Transport of beta-alanine and biosynthesis of carnosine by skeletal muscle cells in primary culture.

Uptake of beta-alanine and synthesis of carnosine (beta-alanyl-histidine) could be demonstrated in primary cell cultures derived from embryonic chick pectoral muscle. Concomitant with the morphological changes, cessation of cell division and the induction of creatine kinase, a rapid increase in the rate of beta-alanine uptake and also in the rate of carnosine synthesis could be observed. The uptake of beta-alanine is sodium and chloride dependent and obeys Michaelis-Menten kinetics with Km values of about 40 microM that are essentially identical for myoblasts and myotubes. In contrast, Vmax increases considerably during differentiation. The beta-alanine transport system is highly specific for beta-amino acids and exhibits a substantial anion dependency (Cl- > J- > CSN- > SO(4)2-). Stoichiometric studies suggest that the transport of one beta-alanine molecule involves two sodium ions and one chloride ion. This ratio is not altered by the process of cell differentiation.