Cocaine produces cardiac hypertrophy by protein kinase C dependent mechanisms

Predicting cardiovascular risk using a novel risk score in young and middle-age adults with HIV: associations with biomarkers and carotid atherosclerotic plaque

BACKGROUND

Traditional risk factors associated with cardiovascular disease (CVD) include older age, smoking, poor diet, lack of exercise, obesity, high blood pressure, high cholesterol, and family history. Young-to-middle age adults (YMAA) are less often identified as being at risk of CVD, but traditional risk scores primarily target older adults and do not accurately estimate risk among YMAA.

METHODS

This study examined biomarkers associated with CVD risk in YMAA in the context of HIV and cocaine use; risk was assessed by two methods: (1) a relative cardiovascular (CV) risk score that includes several factors and (2) carotid atherosclerotic plaque. Associations between CVD risk (CV risk score and carotid atherosclerotic plaque) and proinflammatory cytokines, markers of immune activation, HIV status, and cocaine use were examined. Participants (N = 506) included people with and without HIV and people who use or do not use cocaine.

RESULTS

Participants' mean age was 36 (SD = 9.53); half (51%) were men. Cocaine use and C-reactive protein were associated with greater relative CV risk scores, but no associations between biomarkers and CV risk emerged. Age and CV risk scores were associated with carotid atherosclerotic plaque, but biomarkers were not. HIV was not associated with CV risk scores or carotid atherosclerotic plaque.

CONCLUSIONS

Among YMAA, CV risk scores may help providers identify lifestyle changes needed among those at risk for CVD before more advanced risk (e.g., atherosclerotic plaque) is identified. Implications are discussed.

Cardiovascular and Hepatic Toxicity of Cocaine: Potential Beneficial Effects of Modulators of Oxidative Stress

Oxidative stress (OS) is thought to play an important role in the pharmacological and toxic effects of various drugs of abuse. Herein we review the literature on the mechanisms responsible for the cardiovascular and hepatic toxicity of cocaine with special focus on OS-related mechanisms. We also review the preclinical and clinical literature concerning the putative therapeutic effects of OS modulators (such as N-acetylcysteine, superoxide dismutase mimetics, nitroxides and nitrones, NADPH oxidase inhibitors, xanthine oxidase inhibitors, and mitochondriotropic antioxidants) for the treatment of cocaine toxicity. We conclude that available OS modulators do not appear to have clinical efficacy.

Cocaine and beta-blockers: the paradigm

Cocaine is one of the most commonly used substances of abuse. The use of beta-blockers in cocaine induced acute coronary syndrome has long been a matter of debate. While it is widely believed that beta-blockers are contraindicated in cocaine toxicity, there appears to be some recognizable role for certain beta-blockers in ameliorating the cardiovascular as well as central nervous system effects of cocaine. This article explores the role of beta-blockers in the management of cocaine toxicity.

Cocaine-related sudden death: a prospective investigation in south-west Spain

AIMS

With an estimated 12 million consumers in Europe, cocaine (COC) is the illicit drug leading to the most emergency department visits. The aim of this study was to examine a consecutive series of sudden deaths (SDs) to focus on the prevalence, the toxicological characteristics, and the causes of death in COC-related fatalities.

METHODS AND RESULTS

Prospective case-control study of forensic autopsies was carried out in the time interval November 2003 to June 2006 at the Institute of Legal Medicine, Seville, south-west Spain, with a reference population of 1 875 462 inhabitants. Toxicology included blood ethanol analysis and blood and urine investigation for drugs of abuse and medical drugs. Autopsy was performed according to the European standardized protocol. Ten age- and sex-matched patients who died of violent causes with no antecedents of COC consumption and negative toxicology served as controls. During the study period, 2477 forensic autopsies were performed, including 1114 natural deaths. Among the latter, 668 fulfilled the criteria of SD and 21 (all males, mean age 34.6 +/- 7.3 years) resulted to be COC-related (3.1%). Cocaine was detected in 67.1% of the blood (median 0.17 mg/L, interquartile range 0.08-0.42) and in 83.0% of the urine samples (median 1.15 mg/L, interquartile range 0.37-17.34). A concomitant use of ethanol was found in 76.0% and cigarette smoking in 81.0%. Causes of SD were cardiovascular in 62.0%, cerebrovascular in 14.0%, excited delirium in 14.0%, respiratory and metabolic in 5.0% each. Left ventricular hypertrophy was observed in 57.0%, small vessels disease in 42.9%, severe atherosclerotic coronary artery disease in 28.6%, and coronary thrombosis in 14.3%.

