SERUM FRACTIONS FROM AMYOTROPHIC-LATERAL-SCLEROSIS PATIENTS DEPRESS VOLTAGE-ACTIVATED CA2+ CURRENTS OF RAT CEREBELLAR GRANULE CELLS IN CULTURE

Whole-cell patch clamp recording from rat cerebellar granule cells in culture was used to study the effect of immune protein fractions extra cted from the serum of amyotrophic lateral sclerosis (ALS) patients on voltage-activated Ca2+ currents. The inward currents, carried by Ba2, were induced by depolarizing step commands positive to -50 mV and sh owed typical voltage-dependent inactivation. Application of immunoprot ein fractions obtained from the serum of ALS patients produced a stron g depression of the inward current amplitude without changing its thre shold potential at which the maximum was attained, or its time course. These data support the hypothesis that the serum of ALS patients cont ains an immunoprotein capable of interacting with high threshold Ca2channels of central neurones.