Fig. 4: Effects of DR-Ab on glutamate-induced intracellular calcium increase and NKA and NCX activities in primary cultured neurons.

a Pretreatment with DR-Ab for 1 h accelerated the extrusion of glutamate-induced increase in intracellular Ca²⁺ from neurons. b DR-Ab significantly reduced the decay time (T90, 90% of calcium level returned to baseline). Cells were treated with glutamate (100 µM) + glycine (10 µM) for 30 s followed by wash-out, n = 8 for NS + Glu group, n = 6 for DR + Glu group. Unpaired t test, two-tailed, ***p < 0.001. c Representative confocal microscopy images showing DR-Ab decreased intracellular calcium level in neurons treated with DR-Ab + glutamate. Blockade of NCX with KB-R7943 abolished the effect of DR-Ab. DR: DR-Ab; Glu: glutamate (100 µM) + glycine (10 μΜ) for 30 s; NS: IgG purified from normal rat serum. d DR-Ab stimulated NKA activity, n = 10/group. Unpaired t test, two-tailed, ***p < 0.001. e Typical membrane currents (lower panel) recorded from a neuron elicited by the ramp protocol (upper panel) in the presence of 5 mmol/L Ni²⁺. f Representative NCX currents recorded at different membrane potential in both NS (left panel) and DR-Ab (right panel) treatment groups. g Current–voltage (I–V) relation curve plotted from the currents recorded in both NS (n = 19) and DR-Ab treatment (n = 19) groups. h Statistic analysis showing that the effect of DR-Ab on NCX currents in both reverse and forward (outward) modes of operation, n = 19/group. Unpaired t test, two-tailed, *p < 0.05, ***p < 0.001. DR: DR-Ab; NS: IgG purified from normal rat serum