Vasodilation caffeine, effect

Headaches Arising from Contact with NG or Dynamites. Test exposure (oral and skin contact) to a 20% NG Dynamite produced severe headaches, nausea and vomiting. These effects are ascribed to intracranial vasodilation produced by the NG vapors or liquid. Headaches were alleviated by intramuscular injection of caffeine-Na-benzoate followed by oral administration of... 

Caffeine is the most widely used of all the stimulants. Small doses of this chemical (50 to 200 mg) can increase alertness and reduce drowsiness and fatigue. The No-Doz tablet lists caffeine as the main ingredient. In addition, it affects blood circulation since the heart is stimulated and blood vessels are relaxed (vasodilation). It also acts as a diuretic. There are side effects. Large doses of over 200 mg can result in insomnia, restlessness, headaches, and muscle tremors ( coffee nerves ). Continued, heavy use may bring on physical dependence. (How many of you know somebody who cannot function in the morning until they have that first cup of coffee )... 

The major bases found in nucleic acids are adenine and guanine (purines) and uracil, cytosine, and thymine (pyrimidines). Thymine is found primarily in DNA, uracil in RNA, and the others in both DNA and RNA. Their structures, along with their chemical parent compounds, purine and pyrimidine, are shown in Figure 10.1, which also indicates other biologically important purines that are not components of nucleic acids. Hypoxanthine, orotic acid, and xanthine are biosynthetic and/or degradation intermediates of purine and pyrimidine bases, whereas xanthine derivatives—caffeine, theophylline, and theobromine—are alkaloids from plant sources. Caffeine is a component of coffee beans and tea, and its effects on metabolism are mentioned in Chapter 16. Theophylline is found in tea and is used therapeutically in asthma, because it is a smooth muscle relaxant. Theobromine is found in chocolate. It is a diuretic, heart stimulant, and vasodilator. 

The hypotension that has been noted with overdoses of caffeine is primarily due to two mechanisms. First, caffeine-induced tachydysrhythmias lead to inadequate filling of the heart and subsequent decrease in cardiac output. Second, caffeine augments S2-effects and causes subsequent vasodilation with resulting hypotension. 

The drug pentoxifylline, a 2-hexanoyl analog of such xanthines as theophylline and caffeine, has the ability to lower blood viscosity by increasing the flexibility of red blood cell membranes in patients. This is most probably due to PDE inhibition, which increases c-AMP levels. Unlike the vasodilators considered earlier, pentoxifylline is effective in claudication. 

It appears that xanthine derivatives such as caffeine and theophylline might antagonise some of the haemodynamic effects of dipyridamole because they act as competitive antagonists of adenosine (an endogenous vasodilator involved in the action of dipyridamole). Due to these opposing effects, parenteral aminophylline has been used to treat adverse events associated with intravenous dipyridamole, - and it is recommended that aminophylline should be made available before beginning dipyridamole echocardiography. ... 

Xanthine bases or purine alkaloids are secondary metabolites, derivatives of xanthine caffeine, theophylline and theobromine are three very well-known examples. These compounds occur naturally in the seeds of coffee, cola, guarana and cacao, as well as in the leaves of tea and mate (Council of Europe, 1989 Zheng et al 2004). These compounds improve and stimulate blood circulation, an action that justifies the use of these vegetable compounds in anti-cellulite cosmetic formulations (Bertin et al 2001). Such an effect is the consequence of their adenosine-antagonist action, which influences the )S-adrenergic system by stimulating the vasodilator response. Additionally, xanthine bases specifically... 

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