Mean heart rate over 10 heartbeats preceding and following three air breaths under different conditions
| . | Normoxia . | Hypoxia . | Propranolol . | Atropine . | Total blockade . |
|---|---|---|---|---|---|
| Pre-AB | 32.1±1.8a | 26.2±2.1b | 19.8±1.6c | – | 81.1±2.3d |
| Post-AB | 32.1±1.8a | 47.6±1.3b | 42.7±1.5c | – | 81.2±1.9d |
| Pre-AB* | 31.4±2.8a | 24.9±3.3b | – | 92.3±0.5c | 83.6±1.9d |
| Post-AB* | 31.4±2.8a | 52.8±1.9b | – | 93.5±0.5c | 83.2±1.8d |
| . | Normoxia . | Hypoxia . | Propranolol . | Atropine . | Total blockade . |
|---|---|---|---|---|---|
| Pre-AB | 32.1±1.8a | 26.2±2.1b | 19.8±1.6c | – | 81.1±2.3d |
| Post-AB | 32.1±1.8a | 47.6±1.3b | 42.7±1.5c | – | 81.2±1.9d |
| Pre-AB* | 31.4±2.8a | 24.9±3.3b | – | 92.3±0.5c | 83.6±1.9d |
| Post-AB* | 31.4±2.8a | 52.8±1.9b | – | 93.5±0.5c | 83.2±1.8d |
Heart rate data (beats min–1) are means ± s.e.m. for 21 observations on seven jeju exposed to hypoxia and then infused 2 h later with propranolol and then atropine. AB, air breaths. Asterisks indicate N=4 jeju exposed to hypoxia and then infused with atropine and 2 h later with propranolol. Normoxic fish did not air breath and therefore pre-and post-AB values are mean rates taken from randomly selected sections of ECG trace containing 20 heartbeats. Means with a common superscript letter within rows are not significantly different (P>0.05) by Fisher's least significant difference procedure