Expression of two ATP-gated ion channels, P2X(5) and P2X(6) in developing chick skeletal muscle

Physiological and pharmacological studies have shown that ATP has potent ef fects on developing chick skeletal muscle. These effects have previously be en shown to be developmentally regulated, and the responses were characteri stic of activation of the P2X ligand-gated ion-channel family of ATP recept ors. Here, using immunohistochemistry, we describe the expression patterns of two members of the P2X receptor family, P2X(5) and P2X(6), during develo pment of skeletal muscle in the chick embryo. These receptors were first ex pressed at early stages of skeletal muscle development, and expression disa ppeared immediately before the stage at which fusion of myoblasts to form m yotubes occurs. P2X(5) was also demonstrated in nerves supplying developing skeletal muscle, in some dorsal root ganglion cells, and in dorsal and ven tral spinal cord. No expression of the other five members of the P2X family were demonstrated in developing skeletal muscle. (C) 1999 Wiley-Liss, Inc.