The effect of beta blocking drugs on lipid peroxidation in rat heartin vitro

Drugs Repurposed as Antiferroptosis Agents Suppress Organ Damage, Including AKI, by Functioning as Lipid Peroxyl Radical Scavengers

BACKGROUND

Ferroptosis, nonapoptotic cell death mediated by free radical reactions and driven by the oxidative degradation of lipids, is a therapeutic target because of its role in organ damage, including AKI. Ferroptosis-causing radicals that are targeted by ferroptosis suppressors have not been unequivocally identified. Because certain cytochrome P450 substrate drugs can prevent lipid peroxidation via obscure mechanisms, we evaluated their antiferroptotic potential and used them to identify ferroptosis-causing radicals.

METHODS

Using a cell-based assay, we screened cytochrome P450 substrate compounds to identify drugs with antiferroptotic activity and investigated the underlying mechanism. To evaluate radical-scavenging activity, we used electron paramagnetic resonance-spin trapping methods and a fluorescence probe for lipid radicals, NBD-Pen, that we had developed. We then assessed the therapeutic potency of these drugs in mouse models of cisplatin-induced AKI and LPS/galactosamine-induced liver injury.

RESULTS

We identified various US Food and Drug Administration-approved drugs and hormones that have antiferroptotic properties, including rifampicin, promethazine, omeprazole, indole-3-carbinol, carvedilol, propranolol, estradiol, and thyroid hormones. The antiferroptotic drug effects were closely associated with the scavenging of lipid peroxyl radicals but not significantly related to interactions with other radicals. The elevated lipid peroxyl radical levels were associated with ferroptosis onset, and known ferroptosis suppressors, such as ferrostatin-1, also functioned as lipid peroxyl radical scavengers. The drugs exerted antiferroptotic activities in various cell types, including tubules, podocytes, and renal fibroblasts. Moreover, in mice, the drugs ameliorated AKI and liver injury, with suppression of tissue lipid peroxidation and decreased cell death.

CONCLUSIONS

Although elevated lipid peroxyl radical levels can trigger ferroptosis onset, some drugs that scavenge lipid peroxyl radicals can help control ferroptosis-related disorders, including AKI.

Comparison of Pyrroloquinoline Quinone and/or Metoprolol on Myocardial Infarct Size and Mitochondrial Damage in a Rat Model of Ischemia/Reperfusion Injury

The cardioprotective effectiveness of low-dose pyrroloquinoline quinone (PQQ, 3 mg/kg) was compared with metoprolol, a β1-selective adrenoceptor antagonist. Rats underwent 30 minutes of left anterior descending coronary artery occlusion and 2 hours of reperfusion. Metoprolol and/or PQQ were given at the onset of reperfusion to mimic clinical treatment. Metoprolol and/or PQQ reduced infarct size and protected against ischemia-induced left ventricular dysfunction after 2 hours of reper-fusion. Combined therapy augmented left ventricular developed pressure at the end of reperfusion. Metoprolol or PQQ alone enhanced mitochondrial respiratory ratios in ischemic and nonischemic myocardium. Although the PQQ/metoprolol combination therapy increased respiratory ratio values, the effects were small when compared with PQQ alone. Only PQQ decreased lipid peroxidation. Metoprolol and/or PQQ given at the onset of reperfusion reduce infarct size and improve cardiac function. Combination therapy further reduces infarct size. PQQ is superior to metoprolol in protecting mitochondria from ischemia/reperfusion oxidative damage

Comparison of Carvedilol and Metoprolol for Preventing Contrast-Induced Nephropathy after Coronary Angiography

AIMS

Contrast-induced nephropathy (CIN) is one of the most common causes of hospital-acquired acute renal failure. Oxidative stress and vasoconstriction might play key roles in its pathogenesis. In a few experimental models, antioxidant properties of carvedilol have been documented. The aim of this study was to analyze and compare the effects of carvedilol and metoprolol on the development of CIN in patients undergoing coronary angiography.

METHODS

One hundred patients currently taking metoprolol and 100 patients currently taking carvedilol were enrolled into the study. Venous blood samples were obtained before and 48 h after contrast administration. Cystatin C and malondialdehyde values were examined and compared. CIN was defined as a creatinine increase of at least 25% or 0.5 mg/dl from the baseline value.

RESULTS

Seven patients in the carvedilol group (7%) and 22 patients in the metoprolol group (22%) developed CIN (p = 0.003). In the metoprolol group, the median cystatin C concentration increased significantly from 978 to 1,086 ng/ml (p = 0.001) 48 h after radiocontrast administration. In the carvedilol group, the median cystatin C concentration did not change significantly (1,143 vs. 1,068 ng/ml; p = 0.94). In the metoprolol group, the mean malondialdehyde concentration increased significantly from 7.09 ± 1.48 to 8.38 ± 2.6 nmol/l (p < 0.001). In the carvedilol group, the mean serum malondialdehyde concentration did not change significantly (7.44 ± 1.21 vs. 7.56 ± 1.11 nmol/l; p = 0.59).

