Free amino acids and isosmotic intracellular regulation in the shrimp Crangon crangon

Abstract

The concentrations of non-protein nitrogenous material and individual free amino acids in muscle tissue of the euryhaline shrimp Crangon grancon are measured. The cellular ninhydrin-positive component closely follows blood osmolarity over a range of ambient salinities and temperatures. The three most abundant amino acids, glycine, proline and alanine, are primarily involved in adjusting intracellular osmotic concentrations to the salinity-induced variation in blood. The cellular adjustment to changed salinity is rapid; parallel observations on blood concentrations suggest that the cellular regulation involves an exchange of nitrogenous material through the cell membranes.