Ventricular myocyte caspases are directly responsible for endotoxin-induced cardiac dysfunction.
BACKGROUND
Although most of the deleterious effects of sepsis-induced apoptosis have been attributed to increased lymphocyte cell death, caspase activation may directly alter cell function of different organ systems. We postulated that left ventricular (LV) cardiomyocyte caspase activation is directly involved in sepsis-induced heart contractile dysfunction.


RESULTS
LV cardiomyocytes isolated 4 hours after rat treatment with endotoxin injection (10 mg/kg) displayed major reductions in contractile reserve and myofilament response to Ca2+. Concomitantly, endotoxin also induced increases in LV cardiomyocyte caspase-3, -8, and -9-like activities, which were associated with sarcomeric structure destruction and cleavage of components of the cardiac myofilament. Interestingly, zVAD.fmk treatment of septic rat prevented LV cardiomyocyte contractile dysfunction, reductions in myofilament response to calcium, troponin T cleavage, and sarcomere destruction. Serum (10%) of endotoxin-treated rats induced contractile dysfunction, caspase-3-like activity increase, and troponin T cleavage of naive LV cardiomyocytes. The effects of septic serum were prevented in LV cardiomyocytes isolated from zVAD.fmk- or zDEVD.cmk-treated rats or LV cardiomyocytes preincubated with zVAD.fmk or zDEVD.cmk.


CONCLUSIONS
The results show an important relationship between endotoxin-induced caspase activation and reduced contractile reserve and sarcomere disarray at the level of single LV cardiomyocytes.
Lancel
Steve
S
EA 2689, CHRU, and Université de Lille 2, IFR 114 IMPRT, Lille, France.
Joulin
Olivier
O
Favory
Raphael
R
Goossens
Jean Francois
JF
Kluza
Jérome
J
Chopin
Claude
C
Formstecher
Pierre
P
Marchetti
Philippe
P
Neviere
Remi
R
D008841:Actin Cytoskeleton / Q000473:pathology; D000818:Animals; D002118:Calcium / Q000494:pharmacology; D020169:Caspases / Q000378:metabolism*; D004731:Endotoxins / Q000009:adverse effects*; D006331:Heart Diseases / Q000209:etiology* / Q000473:pathology; D006352:Heart Ventricles / Q000201:enzymology / Q000473:pathology*; D008297:Male; D009200:Myocardial Contraction; D032383:Myocytes, Cardiac / Q000201:enzymology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012518:Sarcomeres / Q000473:pathology; D018805:Sepsis / Q000150:complications / Q000473:pathology / Q000503:physiopathology*; D020107:Troponin T / Q000378:metabolism
D004731:Endotoxins; D020107:Troponin T; D020169:Caspases; D002118:Calcium