Average breathing frequencies, number of pauses after return to normoxia, and chemoreceptors immunoreactive to 5HT (5HT-IR) per gill filament,of fish pre-exposed to hyperoxia, hypoxia or hypercapnia, as well as control fish
| Group . | Resting fR (breaths min-1) . | Resting pausing frequency (min-1) . | Density of 5HT-IR NECs (filament-1) . |
|---|---|---|---|
| Control | 191±12 (36) | 19±3.8 (4) | 36.8±2.8 (8) |
| 28 days hyperoxia | 199±14 (27) | 12±3.6 (5) | 22.6±2.3* (8) |
| 28 days hypoxia | 165±16* (21) | 0* (21) | 32.9±1.8 (4) |
| 28 days hypercapnia | 213±13 (30) | 0* (30) | 37.5±5.8 (3) |
| Group . | Resting fR (breaths min-1) . | Resting pausing frequency (min-1) . | Density of 5HT-IR NECs (filament-1) . |
|---|---|---|---|
| Control | 191±12 (36) | 19±3.8 (4) | 36.8±2.8 (8) |
| 28 days hyperoxia | 199±14 (27) | 12±3.6 (5) | 22.6±2.3* (8) |
| 28 days hypoxia | 165±16* (21) | 0* (21) | 32.9±1.8 (4) |
| 28 days hypercapnia | 213±13 (30) | 0* (30) | 37.5±5.8 (3) |
Values are means ± s.e.m.; N values for each treatment are given in parentheses.
Resting pause frequency was measured in normoxia 3 h post exposure to 28 days hypoxia, hyperoxia or hypercapnia, and in control fish.
NECs, neuroepithelial cells.
Significant difference between groups (one-way RM ANOVA, P<0.05).