Oscillation in the activities of MEK/ERK1/2 during cardiopulmonary bypass in pigs.
BACKGROUND
Because cardiopulmonary bypass (CPB) is associated with edema and vasoreactive dysfunction and ERK1/2 pathway is involved in vascular contractility and permeability, a time course study was performed to monitor MEK/ERK1/2/Elk-1 activities during CPB.


METHODS
Pigs were subjected to normothermic CPB for 90 minutes followed by post-CPB perfusion for 180 minutes. Atrial myocardium was sampled before CPB, 5 minutes after CPB onset, 5 minutes after weaning from CPB, and at the end of post-CPB. Skeletal muscle and mesenteric vessels samples were harvested before CPB, 5 minutes after CPB institution, and every 30 minutes thereafter to the end of post-CPB. Samples were analyzed by immunoblotting and immunofluorescence microscopy with the use of specific antibodies against active (phosphorylated) forms of ERK1/2, MEK1/2, and Elk-1.


RESULTS
Pigs that were subjected to CPB showed an increase in phospho-ERK1/2 after 30 minutes of CPB, followed by a decrease after 90 minutes. Another phosphorylation peak was observed 30 to 60 minutes of post-CPB, followed by a decrease to below baseline at the end of reperfusion. MEK1/2 and Elk-1 activation profiles paralleled ERK1/2 activity peaks. Control samples showed no significant increase above basal levels.


CONCLUSIONS
Activation of MEK/ERK1/2/Elk-1 pathways closely follows major CPB surgical manipulations (institution and termination) and could be related to morbidity during and after CPB.
Araujo
E G
EG
Division of Cardiothoracic Surgery, Department of Surgery, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA 02115, USA.
Bianchi
C
C
Faro
R
R
Sellke
F W
FW
D000818:Animals; D001784:Blood Gas Analysis; D001794:Blood Pressure; D015153:Blotting, Western; D002315:Cardiopulmonary Bypass; D004268:DNA-Binding Proteins; D004789:Enzyme Activation / Q000502:physiology; D005260:Female; D005455:Fluorescent Antibody Technique; D006325:Heart Atria / Q000201:enzymology; D020935:MAP Kinase Signaling System / Q000502:physiology*; D008297:Male; D008638:Mesenteric Arteries / Q000201:enzymology; D008642:Mesenteric Veins / Q000201:enzymology; D019950:Mitogen-Activated Protein Kinase 1 / Q000032:analysis / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000032:analysis / Q000378:metabolism; D018482:Muscle, Skeletal / Q000201:enzymology; D009206:Myocardium / Q000201:enzymology; D010507:Periodicity; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000032:analysis / Q000378:metabolism*; D011518:Proto-Oncogene Proteins / Q000378:metabolism; D013552:Swine; D014157:Transcription Factors; D050807:ets-Domain Protein Elk-1
D004268:DNA-Binding Proteins; D011518:Proto-Oncogene Proteins; D014157:Transcription Factors; D050807:ets-Domain Protein Elk-1; D017346:Protein Serine-Threonine Kinases; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases