Cocaine Cardiotoxicity Research Articles

Subcellular Effectors of Cocaine Cardiotoxicity: All Roads Lead to Mitochondria-A Systematic Review of the Literature.

Cocaine abuse is a serious public health problem as this drug exerts a plethora of functional and histopathological changes that potentially lead to death. Cocaine causes complex multiorgan toxicity, including in the heart where the blockade of the sodium channels causes increased catecholamine levels and alteration in calcium homeostasis, thus inducing an increased oxygen demand. Moreover, there is evidence to suggest that mitochondria alterations play a crucial role in the development of cocaine cardiotoxicity. We performed a systematic review according to the Preferred Reporting Items for Systemic Reviews and Meta-Analysis (PRISMA) scheme to evaluate the mitochondrial mechanisms determining cocaine cardiotoxicity. Among the initial 106 articles from the Pubmed database and the 17 articles identified through citation searching, 14 final relevant studies were extensively reviewed. Thirteen articles included animal models and reported the alteration of specific mitochondria-dependent mechanisms such as reduced energy production, imbalance of membrane potential, increased oxidative stress, and promotion of apoptosis. However, only one study evaluated human cocaine overdose samples and observed the role of cocaine in oxidative stress and the induction of apoptosis though mitochondria. Understanding the complex processes mediated by mitochondria through forensic analysis and experimental models is crucial for identifying potential therapeutic targets to mitigate or reverse cocaine cardiotoxicity in humans.

Contraction Band Necrosis with Dephosphorylated Connexin 43 in Rat Myocardium after Daily Cocaine Administration.

Contraction band necrosis (CBN) is a common abnormality found in the myocardium of cocaine abusers, but is rarely reported in experimental models of cocaine abuse. Connexin 43 (Cx43) is essential for cardiac intercellular communication and the propagation of CBN. Under stress or injury, cardiac Cx43 is dephosphorylated, which is related to cardiomyocyte dysfunction and pathogenesis, whereas adiponectin exerts beneficial effects in the myocardium. In this study, we explore the effects of cocaine on cardiac Cx43 in vivo. Rats were administered cocaine via the tail vein at 20 mg/kg/day for 14 days, and showed widespread CBN, microfocal myocarditis and myocardial fibrosis, corresponding to a dysfunction of cardiac mitochondria under increased oxidative stress. The increase in dephosphorylated cardiac Cx43 and its negative correlation with the myocardial distribution of CBN after cocaine administration were determined. In addition, apoptosis and necroptosis, as well as increased adiponectin levels, were observed in the myocardium after cocaine exposure. Accordingly, we found altered profiles of cardiac Cx43, CBN and its negative correlation with dephosphorylated cardiac Cx43, and the possible involvement of adiponectin in the myocardium after 14 days of cocaine administration. The latter might play a protective role in the cardiotoxicity of cocaine. The current findings would be beneficial for establishing novel therapeutic strategies in cocaine-induced cardiac consequences.

Substance abuse and cardiovascular risk: cocaine

Cocaine abuse is widely increasing, especially in younger individuals. Cocaine is a major cause of chest pain and acute coronary syndrome and is the leading cause for drug abuse-related visits to emergency departments, most of which are due to cardiovascular complaints. Cocaine use, especially long-term, is associated with an increased risk of all-cause mortality, and with several significant, life-threatening cardiovascular diseases although the multifactorial underlying cellular and molecular pathophysiological mechanisms of acute and chronic cocaine cardiotoxicity are not well established due to limited studies. Current findings have important public health implications, reinforcing recommendations for substance use screening among young adults with heart diseases, and highlighting the need for education on its deleterious effects. Cocaine should be considered a cardiovascular risk factor, requiring attention to early detection of vascular disease in cocaine users.

