Fig. 1.
Episodic microinjections of 5-HT in the RTN/pFRG evoke abdominal expiratory activity in anesthetized vagus-intact rats. A and B: pulsatile arterial pressure (PAP), raw and integrated (∫) diaphragmatic (DIAEMG) and abdominal (ABDEMG) electromyographic recordings of vagus-intact animals, representative from their respective group, illustrating the effects of single (A, arrow) and episodic (B, arrows) bilateral microinjections of 5-HT in the RTN/pFRG. C and D: expanded tracings from A and B, respectively, illustrating the PAP recordings and the integrated DIAEMG and ABDEMG activities before (1 and I) and at 30 (2 and II) and 60 min (3 and III) after microinjections. E–I: average values of DIA burst amplitude (E) and frequency (F), ABD mean activity (G), mean arterial pressure (MAP, H), and heart rate (HR; I) before (basal) and after microinjections of vehicle (n = 5), single 5-HT (n = 8) and episodic 5-HT (n = 7) in the RTN/pFRG. J: photomicrography of a coronal slice of the brain stem from a representative rat of the group, showing the sites of microinjections in the RTN/pFRG (arrows). Abbreviations: VII, facial nucleus; py, pyramidal tract; RPa, raphe pallidus nucleus; sp5, spinal trigeminal tract. *Different from respective basal values, P < 0.05. #Different from vehicle group at the corresponding time, P < 0.05.