Diacylglycerol Signaling Underlies Astrocytic ATP Release
PKC activation is not necessary for OAG-induced release of ATP from astrocytes. (a) Adding 1 μM GF 109203X (GFX) during the second imaging period does not reduce calcium oscillations (, control , GFX ) in response to 100 μM OAG. Pretreating astrocytes with 1 μM GFX and including GFX during and does not reduce calcium oscillations induced by 100 μM OAG (, control , GFX = 5), although there is a significant () increase in calcium oscillations after washout in this GFX condition. The serine/threonine kinase inhibitor staurosporine does not have an effect on calcium oscillations induced by 100 μM OAG when added during (, control , staurosporine ). (b) Astrocytes display robust OAG-induced calcium oscillations in nominally calcium-free external solution. (c) Incubation with 100 nM Calphostin C during a 15-minute light activation period followed by incubation during abolished calcium oscillation and induced a slow increase in Fluo4 signal during the OAG incubation. (d) The slow increase in Fluo4 signal is abolished in the absence of external calcium and oscillations are absent in the presence of 100 nM Calphostin C and 30 μM OAG. (e) Calcium oscillations in nominally calcium-free medium induced by 30 μM OAG are significantly reduced by the addition of 100 nM Calphostin C (, control , calphostin C ). As calphostin C is irreversible, there is no washout period () for (e).
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