Effect of lactate on collagen proline hydroxylase activity in cultured L-929 fibroblasts

Recent studies with fibroblasts have shown that peptidylhydroxyproline formation begins toward the end of the log phase of growth and is an expression of the activity of the enzyme, collagen proline hydroxylase, which increase in late log-phase cells. This communication reports a two- to fivefold increase in hydroxylase activity on incubating early log-phase cells with lactate. The activation effect is apparently specific for lactate and, although independent of new protein synthesis, requires incubation with intact cells for its expression. Since lactate concentration increases in cells as they normally enter the stationary phase, lactate may play an important role as an activator of one of the collagen-forming enzymes.