An Enhancing Effect Of Smoking On Fibrinolysis

The effect of smoking two cigarettes in 15 minutes on the fibrinolytic enzyme system in blood, was investigated. Samples were taken, using an indwelling catheter over a 1 hr period (starting at 9 a.m.), from 18 apparently healthy volunteers in fasting condition. The pre-smoking sample, considered to be a true base-line sample, was taken 30 minutes after the initial sample. In the subsequent 15 minutes two average (re: tar and nicotine) cigarettes were smoked; controls “smoked” unlit cigarettes. Samples were taken at the middle and at the end of the smoking period, as well as + 22.5 and + 30 minutes from the start of smoking. The heart rate was monitored throughout.

Haematocrit values, before and after smoking, did not change significantly, but carboxyhaemoglobin levels rose on average in inhaling smokers from 3.0 to 5.1% and the average heart rate increased from 64 to 76 beats/minute after smoking.

On screening euglobulin fractions of each sample on normal fibrin plates a small, but consistent, increase in fibrinolytic activity was seen, apparently due to smoking (an increase of up to 2.1 BAU). Activation of intrinsic systems, via factor XII, could not be demonstrated, but further analysis of the increase in fibrinolytic activity revealed quenching by anti-tissue activator antibodies and not by anti-urokinase antibodies.

Thus, in conclusion a small, but consistent increase in the circulating level of extrinsic plasminogen activator activity was detected after smoking 2 cigarettes.