Airway hyperresponsiveness (AHR) is a key feature of asthma, characterized by exaggerated rate and extent of shortening of airway smooth muscle. Two isoforms of the smooth muscle myosin differ by the presence [(+)insert] or absence [(-)insert] of a 7 amino acid insert. The (+)insert exhibits a 2-fold greater ATPase activity and velocity of actin filament propulsion in the in vitro motility assay. The expression of these isoforms and other contractile proteins was quantified in the trachea of the Fisher and Lewis rat model of innate AHR. We found 95% greater mRNA and 45% greater protein expression of the (+)insert isoform in the trachea of the hyperresponsive Fisher animal (p<0.01), but no difference in other contractile proteins. A greater extent of myosin phosphorylation was also observed (55.1+/- d6.4 vs. 41.4+/-d6.1, p<0.01). These results suggest that in addition to greater myosin activation, an increased expression of the (+)insert isoform contribute to AHR.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.98708 |
| Date | January 2006 |
| Creators | Gil, F. Roberto. |
| 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 | Master of Science (Department of Physiology.) |
| Rights | © F. Roberto Gil, 2006 |
| Relation | alephsysno: 002330129, proquestno: AAIMR24677, Theses scanned by UMI/ProQuest. |
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