Altered cardiac mitochondrial dynamics and biogenesis in rat after short-term cocaine administration

Abuse of the potent psychostimulant cocaine is widely established to have cardiovascular consequences. The cardiotoxicity of cocaine is mainly associated with oxidative stress and mitochondrial dysfunction. Mitochondrial dynamics and biogenesis, as well as the mitochondrial unfolded protein response (UPRmt), guarantee cardiac mitochondrial homeostasis. Collectively, these mechanisms act to protect against stress, injury, and the detrimental effects of chemicals on mitochondria. In this study, we examined the effects of cocaine on cardiac mitochondrial dynamics, biogenesis, and UPRmt in vivo. Rats administered cocaine via the tail vein at a dose of 20 mg/kg/day for 7 days showed no structural changes in the myocardium, but electron microscopy revealed a significant increase in the number of cardiac mitochondria. Correspondingly, the expressions of the mitochondrial fission gene and mitochondrial biogenesis were increased after cocaine administration. Significant increase in the expression and nuclear translocation of activating transcription factor 5, the major active regulator of UPRmt, were observed after cocaine administration. Accordingly, our findings show that before any structural changes are observable in the myocardium, cocaine alters mitochondrial dynamics, elevates mitochondrial biogenesis, and induces the activation of UPRmt. These alterations might reflect cardiac mitochondrial compensation to protect against the cardiotoxicity of cocaine.

Ethanol addictively enhances the in vitro cardiotoxicity of cocaine through oxidative damage, energetic deregulation, and apoptosis.

Cocaine (COC) is frequently consumed in polydrug abuse settings, and ethanol (EtOH) is the most prominent co-abused substance. Clinical data and experimental evidence suggest that the co-administration of COC with EtOH can be more cardiotoxic than EtOH or COC alone, but information on the molecular pathways involved is scarce. Since these data are crucial to potentiate the identification of therapeutic targets to treat intoxications, we sought to (i) elucidate the type of interaction that occurs between both substances, and (ii) assess the mechanisms implicated in the cardiotoxic effects elicited by COC combined with EtOH. For this purpose, H9c2 cardiomyocytes were exposed to COC (104µM-6.5mM) and EtOH (977µM-4M), individually or combined at a molar ratio based on blood concentrations of intoxicated abusers (COC 1: EtOH 9; 206µM-110mM). After 24h, cell metabolic viability was recorded by the MTT assay and mixture toxicity expectations were calculated using the independent action (IA) and concentration addition (CA) models. EtOH (EC50 305.26mM) proved to act additively with COC (EC50 2.60mM) to significantly increase the drug in vitro cardiotoxicity, even when both substances were combined at individually non-cytotoxic concentrations. Experimental mixture testing (EC50 19.18 ± 3.36mM) demonstrated that the cardiotoxicity was fairly similar to that predicted by IA (EC50 22.95mM) and CA (EC50 21.75mM), supporting additivity. Concentration-dependent increases of intracellular ROS/RNS and GSSG, depletion of GSH and ATP, along with mitochondrial hyperpolarization and activation of intrinsic, extrinsic, and common apoptosis pathways were observed both for single and combined exposures. In general, the mixture exhibited a toxicological profile that mechanistically did not deviate from the single drugs, suggesting that interventions such asantioxidant administration might aid in the clinical treatment of this type of polydrug intoxication. In a clinical perspective, the observed additive mixture effect may reflect the increased hazards at which users of this combination are exposed to in recreational settings.

Improvement in clinical outcomes of patients with heart failure and active cocaine use after β-blocker therapy.

Cocaine use has a high prevalence in the United States and can be associated with significant cardiovascular disease, even in asymptomatic users. β-Adrenergic receptor hyperactivation is the underlying pathophysiologic pathway of cocaine cardiotoxicity. β-Blocker therapy is controversial in patients with active cocaine use. β-Blocker therapy is associated with clinical improvement in patients with heart failure despite active cocaine use. In a single-center, retrospective chart analysis, patients with newly diagnosed heart failure and active cocaine use who had been started on β-blocker therapy were reviewed. The New York Heart Association (NYHA) functional class and the left ventricular ejection fraction (LVEF) were recorded at baseline and after 12 monthsnthsnths of β-blocker use. Patients were excluded if they had been on prior β-blocker therapy, had other reasons for volume overload, had chronic kidney disease stages G4 or G5, or had a life expectancy <12 months. Thirty-eight patients were identified; most were African American males. A statistically significant improvement was found in both NYHA functional class (P < 0.0001) and LVEF (P < 0.0001) after 12 months of β-blocker therapy. No major adverse cardiovascular events occurred in this population. β-Blocker use in cocaine users with heart failure with a reduced ejection fraction is associated with a lower NYHA functional class and a higher LVEF at 12-month follow-up. No major adverse cardiovascular events were observed.

