Extracellular nucleotides (eNTP) occur outside the cytoplasm in the extracellular matrix, were discovered almost 100 years ago in animal cells. These studies showed that the nucleotides are not only building a strand of DNA/RNA or constitute reservoir of energy (eg ATP or GTP) for various biochemical processes, but also may play role in cell growth and development. Extracellular nucleotides are also involved in maintaining homeostasis in the whole animal organism by maintaining adequate blood pressure and immune response.