Effects of smoking and abstention from smoking on fibrinogen synthesis in humans

Cigarette smoking and hyperfibrinogenaemia are both significant risk factor s for the development of cardiovascular disease. Two studies are described here which aimed to establish the metabolic mechanism responsible for the r aised plasma fibrinogen concentration observed in smokers. Chronic smokers had a significantly elevated absolute rate of fibrinogen synthesis (ASR) co mpared with non-smokers (22.7 +/- 1.3 mg/kg per day versus 16.0 +/- 1.3 mg/ kg per day; means +/- S.E.M., P < 0.01), with plasma levels of fibrinogen s ignificantly correlated with fibrinogen synthesis (r = 0.65, P = 0.04). Unl ike fibrinogen, plasma albumin concentrations were lower in smokers than in non-smokers (45 <plus/minus> 0.4 versus 47 +/- 0.7 g/l, P < 0.05), but the re was no difference in rates of albumin synthesis between the two groups. Two weeks cessation from smoking by previously chronic smokers was associat ed with a rapid and marked fall in plasma fibrinogen concentration (from 3. 06 <plus/minus> 0.11 g/l to 2.49 +/- 14 g/l, P < 0.001), and a significant reduction in ASR (a 33% reduction, from 24.1 <plus/minus> 1.7 to 16.1 +/- 1 .0 mg/kg per day, P < 0.001). These studies suggest a primary role for incr eased synthesis in producing the hyperfibrinogenaemia associated with smoki ng. Moreover, abstention from smoking for a period of only 2 weeks induces a significant decrease in the rate of fibrinogen synthesis by the liver, wi th a concomitant reduction in the plasma fibrinogen concentration.