicate that both chiral centers are determinants of agonist potency at all three subtypes of the beta adrenoceptor. Furthermore, agonist activity at beta-1, beta-2 and beta-3 adrenoceptors resides predominantly with the RR enantiomer. Finally, the RR enantiomer of BRL 37344 was a more potent agonist in brown adipocytes (EC50 = 3.3 +/- 0.8 nM) than in white adipocytes (EC50 = 5.7 +/- 0.9 nM) or colon (EC50 = 27.5 +/- 7.7 nM).

Adrenergic beta-Agonists↗
PubMed1996

Combined potassium and calcium channel blocking activities as a basis for antiarrhythmic efficacy with low proarrhythmic risk: experimental profile of BRL-32872.

In the search for novel antiarrhythmic agents, compounds with a diversity of electrophysiological actions have been suggested to result in treatments with potentially improved efficacy but with reduced proarrhythmic risk. To test this hypothesis, the antiarrhythmic versus proarrhythmic profile of BRL-32872, a novel agent with combined potassium and calcium channel blocking activity, was assessed in two different in vivo models of ventricular arrhythmia. Furthermore, the effects of potassium and calcium channel antagonists given either alone or in combination were assessed in the same models. Dogs with myocardial infarction received intravenously either vehicle, BRL-32872, the class III antiarrhythmic agent, E-4031, verapamil or a combination of E-4031 with verapamil (n = 8 per group). Ventricular tachyarrhythmias were induced by programmed electrical stimulation (PES). BRL-32872 (0.1, 0.3, 1.0 mg/kg) significantly increased QTc interval (from 387 +/- 10 to 462 +/- 19 msec.sec-1/2 at 1.0 mg/kg, P < .01). Ventricular effective refractory periods were increased in normal and infarcted areas (P < .01). Similar effects were observed with E-4031 (0.1, 0.3, 1.0 mg/kg). Verapamil (0.03, 0.1, 0.3 mg/kg) reduced heart rate, mean arterial pressure and, to a lesser extent, (+)dP/dtmax. Verapamil did not change QTc interval and ventricular effective refractory periods, but increased PR interval (P < .001). PES-induced tachyarrhythmias were not changed by vehicle or increasing doses of verapamil. E-4031 reduced the severity of arrhythmias from sustained ventricular tachycardia (VT) to nonsustained VT (7 dogs at 1.0 mg/kg, P = .013 vs. vehicle). BRL-32872 (0.1 and 0.3 mg/kg) suppressed the induction of sustained VT in six dogs (P = .02 vs. vehicle). In the presence of BRL-32872, 1.0 mg/kg, five dogs became noninducible to PES (P = .013 vs. vehicle). Combination of E-4031 (0.1 mg/kg) with verapamil provided a degree of protection that was similar to that observed with BRL-32872. In a second model, the proarrhythmic potential of BRL-32872 was assessed in anesthetized rabbits sensitized to develop torsades de pointes (TdP). BRL-32872 was compared with the class III antiarrhythmic agents, E-4031, dofetilide, clofilium and RP-58866. The pure class III antiarrhythmic agents induced TdP in 50 to 90% of the rabbits, and prolonged QT interval by 20 to 50%. BRL-32872 (10 micrograms/kg/min) increased QT interval by 35 +/- 5%, but did not promote TdP. In additional experiments, verapamil reduced the incidence of TdP induced by E-4031. These results show that BRL-32872 is a potent antiarrhythmic compound in a model of PES-induced arrhythmias and induces fewer proarrhythmic events than typical class III antiarrhythmic agents. The effects observed with BRL-32872 suggest that a compound with a combination of potassium (class III) and calcium (class IV) channel antagonistic properties might constitute a novel antiarrhythmic agent with reduced proarrhythmic risk.

Animals↗
PubMed1995

Carvedilol prevents low-density lipoprotein (LDL)-enhanced monocyte adhesion to endothelial cells by inhibition of LDL oxidation.

