Medicine and Pharmacology2 - Essay Example

here is also evidence showing that ATP is a cotransmitter with norepinephrine, where ATP may be a cotransmitter with acetylcholine (ACh) in certain postganglionic parasympathetic nerves (Brake and Julius, 1996). The purinergic receptors are found on the cell surface. These may be divided into the adenosine (P1) receptors and the receptors for ATP (P2X and P2Y receptors). P1 and P2 receptors have been known to have various subtypes. There are four adenosine receptors, namely A1, A2A, A2B, and A3 and multiple subtypes of P2X and P2Y receptors throughout the body.

It has been suggested that these adenosine receptors and the P2Y receptors act via the G proteins to mediate physiological responses. On the other hand, the P2X receptors act through ion channels that are ligand gated (Burnstock, 2006). Following extensive research, it has now been established that ATP is a cotransmitter with classic transmitters both at in both the peripheral and central nervous systems, and through purinergic systems, purines are also powerful extracellular messengers to nonneuronal cells.

The presence of purinergic signaling system in extraneural tissues such as exocrine, endocrine, secretory, endothelial, musculoskeletal, immune, and inflammatory cellular systems has been established (Burnstock and Knight, 2004). As this indicates, the distribution and functional roles of these P2 receptors have been elucidated further with ongoing research. In short, the purinergic signaling system is a rapid synaptic neurotransmitter system. This is involved in contraction and relaxation of smooth muscle and in exocrine and endocrine secretion.

It has been evident now that purinergic signaling regulates many long-term cellular events in all tissues. These functions include cell proliferation, differentiation, migration, and death in cell development, cellular regeneration, and hence in wound healing. Another area is embryonic development where both P2X and P2Y receptors play prominent roles both