Myosin-binding protein C phosphorylation, myofibril structure, and contractile function during low-flow ischemia.
BACKGROUND
Contractile dysfunction develops in the chronically instrumented canine myocardium after bouts of low-flow ischemia and persists after reperfusion. The objective of this study is to identify whether changes in the phosphorylation state of myosin-binding protein C (MyBP-C) are a potential cause of dysfunction.


RESULTS
During low-flow ischemia, MyBP-C is dephosphorylated, and the number of actomyosin cross-bridges in the central core of the sarcomere decreases as thick filaments dissemble from the periphery of the myofibril. During reperfusion, MyBP-C remains dephosphorylated, and its degradation is accelerated.


CONCLUSIONS
Dephosphorylation of MyBP-C may initiate changes in myofibril thick filament structure that decrease the interaction of myosin heads with actin thin filaments. Limiting the formation of actomyosin cross-bridges may contribute to the contractile dysfunction that is apparent after low-flow ischemia. Breakdown of MyBP-C during reperfusion may prolong myocardial stunning.
Decker
Robert S
RS
Feinberg Cardiovascular Research Institute, Tarry 12-733, Feinberg School of Medicine, Northwestern University, 303 E Chicago Ave, Chicago, IL 60611-3008, USA. r-decker@northwestern.edu
Decker
Marlene L
ML
Kulikovskaya
Irina
I
Nakamura
Sakie
S
Lee
Daniel C
DC
Harris
Kathleen
K
Klocke
Francis J
FJ
Winegrad
Saul
S
D000199:Actins / Q000378:metabolism; D000205:Actomyosin / Q000378:metabolism; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D004285:Dogs; D009200:Myocardial Contraction; D017202:Myocardial Ischemia / Q000209:etiology / Q000378:metabolism / Q000503:physiopathology*; D015425:Myocardial Reperfusion; D009210:Myofibrils / Q000648:ultrastructure*; D009218:Myosins / Q000378:metabolism; D010766:Phosphorylation; D000099163:Myosin Binding Protein C
D000199:Actins; D000205:Actomyosin; D002352:Carrier Proteins; D009218:Myosins; D000099163:Myosin Binding Protein C