CALCIUM-PERMEABLE ION CHANNELS IN CEREBELLAR NEURONS FROM MDX MICE

Recordings of single-channel activity were made from cell-attached patches on cerebellar granule cells from normal and mdx mice. Recordings from mdx granule cells show the activity of ion channels that are open for seconds at negative holding potentials near rest. These channels are permeable to divalent cations and have a conductance of 8-10 pS with either Ca2+ or Ba2+ as the charge carrier in the patch electrode. Under similar recording conditions, channel activity is virtually absent from normal mouse granule cells. The absence of dystrophin in neurons, as well as in skeletal muscle, is associated with an increase in the activity of Ca2+- permeable ion channels. Increased channel activity may be an early event leading to pathophysiological accumulation of intracellular Ca2+ in Duchenne muscular dystrophy.