Cocaine increases beta-myosin heavy-chain protein expression in cardiac myocytes

Effects of environmental cocaine concentrations on the skeletal muscle of the European eel (Anguilla anguilla)

The presence of illicit drugs in the aquatic environment represents a new potential risk for aquatic organisms, due to their constant exposure to substances with strong pharmacological activity. Currently, little is known about the ecological effects of illicit drugs. The aim of this study was to evaluate the influence of environmental concentrations of cocaine, an illicit drug widespread in surface waters, on the skeletal muscle of the European eel (Anguilla anguilla). The skeletal muscle of silver eels exposed to 20 ng L^-1 of cocaine for 50 days were compared to control, vehicle control and two post-exposure recovery groups (3 and 10 days after interruption of cocaine). The eels general health, the morphology of the skeletal muscle and several parameters indicative of the skeletal muscle physiology were evaluated, namely the muscle whole protein profile, marker of the expression levels of the main muscle proteins; cytochrome oxidase activity, markers of oxidative metabolism; caspase-3, marker of apoptosis activation; serum levels of creatine kinase, lactate dehydrogenase and aspartate aminotransferase, markers of skeletal muscle damages. Cocaine-exposed eels appeared hyperactive but they showed the same general health status as the other groups. In contrast, their skeletal muscle showed evidence of serious injury, including muscle breakdown and swelling, similar to that typical of rhabdomyolysis. These changes were still present 10 days after the interruption of cocaine exposure. In fact, with the exception of the expression levels of the main muscle proteins, which remained unchanged, all the other parameters examined showed alterations that persisted for at least 10 days after the interruption of cocaine exposure. This study shows that even low environmental concentrations of cocaine cause severe damage to the morphology and physiology of the skeletal muscle of the silver eel, confirming the harmful impact of cocaine in the environment that potentially affects the survival of this species.

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.

Methylenedioxymethamphetamine (ecstasy)-related myocardial hypertrophy: an autopsy study

BACKGROUND

Myocardial hypertrophy is a well-recognized complication of cocaine and methamphetamine abuse and is a strong, independent risk factor for sudden death, myocardial infarction, and congestive heart failure. We sought to determine if use of MDMA (methylenedioxyamphetamine or "ecstasy") is associated with myocardial hypertrophy at death.

METHODS AND RESULTS

A matched, retrospective study using medical examiner (ME) death reports. Consecutive MDMA positive (+) and MDMA negative (-) deaths identified from MEs in 10 states and a local county, respectively. Five MDMA(-) cases were matched to each MDMA(+) case for age, sex, and ethnicity. MDMA(+) cases were confirmed using GC/MS and other drugs of abuse (e.g., cocaine and methamphetamine) were absent. Matched MDMA(-) cases were trauma fatalities with intact hearts and blood negative for all illicit stimulants. Cardiac weights were compared between the two groups. Twenty seven MDMA(+) deaths and 135 matched MDMA(-) deaths were enrolled. Mean age was 20 years (range 16--33 years); 44% were female. 70.4% were Caucasian, 14.8% African-American, 11.1% Asian, and 3.7% Hispanic. Mean heart weight of MDMA(+) fatalities was 315.7 and 277.2g for MDMA(-) fatalities (Diff=38.5 g; 95% CI=18.3--8.7). Multivariate analysis revealed that MDMA(+) fatalities were more likely to have an enlarged heart (OR=18.3; 95% CI=3.6--1.6).

CONCLUSION

The findings of this study suggest that MDMA users might also be at risk for myocardial hypertrophy and possible cardiac toxicity, similar to other stimulants.

Long-term cocaine use is related to cardiac diastolic dysfunction in an African-American population in Baltimore, Maryland

BACKGROUND

Only limited studies have been done on the effects of long-term cocaine use on the human heart, and the results remain controversial. In this study, we examined and compared the diastolic function of non-cocaine users and chronic cocaine users to reveal the impact of long-term cocaine use on the human heart.

METHODS

Two-dimensional echocardiogram and pulsed Doppler transmitral blood flow pattern were obtained from 138 recruited study participants with different cocaine histories. The indices of cardiac structure and function were measured from the echocardiogram of each participant. Student's t-test was used to compare the average echocardiographic measurements of the non-cocaine user group and the cocaine user group. Multivariate regression analysis was deployed to eliminate the effects of age, gender, blood pressure, and HIV infection on the functional measurements of the two groups.

RESULTS

The cocaine user group had a significantly longer average deceleration time than did the non-cocaine user group (208.1 +/- 38.2 vs. 167.5 +/- 39.1 ms, P<0.001). A linear association existed between the deceleration time and the log-transformed duration of cocaine use (beta=0.00351, S.E.=0.00104, P=0.001). Cocaine users in this study were approximately five times more likely to have an elongated deceleration time (>200 ms) than were non-users (OR, 4.799; 95% CI, 1.000-23.044; P=0.05). No significant differences were observed in the other measured diastolic functional parameters, such as isovolumic ventricular relaxation time, E wave, A wave, and E/A ratio.

