Diminished release of tissue plasminogen activator during venous occlusion in manual workers

Abstract

The effect of intensive and regular manual work on fibrinolytic response after venous occlusion of the upper arm was studied in 13 male manual workers (masons, foundry workers and grinders) and in 11 male intellectual workers (controls). Fibrinolytic response after 20 min venous occlusion was measured with euglobulin clot lysis, specific assay for tissue plasminogen activator (t-PA) activity, t-PA antigen and t-PA inhibitor (PAI) activity assay. A significant reduction in fibrinolytic potential (difference between post- and preocclusion value) was observed in manual workers. Their fibrinolytic potential measured by t-PA activity assay and by euglobulin clot lysis was 85% and 55% lower, respectively, than in controls. Simultaneously, decrease in PAI activity after venous occlusion was significantly smaller in workers than in controls. t-PA antigen determinations showed that the reduction in fibrinolytic potential was due to decreased t-PA antigen release 40% lower compared to controls) and not the consequence of increased preocclusion PAI activity that could mask fibrinolytic response. It was concluded that chronic muscular work with the arms reduced the amount of t-PA that could be released from the endothelium by venous occlusion. A larger study is required to confirm this observation.