Receptor Cell signalling Cellular localization Physiological function Reference
A1 Low cAMP Central nervous system
Neurons
Astrocyte
Oligodendroglia

Microglia

Inhibition of acetylcholine release
Regulation of growth and development
Control of myelination
Neuronal survival
Microglial proliferation

[113]
[114]
[115]
[116]
[116]
Cardiovascular system
Heart

Endothelial cells

Regulation of Ca2+ and K+M chanels
Protection against ischemia
Synthesis and release of NO
Vasodilation

[117]
[117]
[118,119]
[118,119]
Immune system
Macrophages

Leucocytes
Macrophage activation
Release of cytokines
Promotion of adhesion to endothelial cells
Release of proinflammatory mediators
[120]
[120]
[121]
[121]
Liver Protection against ischemic damage [122]
Adipose tissue Inhibition of lypolisis [123]
Endocrine pancreas Secretion of insulin
Release of glucagon
[124]
[124]
Kidney Urine production
Renal constriction
[125]
[125]
A2A High cAMP Central nervous system
Neurons
Astrocyte
Oligodendroglia
Microglia

Stimulation of acethilcholine release
Regulation og growth and development
Ischaemia  protection
Neuronal survival
Microglial proliferation

[113]
[114]
[126]
[127]
[127]
Cardiovascular system
Endothelial cells
Synthesis ands release of NO Vasodilation [37,128]
[37,128]
Immune system
Macrophages

Leucocytes

Lymphocytes
Macrophage activation
Release of cytokines
Promotion of adhesion to endothelial cells
Release of proinflammatory mediators
Regulation of proliferation
[129]
[129]
[130]
[130]
[131]
Liver Protection  against ischemic damage [132]
Endocrine pancreas Release of glucagon [133]
A2B High cAMP Central nervous system
Astrocyte
Microglia

Regulation og growth and development
Neuronal survival
Microglial proliferation

[114]
[116]
[116]
Cardiovascular system
Endothelial cells
Synthesis ands release of  NO, vasodilation [128]
Immune system
Macrophages
Leucocytes
Lymphocytes
Macrophage activation
Release of cytokines
Promotion of adehesion to endothelial cells
Release of proinflammatory mediators
Lymphocyte activation
[134]
[134]
[135]
[135]
[136]
Liver Gluconeogenesis regulation
Glycogenolysis
[137]
[137]
A3 Low cAMP Central nervous system
Astrocyte
Microglia
Regulation og growth and development
Neuronal survival
Microglial proliferation
[138]
[139]
[139]
Cardiovascular system
Heart
Protection against ischemia [118,140]
Immune system
Macrophages
Leucocytes
Macrophage activation
Release of cytokines
Promotion of  adhesion to endothelial cells
Release of proinflammatory mediators
[141]
[141]
[142]
[142]
cAMP: Cyclic Adenosine Monophosphate; NO: Nitric Oxide
Table 2: Adenosine receptor subtypes and main physiological functions.