Cultured human umbilical vein endothelial cells oxidize low-density lipoproteins (LDL), assessed as increase in thiobarbituric acid reactive substance formation and oxidized LDL-induced cytotoxicity (lactate dehydrogenase (LDH) release). Endothelial cell-generated oxidized also enhances the adhesiveness of endothelial cells to monocytes. Carvedilol, a new vasodilating beta-adrenoceptor antagonist, inhibits the oxidation of LDL by endothelial cells and reduces oxidized LDL-induced LDH release from endothelial cells in a concentration-dependent manner with IC50 values of 2.56 and 1.38 microM, respectively. Moreover, carvedilol inhibits oxidized LDL-induced adhesion of monocytes to the endothelial cells in a similar concentration-dependent manner. Under the same conditions, propranolol, atenolol, pindolol and labetalol had only weak or no consistent effects on both LDL oxidation by endothelial cells and adhesion of monocytes to the endothelial cells. Monoclonal antibodies against human intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1) or E-selectin (ELAM-1) partially blocked oxidized LDL-stimulated adhesion of endothelial cells to monocytes. The inhibitory effects of carvedilol on LDL oxidation and monocyte adhesion to endothelial cells may protect blood vessels from atherosclerotic processes associated with oxidized LDL-induced injuries.

Adrenergic beta-Antagonists↗
PubMed1995

Discovery of adrenomedullin in rat ischemic cortex and evidence for its role in exacerbating focal brain ischemic damage.

Focal brain ischemia is the most common event leading to stroke in humans. To understand the molecular mechanisms associated with brain ischemia, we applied the technique of mRNA differential display and isolated a gene that encodes a recently discovered peptide, adrenomedullin (AM), which is a member of the calcitonin gene-related peptide (CGRP) family. Using the rat focal stroke model of middle cerebral artery occlusion (MCAO), we determined that AM mRNA expression was significantly increased in the ischemic cortex up to 17.4-fold at 3 h post-MCAO (P < 0.05) and 21.7-fold at 6 h post-MCAO (P < 0.05) and remained elevated for up to 15 days (9.6-fold increase; P < 0.05). Immunohistochemical studies localized AM to ischemic neuronal processes, and radioligand (125I-labeled CGRP) displacement revealed high-affinity (IC50 = 80.3 nmol) binding of AM to CGRP receptors in brain cortex. The cerebrovascular function of AM was studied using synthetic AM microinjected onto rat pial vessels using a cranial window or applied to canine basilar arteries in vitro. AM, applied abluminally, produced dose-dependent relaxation of preconstricted pial vessels (P < 0.05). Intracerebroventricular (but not systemic) AM administration at a high dose (8 nmol), prior to and after MCAO, increased the degree of focal ischemic injury (P < 0.05). The ischemia-induced expression of both AM mRNA and peptide in ischemic cortical neurons, the demonstration of the direct vasodilating effects of the peptide on cerebral vessels, and the ability of AM to exacerbate ischemic brain damage suggests that AM plays a significant role in focal ischemic brain injury.

Adrenomedullin↗
PubMed1995

Possible structural and functional relationships between imidazoline receptors and alpha 2-adrenoceptors.

Although it is now well established that imidazoline receptors and alpha 2-adrenoceptors are discrete entities with distinct endogenous ligands, the two receptor classes apparently have several common features. While the catecholamines stimulate alpha 2-adrenoceptors but not imidazoline receptors, agmatine, a guanidine analog that may be an endogenous imidazoline receptor ligand, can interact with both I1 and I2 imidazoline receptors as well as alpha 2-adrenoceptors, although, interestingly, other guanidines such as guanabenz are highly selective for alpha 2-adrenoceptors versus I1 receptors. Most I1 receptor agonists such as moxonidine, rilmenidine, and clonidine can also stimulate alpha 2-adrenoceptors, and the same physiological response is produced by activation of central I1 receptors and alpha 2-adrenoceptors, but their anatomical locations differ. The imidazoline idazoxan is an antagonist at I1, I2, and alpha 2-receptors, but minor structural alterations of idazoxan can result in molecules with selectivity for either alpha 2-adrenoceptors or imidazoline receptors. The precise mode of interaction of imidazoline agonists and antagonists with the alpha 2-adrenoceptor is not yet understood, and structures of the imidazoline receptors are still unknown. Nevertheless, the fact that many agents can stimulate or block both receptor classes, combined with the fact that alpha 2-adrenoceptors and I1 receptors can mediate identical physiological responses, suggests that many common structural features may be present.

