Diabetes, Vol 46, Issue 8 1368-1371, Copyright © 1997 by American Diabetes Association
Evidence for acute stimulation of fibrinogen production by glucagon in humans
P Tessari, E Iori, M Vettore, M Zanetti, E Kiwanuka, G Davanzo and R Barazzoni
Department of Metabolic Diseases, University of Padua, Italy.
Fibrinogen, an acute-phase protein, and glucagon, a stress hormone, are
often elevated in many conditions of physical and metabolic stress,
including uncontrolled diabetes. However, the possible mechanisms for this
association are poorly known. We have studied the acute effects of
selective hyperglucagonemia (raised from -200 to -350 pg/ml for 3 h) on
fibrinogen fractional secretion rate (FSR) in eight normal subjects during
infusion of somatostatin and replacement doses of insulin, glucagon, and
growth hormone. Fibrinogen FSR was evaluated by precursor-product
relationships using either Phe (n = 8) or Leu (n = 2) tracers.
Hyperglucagonemia did not change either plasma Phe or Tyr specific
activity. After hyperglucagonemia, fibrinogen FSR increased by
approximately 65% (from 12.9 +/- 3.6 to 21.5 +/- 6.1% per day, P <
0.025) using plasma Phe specific activity as the precursor pool. FSR
increased by approximately 80% (from 16.6 +/- 4.8 to 29.4 +/- 8.8% per day,
P < 0.025) if plasma Phe specific activity was corrected for the
ketoisocaproate/Leu enrichment (or specific activity) ratio to obtain an
approximate estimate of intrahepatic Phe specific activity. FSR increased
by approximately 60% when using plasma Tyr specific activity as precursor
pool (n = 8) (P < 0.05), as well as when using the Leu tracer
precursor-product relationship (n = 2). In conclusion, selective
hyperglucagonemia for approximately 3 h acutely stimulated fibrinogen FSR
using a Phe tracer method. Thus, glucagon may be involved in the increase
of fibrinogen concentration and FSR observed under stressed or pathologic
conditions.