Subcellular distribution of protein kinase C isozymes during cardioplegic arrest.
BACKGROUND
On the basis of the hypothesis that cardioplegia-associated myocardial depression was due to activation of protein kinase C, we examined whether specific protein kinase C isozymes would translocate to a cellular fraction containing myofilaments.


METHODS
Isolated rat hearts were perfused with Krebs-Ringer bicarbonate buffer for 30 minutes and arrested with 4 degrees C St Thomas No. 2 cardioplegic solution for 0 to 120 minutes (n = 5 per group). The 3 fractions of the left ventricle tissue represented the myofibrillar/nuclear fraction (P1), membranes (P2), and cytosol (supernatant). The distributions of protein kinase C isozymes alpha, delta, epsilon, and eta were examined after separation by electrophoresis, immunoblotting/chemiluminescence, and densitometry.


RESULTS
A significant increase in protein kinase C-delta in the P1 fraction was detected after 5 minutes of cardioplegic arrest and remained increased for 60 minutes. Increases in P1 protein kinase C-alpha and -epsilon were seen transiently at 5 minutes, and protein kinase C-epsilon demonstrated a secondary increase in P1 at 30 to 60 minutes. There was also a significant relative increase in protein kinase C-alpha and protein kinase C-delta in the P2 fraction after 60 minutes of cardioplegia.


CONCLUSIONS
These data are consistent with our hypothesis that activation of protein kinase C isozymes is associated with altered myofilament function after cardioplegic arrest.
Jonjev
Zivojin S
ZS
Research Service, West Side Veterans Administration Medical Center, Chicago, IL, USA.
Schwertz
Dorie W
DW
Beck
Jennifer M
JM
Ross
James D
JD
Law
William R
WR
D000818:Animals; D015153:Blotting, Western; D002458:Cell Fractionation; D002467:Cell Nucleus / Q000201:enzymology; D003600:Cytosol / Q000201:enzymology; D006324:Heart Arrest, Induced; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000201:enzymology*; D006439:Hemodynamics; D066298:In Vitro Techniques; D007425:Intracellular Membranes / Q000201:enzymology; D007527:Isoenzymes / Q000032:analysis; D008297:Male; D009210:Myofibrils / Q000201:enzymology; D011493:Protein Kinase C / Q000032:analysis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014463:Ultrasonography
D007527:Isoenzymes; D011493:Protein Kinase C