Cg. Carlson, ACETYLCHOLINE-RECEPTOR AND CALCIUM LEAKAGE ACTIVITY IN NONDYSTROPHIC AND DYSTROPHIC MYOTUBES (MDX), Muscle & nerve, 19(10), 1996, pp. 1258-1267
To determine whether the lack of dystrophin alters the occurrence of c
alcium leakage activity (CLA) and acetylcholine receptor (AChR) activi
ty, the frequency of each event class was determined from several cell
attached patches on nondystrophic and dystrophic (mdx) myotubes, The
frequency of CLA observed in the presence of ACh was significantly (P
< 0.05) elevated in mdx myotubes, an effect which was partly due to a
significant (P < 0.05) increase in the proportion of cell attached pat
ches that exhibited 100% CLA with no AChR activity. Areas of mdx and n
ondystrophic membrane that exhibited reduced or absent AChR activity h
ad significantly (P < 0.01) and substantially elevated calcium leakage
event frequencies. This inverse and discontinuous relationship betwee
n CLA and AChR activity provides further evidence that some CLA in dys
trophic muscle is produced by clusters of AChRs that form unusual phys
ical associations with the dystrophic cytoskeleton during the processe
s associated with receptor localization and stabilization. (C) 1996 Jo
hn Wiley & Sons, Inc.