Effects of prenatal steroids on the guinea pig (Cavia porcellus) diaphragm
Robert Alexander and Jennifer L. Dearolf, Biology Department, Hendrix College, Conway, AR
Although glucocorticoids are frequently used to treat respiratory distress syndrome in premature babies, the effects of these steroids on the structure of the breathing muscles is unclear. In order to investigate the effects of betamethasone on the development of the diaphragm, we injected half of a group of pregnant guinea pigs with betamethasone at 70% gestation and then collected diaphragm tissue from treated and control fetuses for histochemical analysis. By using the myosin ATPase stain, we classified fibers as either slow- or fast-twitch, as well as collected data on the average diameter of the fibers. The fiber-type profiles (percent slow-twitch) did not differ between treated (11.5 +/- 1) and control (12.4 +/- 0.2) fetuses. In addition, the diameters of the slow- and fast-twitch fibers were similar. These results suggest that our betamethasone treatment had no effect on the development of guinea pig breathing muscles.
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