CONCLUSION

When compared to metoprolol, carvedilol might decrease oxidative stress and subsequent development of CIN.

A clinical study about contrast nephropathy: risk factors and the role of beta blockers

Objective:

There is still a group of patient that have unpredictable risk for the development of contrast nephropathy (CN). There is also an effort to find more effficient strategies to prevent CN. Carvedilol, metoprolol and nebivolol seem to have theoretical potentials for the prevention of CN. In this study, we aimed to investigate their effects on the prevention of CN. We also aimed to define the risk factors associated with the development of CN in our study group.

Methods:

In this prospective, cross-sectional study, the patients were divided into four groups according to whether they were taking 25 mg/day carvedilol (n:56), 5 mg/day nebivolol (n:60), 50 mg/day metoprolol (n:68) or none (n:63). We made analysis to determine the agents’ efficiency on the prevention of CN. We also performed multiple logistic regression analysis including all groups to define the risk factors associated with CN.

Results:

The incidents of CN were the lowest in the carvedilol group (4%) while the worst performance occurred in those taking metoprolol (10%). The difference between the groups in terms of the development of CN did not reach statistical significance (p>0.05). Multiple logistic regression analysis showed age (p=0.003), higher triglyceride levels (p=0.011) and family history of coronary artery disease (p=0.038) to be the predictors of CN.

Conclusion:

In this study, we didn’t find any relation between the development of CN and carvedilol, metoprolol or nebivolol usage. We found age, higher levels of triglyceride and family history of coronary artery disease to be risk factors for predicting CN.

Activation of calcium-independent phospholipase A2 (iPLA2) in brain mitochondria and release of apoptogenic factors by BAX and truncated BID

Cleaved or truncated BID (tBID) is known to oligomerize both BAK and BAX. Previously, BAK and BAX lacing the C-terminal fragment (BAXDeltaC) were shown to induce modest cytochrome c (Cyt c) release from rat brain mitochondria when activated by tBID. We now show that tBID plus monomeric full-length BAX induce extensive release of Cyt c, Smac/DIABLO, and Omi/HtrA2 (but not endonuclease G and the apoptosis inducing factor) comparable to the release induced by alamethicin. This occurs independently of the permeability transition without overt changes in mitochondrial morphology. The mechanism of the release may involve formation of reactive oxygen species (ROS) and activation of calcium-independent phospholipase A(2) (iPLA(2)). Indeed, increased ROS production and activated iPLA(2) were observed prior to massive Cyt c release. Furthermore, the extent of inhibition of Cyt c release correlated with the degree of suppression of iPLA(2) by the inhibitors propranolol, dibucaine, 4-bromophenacyl bromide, and bromenol lactone. Consistent with a requirement for iPLA(2) in Cyt c release from brain mitochondria, synthetic liposomes composed of lipids mimicking the outer mitochondrial membrane (OMM) but lacing iPLA(2) failed to release 10 kDa fluorescent dextran (FD-10) in response to tBID plus BAX. We propose that tBID plus BAX activate ROS generation, which subsequently augments iPLA(2) activity leading to changes in the OMM that allow translocation of certain mitochondrial proteins from the intermembrane space.

Isoproterenol-induced myocardial infarction in rabbits. Protection by propranolol or labetalol: a proposed non-invasive procedure

Myocardial infarction is usually induced in small animals by means of invasive techniques based on mechanical coronary obstruction. As it has been reported that isoproterenol can cause ischemic myocardial alterations, lipid peroxide generation and procoagulant activity, we administered it to rabbits in order to induce a non-invasive myocardial infarction associated with above mentioned cardiovascular risk factors. Considerable ischemic alterations were observed in the animals treated with isoproterenol, including areas of myocardial necrosis, contraction band necrosis, increased plasma levels of cardiac necrosis markers (c-troponin I and myoglobin), and electrocardiographic modifications (ST segment changes and T wave inversion). The myocardial infarction was attributed to the inotropic activity of isoproterenol leading to intracellular calcium overload. The cardiac necrosis phenomena appear to be associated with isoproterenol-induced lipid peroxide generation (as shown by the decrease in plasma Vitamin E levels) and increased procoagulant activity (a shortened PTT). As this model of myocardial damage is based on the use of beta-stimulatory isoproterenol, the beta-blockers propranolol and labetalol were administered to isoproterenol-treated animals. Pretreatment with propranolol or labetalol counteracted the appearance of the myocardial histological alterations and the associated ECG and biochemical lesions. This protective activity was attributed to the beta-blockade. The results of this study demonstrate that myocardial infarction can be induced chemically and non-invasively in small laboratory animals. The procedure is proposed for the study of early ischemic myocardial lesions and the screening of drugs (such as beta-blockers) that can prevent myocardial necrosis damage and the associated risk factors.

