Collagen biosynthesis in normal and abnormal human heart valves.

Absolute rates of collagen and non-collagen protein synthesis were measured in organ cultures of normal, rheumatic and floppy heart valves. The incorporation of 14C-proline into the cultures was measured and standardised according to the specific activity of the isotope in the tissue and the amount of DNA present. It was observed that the mean rate of collagen synthesis in floppy and rheumatic valves was significantly higher than normal, but that there was no difference in the rates of non-collagen protein synthesis. This stimulated synthetic activity in the abnormal valves was coupled with elevated collagen and total protein content of the tissue. The proportion of total protein synthesis that was devoted to the production of collagen was also significantly higher in the pathological tissues.