Effect of cell density on the incorporation of [3H] proline into collagen by rabbit aortic smooth muscle cells in culture.

: When stationary phase cultures of rabbit aortic smooth muscle cells (SMCs) with different cell densities were incubated with [3H] proline in order to study the rates of collagen and total protein syntheses, the incorporation of [3H] proline into collagen and total protein decreased with increasing cell density. This association was mainly due to a negative correlation between cell density and the specific activity of [3H] proline within the free intracellular proline pool. After correction for the specific radioactivity of free intracellular proline, the synthesis rate of collagen was not significantly correlated with cell density, but the negative association between cell density and the incorporation of [3H] proline into total protein was not completely abolished.