Cardiovascular system caffeine, effects

Some effects of caffeine on the cardiovascular system may be related to modification of the Ca2+ content of the cells or its distribution within the cell. 

Methylxanthines have a number of other effects, including effects on smooth muscles and the cardiovascular system. The most notable effect on smooth muscles is relaxing the bronchi of the lungs. Theophylline is prescribed to treat mild forms of asthma. While both caffeine and theophylline will relax the bronchial smooth muscles, theophylline is used therapeutically because of its longer half-life. This allows the drug to stay in the therapeutic range longer. 

Ephedra (ma huang) is a popular botanical incorporated into a variety of formulations for weight loss, energy or performance enhancement, and symptomatic control of asthma. A pharmacodynamic interaction leading to a fatality has been reported with concurrent use of caffeine and ephedra (62), possibly as a result of additive adrenergic agonist effect of the ephedrine alkaloids and caffeine on the cardiovascular system and the CNS (63). Ephedra was recently withdrawn from the market (64). 

Cardiovascular system. Both caffeine and theophylline directly stimulate the myocardium and cause increased cardiac output, tachycardia and sometimes ectopic beats and palpitations. This effect occurs almost at once after i.v. injection and lasts half an hour. Theophylline contributes usefuUy to the relief of acute left ventricular failure. There is peripheral (but not cerebral) vasodilatation due to a direct action of the drugs on the blood vessels, but stimulation of the vasomotor centre tends to counter this. Changes in the blood pressure are therefore somewhat unpredictable, but caffeine 250 mg (single dose) usually causes a transient rise of blood pressure of about 14/10 mmHg in occasional coffee drinkers (but has no additional effect in habitual drinkers) this effect can be used advantageously in patients with autonomic nervous system failure who experience postprandial hypotension (2 cups of coffee with breakfast may suffice for the day). In occasional coffee drinkers 2 cups of coffee (about 160 mg caffeine) per day raise blood pressure by 5/4 mmHg. Increased coronary artery blood flow may occur but increased cardiac work counterbalances this in angina pectoris. 

Caffeine can have profound effects on the cardiovascular system. At least four mechanisms have been proposed for the pro-arrhythmic potential of caffeine in overdose. First, caffeine increases circulating catecholamines. Second, caffeine inhibits phosphodiesterase. Increased circulating catecholamines after caffeine overdose increase jSl-receptor stimulation. Stimulation of jSl-receptors increases intracellular cAMP by G protein stimulation of adenylate cyclase. The activity of cAMP is prolonged due to its decreased metabolism as phosphodiesterase is inhibited by caffeine. Subsequently, jSl-receptor effects are exaggerated and tachydysrhythmias are induced. Third, caffeine increases myocardial intracellular calcium. Caffeine both induces release of calcium... 

Precautions An alkoloid (group of nitrogenous organic compounds, mostly used as pain relievers such as cocaine, quinine, caffeine) from tobacco. A deadly human poison. A human teratogen (abnormal fetal development) by swallowing, causes developmental abnormalities of the cardiovascular system. Causes blood pressure effects. Can be absorbed by intact skin. 

Death from SNA Intoxication appears to Involve both cardiovascular and respiratory systems. 2 SNA Increases the effects of pentobarbital on both respiration and heart rate. The depressant effects of SNA on the myocardium and on the Purklnje system are antagonized effectively by epinephrine, but not by Metrazol (pentylenetetrazol) and caffeine. Artificial respiration restored cardiac stability and regularity. It was suggested that SNA Interferes with oxygen utilization In animals. The circulatory and respiratory responses to SNA were considered to be mediated through the medulla oblongata. 2... 

In addition to being a stimulant, caffeine also has many effects outside of the nervous system. Caffeine is a cardiovascular stimulant, causing the heart rate to increase while constricting blood vessels, both of which can cause increases in blood pressure. Caffeine is also a diuretic (i.e., it increases urination), so it can sometimes cause dehydration and low calcium levels. If taken during pregnancy, the amount of caffeine should be limited to 300 mg per day, as birth problems have been reported in pregnant women who consume more than this amount. 

Ephedra supplements typically contain caffeine, and users may consume caffeine in carbonated beverages, coffee, or tea. Researchers suspect that caffeine may enhance ephedra s stimulant effects on cardiovascular and/or central nervous system responses. This may account for the types of adverse events that have been reported by ephedra users. 

Uncertain. Simple additive hypertensive effects would seem to be part of the explanation. The effects of caffeine may compound the effects of these sympathomimetic drugs on the cardiovascular and central nervous systems by blocking adenosine receptors (causing vasoconstriction) and also augmenting the release of catecholamines. ... 

Documented effects The biological activity is due to the presence of saponins, and removal of the saponins from the tincture leads to complete loss of the pharmacological properties (Ivanova 1963). The sedative effect of this species is nearly twice as strong as that of Valeriana (Tolmachev 1976). The roots of this species reduce excitability of the nervous system. Clinical tests showed that application of an alcohol infusion stopped or noticeably reduced chest pain as well as nervous and cardiovascular excitation caused by hypodermic introduction of caffeine (Akopov 1990). 

These three alkaloids are well-known compounds, as they are present in everyday foods and beverages, such as cocoa, drinking chocolate, tea, and cola, as well as in pharmaceutical products. In cocoa products, theobromine is the major alkaloid, followed by caffeine, which is found in small quantities. Slight traces of theophylline have been identified therefore, it is not considered relevant and is not reviewed in the cocoa products [22,23], The range of methylxanthines also depends on variables such as the origin of the cocoa beans, the fermentation process, and the cocoa production process. Thus, for instance, defatted cocoa beans may contain about 4% and 0.2% of theobromine and caffeine, respectively [24], Regarding their physiological effects in humans, methylxanthines have been related to various body systems, mainly the central nervous system, but also the cardiovascular, renal, and respiratory systems [25,26],... 

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