CONCLUSIONS

Long-term cocaine use is linked to decline in diastolic function.

Maternal methamphetamine administration during pregnancy influences on fetal rat heart development

Methamphetamine (MAP) is one of the most abused drugs in Japan. The rate of MAP abuse by young women has recently reached more than 50 percent in adolescents. A major health concern is that these women will continue to use MAP during pregnancy. The purpose of this study was to investigate whether MAP administered to the mother during pregnancy would change the expression of alpha- and beta- myosin heavy chain (MHC) mRNA in rat neonatal hearts, as detected by quantitative RT-PCR. In addition, morphological changes in the rat neonatal ventricles were examined. Pregnant rats were injected intraperitoneally with MAP (1 mg/kg/day) starting at day 0 of gestation and ending at day 21. There was a significant increase in alpha-MHC mRNA expression in the neonatal ventricular muscle in the experimental group compared with the control at postnatal day (P) 0 and 5. alpha-MHC mRNA expression in both groups was similar after P9. beta-MHC mRNA expression was similar in both groups at P0. Postnatal beta-MHC mRNA expression decreased rapidly, but significant alteration was not detected. Neonatal rats at P0 exhibited some cardiac changes, including hypertrophy, degeneration, and disarrangement of myofibers, but these lesions disappeared by P14. We conclude that chronic maternal administration of MAP changes the alpha- and beta-MHC mRNA expression pattern in fetal and neonatal hearts, correlating with abnormal development, plasma level of hormones, and myocardial damage. At the same time, it is indicated that neonatal cardiomyocytes have reversibility.

Cocaine produces cardiac hypertrophy by protein kinase C dependent mechanisms

BACKGROUND

Chronic cocaine users can have as much as a 69% increase in left ventricular muscle mass without associated increases in arterial blood pressure, heart rate, renin, aldosterone, or cortisol. We determined whether cocaine directly increases cardiomyocyte protein content and whether protein kinase C is important in this process.

METHODS AND RESULTS

Adult rat cardiomyocytes were isolated and grown in cultures. In Series I experiments, cocaine, 10(-8) to 10(-6) M, or vehicle, in the absence or presence of phentolamine or metoprolol, was added to each culture and the cells were subsequently harvested. In Series II, cocaine, 10(-6) M, cocaine, 10(-6) M, plus bisindolylmaleimide, 10(-6) M, a protein kinase C inhibitor, or vehicle were added to each culture and the cells subsequently harvested. We determined the total protein content, the content of alpha-myosin and fetal beta-myosin heavy-chain protein, and the presence of protein kinase C isoforms in the cardiomyocyte soluble and particulate fractions. Protein kinase C translocation from the soluble to particulate fraction is indicative of activation. In Series III, we determined the cocaine effects on ERK, SAPK/JNK, and p38. In Series I, cocaine, 10(-8) to 10(-6) M, dose-dependently increased myocyte protein content by as much as 28%+/-2% (P<.001) and fetal beta-myosin heavy-chain protein content by 80%+/-2% (P<.001). Neither phentolamine nor metoprolol inhibited this process. In Series II, we determined that ventricular myocytes contain alpha (alpha), beta (beta), delta (delta), epsilon (epsilon), and zeta (zeta) protein kinase C isoforms. Cocaine, 10(-6) M, caused a 45+/-5% increase (P<.001) in protein kinase Calpha in the particulate fraction. The addition of a protein kinase C inhibitor to the myocyte cultures prevented the cocaine-induced translocation of protein kinase Calpha and limited the increase in beta-myosin heavy-chain protein content by >75% (P<.001). However, cocaine did not increase the phosphorylation of ERK, SAPK/JNK or p38 in Series III.

CONCLUSIONS

Cocaine increases adult cardiomyocyte protein content by protein kinase Calpha-dependent mechanisms, and this process can contribute to the cardiac hypertrophy and cardiomyopathy that results from chronic cocaine use.

Cardiovascular manifestations of substance abuse part 1: cocaine

Substance abuse with cocaine is associated with multiple cardiovascular conditions, including myocardial infarction, dissection, left ventricular hypertrophy, arrhythmias, sudden death, and cardiomyopathy. Cocaine has effects to potentiate the physiologic actions of catecholamines and has direct effects on voltage-dependent sodium ion channels related to local anesthetic properties. The effects of cocaine can be augmented with concomitant alcohol consumption. Acute myocardial ischemia caused by cocaine may be related to in situ thromboisis and/or coronary vasospasm. Treatment strategies for cocaine-induced myocardial infarction would include antiplatelet therapy, thrombolysis, and vasodilators (eg, nitrates, nifedipine). Beta-adrenergic blockers should not be used unless concomitant vasodilator therapy is given.