Cardiac depression induced by cocaine or cocaethylene is alleviated by lipid emulsion more effectively than by sulfobutylether-β-cyclodextrin.

Cocaine intoxication leads to over 500,000 emergency department visits annually in the United States and ethanol cointoxication occurs in 34% of those cases. Cardiotoxicity is an ominous complication of cocaine and cocaethylene overdose for which no specific antidote exists. Because infusion of lipid emulsion (Intralipid) can treat lipophilic local anesthetic toxicity and cocaine is an amphipathic local anesthetic, the authors tested whether lipid emulsion could attenuate cocaine cardiotoxicity invivo. The effects of lipid emulsion were compared with the metabolically inert sulfobutylether-β-cyclodextrin (SBE-β-CD; Captisol) in an isolated heart model of cocaine and cocaethylene toxicity to determine if capture alone could exert similar benefit as lipid emulsion, which exhibits multimodal effects. The authors then tested if cocaine and cocaethylene, like bupivacaine, inhibit lipid-based metabolism in isolated cardiac mitochondria. For whole animal experiments, Sprague-Dawley rats were anesthetized, instrumented, and pretreated with lipid emulsion followed by a continuous infusion of cocaine to assess time of onset of cocaine toxicity. For exvivo experiments, rat hearts were placed onto a nonrecirculating Langendorff system perfused with Krebs-Henseleit solution. Heart rate, left ventricle maximum developed pressure (LVdevP), left ventricle diastolic pressure, maximum rate of contraction (+dP/dtmax), maximum rate of relaxation (-dP/dtmax), rate-pressure product (RPP=heart rate×LVdevP), and line pressure were monitored continuously during the experiment. A dose response to cocaine (10, 30, 50, and 100μmol/L) and cocaethylene (10, 30, and 50μmol/L) was generated in the absence or presence of either 0.25% lipid emulsion or SBE-β-CD. Substrate-specific rates of oxygen consumption were measured in interfibrillar cardiac mitochondria in the presence of cocaine, cocaethylene, ecgonine, and benzoylecgonine. Treatment with lipid emulsion delayed onset of hypotension (140seconds vs. 279seconds; p=0.008) and asystole (369seconds vs. 607seconds; p=0.02) in whole animals. Cocaine and cocaethylene induced dose-dependent decreases in RPP, +dP/dtmax, and -dP/dtmaxabs (p<0.0001) in Langendorff hearts; line pressure was increased by cocaine and cocaethylene infusion, but not altered bytreatment. Lipid emulsion attenuated cocaine- and cocaethylene-induced cardiac depression. SBE-β-CDalone evoked a mild cardiodepressant effect (p<0.0001) butattenuated further cocaine- and cocaethylene-induced decrements in cardiac contractility at high concentrations of drug (100μmol/L; p<0.001). Finally, both cocaine and cocaethylene, but not ecgonine and benzoylecgonine, inhibited lipid-dependent mitochondrial respiration by blocking carnitine exchange (p<0.05). A commercially available lipid emulsion was able to delay progression of cocaine cardiac toxicity invivo. Further, it improved acute cocaine- and cocaethylene-induced cardiac toxicity in rat isolated heart while SBE-β-CDwas effective only at the highest cocaine concentration. Further, both cocaine and cocaethylene inhibited lipid-dependent mitochondrial respiration. Collectively, this suggests that scavenging-independent effects of lipid emulsion may contribute to reversal of acute cocaine and cocaethylene cardiotoxicity, and the beneficial effects may involve mitochondrial lipid processing.

Long term effects of cocaine on the heart assessed by cardiovascular magnetic resonance at 3T.

