Previous reports of the effects of tetrodotoxin (TTX)-induced muscular disuse have demonstrated alterations in muscle force, speed, and fatiguability that might suggest changes in the quality of contractile proteins. These studies were extended to the effects of TTX-induced disuse on the Ca$ sp{2+}$-activation characteristics of myofibrillar ATPase of the rat gastrocnemius. Atrophic responses after TTX treatment were as previously reported with a significant decrease in left gastrocnemius weight (g) compared to the control-pump (C) group (1.25 $ pm$ 0.04 for C vs 0.72 $ pm$ 0.04 for TTX, X $ pm$ SEM, p $ leq$ 0.01). Myofibrillar protein yield (mg$ cdot$g$ sp{-1}$ wet weight) was also depressed (92.8 $ pm$ 4.6 for C vs 70.3 $ pm$ 3.7 for TTX; p $ leq$ 0.01). Maximum ATPase of myofibrils (nmol Pi$ cdot$mg$ sp{-1} cdot$min$ sp{-1}$) was decreased (424 $ pm$ 46 for C vs 199 $ pm$ 27 for TTX, p $ leq$ 0.01). Furthermore, the Hill n which reflects the cooperative aspects of Ca$ sp{2+}$-activation of the myofibrillar ATPase was significantly depressed (1.58 $ pm$ 0.07 for C vs 1.29 $ pm$ 0.09 for TTX; p $ leq$ 0.05) after TTX treatment. The results of the present study suggest that muscle perturbations that result from TTX-induced disuse are at least partially related to changes in the myofibrillar fraction.
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.59523 |
| Date | January 1989 |
| Creators | Panenic, Robert |
| 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 Arts (Department of Physical Education.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001067433, proquestno: AAIMM63650, Theses scanned by UMI/ProQuest. |
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