Figure 6. Phrenic nerve activity in the anaesthetized adult rat.

A, representative integrated phrenic nerve activity and arterial blood pressure of control and NCT rats at different CO₂ levels (i.e. baseline, +5, and +10 mmHg above baseline). B, mean absolute values of integrated phrenic nerve minute activity, phrenic nerve amplitude, and phrenic nerve frequency at baseline, +5 and +10 mmHg in control (open circles, n= 7) and NCT (neonatal caffeine treatment, filled circles, n= 7) rats. C, percentage changes compared to baseline in response to hypercapnia of phrenic nerve minute activity, amplitude, and frequency. D, percentage of CO₂ maximal phrenic activity for minute activity, amplitude and frequency. Values are expressed as means ±s.e.m.*Mean values significantly (P < 0.05) different from controls. iPNA, integrated phrenic nerve activity. BP, blood pressure.