BackgroundCocaine is an addictive, sympathomimetic drug with potentially lethal effects. The prevalence and features of cocaine cardiotoxicity are not well known. We aimed to assess these effects using a comprehensive cardiovascular magnetic resonance (CMR) protocol in a large group of asymptomatic cocaine users.MethodsConsecutive (n = 94, 81 males, 36.6 ±7 years), non-selected, cocaine abusers were recruited and had a medical history, examination, ECG, blood test and CMR. The CMR study included measurement of left and right ventricular (LV, RV) dimensions and ejection fraction (EF), sequences for detection of myocardial oedema and late gadolinium enhancement (LGE). Images were compared to a cohort of healthy controls.ResultsYears of regular cocaine use were 13.9 ± 9. When compared to the age-matched healthy cohort, the cocaine abusers had increased LV end-systolic volume, LV mass index and RV end-systolic volume, with decreased LVEF and RVEF. No subject had myocardial oedema, but 30% had myocardial LGE indicating myocardial damage.ConclusionsCMR detected cardiovascular disease in 71% of this cohort of consecutive asymptomatic cocaine abusers and mean duration of abuse was related to probability of LV systolic dysfunction.

Cardiovascular Effects of Cocaine: Cellular, Ionic and Molecular Mechanisms

Cocaine is a widely abused drug responsible for the majority of deaths ascribed to drug overdose. Many mechanisms have been proposed in order to explain the various cocaine associated cardiovascular complications. Conventionally, cocaine cardiotoxicity has been thought to be mediated indirectly through its sympathomimetic effect, i.e., by inhibiting the reuptake and thus increasing the levels of neuronal catecholamines at work on adrenoceptors. Increased oxidative stress, reactive oxygen species, and cocaine-induced apoptosis in the heart muscle have suggested a new way to understand the cardiotoxic effects of cocaine. More recent studies have led the attention to the interaction of cocaine and some metabolites with cardiac sodium, calcium and potassium channels. The current paper is aimed to investigate the molecular mechanisms of cocaine cardiotoxicity which have a specific clinical and forensic interest. From a clinical point of view the full knowledge of the exact mechanisms by which cocaine exerts cardio - vascular damage is essential to identify potential therapeutic targets and improve novel strategies for cocaine related cardiovascular diseases. From a forensic point of view, it is to be underlined that cocaine use is often associated to sudden death in young, otherwise healthy individuals. While such events are widely reported, the relationship between cardiac morphological alterations and molecular/cellular mechanisms is still controversial. In conclusion, the study of cocaine cardiovascular toxicity needs a strict collaboration between clinicians and pathologists which may be very effective in further dissecting the mechanisms underlying cocaine cardiotoxicity and understanding the cardiac cocaine connection.

Role of Oxidative Stress in Cocaine-Induced Cardiotoxicity and Cocaine-Related Death

Cocaine-induced cardiovascular disorders such as hypertension, thrombosis, myocardial dysfunction, cardiac dysrhythmias and endocarditis have received widespread attention in the context of cocaine abuse. The number of sudden deaths from cardiac causes, including myocardial infarction, ventricular tachyarrhythmia or aortic dissection, is also increasing. This manuscript will highlight the recent employment of study about cocaine cardiotoxicity and oxidative stress. Evidence has revealed that cardiac oxidative stress is a prominent early event of cocaine administration, which severely compromises the cardiac antioxidant cellular system and causes cardiac antioxidant cellular system injuries. Oxidative damage such as peroxidation of membrane phospholipids and depletion of nonenzymatic antioxidants such as glutathione have been found in the myocardium of chronic cocaine-treated animals and in patients. The data indicate that cocaine administration compromised the heart's antioxidant defense system. About the mechanisms involved in the cellular damage, the evidence that cocaine causes apoptosis in the heart comes from in vivo study. In animals model after short-term and long term-cocaine administration, the investigators demonstrates the role of Reactive Oxygen Species as a trigger of cardiac injury induced by cocaine. Cocaine also increased infiltration of inflammatory cells in the heart, and apoptotic cells were predominantly found near inflammatory cells. The role of oxidative stress in cocaine-induced apoptosis in the heart is wide studied and documented.

