Figure 4.

Effects of inhibitors of nicotinic acetylcholine receptor subunits on nicotine-evoked secretion. The I_sc induced by nicotine (10⁻⁴ mol/L, applied in the presence of tetrodotoxin) across colonic mucosa preparations was tested either under control conditions (open bars) or in the presence of different inhibitors of nicotinic acetylcholine receptor subunits (solid bars). Inhibitors: dihydro-β-erythroidine (DhβE; 10⁻⁵ mol/L), α-bungarotoxin (10⁻⁶ mol/L), strychnine (10⁻⁵ mol/L), or (a high concentration of) atropine (2.5 × 10⁻⁵ mol/L). Values are given as increase in I_sc (ΔI_sc) above baseline just prior administration of nicotine and are means ± SEM; n = 5–6. *P < 0.05 vs. response evoked by nicotine in the respective control series.