Alkylxanthines as research tools

(1) The methylxanthine caffeine has many pharmacological effects, most of w hich can be Linked to blockade of adenosine receptors, inhibition of phosph odiesterases, and augmentation of calcium-dependent release of calcium from intracellular stores. (2) A variety of xanthines have been developed as po tent and/or selective antagonists for adenosine receptors. (3) Several xant hines have been developed that are more potent and more selective inhibitor s of cyclic nucleotide phosphodiesterase than caffeine or theophylline. (4) Caffeine remains the xanthine of choice for activation of intracellular ca lcium-sensitive calcium release channels although millimolar concentrations are required, which can have effects on other aspects of calcium regulatio n. (C) 2000 Elsevier Science BN. All rights reserved.