Fig. 2.

Effect of N-methyl-d-aspartate (NMDA) or non-NMDA receptor antagonism on ventilatory long-term facilitation in awake rats. Minute ventilation was measured before (baseline; BL), during, and after AIH (5 episodes of 5-min 10% O₂ hypoxia). Data recorded during AIH are not included. Ventilatory long-term facilitation was measured twice in each rat in A (n = 6, no vehicle data in 1 rat), B (n = 6), and C (n = 4), with vehicle injection in the first measurement and APV injection in the second one. Ventilatory long-term facilitation was measured (after CNQX injection) only once in both 5 mg/kg (n = 6) and 10 mg/kg (n = 6) groups in D, with control group data being the combination of 5 vehicle rats in A and 1 vehicle rat in the 5 mg/kg CNQX group. Many error bars are totally masked by the relatively bigger symbols. Results are expressed as means ± SE. *Significant difference from BL, P < 0.05. †Significant difference from vehicle group, P < 0.05.