Figure 3.

Sample records of electrophysiological responses to OA and 5-HT in the sensory neurons expressing GFP (B1, C1, D1) or GFP plus Ap oa₁ (B2, C2, C3, D2, D3). Resting potential (B1, B2), membrane excitability (C1–C3), and spike duration (D1–D3) were measured before (Control) and after drug applications. The cells B1, C1, and D1 were injected with pNEXδ-GFP, and the cells B2, C2, C3, D2, and D3 were injected with both pNEXδ-GFP and pNEXδ-Ap oa₁. All these cells were GFP-positive. (A) Light (Left) and fluorescent (Right) photographs showing an example of GFP/Ap oa₁-positive sensory neurons in a pleural ganglion. The cell bodies of these neurons are shown around the center of the fluorescent photograph. Bar = 250 μm. (B) Membrane depolarization by OA and 5-HT in a GFP-expressing cell (B1) and in a GFP/Ap oa₁-expressing cell (B2). (C) Action potentials were recorded by injecting a depolarizing current (0.1–0.3 nA) for 500 ms. Membrane excitability was enhanced by 5-HT in a GFP-expressing cell (C1) and by OA and 5-HT in GFP/Ap oa₁-expressing cells (C2, C3). (D) Superimposed action potentials demonstrating increases in spike duration after treatments with OA and 5-HT. Spike broadening by treatment with 5-HT in a GFP-expressing cell (D1) and with 5-HT and OA in GFP/Ap oa₁-expressing cells (D2, D3). The shapes of single spikes were recorded by delivering a 0.4-nA current pulse for 15 ms. OA + 5-HT, 5-HT was applied later in the presence of OA (C1, C2, D1, D2). 5-HT + OA, OA was applied later in the presence of 5-HT (C3, D3).