Figure 2.

Sensitivity of nicotine-evoked presynaptic Ca²⁺ increases to various nicotinic antagonists and to Aβ for preparations from various regions of the brain. A, Average maximal Ca²⁺ responses to 500 n_M nicotine in hippocampal synaptosomes in the absence (n = 34) or presence of 5 μm dihydro-β-erythroidine (DHβE;n=26), 500nmα-bungarotoxin (BgTx; n= 9), 10 μm mecamylamine (Mec; n = 18), or BgTx plus Mec (n = 11) during the second stimulation, using the successive stimulation protocol described in the legend to Figure 1. B, Inhibitory effects of 100 nm Aβ_1-42 on nicotine-evoked Ca²⁺ responses in synaptosomes from hippocampus (Hippo; n = 17), cortex (CTX; n = 13), or striatum (Str; n = 10). Qualitatively similar results were obtained using 100 pm Aβ_1-42. ^*p < 0.05; t test with paired control.