Cocaine cardiotoxicity: a review of the pathophysiology, pathology, and treatment options.

Cocaine is a powerful stimulant that gives users a temporary sense of euphoria, mental alertness, talkativeness, and a decreased need for food and sleep. Cocaine intoxication is the most frequent cause of drug-related death reported by medical examiners in the US, and these events are most often related to the cardiovascular manifestations of the drug. Once playing a vital role in medicine as a local anesthetic, decades of research have established that cocaine has the ability to cause irreversible structural damage to the heart, greatly accelerate cardiovascular disease, and initiate sudden cardiac death. Although pathologic findings are often reported in the literature, few images are available to support these findings, and reviews of cocaine cardiopathology are rare. We describe the major pathologic findings linked to cocaine abuse in earlier research, their underlying mechanisms, and the treatment approaches currently being used in this patient population. A MEDLINE search was conducted to identify all English language articles from January 2000 to June 2008 with the subject headings and key words 'cocaine', 'heart', 'toxicity', and 'cardiotoxicity'. Epidemiologic, laboratory, and clinical studies on the pathology, pathophysiology, and pharmacology of the effects of cocaine on the heart were reviewed, along with relevant treatment options. Reference lists were used to identify earlier studies on these topics, and related articles from Google Scholar were also included. There is an established connection between cocaine use and myocardial infarction (MI), arrhythmia, heart failure, and sudden cardiac death. Numerous mechanisms have been postulated to explain how cocaine contributes to these conditions. Among these, cocaine may lead to MI by causing coronary artery vasoconstriction and accelerated atherosclerosis, and by initiating thrombus formation. Cocaine has also been shown to block K+ channels, increase L-type Ca2+ channel current, and inhibit Na+ influx during depolarization, all possible causes for arrhythmia. Additionally, cocaine use has been associated with left ventricular hypertrophy, myocarditis, and dilated cardiomyopathy, which can lead to heart failure if drug use is continued. Certain diagnostic tools, including ECG and serial cardiac markers, are not as accurate in identifying MI in cocaine users experiencing chest pain. As a result, clinicians should be suspicious of cocaine use in their differential diagnosis of chest pain, especially in the younger male population, and proceed more cautiously when use is suspected. Treatment for cocaine-related cardiovascular disease is in many ways similar to treatment for traditional cardiovascular disease. However use of beta-receptor antagonists and class Ia and III anti-arrhythmics is strongly discouraged if the patient is likely to continue cocaine use, because of documented adverse effects. The medical community is in urgent need of a pharmacologic adjunct to cocaine-dependence treatment that can deter relapse and reduce the risks associated with cardiovascular disease in these patients.

A thermostable mutant of a bacterial cocaine esterase reverses acute cocaine toxicity in the rabbit isolated heart

Cocaine use is reported to be the most common cause for drug‐related hospital emergency department visits. Currently, there are no effective therapeutic agents available to directly treat cocaine‐associated toxicity. Cardiovascular events associated with cocaine use include angina pectoris, myocardial infarction, arrhythmias and aortic dissection. The goal of this study was to test the ability of a thermostable mutant of a bacterial cocaine esterase (CocE) to reverse the cardiotoxicty associated with acute cocaine use. The effects of cocaine and CocE treatment on cardiovascular functional parameters and markers of injury were examined in the Langendorff perfused rabbit isolated heart. Cocaine, when added to the perfusion buffer, caused a significant decrease in heart rate, an increase in left ventricular end‐diastolic pressure (LVEDP), an increase in coronary perfusion pressure and a decrease in left ventricular developed pressure. CocE infusion was able to completely reverse the effects on heart rate, LVEDP and developed pressure. CocE was also able to reduce the degree of propidium iodide staining for irreversibly damaged cells in isolated heart sections. In conclusion, this thermostable mutant of CocE is effective in reversing acute cocaine cardiotoxicity. Funding for this project is provided by the University of Michigan Cardiovascular Research Fund.

