Combined effects of cocaine and nicotine on cardiovascular performance in a canine model

E-cigarettes may serve as a gateway to conventional cigarettes and other addictive drugs

Electronic cigarettes (e-cigarettes) are devices that allow the user to inhale nicotine in a vapor, and are primarily marketed as a means of quitting smoking and a less harmful replacement for traditional cigarette smoking. However, further research is needed to determine if vaping nicotine via e-cigarettes can be effective. Conversely, nicotine has been considered a gateway drug to alcohol and other addictive drugs and e-cigarettes containing nicotine may have the same effects. Previous reports have shown that e-cigarette use may open the gate for the use of other drugs including conventional cigarettes, cannabis, opioids, etc. The increasing prevalence of e-cigarettes, particularly among youth and adolescents in the last decade have led to an increase in the dual use of e-cigarettes with alcohol, cannabis, and other illicit drug use like heroin and 3-4-methylenedioxymethamphetamine (MDMA). The advent of e-cigarettes as a device to self-administer addictive agents such as cocaine and synthetic cathinones may bring about additional adverse health effects associated with their concurrent use. This review aims to briefly describe e-cigarettes and their different generations, and their co-use with other addictive drugs as well as the use of the device as a tool to self-administer addictive drugs, such as cocaine, etc.

An error in interpretation and real extraordinary electrocardiographic changes in patient with acute traumatic spondylolisthesis

Background

Acute cervical spinal trauma may lead to cardiac effects by influencing cardiac sympathetic preganglionic fibers. Some of these effects, which are vital, may occur in ECG.

Case presentation

A 52-year-old female patient admitted to the emergency department with acute traumatic spondylolisthesis at C6-C7 level and paraplegia. Positive QRS complex, ST segment depressions and prolongation of QTc interval were observed on ECG according to sudden autonomic disruption because of sympathetic nerve compression. It was mentioned that changes in QRS complex axis was normal which was dependent to the ECG display format of Cabrera sequence used differently from the classical system. After surgical correction, evident ST depressions were recovered and QTc intervalwas narrowed but still prolonged in control ECG.

Conclusions

Autonomic dysfunction can lead to extraordinary electrocardiographic presentation including widespread ST depressions with prolonged QTc interval. However, when evaluating the changes in the ECG, attention should be paid to ECG display format to avoid errors in interpretation.

Smokeless tobacco, sport and the heart

Smokeless tobacco (snuff) is a finely ground or shredded tobacco that is sniffed through the nose or placed between the cheek and gum. Chewing tobacco is used by putting a wad of tobacco inside the cheek. Smokeless tobacco is widely used by young athletes to enhance performance because nicotine improves some aspects of physiology. However, smokeless tobacco has harmful health effects, including cardiovascular disorders, linked to nicotine physiological effects, mainly through catecholamine release. Nicotine decreases heart rate variability and the ventricular fibrillation threshold, and promotes the occurrence of various arrhythmias; it also impairs endothelial-dependent vasodilation and could therefore promote premature atherogenesis. At rest, heart rate, blood pressure, inotropism, cardiac output and myocardial oxygen consumption are increased by nicotine, leading to an imbalance between myocardial oxygen demand and supply. The same occurs at submaximal levels of exercise. These increases are accompanied by a rise in systemic resistances. At maximal exercise, heart rate, cardiac output and maximal oxygen uptake (V˙O2max) are unaffected by nicotine. Because endothelial dysfunction is promoted by nicotine, paradoxical coronary vasoconstriction may occur during exercise and recovery. Nicotine induces a decrease in muscular strength and impairs anaerobic performance. However, nicotine is used in sports as it diminishes anxiety, enhances concentration and agility, improves aerobic performance and favours weight control. Importantly, smokeless tobacco, similar to cigarette smoking, leads to nicotine dependence through dopaminergic pathways. Smokeless tobacco has harmful cardiovascular effects and is addictive: it fulfils all the criteria for inclusion in the World Anti-Doping Agency prohibited list as a doping product. Smokeless tobacco use in sporting activities must be discouraged.

