Selective Increases in the Activities of Rat Liver Polysomes following Burn Trauma 1

Abstract

Summary

Increases in the nascent protein specific activities of certain polysome size groups have been found in rat livers following a 20% full-thickness skin burn. The ratio of monosomes to polysomes was approximately 0.10 for the sham-burn animals and 0.06, 0.08, and 0.12 for the 1-, 5-, and 12-day postburn animals, respectively. The specific activities increased 70-170% above sham values 24-hr postburn and returned to sham levels by 5-day postburn. Studies in vitro, using a rabbit reticulocyte-message-dependent lysate system produced similar results. Free polysomes isolated from postburn rat livers stimulated protein synthesis in the cell-free system to a greater extent than the corresponding shams 24 hr following burn injury. By 5 days the stimulation from the burn polysomes was not statistically different from that of the shams. Separating the polysomes into narrower size classes eliminated the stimulatory effect observed in vitro at 1-day postburn. These data are consistent with the formation of a polysome-associated factor induced by burn trauma that potentiates protein synthesis, but which is unstable to polysome subfractionation.

We are indebted to Ms. Karen R. Lawley for carrying out amino acid analyses and Drs. Ajit Kumar and Daniel Malamud for helpful discussions.