Targeted Disruption of KATP Channels Aggravates Cardiac Toxicity in Cocaine Abuse

Cocaine is the most frequently used illicit drug among individuals seeking emergency-room care, with fatal outcome most often attributable to the cardiovascular manifestations of drug abuse. While the symptomatic presentations of cocaine toxicity are increasingly understood, the molecular determinants that define outcome remain largely unknown. Here, we report that the susceptibility to cocaine-induced cardiotoxicity is genetically regulated. Targeted deletion of the KCNJ11-encoded Kir6.2 pore-forming subunit of sarcolemmal K(ATP) channels resulted in amplified vulnerability to the toxic effects of chronic cocaine abuse. Under the hyperadrenergic stress, imposed by daily 3-week-long intraperitoneal administration of 30 mg/kg cocaine in Kir6.2-knockout mice, failure to maintain cardiac homeostasis translated into decreased exercise tolerance revealed by poor treadmill stress performance, and dilated hypokinetic left hearts with aggravated cellular hypertrophy and pathognomonic characteristics of chronic cocaine-induced cardiac toxicity. This study therefore reveals a previously unrecognized role of Kir6.2-encoded K(ATP) channels in determining cardiovascular outcome in chronic cocaine abuse, identifying a novel molecular determinant of cocaine cardiotoxicity.

Cocaine and Ethanol: Combined Effects on Coronary Artery Blood Flow and Myocardial Function in Dogs

In combination, cocaine and ethanol are more cardiotoxic than is either substance alone. These substances together constitute a drug abuse combination that commonly results in fatality. Previously the authors have demonstrated that cardiotoxicity of cocaine and ethanol is in part due to synergistic myocardial-depressant effects. However, it remains unclear whether this myocardial depression is associated with concomitant adverse effects on coronary blood flow in relation to these substances. The aim of this study was to investigate combined effects of cocaine and ethanol on myocardial blood flow, in relation to indices of myocardial function. Anesthetized dogs were instrumented for hemodynamic monitoring with Doppler flow probes placed on the circumflex and left anterior descending (LAD) coronary arteries. Dogs were randomized to three groups (each n = 6): ethanol (E, 1.5 g/kg followed by placebo), cocaine (C, placebo followed by cocaine, 7.5 mg/kg IV), or cocaine plus ethanol (C + E). All measurements were made at control, after placebo or ethanol, and then at fixed time intervals after cocaine or placebo bolus over 3 hours. In both the C + E and the C groups, circumflex blood flow (CBF) decreased by 71% (95% confidence interval [CI] = 56% to 85%) and 57% (95% CI = 43% to 72%, both p < 0.04 vs. baseline) immediately after cocaine bolus. This was associated with transient depression of cardiac output, myocardial contractile function, and rate-pressure product (RPP), all indices of myocardial oxygen demand. A subsequent rebound increase of coronary sinus blood flow (CSBF) of 56% (95% CI = 26% to 137%, p < 0.03) compared to baseline occurred only in the C group and was associated with increases of myocardial contractile function and RPP. In the C + E group, 2 hours after drug administration, there was a decrease in CSBF of 49% (95% CI = 32% to 67%; p < 0.01) compared to baseline, which was associated with concomitant numerical decreases of the indices of myocardial oxygen demand and accumulation of cocaethylene. Acute decreases in myocardial flow secondary to cocaine, and cocaine and ethanol in combination, were similar and temporally associated with cocaine's direct myocardial-depressant effects. Rebound increases in myocardial function and blood flow due to cocaine were attenuated by ethanol. Delayed myocardial depression and decreases in myocardial blood flow were observed only with coadministration of cocaine and ethanol.

Chronic Cocaine-Induced Cardiac Oxidative Stress and Mitogen-Activated Protein Kinase Activation: The Role of Nox2 Oxidase