Animals↗
PubMed1995

Carvedilol, a novel multiple action antihypertensive agent with antioxidant activity and the potential for myocardial and vascular protection.

Carvedilol is a vasodilating, beta-adrenoceptor antagonist currently marketed for the treatment of mild to moderate hypertension. Carvedilol acts to reduce total peripheral resistance by blocking peripheral vascular alpha 1-adrenoceptors, thereby producing systemic arterial vasodilation, while at the same time inhibiting reflex tachycardia through the blockade of myocardial beta-adrenoceptors. In addition to its established efficacy and safety as an antihypertensive agent, carvedilol has been shown to produce significant cardioprotection in experimental animal models of acute myocardial infarction, with the most dramatic effect being observed in the pig model of myocardial ischaemia and reperfusion, where the reduction in infarct size reached 91%. Recent pharmacological studies have revealed additional novel properties of carvedilol which may account for the marked protection produced by the drug in the ischaemic myocardium and which may also result in protection against other chronic pathological processes, such as atherosclerosis and acute vascular injuries. The latter arise from surgical procedures, such as percutaneous transluminal coronary angioplasty and coronary artery bypass grafting. Specifically, carvedilol, as well as some of its hydroxylated metabolites, are potent antioxidants. In physicochemical, biochemical and cellular assays, carvedilol and several of its metabolites prevent lipid peroxidation and the depletion of endogenous antioxidants, such as vitamin E and glutathione. Moreover, carvedilol and its metabolites prevent the oxidation of LDL to oxidized LDL, the latter being directly cytotoxic and known to activate monocytes/macrophages and to stimulate foam cell formation. In addition, carvedilol was found to inhibit both rat and human vascular smooth muscle cell proliferation and migration.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic alpha-Antagonists↗
PubMed1995

Cardioprotection and thrombolysis by anistreplase in anesthetized dogs.

Anistreplase is a thrombolytic agent comprising a complex of streptokinase, lys-plasminogen, and a p-anisoyl group, which temporarily protects the catalytic center of the enzyme complex. Streptokinase was previously shown to reduce infarct size (IS) in dogs with a fibrin-rich clot in the left anterior descending coronary artery (LAD) without necessarily producing reperfusion. Therefore, we hypothesized that IS in this model would be reduced by anistreplase. In addition, we studied the effect of tissue-type plasminogen activator (t-PA) on IS, testing our hypothesis in anesthetized dogs in which thrombin (100 U) and calcium (50 microliters, 0.05 M) were sequentially injected into the LAD to form a thrombus, anistreplase [0.01, 0.05, or 0.10 U/kg intravenous (i.v.) bolus], t-PA (0.1, 0.5, 2, or 8 micrograms/kg/min infusion for 60 min) or vehicle (VEH) was administered 55 min later. Anistreplase (0.05 or 0.10 U/kg) significantly (p < 0.05) reduced clot weight (VEH 22 +/- 3 mg; anistreplase 0.05 U/kg, 13 +/- 4 mg; anistreplase 0.10 U/kg, 0.7 +/- 0.6 mg), increased incidence of reperfusion (VEH 0%; anistreplase 0.05 U/kg, 42%; anistreplase 0.10 U/kg, 100%) and reduced IS (VEH 23 +/- 3%; anistreplase, 0.05 U/kg, 14 +/- 2%; anistreplase 0.10 U/kg, 15 +/- 2%). t-PA reduced thrombin weight (VEH 26 +/- 3 mg; 2 micrograms/kg/min t-PA 12 +/- 4; 8 micrograms/kg/min t-PA 2 +/- 2 mg) and increased incidence of reperfusion (VEH 0%; 2 micrograms/kg/min 75%; 8 micrograms/kg/min 100%), but IS was not altered (VEH 19 +/- 3%; 0.1 microgram/kg/min 18 +/- 3%; 0.5 microgram/kg/min 23 +/- 2%; 2 micrograms/kg/min 16 +/- 5%; 8 micrograms/kg/min: 19 +/- 3%).(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthesia↗