Figure 3. Physiological effects of systemic methamphetamine (METH) before and after compensating METH‐evoked increases in expired CO₂ .

A, representative example of expired CO_2, ventilation rate (right axis, grey), integrated and raw phrenic nerve activity during (a) control period and (b) after METH (5 mg kg⁻¹)‐evoked changes in expired CO₂ were compensated by increasing ventilation rate. B, comparison of integrated phrenic nerve activity respiratory period in control (grey line) and following METH (5 mg kg⁻¹) with compensation of expired CO₂ (continuous line). C, group data comparing peak responses following vehicle (open bar), METH (filled bar) and METH with CO₂ compensation (shaded bar) and. Grouped data are presented as means ± SEM; *P < 0.05, **P < 0.01, ***P < 0.001 vs. control.