Production of Fibrinogen Following an Endotoxin Injection

Abstract

Several studies have shown that injection of endotoxins causes the plasma fibrinogen level to rise (1-51). Fibrinogen is apparently synthesized in parenchymal cells in the liver (6) and secreted into the lymph (7,8). The regulatory mechanism for the plasma fibrinogen level is not understood. Perfusion studies have indicated that the rate of synthesis depends upon the level of fibrinogen in the blood (9), but observations in vivo failed to show any relation between an elevated fibrinogen level and rate of synthesis In the present work it is shown that in rats the fibrinogen level rises abruptly starting about 8 hr after injecting a small dose of endotoxin subcutaneously. The rate of incorporation of glycine-lT also increases markedly during the period from 8 to 16 hr after injection of the endotoxin. It is suggested that some step in the cellular reaction to inflammation initiates the increase in the plasma fibrinogen level.Materials and Methods. Animals. Young adult female rats of the Carworth Wistar CFN strain were used. They weighed from 150 to 225 g. They were kept in individual cages to which they were accustomed for several days prior to the experiment.Sampling. Blood samples were drawn from the heart under ether anesthesia. For dose response experiments, 0.5 ml of blood was mixed in the syringe with 0.05 ml of 0.1 M sodium citrate. For experiments requiring serial samples from the same rats 0.2 ml of blood was mixed with 0.3 ml of isotonic buffer. The buffer is prepared from MacI1vaine's buffer at pH 6.6 by diluting in the proportion of 3 vol of buffer to 1 vol of water. The packed cell volume is measured and this enables calculation of the extent of (8).dilution of the plasma. Further details were published previously ( 10).Fibrinogen assay. Plasma fibrinogen was determined either by a microgravimetric method (11) or by a heat-turbidity procedure. The heat-turbidity procedure involved mixing 0.1 ml of plasma or 0.2 ml of diluted plasma with 6.0 ml of MacIlvaine's buffer a t pH 5.2. The mixture was heated at 55" for about 20 min. The resulting turbidity was measured as absorbance at a wavelength of 400 nm and converted to fibrinogen concentration by using a reference chart. This was a plot of heat turbidity vs. the concentration of fibrinogen as determined by a gravimetric reference procedure (12).Endotoxins. Bacterial polysaccharides (Difco) from five bacteria were used s e prately for dose response experiments. The polysaccharides were from Serratia marcescens, Escherichia coli, Staphylococcus aureus, Sdmonella typhosa, and Salmonella t yphimuri-The Difco polysaccharides were dissolved or suspended in physiological saline at a concentration of 300/pg/ml. Subcutaneous injections were made with the desired amount in 1.0 ml of saline.Glycine-'4C incorporation. In order to study the rate of incorporation of labeled glycine into fibrinogen a t different times after injection of polysaccharide, the first 24 hr were divided into three periods of 8 hr each. Serratia, marcescens polysaccharide (30 pg/ rat) was inj...

In vivo stimulation and restoration of the immune response by the noninflammatory fragment 163-171 of human interleukin 1 beta.

“…Fibrinogen was measured in EDTA-treated plasma obtained 24 h after intravenous treatments by the heat-turbidity method of Wycoff (34) .…”

Hemodynamic and blood biochemical profile during endotoxemia and after therapeutic intervention in buffalo calves.

“…Non-significant increase in plasma fibrinogen concentration was observed in the present investigation during endotoxemia well as after treatment (Table 2). This could be due to fact that endotoxin accelerates fibrinogen synthesis rate (Wycoff 1970). Table 1: Hemodynamic profile during endotoxic shock and after treatment with HSS, Flunixin Meglumine, Dextran-40 and blood in buffalo calves.…”

Rate of Clearance of Interleukin-1 from the Blood of Normal and Nephrectomized Rats

“…The rats without kidneys cleared the rabbit IL-1 somewhat slower, but Each plasma donor both nephrectomized X and shamoperated 0 received an iv injection of 5 pyrogenic units of partially purified rabbit IL-1. The plasma from each donor rat was injected into two to three normal rats and fibrinogen determined 24 hr later by the heat turbidity method (9). The number of rats is shown in parentheses and the standard error by brackets.…”

“…Individual rats were used only once in the time-course experiments. Fibrinogen was determined by the heat turbidity method of Wycoff (9). Determining the rate of IL-1 disappearance from blood.…”