PHOSPHATIDYLSERINE VESICLES INCREASE CA-2+ UPTAKE BY RAT-BRAIN SYNAPTOSOMES

Phosphatidylserine (PS) vesicles incorporated into rat brain synaptosomes increased total Ca2+ uptake. Total Ca2+ uptake was resolved in three components: K+ depolarization-induced Ca2+ uptake, Na+ Ca2+ exchange, and passive Ca2+ entry, which were differently affected by PS depending on the amount of incorporated phospholipid. K+ depolarization-induced Ca2+ uptake was stimulated by 0.05-0.10 μmol PS/mg protein while 0.10-0.30 μmol PS/mg protein increased Na+ Ca2+ exchange activity and passive Ca2+ entry but not K+ depolarization-induced Ca2+ uptake. High amounts of incorporated PS also increased passive Rb+ uptake. © 1991.