title: The effect of age on the nucleic acid content of slow- and fast-twitch muscle in normal and dystrophic mice and their litter mates.
abstract: RNA, DNA, and NCP content were measured in fast- and slow-twitch skeletal muscle of normal and dystrophic mice (HDM) and their littermates at ages 4 through 29 weeks. In normal and litter mate mice RNA and DNA content were far greater in the soleus than in the gastrocnemius while the RNA/DNA ratio and NCP content were greater in the gastrocnemius. In dystrophic mice, however, the differences between nuleic acid content of the 2 muscles were far less, apparently due to a proportionately higher content in the dystrophic gastrocnemius. Due to a proportionately lower ratio in the gastrocnemius, dystrophic RNA/DNA ratios for the 2 muscles were essentially the same. Age had a marked effect on the nucleic acid content of both muscles in all 3 mice types but to varying degrees. In the soleus, RNA and DNA content rapidly decreased until 9 to 10 weeks of age followed by a gradual decline. Soleus RNA/DNA ratios showed little change with age except in the HDM mice in which there was a significant overall decline. In the gastrocnemius, RNA content followed the same pattern but with a smaller decline in the younger ages. Age had no affect on DNA content in the normal gastrocnemius, but there was significant decline in the HDM gastrocnemius. RNA/DNA gastrocnemius ratios showed marked fluctuations in both normal and dystrophic mice but did not appear to be affected by age.
mesh_terms: D000367:Age Factors; D000818:Animals; D004247:DNA / Q000032:analysis; D051379:Mice; D009119:Muscle Contraction; D009124:Muscle Proteins / Q000032:analysis; D009132:Muscles / Q000032:analysis*; D009137:Muscular Dystrophy, Animal / Q000378:metabolism*; D009696:Nucleic Acids / Q000032:analysis*; D012313:RNA / Q000032:analysis
chemical_list: D009124:Muscle Proteins; D009696:Nucleic Acids; D012313:RNA; D004247:DNA