Abstract
Myotonia induced in rats by 20,25-diazacholesterol is accompanied by accumulation of desmosterol in serum, fragmented sarcoplasmic reticulum, and sarcolemma. Activities of (Na+,K+)- and Ca2+-stimulated adenosine triphosphatases of the sarcolemma are increased, but not the Mg2+-stimulated adenosine triphosphatase. The altered sterol composition of the sarcolemma may cause this type of myotonia by decreasing the chloride conductance of the membrane.