Phorbol ester, but not ischemic preconditioning, activates protein kinase D in the rat heart.
The signal transduction pathways that mediate the cardioprotective effects of ischemic preconditioning remain unclear. Here we have determined the role of a novel kinase, protein kinase D (PKD), in mediating preconditioning in the rat heart. Isolated rat hearts (n=6/group) were subjected to either: (i) 36 min aerobic perfusion (control); (ii) 20 min aerobic perfusion plus 3 min no-flow ischemia, 3 min reperfusion, 5 min no-flow ischemia, 5 min reperfusion (ischemic preconditioning); (iii) 20 min aerobic perfusion plus 200 nmol/l phorbol 12-myristate 13-acetate (PMA) given as a substitute for ischemic preconditioning. The left ventricle then was excised, homogenized and PKD immunoprecipitated from the homogenate. Activity of the purified kinase was determined following bincubation with [gamma32P]-ATP+/-syntide-2, a substrate for PKD. Significant PKD autophosphorylation and syntide-2 phosphorylation occurred in PMA-treated hearts, but not in control or preconditioned hearts. Additional studies confirmed that recovery of LVDP was greater and initiation of ischemic contracture and time-to-peak contracture were less, in ischemic preconditioned hearts compared with controls (P<0.05). Our results suggest that the early events that mediate ischemic preconditioning in the rat heart occur via a PKD-independent mechanism.
Brooks
G
G
Cardiovascular Research, The Rayne Institute, St Thomas' Hospital, London SE1 7EH, UK.
Goss
M W
MW
Rozengurt
E
E
Galiñanes
M
M
D016475:3T3 Cells; D000332:Aerobiosis; D000818:Animals; D002478:Cells, Cultured; D004789:Enzyme Activation / Q000187:drug effects; D005347:Fibroblasts; D006321:Heart / Q000187:drug effects*; D036341:Intercellular Signaling Peptides and Proteins; D019157:Ischemic Preconditioning, Myocardial; D008297:Male; D051379:Mice; D017202:Myocardial Ischemia / Q000201:enzymology; D009206:Myocardium / Q000201:enzymology*; D010455:Peptides / Q000378:metabolism; D010477:Perfusion; D010766:Phosphorylation; D011493:Protein Kinase C; D011499:Protein Processing, Post-Translational; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D015398:Signal Transduction / Q000187:drug effects; D013268:Stimulation, Chemical; D013347:Subcellular Fractions / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*
D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides; C063391:syntide-2; C089212:protein kinase D; D017346:Protein Serine-Threonine Kinases; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate