Methyl xanthines acts on
(Adenosine receptors) (202-3-KDT) (220-KDT 6th)Mechanism of action of Methylxanthines - Three distinct cellular actions(a) Release of Ca++ from sarcoplasmic reticulum especially in skeletal and cardiac muscle.(b) Inhibition of phosphodiesterase which degrades cyclic nucleotides intracellularly.ATPorGTPAdenylcyclase------------guanylcyclasecAMPorcGMPPhosphodiesterase--------------------Inhibited by Theophylline5 AMPor5 GMP(c) ** Blockade of adenosine receptors: adenosine acts as a local mediator in CNS, CVS and other organs- contracts smooth muscles, especially bronchial, dilates cerebral blood vessels, depresses cardiac pacemaker and inhibits gastric secretion. Methylxanthines produces opposite effects.
Asthma
Histamine receptors
Adenosine receptors
Mast cells
Cholinergic receptors
Adenosine receptors