Alterations in protein kinase A and protein kinase C levels in heart failure due to genetic cardiomyopathy.
BACKGROUND
It is becoming evident that both cardiac and skeletal muscles are affected in congestive heart failure. Although protein kinases are known to regulate cardiac function, very little is known about their status in cardiac and skeletal muscles during the development of congestive heart failure.


OBJECTIVE
To determine changes in the activities and protein levels of protein kinase A (PKA) and protein kinase C (PKC) in cardiac and skeletal muscles in congestive heart failure due to genetic cardiomyopathy on the basis that PKA and PKC are crucial for protein phosphorylation.


METHODS
Genetically cardiomyopathic UM-X7.1 hamsters (250 to 300 days old) and age-matched Syrian hamsters were used in this study. PKA and PKC activities were assayed by measuring 32P from [gamma-32P]ATP incorporated into synthetic substrates. Relative protein contents of these protein kinases were obtained by using immunoblot analysis in control and failing hamster hearts and skeletal muscles.


RESULTS
PKC activity was significantly increased in the failing hearts compared with control preparations. The relative protein contents of cytosolic PKC-alpha and -epsilon , and of particulate PKC-epsilon isozymes were significantly increased in failing hearts. PKC activity was also markedly increased in cardiomyopathic skeletal muscle. Furthermore, PKA activity and protein level in both cardiac and skeletal muscles were significantly increased in the failing heart group compared with control values.


CONCLUSIONS
Increased PKC activity in heart failure may be due to changes in PKC-alpha and -epsilon isozymes in cardiomyopathic hearts. Alterations of PKA and PKC in congestive heart failure were not limited to the heart because similar changes in enzyme activities were evident in skeletal muscle.
Wang
J
J
St Boniface Hospital Research Centre, Winnipeg, Canada.
Liu
X
X
Arneja
A S
AS
Dhalla
N S
NS
D000818:Animals; D002311:Cardiomyopathy, Dilated / Q000235:genetics* / Q000378:metabolism; D006224:Cricetinae; D017868:Cyclic AMP-Dependent Protein Kinases / Q000032:analysis*; D004195:Disease Models, Animal; D006333:Heart Failure / Q000235:genetics* / Q000378:metabolism; D006801:Humans; D008297:Male; D008647:Mesocricetus; D011493:Protein Kinase C / Q000032:analysis*
D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C