AMYOTROPHIC-LATERAL-SCLEROSIS - SERUM FACTORS ENHANCE SPONTANEOUS ANDEVOKED TRANSMITTER RELEASE AT THE NEUROMUSCULAR-JUNCTION

Sera from 30 patients with sporadic amyotrophic lateral sclerosis (ALS ) were tested to determine their effects at the neuromuscular junction . Spontaneous transmitter release was significantly increased, as evid enced by a 151% increase in MEPP frequency, by sera from 16 ALS patien ts. In addition, 16 patients' sera elevated EEP quantal content by an average of 89%. Eleven sera produced both effects. There was no consis tent change in MEPP amplitude or time course, indicating the absence o f a humoral effect on postjunctional ACh receptors or endplate membran e function. These results suggest that a portion of the sporadic ALS p atient population possess serum factors that can alter presynaptic fun ction of the motor nerve terminal. Evidence from the present experimen ts indicates that alterations at the neuromuscular junction are a resu lt of a combination of increased Ca2+ influx into the cell and an inde pendent increase in intracellular calcium concentration. (C) 1998 John Wiley & Sons, Inc.