Figure 10.

Electrical stimulation of RM facilitates endogenous release of 5-HT and activates 5-HT2 receptor presumably in the pre-BötC. A, Integrated EMG activity obtained from intercostal muscle under control conditions (top trace) and following the injection of the 5-HT2 antagonist (ketanserin 80 μm, 0.6 μl, bottom trace). B, EMG activity recorded during RM stimulation under control conditions (top trace) and following the injection of ketanserin (bottom trace). C–E, Bar graphs illustrating the effects of ketanserin on integrated EMG amplitude (C, ns, n = 8), frequency (D, *p < 0.05), and regularity of respiratory frequency (E, ns). F, G, Bar graphs illustrating that RM stimulation (blue bars) affects respiratory frequency (F, *p < 0.05, n = 8) and the regularity of the frequency (G, irregularity score, *p < 0.05) under control conditions (white bars) and following the injection of ketanserin (green bars).