Surgical stress induces acute coronary release of tissue-type plasminogen activator in the pig.
BACKGROUND
Tissue-type plasminogen activator (t-PA) is an endothelium derived key enzyme in the initiation of endogenous fibrinolysis. Acute regulated release of active t-PA occurs within minutes in response to threatening thrombotic vessel occlusion. The aim of this study was to investigate the impact of surgical stimulation on the kinetics of t-PA release in the coronary vascular bed in the pig.


METHODS
In anaesthetised pigs (n=16), arterio-venous concentration gradients of t-PA, and plasma flows (retrograde thermodilution) were obtained across the coronary vascular bed before (control) and at 1, 3, 5 and 10 min after sternotomy.


RESULTS
At control, no significant coronary net flux (release or uptake) of t-PA was observed, while sternotomy induced a rapid net release of total t-PA (132.6 ng x min(-1)), with an associated increase in active t-PA (93.6 ng x min(-1)). This response, evident already after 1 min, showed a peak at 5 min and returned towards baseline levels within 10 min. No concurrent alterations in aortic levels of active t-PA were found and haemodynamic variables were unaltered.


CONCLUSIONS
The rapidly increasing and transient net coronary release of t-PA after sternotomy suggests that the endothelium actively promotes local endogenous fibrinolysis during surgery. Such events could reflect a dynamic responsiveness to protect the coronary circulation during stress.
Osterlund
B
B
Department of Surgical and Perioperative Science, Anaesthesiology and Intensive Care, Umeå University, Sweden. barbro.osterlund.us@vll.se
Holmgren
A
A
Häggmark
S
S
Jern
C
C
Johansson
G
G
Seeman-Lodding
H
H
Biber
B
B
D000818:Animals; D003331:Coronary Vessels / Q000378:metabolism*; D013249:Sternum / Q000601:surgery*; D013552:Swine; D010959:Tissue Plasminogen Activator / Q000097:blood / Q000378:metabolism*
D010959:Tissue Plasminogen Activator