What resolves this contention: Disagreement on the Ca2+-dependence and physiolo…

What resolves this contention: Disagreement on the Ca2+-dependence and physiological relevance of gliotransmitter release — whether endogenous stimuli can evoke release or only non-physiological calcium loads can. / Physiological Ca2+ elevations in astrocytes (via Ca2+ clamp / receptor-mediated signalling) trigger D-serine release required for LTP / Only artificial photolysis of caged Ca2+ — not receptor-mediated Ca2+ signalling — triggers measurable astrocytic glutamate release, implying that physiological Ca2+ transients are insufficient