Fig. 3.

Hypercapnic responsiveness in frequency (top) and minute ventilation (bottom) for A/J (open bars) and B6 (filled bars) mice injected with vehicle (saline), 4 doses of buspirone (1.5, 3, 5, and 10 mg/kg), or buspirone in addition to p-MPPI (5 mg/kg each). Results are presented as percent change from resting breathing in room air compared with the first 30 s of breathing after exposure to hypercapnia. Significant difference between strains: †P < 0.05; ††P < 0.01. Significant difference between a dose and vehicle: *P < 0.05; **P < 0.01.