Chronic cocaine exposure is associated with severe cardiac complications, but the mechanisms of cocaine cardiotoxicity remain unclear, and current therapies are unsatisfactory. We investigated the hypothesis of oxidative stress-mediated cardiotoxicity and the role of NADPH oxidase in this process in a mouse model of chronic escalating "binge" cocaine administration (milligrams per kilogram): days 1 to 4 at 3 x 15 mg, days 5 to 8 at 3 x 20 mg, days 9 to 12 at 3 x 25 mg, and days 13 to 14 at 3 x 30 mg. Compared with vehicle controls, chronic binge cocaine administration significantly increased the cardiac NADPH-dependent O(2)(.) production (1.96- +/- 0.4-fold) as detected by tiron (an O(2)(.) scavenger)-inhibitable lucigenin chemiluminescence and dihydroethidium fluorescence. Cocaine-induced reactive oxygen species (ROS) production was associated with significant increases ( approximately 2-fold) in the protein expressions of Nox2 (an isoform of NADPH oxidase) and its regulatory subunits: p22(phox), p67(phox), p47(phox), p40(phox), and Rac1, and in p47(phox) phosphorylation as detected by immunoblotting (all p < 0.03). Increased Nox2 activity was accompanied by the activation of extracellular signal-regulated kinase 1/2, p38 mitogen-activated protein kinase (MAPK), and c-Jun NH(2)-terminal kinase, notably in the cardiomyocytes. Cell culture experiments revealed that cocaine-induced ROS production was primarily a direct action of cocaine on cardiac myocytes, which caused severe oxidative damage to myocytes and cell death as detected by terminal deoxynucleotidyl transferase dUTP nick-end labeling assay. These could be inhibited by inhibitors to protein kinase C (bisindolymaleimide) or by depletion of Nox2 using small interfering RNA. In conclusion, chronic cocaine administration directly causes severe myocardial oxidative stress through the activation of Nox2 oxidase. Increased ROS production contributes to MAPK activation and the subsequent myocyte damage. Inhibitors to NADPH oxidase or antioxidants may have therapeutic potential in the treatment of cocaine cardiotoxicity.

Cocaine, ethanol, and cocaethylene cardiotoxity in an animal model of cocaine and ethanol abuse.

Simultaneous abuse of cocaine and ethanol affects 12 million Americans annually. In combination, these substances are substantially more toxic than either drug alone. Their combined cardiac toxicity may be due to independent effects of each drug; however, they may also be due to cocaethylene (CE), a cocaine metabolite formed only in the presence of ethanol. The purpose of this study was to delineate the role of CE in the combined cardiotoxicity of cocaine and ethanol in a model simulating their abuse. Twenty-three dogs were randomized to receive either 1) three intravenous (IV) boluses of cocaine 7.5 mg/kg with ethanol (1 g/kg) as an IV infusion (C+E, n = 8), 2) three cocaine boluses only (C, n = 6), 3) ethanol infusion only (E, n = 5), or 4) placebo boluses and infusion (n = 4). Hemodynamic measurements, electrocardiograms, and serum drug concentrations were obtained at baseline, and then at fixed time intervals after each drug was administered. Two of eight dogs in the C+E group experienced cardiovascular collapse. The most dramatic hemodynamic changes occurred after each cocaine bolus in the C+E and C only groups; however, persistent hemodynamic changes occurred in the C+E group. Peak CE levels were associated with a 45% (SD +/- 22%, 95% CI = 22% to 69%) decrease in cardiac output (p < 0.05), a 56% (SD +/- 23%, 95% CI = 32% to 80%) decrease in dP/dt(max) (p <.006), and a 23% (SD +/- 15%, 95% CI = 7% to 49%) decrease in SVO(2) (p < 0.025). Ventricular arrhythmias were primarily observed in the C+E group, in which four of eight dogs experienced ventricular tachycardia. Cocaine and ethanol in combination were more toxic than either substance alone. Co-administration resulted in prolonged cardiac toxicity and was dysrhythmogenic. Peak serum cocaethylene concentrations were associated with prolonged myocardial depression.

