Accumulation of tropoelastin by a short-term ascorbic acid treatment in the culture medium of aortic smooth muscle cells in vitro

Abstract

Treatment of cultured smooth muscle cells with ascorbic acid resulted in an accumulation of tropoelastin in the culture medium in dose-dependent and exposure time-dependent manner under the condition in which collagen synthesis was stimulated 2-fold. The steady-state level of elastin mRNA was essentially unchanged, whereas collagen mRNA content increased 2-fold by ascorbic acid treatment. Newly synthesized tropoelastin was hydroxylated in the presence of ascorbic acid but was underhydroxylated in a scorbutic condition. Short pulse experiments showed that the secretion rate of tropoelastin was unaltered by ascorbic acid treatment. Pulse-chase experiment demonstrated that the level of fully hydroxylated tropoelastin in the medium of ascorbate-treated cells was greater than that of underhydroxylated tropoelastin. These results indicate that accumulation of tropoelastin in the medium by ascorbic acid is related to an increased stability of hydroxylated tropoelastin and/or its impaired incorporation into insoluble elastin. © 1995, The Keio Journal of Medicine. All rights reserved.