CONCLUSION

Systematic toxicology investigation indicates that 3.1% of SDs are COC-related and are mainly due to cardio-cerebrovascular causes. Left ventricular hypertrophy, small vessel disease, and premature coronary artery atherosclerosis, with or without lumen thrombosis, are frequent findings that may account for myocardial ischaemia at risk of cardiac arrest in COC addicts.

Cocaine activates calcium/calmodulin kinase II and causes cardiomyocyte hypertrophy

Cardiac hypertrophy occurs in as many as 47% of normotensive individuals who chronically use cocaine. We investigated the effects of cocaine, in concentrations commonly found in chronic cocaine users, on calcium/calmodulin kinase (CaMK), and whether cocaine can activate CaMK, increase cardiac myocyte protein expression, and cause cardiac hypertrophy in this manner. In series I to III, 0 (control) or cocaine in concentrations of 10 to 10 mol/L was added to cultured adult rat cardiac ventricular myocytes to determine by Western blots and by P incorporation the optimal treatment time and the optimal dose for CaMK activation. In series I, cocaine, 10 mol/L, increased myocyte CaMKII translocation from myocyte soluble to particulate fractions by > or =73 +/- 9% (P < 0.01) in comparison with controls but did not cause the translocation of CaMKI or CaMKIV. In series II and III, cocaine treatment of myocytes for 15 minutes increased maximal CaMKII activity by 86.5 +/- 13.3% (P < 0.001) and a cocaine dose of 5 x 10 mol/L increased CaMKII activity by 169.5 +/- 18.1% (P < 0.001). In series IV we measured by silver staining beta-myosin heavy chain protein (beta-MHC) expression in myocytes before and after cocaine and also CaMK inhibition with KN-62 (1-[N,O-bis-(5-isoquinolinesulfonyl)-N-methyl-L-tyrosyl]-4-phenylpiperazine). In these experiments, cocaine, 5x10 mol/L, increased myocyte protein concentration by 29.2 +/- 2.8%, and beta-MHC by 93.2 +/- 8.8% (P < 0.001). In series V and VI, cocaine effects on calcium currents (ICa) and intracellular Ca ([Ca]i) were determined before and after CaMK inhibition with KN-62 in rat myocytes. Cocaine, 10 mol/L, enhanced ICa peak amplitude in a voltage-dependent manner (by 173.9 +/- 14.9% at -20 mV and by 38.4 +/- 6.9% at 0 mV P < 0.01). Cocaine, 10 to 10 mol/L, in series VI promoted Ca transients from myocyte sarcoplasmic reticulum and increased [Ca]i to 607 +/- 141 x 10 mol/L (P < 0.05). KN-62 decreased cocaine-induced myocyte protein expression by 76.6%, and beta-MHC by 66.2% (P < 0.01) and significantly decreased cocaine-induced Ca transients and [Ca]i. We conclude that CaMKII activation is an important mechanism whereby cocaine can cause myocyte hypertrophy.

Cocaethylene affects human microvascular endothelial cell p38 mitogen-activated protein kinase activation and nuclear factor-kappaB DNA-binding activity

BACKGROUND

Cocaethylene (CE) is known to increase the permeability of human microvascular endothelial cell monolayers. The molecular mechanism underlying this increase may involve calcium-modulated signaling pathways such as the p38 mitogen-activated protein kinase (p38 MAPK) and the nuclear factor-kappaB (NF-kappaB) family of transcription factors. The hypothesis of this study was that CE-mediated endothelial permeability change may be mediated by the p38 MAPK and consequently NF-kappaB dimers.

METHODS

We used sandwich ELISA to detect phosphorylated p38 MAPK in the cell line human microvascular endothelial cell 1 (HMEC-1) after treatment with 1 mmol/L CE. We used electrophoretic mobility shift assay to detect changes in NF-kappaB dimers present in HMEC-1 and their DNA-binding activity after treatment with CE. Lipopolysaccharide (LPS) from Salmonella typhosa was used as a positive control for all experiments.

RESULTS

Treatment with CE and LPS had similar effects on HMEC-1 p38 MAPK phosphorylation and NF-kappaB DNA-binding activity. Both treatments increased the phosphorylation of p38 MAPK, consistent with activation of proinflammatory cell signaling. Treatment of HMEC-1 with CE decreased DNA binding of both the RelA/p50 and p50/p50 dimers of the NF-kappaB transcription factor family, whereas treatment with LPS decreased and then increased the DNA binding of these dimers.

