In vivo release of tissue-type plasminogen activator across the human forearm during mental stress.
We have previously shown that plasma levels of endothelium-derived tissue-type plasminogen activator (t-PA) increase during mental stress. The aim of the study was to investigate in vivo release in an intact human muscle vascular bed. Eleven healthy young males (22-36 yrs) were studied at rest and during 10 min of mental stress (forced arithmetic). Net release or uptake were assessed by arterio-venous (AV) concentration gradients across the forearm of t-PA antigen and t-PA activity, and plasminogen activator inhibitor antigen type 1 (PAI-1). Forearm blood flow was measured by venous occlusion plethysmography. At rest, there was a positive AV-difference of t-PA activity across the forearm indicating a net release of t-PA activity of approximately 3.7 fmol x min-1 x 100 ml-1 (Wilcoxon's signed rank test vs 0, p = 0.01). However, t-PA antigen showed a variable release pattern. On the average, there was a net release of 0.17 ng x min-1 x 100 ml-1 after 60 min of rest (Wilcoxon vs 0, p = 0.07). PAI-1 antigen showed net release at rest. In response to stress, forearm blood flow increased from 1.9 to 2.9 ml x min-1 x 100 ml-1 (ANOVA, p = 0.007), and net release of t-PA activity increased to 9.8 fmol x min-1 x 100 ml-1 (ANOVA, p = 0.01 compared with rest). Arterial and venous plasma t-PA levels also increased significantly during stress (ANOVA, p < 0.01). t-PA antigen showed a similar but less pronounced release pattern during stress.(ABSTRACT TRUNCATED AT 250 WORDS)
Department of Clinical Physiology, Ostra Hospital, University of Göteborg, Sweden.
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D000328:Adult; D005542:Forearm / Q000098:blood supply; D006801:Humans; D007261:Infusions, Intra-Arterial; D008297:Male; D009638:Norepinephrine / Q000008:administration & dosage / Q000494:pharmacology; D012636:Secretory Rate / Q000187:drug effects; D013315:Stress, Psychological / Q000097:blood / Q000503:physiopathology*; D010959:Tissue Plasminogen Activator / Q000378:metabolism*
D010959:Tissue Plasminogen Activator; D009638:Norepinephrine