Smoking and fibrinolysis.

In order to study the fibrinolytic activity of vein walls in smokers and nonsmokers, 71 randomly selected heavy smokers, i.e., smoking more than 15 g tobacco per day, and 41 nonsmokers from the population group "Men born in 1914 residing in Malmo" were invited to undergo a health examination. When examined after 12 hours' abstention from tobacco, the smokers were found to have the same fibrinolytic activity as nonsmokers. Out of the 71 heavy smokers, 31 refrained from smoking during 8-9 weeks (as monitored with questionaire and COHb-determinations). Neither in those who had abstained from smoking nor in the controls did the fibrinolytic activity differ from that initially recorded. In a randomly selected subsample of 19 individuals examined after only one week's abstention from tobacco, the fibrinolytic activity, after venous occlusion of forearms, tended to be lower in the blood as well as in superficial hand veins, but the difference was not significant. The effect of smoking six cigarettes during three hours was measured. This level of smoking was associated with an increased fibrinolytic activity in blood, measured as euglobulin clot lysis time, and in superficial hand veins. This increase is probably due to the combined effects of nicotine and carbon monoxide.