Caffeine is one of the most widely used tools to investigate RyR-mediated Ca2+ signaling. It has been used as a pharmacological probe for studying ryanodine receptor (RyR)-mediated Ca2+ release and cardiac arrhythmias.

A central nervous system stimulant believed to act through adenosine receptors and monoamine neurotransmitters. It is an adenosine receptor antagonist and adenosine 3′,5′-cyclic monophosphate (cAMP) phosphodiesterase inhibitor. Levels of cAMP increase in cells following treatment with caffeine.