Fig. 6.

Regulation of NMDA receptor activity during anoxia by Ca²⁺-dependent processes. A, Inhibition of the Ca²⁺ binding protein calmodulin reduced NMDA receptor silencing during anoxia. Cortical sheets were treated with 10 nm calmidazolium 30 min before and during 2 hr anoxia or with O₂ present. NMDA Δ Ca²⁺ was then measured. B, The calcineurin inhibitor cypermethrin, at two concentrations, did not prevent NMDA receptor silencing during anoxia. C, Effects of increasing PKA activity with forskolin or inhibiting it with H8 on NMDA receptor activity during normoxia or anoxia. Test compounds were present during the 2 hr period before assay of receptor activity. For all graphs, bars show means ± SEM, and numbersare number of observations; and *p < 0.05 denotes significant difference compared with control condition within each group (ANOVA).