Factors altering contractility of the diaphragm were investigated in dogs. Contractility was assessed by analysis of transdiaphragmatic pressure (Pdi) generated during supramaximal phrenic stimulation at different frequencies and during spontaneous diaphragmatic contractions. Different conditions variously produced negative inotropic effects on the diaphragm. These effects in decreasing order of magnitude were produced by diaphragmatic fatigue, compensated metabolic acidosis and metabolic acidosis which was equivalent with respiratory acidosis. The fatigued diaphragm was improved by aminophylline, isoproterenol and neostigmine but not by salbutamol. Similarly, during compensated metabolic acidosis aminophylline restored diaphragmatic contractility while salbutamol did not. In respiratory acidosis aminophylline and neostigmine increased contractility but isoproterenol had no effect. Mechanisms underlying the alterations in diaphragmatic contractility produced by various interventions appeared to be related to changes in the amplitude and time course of the twitch.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.71955 |
| Date | January 1984 |
| Creators | Howell, Sandra. |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Medicine.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 000216831, proquestno: AAINL20814, Theses scanned by UMI/ProQuest. |
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