CONCLUSION

In addition to increasing HMEC-1 monolayer permeability, CE also alters transcription factor and kinase activity related to inflammation. Thus, CE causes endothelial activation that can elicit a prolonged and organized cellular response, rather than being directly toxic to endothelial cells.

p38 MAP-kinase in cultured adult rat ventricular cardiomyocytes: expression and involvement in hypertrophic signalling

Both alpha-adrenoceptor- and beta-adrenoceptor-stimulation lead to hypertrophic growth of the myocardium. But only beta-adrenoceptor-stimulation requires the pre-cultivation of cells with active TGF-beta. In order to define signalling molecules that are specifically involved in beta-adrenoceptor-dependent hypertrophy, changes in expression and hypertrophic responsiveness during pre-cultivation with TGF-beta were investigated. Isolated adult ventricular cardiomyocytes from rats were either cultured in 20% (v/v) foetal calf serum (FCS) to activate autocrine released TGF-beta or used without pre-treatment. Protein synthesis was analysed by (14)C-phenylalanine incorporation. Expression of signalling molecules was determined by immunoblotting. During cultivation of cardiomyocytes with active TGF-beta only the expression of p38 MAP-kinase increased. Subsequent stimulation of beta-adrenoceptors induced protein synthesis in a p38 MAP-kinase-dependent way. However, stimulation of beta-adrenoceptors activated p38 MAP-kinase irrespective of pre-treatment with TGF-beta. In the absence of this cytokine, hyperosmolarity or reconstitution of mechanical activity increased protein synthesis via p38 MAP-kinase activation in freshly isolated cells. In conclusion, activation of p38 MAP-kinase is a newly identified necessary signalling step required for beta-adrenoceptor induced hypertrophic growth. Like activation of adenyl cyclase, activation of p38 MAP-kinase is up-stream of the TGF-beta-induced coupling to the regulation of protein synthesis. Reconstitution of mechanical activity mimics the co-activation required and induced by TGF-beta.

Cocaine cardiovascular toxicity

Cocaine abuse kills thousands every year. Preexisting coronary artery disease appears to account for many of the deaths, but often the mechanism is much more complex. There exists a widely held but utterly mistaken notion that cocaine-related deaths are due to drug overdose. Except in the case of drug couriers ("body packers") with massive drug exposure, death is not dose related, and cocaine blood levels cannot be used to predict toxicity. Most deaths occur after prolonged drug use, which initiates a series of changes at the molecular, cellular, and tissue levels. All of these changes favor sudden death. Potentially lethal myocardial alterations include hypertrophy, fibrosis, and microangiopathy. Recently it has become clear that genetic causes, such as fully or partially expressed congenital long QT syndrome, may also play a role. The relative importance of each of these factors is reviewed.

Salusins promote cardiomyocyte growth but does not affect cardiac function in rats

Salusin-alpha and -beta are newly found polypeptides that stimulate proliferation, hypotension and bradycardia in vascular smooth muscle cells (VSMCs) and fibroblasts. Propresalusin mRNA is widespread, and positive stains for salusins have been observed in many human tissues such as endothelium and ventricular tissue. To investigate the bio-effect of salusins on cardiovascular function, 20 nmol/kg salusin-alpha or 2 nmol/kg salusin-beta was intravenously (i.v.) injected into rats, and isolated rat hearts were perfused with 10(-12) to 10(-7) mol/l salusin-alpha or -beta. (45)Ca(2+) uptake and (3)H-Leucine incorporation were determined in cultured neonatal rat cardiomyocytes. Neither salusin-a nor -beta affected cardiac function in vivo or in vitro but salusin-beta decreased mean arterial blood pressure (MAP). The polypeptides' stimulation of (45)Ca(2+) uptake and (3)H-Leucine incorporation was concentration-dependent, and the incorporation was inhibited by nicardipine (Nic) and FK-506 [FK; an inhibitor of calcineurin (CaN)]. PD(98059) [PD; inhibitor of mitogen-activated protein kinase (MAPK)] and chelerythrine [inhibitor of protein kinase C (PKC)] inhibited salusin-stimulated (3)H-Leucine incorporation. Endothelin-1 (ET) synergistically increased salusin-induced (45)Ca(2+) uptake. Our results suggest that salusin-alpha and -beta did not directly affect cardiac function in the rat heart but that they improved calcium uptake and protein synthesis in neonatal rat cardiomyocytes through the calcium, calcineurin, MAPK and PKC signal pathways. Salusins may be regulatory factors for myocardial growth and hypertrophy.