Table 1.

Relevant functional parameters of adenosine receptors

	A1	A2A	A2B	A3
Coupled G proteins	Gi, Go	Gs, Golf, G15/16	Gs, Gq	Gi, Gq
Intracellular messengers	↓ cAMP	↑ cAMP	↑ cAMP	↓ cAMP
	↑ IP3/DAG	↑ IP3	↑ IP3/DAG	↑ IP3/DAG
	↑ Arachidonate
	↑ PEtOH
Selected biologic functions	Bradycardia Antinociception Ischemic preconditioning ↓ Lipolysis, ↓ Glomerular filtration	↓ Platelet aggregation Vasodilation Protection against ischemic damage	Relaxation of vascular smooth muscle cells Stimulation of mast cell mediator release	↑ Mediator release from mast cells (mice) Preconditioning
Potencya (EC50 [μmol/l])	0.31	0.73	23.5	0.29

^aPotency as reflected by intracellular cAMP levels. Adapted from [8,9,18,55]. DAG, diacylglycerol; ED₅₀, 50% effective dose; IP₃, inositoltriphosphate; PetOH, phosphatidylethanol.