TOTAL PARENTERAL-NUTRITION DOES NOT IMPROVE DIAPHRAGM DEVELOPMENT IN PREMATURE BABOONS

We hypothesized that total parenteral nutrition accelerates growth and development of diaphragm muscle (DPH) in prematurely delivered baboon s (140 days gestation). For 10 days after delivery by cesarean section , we administered parenteral nutrition containing glucose, electrolyte s, and water or total parenteral nutrition containing lipids, amino ac ids, glucose, vitamins, and electrolytes. After 10 days of care, dorso lateral and ventrolateral (VL) costal DPH were sampled for histochemic ally determined mean fiber area (MFA) and fiber type percentages. We d etermined isolated bundle isometric tension (normalized for cross-sect ional area), time to peak tension, half-relaxation time, force-frequen cy relationship, and fatigability. Neither sex nor nutritional treatme nt affected contractile properties. Differences among sexes and muscle sites, but not among nutritional treatments, were observed for histoc hemical characteristics. In females, the VL DPH had a lower percentage of type IIo fibers and a greater MFA of type IIc fibers than the dors olateral DPH and a lower percentage of type IIo fibers and greater MFA of type IIc and IIo fibers than the VL DPH in males. Mean fiber cross -sectional area of VL DPH was significantly greater in females than ma les. The larger fibers in females than males suggest a stronger DPH in females. Earlier growth of type II fibers in females could contribute to a better outcome for female than male premature infants with hyali ne membrane disease.