Endotoxin-induced myocardial dysfunction: evidence for a role of sphingosine production.
OBJECTIVE
To determine whether sphingomyelinase pathway activation would participate in myocardial depression induced by endotoxin.


METHODS
Randomized, controlled trial.


METHODS
Experimental laboratory.


METHODS
Male Sprague-Dawley rats, isolated rat heart, and cardiac myocytes.


METHODS
Cardiovascular function was evaluated in rats injected with saline, endotoxin (10 mg/kg, intravenously), and N-oleoylethanolamine (NOE; 10 mg/kg, intravenously). In ex vivo experiments, isolated rat hearts were perfused with endotoxin (5 microg/mL). For pharmacologic intervention, NOE (1 micromol/L) was admixed to the perfusate 20 mins before endotoxin. In in vitro experiments, ventricular myocytes were incubated with sphingosine (20 microM). Myocyte cell shortening and calcium transient were measured. Mitochondrial membrane potential was measured using the cationic dye tetramethylrhodamine methylester fluorescence technique.


RESULTS
Endotoxin treatment at 4 hrs did not alter mean arterial pressure and abdominal blood flow compared with control rats. Left ventricle developed pressure (LVDP) and its first derivatives (i.e., maximal and minimal change in pressure over time [dP/dtmax and dP/dtmin]) were decreased after 4 hrs in endotoxin-treated rats compared with control rats. NOE (10 mg/kg) treatment largely prevented left ventricular systolic function alterations of endotoxin-treated hearts (n = 6 in each group). In isolated rat heart, endotoxin (5 microg/mL) caused increases in tumor necrosis factor-alpha perfusate concentration and delayed depression of LVDP, dP/dtmax, and dP/dtmin after 60 mins, which was partially abrogated in the presence of the ceramidase inhibitor NOE (1 micromol/L). Sphingosine (20 microM) caused decreases in cell fractional shortening, calcium transient, and mitochondrial membrane potential of cardiac myocytes.


CONCLUSIONS
These observations suggest that the sphingomyelinase pathway participates in endotoxin-induced myocardial depression.
Favory
Raphael
R
Université de Lille 2, Faculté de Médecine, Lille, France.
Lancel
Steve
S
Marchetti
Philippe
P
Mordon
Serge
S
Chopin
Claude
C
Formstecher
Pierre
P
Neviere
Remi
R
D000818:Animals; D063388:Endocannabinoids; D004731:Endotoxins / Q000502:physiology*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D004983:Ethanolamines / Q000494:pharmacology; D006321:Heart / Q000187:drug effects; D066298:In Vitro Techniques; D008297:Male; D032342:Muscle Cells / Q000187:drug effects / Q000502:physiology; D009829:Oleic Acids; D011897:Random Allocation; D051381:Rats; D017207:Rats, Sprague-Dawley; D012770:Shock, Cardiogenic / Q000209:etiology*; D013110:Sphingosine / Q000096:biosynthesis / Q000502:physiology*
D063388:Endocannabinoids; D004731:Endotoxins; D004791:Enzyme Inhibitors; D004983:Ethanolamines; D009829:Oleic Acids; C033595:N-oleoylethanolamine; D013110:Sphingosine