Figure 1. Effects of repetitive electrical stimulation (at 80 Hz) of vagus nerve over 1 min (horizontal bar) on phrenic nerve activity in a vagotomized rat.
From top to bottom: phrenic discharges in arbitrary units (a.u.) (Phr); integrated phrenic activity (Int phr); respiratory frequency (f); amplitude of integrated phrenic activity (∫Phr); arterial blood pressure (BP); percentage CO2 level in respired air (CO2 (%)). Each point in the f and ∫Phr traces corresponds to one breath. Insets at the top show expanded views of phrenic discharges in the control period and at the onset and offset of vagal stimulation.