Tissue plasminogen activator attenuates ventilator-induced lung injury in rats.
OBJECTIVE
To test the hypothesis that the tissue plasminogen activator (tPA) may counteract the inhibitory effect of plasminogen activator inhibitors (PAI) and attenuate lung injury in a rat model of ventilator-induced lung injury (VILI).


METHODS
Adult male Sprague-Dawley rats were ventilated with a HVZP (high-volume zero PEEP) protocol for 2 h at a tidal volume of 30 mL/kg, a respiratory rate of 25 breaths/min, and an inspired oxygen fraction of 21%. The rats were divided into 3 groups (n=7 for each): HVZP+tPA group receiving tPA (1.25 mg/kg, iv) 15 min before ventilation, HVZP group receiving HVZP+vehicle injection, and a control group receiving no ventilation. After 2 h of ventilation, the rats were killed; blood and lungs were collected for biochemical and histological analyses.


RESULTS
HVZP ventilation significantly increased total protein content and the concentration of macrophage inflammatory protein-2 (MIP-2) in the bronchoalveolar lavage fluid (BALF) as well as the lung injury score. Rats that received HVZP ventilation had significantly higher lung PAI-1 mRNA expression, plasma PAI-1 and plasma D-dimer levels than the control animals. tPA treatment significantly reduced the BALF total protein and the lung injury score as compared to the HVZP group. tPA treatment also significantly decreased the plasma D-dimer levels and the HVZP ventilation-induced lung vascular fibrin thrombi. tPA treatment showed no effect on MIP-2 level in BALF.


CONCLUSIONS
These results demonstrate that VILI increases lung PAI-1 mRNA expression, plasma levels of PAI-1 and D-dimers, lung injury score and vascular fibrin deposition. tPA can attenuate VILI by decreasing capillary-alveolar protein leakage as well as local and systemic coagulation as shown by decreased lung vascular fibrin deposition and plasma D-dimers.
Graduate Institute of Clinical Medicine, College of Medicine, Taipei Medical University, Taipei, Taiwan, China.
Liang-ti
LT
Huang
Hsiu-chu
HC
Chou
Leng-fang
LF
Wang
Chung-ming
CM
Chen
D000818:Animals; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D013990:Tidal Volume / Q000187:drug effects / Q000502:physiology; D010959:Tissue Plasminogen Activator / Q000494:pharmacology / Q000627:therapeutic use*; D055397:Ventilator-Induced Lung Injury / Q000473:pathology* / Q000503:physiopathology / Q000517:prevention & control*
D010959:Tissue Plasminogen Activator