T. Tatsumi et al., Cytokine-induced nitric oxide production inhibits mitochondrial energy production and impairs contractile function in rat cardiac myocytes, J AM COL C, 35(5), 2000, pp. 1338-1346
Citations number
45
Categorie Soggetti
Cardiovascular & Respiratory Systems","Cardiovascular & Hematology Research
OBJECTIVES The present study examined whether nitric oxide (NO) produced by
inducible nitric oxide synthase (iNOS) can directly inhibit aerobic energy
metabolism and impair cell function in interleukin (IL)-1 beta-stimulated
cardiac myocytes.
BACKGROUND Recent reports have indicated that excessive production of NO in
duced by cytokines can disrupt cellular energy balance through the inhibiti
on of mitochondrial respiration in a variety of cells. However, it is still
largely uncertain whether the NO-induced energy depletion affects myocardi
al contractility.
METHODS Primary cultures of rat neonatal cardiac myocytes were prepared, an
d NO2-/NO3- (NOx) in the culture media was measured using Griess reagent.
RESULTS Treatment with IL-1 beta (10 ng/ml) increased myocyte production of
NOx in a time-dependent manner. The myocytes showed a concomitant signific
ant increase in glucose consumption, a marked increase in lactate productio
n, and a significant decrease in cellular ATP (adenosine 5'-triphosphate).
These metabolic changes were blocked by co-incubation with N-G-monomethyl-L
-arginine(L-NMMA), an inhibitor of NO synthesis. Sodium nitroprusside (SNP)
, a NO donor, induced similar metabolic changes in a dose-dependent manner,
but 8-bromo-cyclic guanosine 3',5'-monophosphate (8-bromo-cGMP), a cGMP do
nor, had no effect on these parameters. The activities of the mitochondrial
iron-sulfur enzymes, NADH-CoQreductase and succinate-CoQ reductase, but no
t oligomycin-sensitive ATPase, were significantly inhibited in the IL-1 bet
a or SNP-treated myocytes. Both IL-1 beta and SNP significantly elevated ma
ximum diastolic potential, reduced peak calcium current (Ic,), and lowered
contractility in the myocytes. KT5823, an inhibitor of cGMP-dependent prote
in kinase, did not block the electrophysiological and contractility effects
,
CONCLUSIONS These data suggest that IL-1 beta-induced NO production in card
iac myocytes lowers energy production and myocardial contractility through
a direct attack on the mitochondria, rather than through cGMP-mediated path
ways. (J Am coil Cardiol 2000;35:1338-46) (C) 2000 by the American College
of Cardiology.