Table 1.
Effects of NMDA and non-NMDA receptor antagonism on ventilatory parameters before, during, and after AIH
| APV Injection |
CNOX Injection | ||||||||
|---|---|---|---|---|---|---|---|---|---|
| Before AIH |
0 min After AIH | 20 min After AIH | Before AIH | ||||||
| Vehicle (n = 5) | 1.5 mg/kg (n = 6) | Vehicle (n = 6) | 1.5 mg/kg (n = 6) | Vehicle (n = 4) | 1.5 mg/kg (n = 4) | Vehicle (n = 6) | 5 mg/kg (n = 6) | 10 mg/kg (n = 6) | |
| V̇e, ml·100 g−1·min−1 | |||||||||
| Baseline | 41.6±0.6 | 41.2±1.0 | 42.9±0.6 | 42.8±0.7 | 42.5±1.3 | 41.3±1.6 | 41.71±0.5 | 41.6±0.9 | 33.9±2.8† |
| HR | 160.3±11.9 | 148.7±10.9 | 156.2±7.9 | 160.6±12.2 | 163.2±13.5 | 156.1±20.5 | 166.3±11.4 | 155.8±10.1 | 151.7±11.9 |
| LTF | 23.4±2.6* | 3.9±2.0† | 21.9±1.1* | 3.9±1.4*† | 20.2±0.9* | 15.5±1.8* | 23.9±2.1* | 23.8±2.2* | 33.6±4.4*† |
| Vt, ml/100 g | |||||||||
| Baseline | 0.52±0.03 | 0.47±0.03 | 0.5±0.04 | 0.51±0.02 | 0.52±0.03 | 0.53±0.02 | 0.54±0.03 | 0.56±0.05 | 0.45±0.04 |
| HR | 28.8±3.5 | 37.9±6.8 | 53.7±5.0 | 49.5±6.1 | 30.6±4.4 | 25.3±7.7 | 28.4±3.1 | 30.4±4.8 | 39.2±7.9 |
| LTF | 8.1±2.1* | 4.7±3.2 | 13.6±5.1* | 10.1±3.2* | 2.0±5.4 | 1.0±3.8 | 8.0±1.9* | 8.9±3.5* | 16.4±4.2* |
| fR, breaths/min | |||||||||
| Baseline | 81.5±5.2 | 89.8±4.4 | 88.7±6.3 | 85.2±4.8 | 82.6±3.7 | 78.5±5.8 | 79.0±5.3 | 74.9±3.1 | 76.3±3.4 |
| HR | 102.8±10.1 | 80.7±5.7 | 67.0±5.0 | 73.9±5.4 | 99.4±11.6 | 104.7±17.4 | 108.2±10.5 | 95.6±3.4 | 84.1±6.7 |
| LTF | 14.2±3.9* | −0.2±3.2† | 7.9±4.1 | −5.1±3.5† | 19.0±7.3* | 15.5±5* | 14.6±7.4* | 14.3±5.4* | 14.4±2.7* |
Values are means ± SE; n, no. of rats. NMDA, N-methyl-d-aspartate; APV, (±)-2-amino-5-phosphonovaleric acid; CNQX, 6-cyano-7-nitrquinoxaline-2,3-dione; AIH, acute intermittent hypoxia (5 episodes of 5-min 10% O2); V̇e, minute ventilation; Vt, tidal volume; fR, respiratory frequency; HR, hypoxic response to 5-min 10% O2 in V̇e, Vt, and fR: % increase above baseline in the respective hypoxic value; LTF, long-term facilitation magnitude of V̇e, Vt, and fR: % increase above baseline in the average of posthypoxia 15–45 min respective values.
Significant difference from 0% increase above baseline, P < 0.05.
Significant difference from respective vehicle group, (P < 0.05).