Carvedilol: a new candidate for reversal of MDR1/P-glycoprotein-mediated multidrug resistance

In 1983, carvedilol [1-[carbazolyl-(4)-oxy]-3-[(2-methoxyphenoxyethyl)amino]-2-propanol] was designed and developed as a beta-adrenoceptor antagonist with vasodilating activity for efficacious and safe treatment of hypertension and coronary artery disease. Carvedilol belongs to the 'third generation' of beta-adrenoceptor antagonists and shows selectivity for the beta1- rather than beta2-adrenoceptor. Carvedilol is also an alpha1-blocking agents, with around 2- to 3-fold more selectivity for beta1- than alpha1-adrenoceptors. This degree of alpha1-blockade is responsible for the moderate vasodilator properties of carvedilol, being different from other beta-adrenoceptor antagonists. In addition, carvedilol is a potent antioxidant, with a 10-fold greater activity than vitamin E. Some carvedilol metabolites found in human plasma also exhibit antioxidative activity approximately 50- to 100-fold greater than carvedilol and other antioxidants. These unique properties of carvedilol, i.e. adrenergic (beta1, beta2 and alpha1) blockade and antioxidative activity, may be important in preventing progressive deterioration of left ventricular dysfunction and chronic heart failure. Recently, carvedilol has been demonstrated to reverse multidrug resistance (MDR) to anticancer drugs in tumor cells in vitro and its reversal effects were comparable with verapamil, which has been used in the first clinical trial for the reversal of MDR. This review introduces the reversal activity and usefulness against MDR, as well as an overview of the pharmacological and pharmacokinetic properties, of carvedilol.

Relationship between the sialic acid content of low-density lipoprotein (LDL) and autoantibodies to oxidized LDL in the plasma of healthy subjects and patients with atherosclerosis

To determine whether the sialic acid (SA) content of the low-density lipoprotein (LDL) is related to the plasma concentration of autoantibodies to oxidized LDL (oxLDL), we measured the SA content of LDL and the concentrations of oxLDL and autoantibodies to oxLDL in plasma of 20 apparently healthy subjects and 20 patients with advanced coronary atherosclerosis. In the healthy subjects the SA content of LDL correlated positively with plasma concentration of autoantibodies to oxLDL. In agreement with the literature the decreased SA content of LDL was associated with an increased fraction of oxLDL; a decreased fraction of oxLDL was associated with an increased plasma concentration of autoantibodies to oxLDL. In the patients the SA content of LDL and plasma concentrations of oxLDL and autoantibodies to oxLDL were not related. We conclude that the SA content of LDL correlates positively with plasma concentration of autoantibodies to oxLDL in healthy subjects. However, this association may vary depending on the stage of atherogenesis. Although our results suggest dependence of LDL SA content on the clearance of oxidatively modified (desialylated and oxidized) LDL from blood by autoantibodies to oxLDL, the mechanisms regulating the SA content of LDL await further studies.

Bopindolol: pharmacological basis and clinical implications

Bopindolol, a non-selective antagonist of beta 1- and beta 2-adrenoceptors (ARs), has been found by pharmacological, molecular biological techniques and molecular modeling to have several unique properties. Bopindolol produces sustained blockade of beta 1- and beta 2-ARs, has intrinsic sympathomimetic as well as membrane stabilizing actions, inhibits renin secretion, and interacts with 5-HT receptors. Also, our recent molecular modeling studies identified possible interaction sites between bopindolol and beta-AR subtypes. The reviewed studies support our findings that bopindolol is non-selective for beta 1- and beta 2-ARs, has low affinity for beta 3-AR subtype and has pharmacological properties that are likely to be beneficial in the treatment of cardiovascular diseases.

Lipolysis is an important determinant of isoproterenol-induced myocardial necrosis

