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MulroySeanDouglas1997 cmr.pdf (1.98 MB)

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Effects of Genetic Dwarfism, Gender and Mechanical Load on Plantaris Muscle Fiber Type Composition

Mulroy, Sean Douglas
http://rave.ohiolink.edu/etdc/view?acc_num=osu1392389901

Abstract Details

1997, Master of Arts, Ohio State University, EDU Physical Activity and Educational Services.
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.
Jon Linderman (Advisor)
W.M. Sherman (Committee Member)
60 p.
Physical Education

Recommended Citations

Citations

  • Mulroy, S. D. (1997). Effects of Genetic Dwarfism, Gender and Mechanical Load on Plantaris Muscle Fiber Type Composition [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1392389901

    APA Style (7th edition)

  • Mulroy, Sean. Effects of Genetic Dwarfism, Gender and Mechanical Load on Plantaris Muscle Fiber Type Composition. 1997. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1392389901.

    MLA Style (8th edition)

  • Mulroy, Sean. "Effects of Genetic Dwarfism, Gender and Mechanical Load on Plantaris Muscle Fiber Type Composition." Master's thesis, Ohio State University, 1997. http://rave.ohiolink.edu/etdc/view?acc_num=osu1392389901

    Chicago Manual of Style (17th edition)

osu1392389901
204
© 1997, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.