Purinergic receptors in skeletal muscles in health and in muscular dystrophy.

T he P2 purinergic (nucleotide) receptor super-family comprises of two families of protein. The P2X, which are channel-forming ionotropic receptors and the P2Y metabotropic re- ceptors activating G protein-mediated signalling pathways. Members of both groups have been identified in skeletal muscle cells at different stages of differentiation. It is well docu - mented that sequential expression and down-regulation of particular P2 receptors on the surface of sarcolemma is closely associated with muscle maturation during embryogenesis and postnatal growth. P2 receptors are also involved in muscle regeneration following in- jury. Moreover, enhanced expression of specific purinergic receptors together with increased availability of extracellular ATP in dystrophic muscles are important elements of the dys- trophic pathophysiology considerably increasing severity.