Protein kinase C isoform activation and endothelin-1 mediated defects in myocyte contractility after cardioplegic arrest and reperfusion.
BACKGROUND
Endothelin-1 (ET-1) is released after hyperkalemic cardioplegic arrest (CA) and reperfusion and may contribute to contractile dysfunction. ET-1 receptor transduction causes activation of protein kinase C (PKC) isoforms, which can cause differential intracellular events. The goal of this study was to determine which PKC isoforms contribute to myocyte contractile dysfunction with ET-1 and CA.


RESULTS
Percent shortening (PERSHORT) and the time to 50% relaxation (T50) were measured in porcine (n =22) left ventricular myocytes, randomized (minimum: 30 cells/group) to normothermia: (cell media for 2 hours/37 degrees C), and CA: (2 hours/4 degrees C, 24 mEq K+ solution followed by reperfusion in cell media), ET-1/CA: (100 pM ET-1 during CA). Studies were performed in the presence and absence of PKC inhibitors (500 nM) against the classical (Beta-I, Beta-II, Gamma) and novel (Epsilon, Eta) isoforms (myocytes from a minimum of 3 pigs per inhibitor). CA reduced PERSHORT by approximately 35% from normothermia (P<0.05), which was further reduced with ET-1. PKC-Beta-II or PKC-Gamma inhibition increased PERSHORT from ET-1/CA as well as CA only (P<0.05). CA prolonged T50 by approximately 19% from normothermia (P<0.05) and was further prolonged with ET-1. Inhibition of the classical PKC isoforms reduced T50 from ET-1/CA (P<0.05). Inhibition of novel PKC isoforms did not yield similar effects on either PERSHORT or T50 with ET-1/CA.


CONCLUSIONS
Inhibition of the classical PKC isoforms relieved the negative inotropic and lusitropic effects of ET-1 after CA. These findings provide mechanistic support for developing targeted inhibitory strategies with respect to ET-1 signaling and myocyte contractile dysfunction with cardioplegic arrest and reperfusion.
Mukherjee
Rupak
R
Division of Cardiothoracic Surgery Research, 770 MUSC Complex, Suite 625, Medical University of South Carolina, Charleston, SC 29425, USA. mukherr@musc.edu
Apple
Kimberly A
KA
Squires
Christina E
CE
Kaplan
Brooke S
BS
McLean
Julie E
JE
Saunders
Stuart M
SM
Stroud
Robert E
RE
Spinale
Francis G
FG
D000818:Animals; D002478:Cells, Cultured / Q000187:drug effects / Q000201:enzymology / Q000502:physiology; D019332:Endothelin-1 / Q000494:pharmacology / Q000502:physiology*; D004789:Enzyme Activation / Q000187:drug effects; D006324:Heart Arrest, Induced / Q000009:adverse effects*; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000502:physiology; D009200:Myocardial Contraction / Q000187:drug effects / Q000502:physiology*; D015428:Myocardial Reperfusion Injury / Q000201:enzymology / Q000503:physiopathology*; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000201:enzymology* / Q000502:physiology; D010455:Peptides / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000502:physiology*; D064546:Protein Kinase C beta; D051744:Protein Kinase C-epsilon / Q000037:antagonists & inhibitors; D011897:Random Allocation; D000075370:Receptors for Activated C Kinase; D034421:Sus scrofa; D013696:Temperature
D019332:Endothelin-1; D007527:Isoenzymes; D010455:Peptides; D000075370:Receptors for Activated C Kinase; C070301:peptide I; C081975:protein kinase C eta; C087857:protein kinase C gamma; D011493:Protein Kinase C; D064546:Protein Kinase C beta; D051744:Protein Kinase C-epsilon