Plasma fibronectin metabolism during hemorrhagic shock and starvation

In this report we characterize the response of the plasma protein fibronectin to hemorrhagic shock and starvation, conditions associated with decreased function of mononuclear phagocyte system (MPS). Rats were starved for 3 days, then half of the animals were subjected to fixed-volume hemorrhagic shock by removing an estimated 35% of their blood volumes for 20 min. After volume replacement, animals were injected iv with [14C]valine. At time points up to 10 hr after hemorrhage, plasma fibronectin concentrations and fibronectin synthesis were quantitated. In additional rats treated identically, fibronectin clearance was assessed by measuring the disappearance of 125I-fibronectin from the plasma. When compared to control animals, either starvation or hemorrhagic shock produced similar perturbations in plasma fibronectin metabolism; fibronectin concentrations were reduced from 241.3 +/- 34.6 micrograms/ml (mean +/- SEM) (controls) to 123 +/- 32.6 micrograms/ml (starvation) or 150.0 +/- 13.0 micrograms/ml (hemorrhage). Plasma [14C]fibronectin specific radioactivities, indicative of fibronectin synthesis, were also significantly reduced. Hemorrhagic shock in rats that previously had been starved did not depress fibronectin concentrations or synthesis to a greater extent than starvation alone. The rates of 125I-fibronectin clearance were increased in starvation and hemorrhagic shock (t1/2 = 233.0 +/- 13.0 min, controls; 174.6 +/- 10.7 min, starvation; 167.4 +/- 13.6 min, hemorrhage). In contrast to changes observed in fibronectin metabolism, total plasma protein concentrations were not significantly altered in any experimental groups. Furthermore, total plasma protein synthesis increased in rats subjected to either starvation or hemorrhagic shock, but decreased in starved rats that were subsequently shocked.(ABSTRACT TRUNCATED AT 250 WORDS)