Fig. 4.

Percent changes from normoxia of respiratory frequency, tidal volume, and V̇e responses to hypoxia measured at peak (A) and at steady state (B) after a single injection of vehicle (open bars) or suramin (40 mg/kg; dark shaded bars) in P4, P7, P12, and P21 rats, or after administration of A-317491 (150 mg/kg; light shaded bars) in P4, P7, and P21 rats. B: percent changes from normoxia of ventilatory equivalent for oxygen and carbon dioxide responses to hypoxia were only determined at steady state. V̇o₂, oxygen consumption; V̇co₂, CO₂ production. Values are means ± SE. n values for vehicle, suramin, and A-317491, respectively, are as follows: 10, 10, and 6 (P4); 6, 12, and 6 (P7); 11 (vehicle) and 10 (suramin) (P12); 10, 11, and 6 (P21). *P < 0.05 vs. vehicle (saline).