Effects of nicotine administration in a mouse model of familial hypertrophic cardiomyopathy, α-tropomyosin D175N

The effects of nicotine (NIC) on normal hearts are fairly well established, yet its effects on hearts displaying familial hypertrophic cardiomyopathy have not been tested. We studied both the acute and chronic effects of NIC on a transgenic (TG) mouse model of FHC caused by a mutation in α-tropomyosin (Tm; i.e., α-Tm D175N TG, or Tm175). For acute effects, intravenously injected NIC increased heart rate, left ventricular (LV) pressure, and the maximal rate of LV pressure increase (+dP/dt) in non-TG (NTG) and Tm175 mice; however, Tm175 showed a significantly smaller increase in the maximal rate of LV pressure decrease (-dP/dt) compared with NTGs. Western blots revealed phosphorylation of phospholamban Ser16 and Thr17 residue increased in NTG mice following NIC injection but not in Tm175 mice. In contrast, phosphorylation of troponin I at serine residues 23 and 24 increased equally in both NTG and Tm175. Thus the attenuated increase in relaxation in Tm175 mice following acute NIC appears to result primarily from attenuated phospholamban phosphorylation. Chronic NIC administration (equivalent to smoking 2 packs of cigarettes/day for 4 mo) also increased +dP/dt in NTG and Tm175 mice compared with chronic saline. However, chronic NIC had little effect on heart rate, LV pressure, -dP/dt, LV wall and chamber dimensions, or collagen content for either group of mice.

Dynamic relations between right and left atrial pressure shifts induced by catecholamines

Acute experiments on cats showed that injection of catecholamines induced unidirectional shifts in right and left atrial pressure in 70% cases (these shifts were positive in one half of cats and negative in the other half). In 30% cases, the left and right atrial pressures changed in opposite direction: right atrial pressure decreased, while left atrial pressure increased (19%), or vice versa (11%). The pressure changes in the left atrium had greater amplitude and longer duration compared to those in the right atrium.

Effect of binge cocaine treatment on hindlimb vascular function

Chronic cocaine abuse is known to cause endothelial dysfunction and atherosclerosis. The present study investigated the effect of binge cocaine treatment, a model for chronic cocaine abuse, on the blood flow responses to the adrenergic agonists norepinephrine, phenylephrine and isoproterenol, the endothelium-dependent vasodilator acetylcholine, and the endothelium independent vasodilator sodium nitroprusside (SNP) in the hindlimb vascular bed of male Sprague Dawley rats. Rats received either single binge or double binge treatment. Each binge treatment consisted of three doses of cocaine (30 mg kg(-1) i.p.) for 3 days. For double binge treatment, there was a 4 day recovery period between the binges. At the end of the treatment the rats were anesthetized and agonists were administered into the right hindlimb circulation through a catheter in the left iliac artery and blood flow responses were measured with a flow probe around the right iliac artery. Rats receiving double cocaine binges showed a significant decrease in the magnitude and duration of the blood flow response to norepinephrine and a decrease in the duration of the blood flow response to phenylephrine, isoproterenol and acetylcholine when compared with saline controls. The blood flow response to SNP was not changed. Total plasma nitrate-nitrite levels were significantly reduced and big endothelin levels were significantly increased in rats receiving double cocaine binges. This study demonstrates that binge cocaine treatment can alter endothelial function, while not changing smooth muscle function, and impairs the adrenergic pathway.

Effects of cocaine and caffeine alone and in combination on cardiovascular performance

BACKGROUND

With the proliferation of cocaine abuse, increased incidence of catastrophic cardiovascular events like angina pectoris, myocardial infarction, ventricular arrhythmias or sudden death are reported. Cocaine-dependent subjects commonly abuse multiple substances. Many of them drink coffee before and after cocaine use. The high frequency of simultaneous exposure to both the drugs may influence outcome of the cocaine's treatment. Cocaine and caffeine's independent effects on cardiodynamics are documented but to our knowledge combined effects of both on complete cardiovascular hemodynamics remains to be examined.

METHODS

Eighteen dogs were instrumented to pass cardiac catheters into right and left heart. The experiments were performed after they recovered from the effects of anesthesia. In phase I (30 experiments on 8 dogs), the doses were established by dose-response curve. In phases II and III, another 10 dogs were subjected to 28 experiments. They were given i.v. cocaine followed by caffeine and vice versa to study their effects on hemodynamics and coronary flow reserve.

