Calcium regulates the mode of exocytosis induced by hypotonic shock in isolated neuronal presynaptic endings.

A decrease in the osmolarity of incubation medium is accompanied by calcium influx in neuronal presynaptic endings. We studied the influence of Ca2+ on exocytosis induced by hypotonic shock using the hydrophilic fluorescent dye acridine orange and the hydrophobic fluorescent dye FM2-10. It was shown using acridine orange that lowering of osmolarity to 230 mOsm/l induces exocytosis both in calcium-containing and calcium-free medium.

Characteristics of the hypoosmosis-induced calcium response in isolated nerve terminals of rat brain.

Background: Cerebral edema contributes significantly to morbidity and death in many common neurological disorders. Ca2+ ions play a important role in the development of pathophysiological reactions in nerve cells. The aim of our research was to elucidate the mechanism of the osmotically-induced entrance of Ca2+ into nerve terminals (synaptosomes) and to estimate the involvement of endoplasmic reticulum Ca2+ stores in intrasynaptosomal Ca2+-dependent processes in hypoosmotic swelling.