Fig. 4.

Quantification of effects of pyloric suppressor (PS) stimulation, Crust-MS (Myo) application and histamine (HA) application in control versus histamine receptor antagonist conditions suggested that PS effects in the stomatogastric ganglion (STG) are mediated largely by Crust-MS. (A) In control saline (white bars), histamine, Crust-MS and PS stimulation significantly increased the cycle period of pyloric dilator (PD) bursting compared with the values measured before the treatments; there were no differences between the effects of the three treatments. However, in the presence of histamine receptor antagonists (10⁻⁶ mol l⁻¹ triprolidine/10⁻⁵ mol l⁻¹ ranitidine; striped bars), PD cycle period increased significantly after Crust-MS bath application and PS stimulation, but not after focal histamine application. Different letters indicate significant differences (repeated-measures ANOVA with Tukey's post hoc test, P<0.0001, N=7 preparations). (B) In control saline (white bars), histamine, Crust-MS and PS stimulation significantly increased burst duration when compared with values measured before treatment; effects of the three treatments did not differ significantly. In the presence of histamine receptor antagonists (striped bars), pyloric (PY) burst duration increased significantly immediately after both Crust-MS bath application and PS stimulation, but not after focal histamine application. Different letters indicate significant differences (repeated-measures ANOVA with Tukey's post hoc test, P<0.0001, N=5). Error bars represent ±s.e.m.