COX-2-dependent and potentially cardioprotective effects of negative inotropic substances released after ischemia.
During reperfusion, cardiodepressive factors are released from isolated rat hearts after ischemia. The present study analyzes the mechanisms by which these substances mediate their cardiodepressive effect. After 10 min of global stop-flow ischemia, rat hearts were reperfused and coronary effluent was collected over a period of 30 s. We tested the effect of this postischemic effluent on systolic cell shortening and Ca(2+) metabolism by application of fluorescence microscopy of field-stimulated rat cardiomyocytes stained with fura-2 AM. Cells were preincubated with various inhibitors, e.g., the cyclooxygenase (COX) inhibitor indomethacin, the COX-2 inhibitors NS-398 and lumiracoxib, the COX-1 inhibitor SC-560, and the potassium (ATP) channel blocker glibenclamide. Lysates of cardiomyocytes and extracts from whole rat hearts were tested for expression of COX-2 with Western blot analysis. As a result, in contrast to nonischemic effluent (control), postischemic effluent induced a reduction of Ca(2+) transient and systolic cell shortening in the rat cardiomyocytes (P < 0.001 vs. control). After preincubation of cells with indomethacin, NS-398, and lumiracoxib, the negative inotropic effect was attenuated. SC-560 did not influence the effect of postischemic effluent. The inducibly expressed COX-2 was detected in cardiomyocytes prepared for fluorescence microscopy. The effect of postischemic effluent was eliminated with applications of glibenclamide. Furthermore, postischemic effluent significantly reduced the intracellular diastolic and systolic Ca(2+) increase (P < 0.01 vs. control). In conclusion, the cardiodepressive effect of postischemic effluent is COX-2 dependent and protective against Ca(2+) overload in the cells.
Innere Klinik B, Ernst-Moritz-Arndt-Universität, Greifswald, Germany.
Katrin
K
Birkenmeier
Alexander
A
Staudt
Wolf-Hagen
WH
Schunck
Irka
I
Janke
Corina
C
Labitzke
Thomas
T
Prange
Christiane
C
Trimpert
Thomas
T
Krieg
Martin
M
Landsberger
Verena
V
Stangl
Stephan B
SB
Felix
D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D020013:Calcium Signaling / Q000187:drug effects; D002478:Cells, Cultured; D051546:Cyclooxygenase 2 / Q000378:metabolism*; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D003864:Depression, Chemical; D003971:Diastole; D004008:Diclofenac / Q000031:analogs & derivatives / Q000494:pharmacology; D004195:Disease Models, Animal; D005905:Glyburide / Q000494:pharmacology; D066298:In Vitro Techniques; D007213:Indomethacin / Q000494:pharmacology; D009200:Myocardial Contraction / Q000187:drug effects; D017202:Myocardial Ischemia / Q000201:enzymology / Q000378:metabolism* / Q000503:physiopathology; D009206:Myocardium / Q000201:enzymology / Q000378:metabolism*; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D009578:Nitrobenzenes / Q000494:pharmacology; D010477:Perfusion; D026902:Potassium Channel Blockers / Q000494:pharmacology; D015221:Potassium Channels / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D015427:Reperfusion Injury / Q000201:enzymology / Q000378:metabolism / Q000503:physiopathology / Q000517:prevention & control*; D012107:Research Design; D013449:Sulfonamides / Q000494:pharmacology; D013599:Systole; D013997:Time Factors
D016861:Cyclooxygenase Inhibitors; D009578:Nitrobenzenes; D026902:Potassium Channel Blockers; D015221:Potassium Channels; D013449:Sulfonamides; C080955:N-(2-cyclohexyloxy-4-nitrophenyl)methanesulfonamide; D004008:Diclofenac; D000255:Adenosine Triphosphate; D051546:Cyclooxygenase 2; C489691:Ptgs2 protein, rat; D005905:Glyburide; C473384:lumiracoxib; D007213:Indomethacin