Biosynthesis of type I and III collagens by cultured smooth muscle cells from human aorta.

The synthesis of collagen by human aortic smooth muscle cells was studied after incubating the cells with [3H]proline and [3H]glycine for 48 hr. The culture medium and cells were lyophilized and then digested with cyanogen bromide (CNBr) in 70% (wt/vol) formic acid. The resultant peptides were subjected to ion exchange chromatography on CM-cellulose and gel filtration on agarose. On the basis of the molar ratios of the alpha1(I)-CB8 and alpha1(III)-CB8 peptides of the alpha1(I) and alpha1(III) chains, approximately one quarter of the collagen synthesized by these cells was identified as type III and three quarters as type I. These data indicate that the smooth muscle can synthesize at least two types of collagen found in the arterial wall.