| Abstract: | Prezant, D. J., M. L. Karwa, B. Richner, D. Maggiore, E. I. Gentry, and J. Cahill. Gender-specific effects of dexamethasone treatment on rat diaphragm structure and function. J. Appl. Physiol. 82(1): 125-133, 1997. The effectsof long-term dexamethasone treatment on diaphragm muscle were studiedin female and male rats. Compared with pair-fed control animals,dexamethasone treatment did not significantly affect estrous cycling orpeak serum estradiol levels; however, testosterone levels weresignificantly increased in females and decreased in males.Dexamethasone significantly reduced body and costal diaphragm weights,but to a lesser extent in females than in males. Reductions indiaphragm weight were proportional to reductions in body weight. Infemales and males, dexamethasone treatment significantly decreaseddiaphragm fiber (types I and II) cross-sectional area and the relativeexpression of myosin heavy chain isoform 2B. With the exception of typeI fiber atrophy, these changes occurred to a lesser extent in females.Dexamethasone did not significantly affect specific forces.Dexamethasone significantly increased twitch one-half relaxation timeand fatigue resistance indexes in males but not in females. Inconclusion, the effects of long-term dexamethasone treatment weregender specific, with significantly fewer effects in females, andchanges in serum testosterone levels were associated with thesefindings. |
