Abstract
The relative inspiratory augmentations of sternomastoid, scalene, external intercostal, interchondral and diaphragmatic electromyographic activities were examined during the progressive asphyxia induced by rebreathing in pentobarbitone/urethane anaesthetized rabbits. Diaphragmatic activity augmented significantly less than that of the scalene, intercostal and interchondral muscles in response to the asphyxic increase in respiratory drive (hyperpnoea). Cervical vagotomy significantly increased the levels of inspiratory activity during the asphyxic hyperpnoea but did not abolish these relations. Dorsal rhizotomy at levels appropriate for the respective recording sites significantly limited the intercostal and interchondral augmentations, and depressed diaphragmatic activity to a less pronounced extent, but did not affect scalene activity. The asphyxic apnoea succeeding the hypernoea was terminated by gasping respiration. Excepting the intercondrals each muscle exhibited significantly greater electromyographic amplitudes during gasping than during the terminal hyperpnoeic efforts. Only during gasping were the sternomastoid muscles recruited. The intercostal and scalene gaps were significantly greater than those exhibited by either the interchondrals or the diaphragm. Such dusproportionate responses were not affected by vagotomy or dorsal rhizotomy. The disparate inspiratory contributions during progressive asphyxia can therefore only be partially accounted for by differences in proprioceptive control.
Original language | English |
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Pages (from-to) | 57-68 |
Number of pages | 12 |
Journal | Respiration Physiology |
Volume | 64 |
Issue number | 1 |
DOIs | |
Publication status | Published - Apr 1986 |
Externally published | Yes |
Keywords
- Asphyxia
- Diaphragm
- External intercostal
- Gasping
- Interchondral
- Muscle spindale
- Rabbit
- Scalene
- Vagotomy