Post-junctional mechanisms involved in the potentiation of cardiac adrenergic responses by cocaine

Cocaine cardiotoxicity is partly due to sympathetic activation of the heart resulting from inhibition of catecholamine uptake at the sympathetic nerve terminal and possible central sympathetic stimulation and/or inhibition. This study evaluated the role of postsynaptic mechanisms in potentiation by cocaine of cardiac adrenergic responses. Cardiovascular responses (arterial and left ventricular pressure, contractility and heart rate) to increasing doses of noradrenaline and to isoproterenol were obtained in anesthetized cats during a control period, after irreversible α-adrenoceptor blockade with phenoxybenzamine (5 mg/kg i.v.), and after cocaine (5 mg/kg, i.v.). Responses to noradrenaline were significantly reduced by phenoxybenzamine with lowering of the maximal rise of all parameters. Cocaine shifted the dose–response curve of noradrenaline to the left and enhanced its maximal effects. Some responses to isoproterenol, which is not taken up by nerve terminals, were also enhanced by cocaine. Pretreatment with chlorisondamine or verapamil prevented the cocaine-induced enhancement of the maximal response to noradrenaline and the response to isoproterenol, but it did not inhibit potentiation of submaximal doses. Lidocaine did not potentiate the response to noradrenaline or isoproterenol. Use of chlorisondamine instead of cocaine potentiated responses to all noradrenaline doses and enhanced the responses to isoproterenol. These results suggest that the potentiation by cocaine of cardiac responses to adrenergic stimuli involves presynaptic mechanisms to block noradrenaline re-uptake, and postsynaptic mechanisms to raise the maximal responses. The latter may result from inhibition of central sympathetic outflow or from activation of cardiac Ca + channels, leading to increased cardiac sensitivity to noradrenaline.

Genetically determined differences in cocaine cardiotoxicity are altered by nitric oxide synthesis inhibition

GENETICALLY DETERMINED DIFFERENCES IN COCAINE CARDIOTOXICITY ARE ALTERED BY NITRIC OXIDE SYNTHESIS INHIBITION J. Heavner;B. Shi; Regional Anesthesia and Pain Medicine

Cocaine cardiotoxicity differs markedly in isolated hearts of two strains of rats exhibiting phenotypic differences in sensitivity to seizures

Isolated hearts from two strains of rats bred for sensitivity or resistance to amygdala kindling that also exhibit, in vivo, differential sensitivity to the cardiotoxicity of cocaine were studied. The goal was to determine if the differential cardiotoxic sensitivity was due, at least in part, to intrinsic strain-dependent differences in the heart. The Langendorff preparation was used (n = 8 per strain). Hearts were perfused with increasing concentrations of cocaine (5 × 10 −6, 1 × 10 −5, 5 × 10 −5, 1 × 10 −4, and 5 × 10 −4 M) for 5 min with a 5 min washout between exposure to successive concentrations. Consistent with in vivo observations, hearts from genetically slow amygdala kindling rats (Slow) required lower cocaine doses to develop cardiac arrhythmias and arrest as compared to the hearts from genetically fast amygdala kindling rats (Fast). At 5 × 10 −5M cocaine arrhythmias occurred in 38% ( 3 8 ) Slow and 0% Fast hearts. Five of 8 Slow hearts and none of 8 Fast hearts were arrested by 10 −4M cocaine. Arrest in Fast hearts occurred only with 5 × 10 −4M cocaine. Cocaine constricted coronary arteries (no significant difference between strains). On the other hand, coronary arteries of Slow but not Fast hearts dilated during cocaine washout after perfusion with all but the highest concentration of cocaine. We conclude that factors intrinsic to the heart and coronary artery influence the sensitivity or response of these structures to cocaine.

Myocardial necrosis and cocaine. A quantitative morphologic study in 26 cocaine-associated deaths.

A quantification of different forms of acute myocardial necrosis, myocardial leukocytic infiltrates and myocardial fibrosis was accomplished in 26 chronic cocaine abusers who died of cocaine intoxication and compared to 45 normal subjects who died from head trauma and 38 who died of acquired immunodeficiency syndrome. The findings were: absence of infarct necrosis, a similar frequency and extent of coagulative myocytolysis (contraction band necrosis) and leukocytic infiltrates in cocaine abusers and normal controls, and an absence of myocardial fibrosis in cocaine abusers. These findings question both the acute and chronic cardiotoxicity of cocaine. The infarct-like pattern in some predisposed subjects may be due to an excess of catecholamine release induced by the drug resulting in coagulative myocytolysis and platelet thrombi.