Effect of bilateral nephrectomy on plasma fibronectin levels: its influence on acute fibronectin response to trauma and RE blockade.

Plasma fibronectin is important to reticuloendothelial (RE) function and resistance to experimental shock. However, the factors that regulate its level have remained undefined. The present study evaluated the concept that the kidneys may play a role in the modulation of plasma fibronectin levels. Immunoreactive and opsonically active fibronectin in blood over a 28-hour period following bilateral nephrectomy was assessed in male rats (250-350 gm) by electroimmunoassay, peritoneal macrophage monolayer assay, and liver slice bioassay. Controls consisted of sham-operated rats. An acute 25%-30% fibronectin deficiency was detected within the initial 1-2 hours posttrauma in both experimental and control rats. Thereafter, a significant (P less than 0.05) increase in immunoreactive fibronectin developed by 24 hours which was much greater after bilateral nephrectomy as compared to controls (P less than 0.05). With the peritoneal macrophage assay or with the liver slice assay, the plasma or serum from bilateral nephrectomized rats has greater opsonic activity as compared to controls. This corresponded to increased hepatic RE phagocytic function in vivo after nephrectomy. In the 24-hour postnephrectomized rats, fibronectin decreased acutely after RE blockade or traumatic shock (NCD) indicating it was biologically active. These data suggest that the kidneys may participate in regulating the blood level of this protein, which has a role in reticuloendothelial system function and shock resistance.