Reduced serine-16 and threonine-17 phospholamban phosphorylation in stunning of conscious dogs: no evidence for any involvement of protein kinase A or protein phosphatases.
OBJECTIVE
Cardiac stunning is the consequence of a brief cardiac ischemia. The underlying mechanism is not completely understood.


METHODS
Here we induced cardiac transient ischemia in conscious instrumented dogs by means of an occluder in the left anterior descending coronary artery (LAD). Contractile performance, monitored by ultrasound crystals, was reduced during and after ischemia in the LAD area. For control in the same animals cardiac performance was measured in the area of left circumflex coronary artery (Ramus circumflexus, RCx). In the RCx area, no decline in contractility was noted. Tissue was obtained from stunned LAD area and from control areas (RCx).


RESULTS
Phospholamban phosphorylation on both serine-16 and threonine-17 was reduced in LAD areas compared to RCx areas. Reduced phosphorylation of PLB is known to inhibit cardiac contractility. While phosphorylation of PLB was reduced, the activity of the appropriate protein phosphatases and protein kinases was not different between tissue obtained from LAD or RCx areas.


CONCLUSIONS
Reduced formation of cAMP might underlie the contractile dysfunction in myocardial stunning.
Weber
Th
T
Klinik und Poliklinik für Anästhesiologie und Operative Intensivmedizin, Universitätsklinikum Münster, Westfälische Wilhelms-Universität, Albert-Schweitzer-Str. 33, 48149, Münster, Germany.
Neumann
J
J
Meissner
A
A
Grosse Hartlage
M
M
Van Aken
H
H
Hanske
G
G
Schmitz
W
W
Boknik
P
P
D000818:Animals; D015153:Blotting, Western; D002135:Calcium-Binding Proteins / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D004285:Dogs; D004591:Electrophoresis, Polyacrylamide Gel; D017682:Myocardial Stunning / Q000378:metabolism*; D010749:Phosphoprotein Phosphatases / Q000378:metabolism; D010766:Phosphorylation; D012694:Serine / Q000378:metabolism*; D013912:Threonine / Q000378:metabolism*; D000099211:Phospholamban
D002135:Calcium-Binding Proteins; D017868:Cyclic AMP-Dependent Protein Kinases; D010749:Phosphoprotein Phosphatases; D012694:Serine; D013912:Threonine; D000099211:Phospholamban