The cardiotoxic effect of isoproterenol (ISO) is associated with, and possibly due to, calcium overload. Prior work suggests that calcium entry into cardiac myocytes after ISO administration occurs in two phases: an early rapid phase, followed by a slow phase beginning about 1 hour after ISO injection, leading to a peak myocardial calcium level after about 4 hours. We have tested the relationship of these phases to myocardial necrosis (MN) by determining the time after ISO administration at which the commitment to MN occurs. This was done by administration of propranolol at various times before and after ISO. In addition, since ISO induces lipolysis, and lipids can be toxic, experiments were conducted to determine if adrenergically-activated lipolysis could play a significant role in ISO-MN. We found that propranolol protected the myocardium equally well when administered anytime within 2 hours of ISO injection, but had no effect when given 4 hours after ISO. This showed that metabolic events taking place more than two hours after ISO injection are required for ISO-MN. As expected from prior work, there was a small and consistent amount of propranolol-resistant ISO-MN. Lipolysis, assessed by measuring serum glycerol levels, increased to tenfold above base line at one hour after ISO administration and returned to near basal levels at 4 hours. Potentiation of lipolysis by intravenous injections of phospholipase A2 (PLA2) or lipoprotein lipase (LPL) to rats treated with ISO substantially augmented MN. Propranolol completely blocked the increase in necrosis produced by PLA2 when given with ISO. Lipases induced only minimal necrosis in the absence of ISO. Administration of adenosine (an anti-lipolytic agent), oxfenicine (an inhibitor of mitochondrial palmitoyl carnitine transferase), or vitamin C (an anti-oxidant) resulted in a 55-60% reduction in MN. These results suggest that critical necrosis-determining events occur between 2 and 4 hours after ISO administration and imply a relationship between ISO-induced lipolysis, calcium influx, and ISO-MN. We hypothesize that importance of lipolysis as a determinant of ISO-MN is related to the generation of free fatty acids, their oxidized/metabolic products, or direct damage to plasma membrane.

Antioxidant properties of ticlopidine on human low density lipoprotein oxidation

We found that ticlopidine, at therapeutically relevant concentrations (2.5-10 microM), but not aspirin nor salicylate, significantly counteracted copper-driven human LDL oxidation. Ticlopidine, at 5 and 10 microM, was also antioxidant on peroxyl radical-induced LDL oxidation; yet it was ineffectual on thiol and ascorbate oxidation mediated by peroxyl radicals themselves, suggesting that drug antioxidant capacity is somehow related to the lipoprotein nature of the oxidizable substrate, but not to radical scavenging. The drug could not indeed react with the stable free radical 1,1-diphenyl-2-pycrylhydrazyl, nor had apparent metal complexing-inactivating activity. Thus, ticlopidine has antioxidant effects on LDL oxidation, which, together with its anti-platelet activity, could confer peculiar antiatherogenic properties to the drug in vivo.

Impact of a combination of a calcium antagonist and a beta-blocker on cell- and copper-mediated oxidation of LDL and on the accumulation and efflux of cholesterol in human macrophages and murine J774 cells

Calcium antagonists and beta-blockers may retard or inhibit atherogenesis. In the absence of data pertaining to the potential cardioprotective action of an association of such agents, we have investigated the impact of nifedipine and atenolol, alone or in combination, on the capacity of monocyte-macrophages (ex vivo) and copper ions (in vitro) to oxidize LDL and on intracellular metabolism and efflux of free and esterified forms of cholesterol in human macrophages and foam cells. At concentrations up to 100 micromol/L, atenolol had no effect on the oxidative resistance of LDL; on the contrary, nifedipine displayed a significant dose-dependent capacity to protect LDL during copper-mediated oxidation (100 micromol/L; P<.001). Using a DPPH radical generating system, nifedipine was shown to exert free radical-trapping activity (molar ratio of scavenging activity, nifedipine:alpha-tocopherol, 1:114). The addition of atenolol to nifedipine was without effect on the antioxidant activity of the calcium antagonist. In experiments in which oxidative modification was mediated by monocyte-macrophages, nifedipine but not atenolol conserved its antioxidant capacity. Furthermore, we demonstrated that association of atenolol with nifedipine did not modify the antioxidant properties of nifedipine itself. Using a human monocyte-derived macrophage culture system, nifedipine, atenolol, or a combination of the two drugs was ineffective in inhibiting foam cell formation induced by acetylated LDL or oxidized LDL. However, atenolol (100 micromol/L) increased cellular accumulation of cholesteryl ester (+17%; P<.05), whereas nifedipine (100 micromol/L) decreased total cholesterol (-37.4%; P<.05) accumulation induced by acetylated LDL in the mouse macrophage cell line J774. A combination of the two drugs neutralized these antagonistic effects. None of these results were reproduced during the oxidized LDL-induced transformation of murine J774 cells into foam cells. Furthermore, cholesterol efflux from preloaded human macrophages was equally unaffected by the addition of the drugs alone or in combination. It therefore seems unlikely that the beneficial effect of atenolol on coronary heart disease is mediated by changes in either LDL oxidizability or cholesterol metabolism in human macrophages and foam cells. Our findings with nifedipine suggest, however, that this calcium antagonist may potentially exert antiatherosclerotic properties via a reduction of the oxidative modification of LDL, thereby affecting a reduction in foam cell formation and in the pathophysiological cellular activities of oxidized lipids, rather than by inducing a direct reduction in cholesterol accumulation in human foam cells of macrophage origin.