Effects of Genetic Dwarfism, Gender and Mechanical Load on Plantaris Muscle Fiber Type Composition
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The Ohio State University / OhioLINK
1997
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| Online Access: | http://rave.ohiolink.edu/etdc/view?acc_num=osu1392389901 |
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ndltd-OhioLink-oai-etd.ohiolink.edu-osu13923899012021-08-03T06:22:10Z Effects of Genetic Dwarfism, Gender and Mechanical Load on Plantaris Muscle Fiber Type Composition Mulroy, Sean Douglas Physical Education The purpose of this study was to examine relationships between pituitary function, gender and mechanical load on plantaris muscle morphology. Muscle fiber cross sectional area (CSA) and myosin heavy chain (MHC) composition were measured in normal and dwarf male and female Lewis rats after six weeks of functional overload (FO) after surgical ablation of synergistic muscles. Serum growth hormone levels were 70-80% less in dwarf rats of both genders and body mass was 62% greater in normal rats when compared to their dwarf counterparts. A three-factor ANOVA detected main effects of gender, dwarfism, and FO for two fiber types. Compared to female rats type IIA and type IIB/X fibers were increased 19% and 18%, respectively for male animals. Similarly, dwarfism decreased type IIA and IIB/X fibers 22% and 19%, respectively. Mechanical load had the greatest effect on fiber CSA, increasing type I, IIA and IIB/X fibers 115%, 101% and 75%, respectively. Type IIA and IIB/X fiber types exhibited a significant three-way interaction of gender, dwarfism and functional overload. This interactive effect resulted in the largest fibers occurring in the male FO, with the smallest fibers in the female Dw muscles. Furthermore, examination of the relationship between fiber size and frequency indicated the existence of populations of large fibers (4-6000 µm2) in male FO, that were absent in dwarf and female animals. In response to FO type I MHC increased with concomitant decreases in type IIB MHC. Expression of type I MHC was increased in female animals compared to male animals but no clear hormonal interactions were evident. Collectively the results suggest that growth of muscle fibers is sensitive to sex hormones and pituitary function, while hypertrophy of muscle fibers is a function of the interaction between increased mechanical load, male sex hormones and pituitary function. 1997 English text The Ohio State University / OhioLINK http://rave.ohiolink.edu/etdc/view?acc_num=osu1392389901 http://rave.ohiolink.edu/etdc/view?acc_num=osu1392389901 unrestricted This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws. |
| collection |
NDLTD |
| language |
English |
| sources |
NDLTD |
| topic |
Physical Education |
| spellingShingle |
Physical Education Mulroy, Sean Douglas Effects of Genetic Dwarfism, Gender and Mechanical Load on Plantaris Muscle Fiber Type Composition |
| author |
Mulroy, Sean Douglas |
| author_facet |
Mulroy, Sean Douglas |
| author_sort |
Mulroy, Sean Douglas |
| title |
Effects of Genetic Dwarfism, Gender and Mechanical Load on Plantaris Muscle Fiber Type Composition |
| title_short |
Effects of Genetic Dwarfism, Gender and Mechanical Load on Plantaris Muscle Fiber Type Composition |
| title_full |
Effects of Genetic Dwarfism, Gender and Mechanical Load on Plantaris Muscle Fiber Type Composition |
| title_fullStr |
Effects of Genetic Dwarfism, Gender and Mechanical Load on Plantaris Muscle Fiber Type Composition |
| title_full_unstemmed |
Effects of Genetic Dwarfism, Gender and Mechanical Load on Plantaris Muscle Fiber Type Composition |
| title_sort |
effects of genetic dwarfism, gender and mechanical load on plantaris muscle fiber type composition |
| publisher |
The Ohio State University / OhioLINK |
| publishDate |
1997 |
| url |
http://rave.ohiolink.edu/etdc/view?acc_num=osu1392389901 |
| work_keys_str_mv |
AT mulroyseandouglas effectsofgeneticdwarfismgenderandmechanicalloadonplantarismusclefibertypecomposition |
| _version_ |
1719435499501780992 |