Fibrinolytic response to venous occlusion in healthy subjects: relationship to age, gender, body weight, blood lipids and insulin.

The physiological variability of fibrinolytic response to 20 min upper arm venous occlusion was studied in 191 healthy women and men, 19-80 years old. It was observed that fibrinolytic response measured by the absolute amount of t-PA antigen after venous occlusion increased with increasing age (from 10.7 at 19-30 years to 25.0 ng/ml at 71-80 years), was higher in men than in women (20.9 vs 15.6 ng/ml), higher in obese than in slim subjects (29.5 vs 12.3 ng/ml) and higher in subjects with moderately elevated blood cholesterol (33.3 vs 18.2 ng/ml) and triglycerides (30.0 vs 24.4 ng/ml, all p < 0.05 or less) than in subjects with normal levels of these variables. Due to simultaneous increase in basal levels of t-PA antigen in all these cases, relative increases in t-PA antigen after venous occlusion were not altered. Fibrinolytic response measured by t-PA activity, but not with euglobulin clot lysis time, increased with age. PAI-1 antigen was not affected by venous occlusion, while PAI activity decreased to zero in most subjects (in 61-80%) regardless of age, gender or blood lipids. However, in obese subjects and especially in subjects with elevated insulin, fibrinolytic response was reduced as determined by residual PAI activity after venous occlusion (1.3 and 10.6 IU/ml, respectively) due to the increased basal level of PAI-1. It was concluded that age, gender, body weight, blood lipids and insulin significantly modulate fibrinolytic response to venous occlusion.