In vitro maturation of rabbit reticulocytes. III. Response of lipoxygenase.

Lipoxygenase activity with linoleic acid as substrate and the immunologically detectable amount of lipoxygenase protein were estimated in the course of in vitro maturation of rabbit reticulocytes withdrawn at the sixth day of an experimental bleeding anaemia. With unseparated cell mixture there was a significant increase in the lipoxygenase activity of 67 +/- 15% after a maturation period of 4 h followed by a decrease up to the initial level. The maturational changes were more pronounced when the fraction of youngest reticulocytes after buoyant density separation in a serum albumin gradient was used, whereas the cells of medium density failed to show the intermittent increase. The lipoxygenase activity was largely paralleled by the amount of lipoxygenase protein. The increase of lipoxygenase was prevented by either anaerobiosis or addition of oligomycin. The protein synthesis was greatly decreased after 4 h of incubation. The decline of the amount of lipoxygenase between 4 and 24 h incubation is probably largely caused by proteolysis. The results support former interpretations as to the synthesis and biological dynamics of lipoxygenase in reticulocytes.