Ornithine and S-adenosylmethionine decarboxylase activities and polyamine contents in developing muscle tissues and primary cultures of normal and polymyopathic hamsters

Abstract

Polyamine (putrescine, spermidine, and spermine) contents and ornithine (ODC) and S-adenosylmethionine (SAMDC) decarboxylase activities have been assessed in an age-dependent manner, in normal and polymyopathic (dystrophic) hamster skeletal muscle, heart, and tongue extracts and in primary tongue myoblast and skin fibroblast cultures. At 2 weeks of age, polyamine contents were significantly elevated in all of the dystrophic hamster tissues studied when compared with their age-matched controls. The degree of this elevation decreased with the age of the animals, generally, to a level where no significant difference in polyamine contents could be noted between normal and dystrophic hamster tissues. ODC and SAMDC activities in whole tissue extracts were consistently highest in 2-week-old muscle extracts and also declined with age. However, no significant changes in ODC or SAMDC activities were evident in any of the dystrophic muscle tissues studied when compared with their age-matched controls. Polyamine contents in dystrophic hamster myoblast and fibroblast primary cultures were also significantly elevated during proliferation (1 and 2 days after the initial seeding) compared with cultures prepared from normal hamsters. ODC and SAMDC activities in primary myoblast and fibroblast cultures clearly reflected the rate of cell proliferation, with highest activities found in subconfluent cell cultures. However, in general, no significant dystrophic-related abnormality in ODC or SAMDC activity was evident in proliferating myoblast or fibroblast cultures. These results suggest that the elevated polyamine contents of dystrophic hamster tissues and primary cultures may be due to a deficiency in polyamine catabolism or transport.Key words: polyamine contents, polyamine synthesis, polymyopathic hamsters.