Skeletal muscle xanthine effects

Mechanism of Action A xanthine derivative that acts as a bronchodilator by directly relaxing smooth muscle of the bronchial airway and pulmonary blood vessels similar to theophylline. Therapeutic Effect Relieves bronchospasm, increases vital capacity, produces cardiac, and skeletal muscle stimulation. 

Xanthine derivatives have a number of pharmacological properties in common. Five major actions are observed (1) central nervous system and respiratory stimulation, (2) skeletal muscle stimulation, (3) diuresis, (4) cardiac stimulation, and (5) smooth-muscle relaxation. Caffeine (29) increases central nervous system activity and its main effect is on the cerebral cortex, where it acts to produce clear thought and reduce drowsiness and fatigue. The normal dose is 100-200 mg (Cordell, 1981). The oral LD50 in mouse is 127-137 mg/kg the oral LD50 in rat for theobromine (31) is 950... 

The phosphodiesterase which cleaves cyclic AMP to adenylate is found in both particulate and soluble fractions of tissue homogenates, and it is inhibited by pyrophosphate and ATP, as well as by caffeine, theophylline, and theobromine. These three methylated xanthines cause central nervous system and respiratory stimulation, smooth muscle relaxation, diuresis, coronary dilatation, cardiac stimulation, and skeletal muscle stimulation these effects are believed to be due to increased tissue concentrations of cyclic AMP resulting from inhibition of phosphodiesterase activity. 

Caffeine belongs to a family of naturally occurring compoimds called xanthines. The xanthines, in the form of their plant progenitors, are possibly the oldest known stimulants. They all, to varying extents, stimulate the central nervous system and the skeletal muscles. This stimulation results in an increased alertness, the ability to put off sleep, and an increased capacity for thinking. Caffeine is the most powerful xanthine in this respect. It is the main ingredient of the popular No-Doz keep-alert tablets. Although caffeine has a powerful effect on the central nervous system, not all xanthines are as effective. Thus, theobromine, the xanthine found in cocoa, has fewer central... 

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