Characterisation of the Major Collagen Species Present in Porcine Aortae and The Synthesis of Their Precursors by Smooth Muscle Cells in Culture

Porcine aortae were digested with pepsin and the solubilised collagen molecules separated by differential salt precipitation at pH 7.5. The fraction precipitated at 1.71 M NaCl was shown to comprise collagen type III as judged by its elution characteristics from CM-cellulose, its α-chain composition on sodium dodecylsulphate polyacryla-mide gel electrophoresis, and amino acid analyses. Pepsin-derived type I collagen was recovered by precipitation at 2.56 M NaCl and similarly characterised.Cultures of porcine arterial smooth muscle cells have been established and radiolabelling studies with [14C]pro-line have demonstrated that these cells synthesise and secrete the precursors of collagen types I and III into the culture medium. Ion-exchange chromatography of these secreted collagen molecules and gel filtration of their pepsin-derived α-chains have demonstrated that type III is the major collagen species present in the medium.