Myocardial ischemia induces coronary t-PA release in the pig.
BACKGROUND
Tissue-type plasminogen activator (t-PA) is the key factor in initiating endogenous fibrinolysis in the vascular compartment. Regulated release of t-PA from endothelial stores is rapidly induced by several humoral factors as well as coagulation activation products. The aim of the present study was to test the hypothesis that regional myocardial ischemia induces regulated release of t-PA in the coronary vasculature in vivo.


METHODS
Healthy anesthetized (pentobarbital) pigs (n=8) were studied before and after a 10-min left anterior descending region coronary artery occlusion (LAD). Coronary fluxes of lactate, total t-PA antigen (ELISA, detecting both complex bound and free fraction) and active t-PA (functional assay detecting biological free fraction) were determined at 1, 3, 5 and 10 min of reflow.


RESULTS
Coronary occlusion induced myocardial lactate production in all animals. Net coronary release of total t-PA, which was 21 ng/min during control, increased rapidly during reflow with a peak after only 1 min (136 ng/min), and returned to baseline within 3 min. Net release of active t-PA mirrored the overall net release response, but fell short of statistical significance.


CONCLUSIONS
Data indicate a local myocardial profibrinolytic response following regional ischemia, which may serve as a prompt defence against coronary thromboembolic events.
Osterlund
B
B
Department of Cardiothoracic, Anesthesiology and Intensive Care, Umeå University Hospital, Sweden. barbro.osterlund.us@vll.se
Andersson
B
B
Häggmark
S
S
Jern
C
C
Johansson
G
G
Seeman-Lodding
H
H
Biber
B
B
D000818:Animals; D001783:Blood Flow Velocity; D003326:Coronary Circulation; D003331:Coronary Vessels; D004797:Enzyme-Linked Immunosorbent Assay; D006439:Hemodynamics; D019344:Lactic Acid / Q000097:blood; D017202:Myocardial Ischemia / Q000097:blood* / Q000503:physiopathology; D009206:Myocardium / Q000378:metabolism; D010100:Oxygen / Q000032:analysis; D013552:Swine; D010959:Tissue Plasminogen Activator / Q000097:blood*; D014680:Veins
D019344:Lactic Acid; D010959:Tissue Plasminogen Activator; D010100:Oxygen