RESULTS

Phase 1: The doses of cocaine (2 mg/kg) and caffeine (5 mg/kg) were established. Phase II: Cocaine increased heart rate, blood pressure and dP/dt but CFR decreased significantly. Caffeine administered after cocaine attenuated these effects (dP/dt decreased to 4910+/-104 from 5066+/-110 mm Hg s; p<NS). Phase III: Caffeine mildly increased hemodynamic parameters but reduced dP/dt. Cocaine's administration as the second drug had synergistic excitatory effects (dP/dt increased to 6166+/-160 from 5055+/-142 mm Hg/s; p<0.04). CFR decreased significantly.

CONCLUSION

Cocaine increased heart rate, blood pressure and dP/dt but reduced CFR. Caffeine mildly increased the hemodynamic variables but decreased CFR. Combined cocaine+caffeine attenuated the excitatory effects of cocaine significantly. A reversed drug combination i.e., caffeine+cocaine generated synergistic excitatory effects on the cardiovascular system of the dogs. CFR showed significant decrease.

Cardiovascular disorders associated with cocaine use: myths and truths

Cocaine produces a pattern of cardiovascular responses that are associated with apparent myocardial ischemia, arrhythmias, and other life-threatening complications in some individuals. Despite recent efforts to better understand the causes of cocaine-induced cardiovascular dysfunction, there remain a number of unanswered questions regarding the specific mechanisms by which cocaine elicits hemodynamic responses. This review will describe the actions of cocaine on the cardiovascular system and the evidence for the mechanisms by which cocaine elicits hemodynamic and pathologic responses in humans and animals. The emphasis will be on experimental data that provide the basis for our understanding of the mechanisms of cardiovascular toxicity associated with cocaine. More importantly, this review will identify several controversies regarding the causes of cocaine-induced cardiovascular toxicity that as yet are still debated. The evidence supporting these findings will be described. Finally, this review will outline the obvious deficits in our current concepts regarding the cardiovascular actions of cocaine in hope of encouraging additional studies on this grave problem in our society.

Effects of cocaine and alcohol alone and in combination on cardiovascular performance in dogs

BACKGROUND

With the proliferation of cocaine abuse, increased incidence of catastrophic cardiovascular events such as angina pectoris, myocardial infarction, ventricular arrhythmias, or sudden death are reported. Many of these patients also drink alcohol before and after cocaine use, leading to a high frequency of simultaneous exposure to both the drugs. Cocaine and ethanol's independent effects on cardiodynamics are well documented, but their combined effects on complete cardiovascular hemodynamics remain unknown. Are effects additive, synergistic, or antagonistic?

METHODS

Sixteen dogs were instrumented to pass cardiac catheters into right and left ventricles. After they recovered from the effects of anesthesia, experiments were performed. In phase I, 18 experiments (6 dogs) established the dose by dose response curve. In phase II and III, another 10 dogs, subjected to 30 experiments, were given i.v. cocaine followed by ethanol and vice versa to study their effects on hemodynamics and coronary flow reserve.

RESULTS

Phase I: doses of cocaine (2 mg/kg) and ethanol (400 mg/kg) were established. Phase II: cocaine increased heart rate, blood pressure and dP/dt but ethanol administered after cocaine attenuated these effects [first derivative of the left ventricular pressure (dP/dt) < 2052 +/- 104 from 2614 +/- 110 mm Hg/sec; P < 0.04)]. Phase III: alcohol mildly increased hemodynamic parameters. Cocaine's administration as the second drug had synergistic excitatory effects (dP/dt > 3300 +/- 160 from 2854 +/- 142 mm Hg/sec; P < 0.004).

CONCLUSION

Cocaine increased heart rate, blood pressure, and dP/dt but reduced CFR. Alcohol mildly increased the hemodynamic variables and CFR. Combined cocaine and alcohol attenuated the excitatory effects of cocaine significantly. A reversed drug combination (ie, alcohol then cocaine) generated synergistic excitatory effects on the cardiovascular system of the dogs.