A. Khedara et al., FEEDING RATS THE NITRIC-OXIDE SYNTHASE INHIBITOR, L-N(OMEGA)NITROARGININE, ELEVATES SERUM TRIGLYCERIDE AND CHOLESTEROL AND LOWERS HEPATIC FATTY-ACID OXIDATION, The Journal of nutrition, 126(10), 1996, pp. 2563-2567
This study was conducted to examine whether nitric oxide regulates lip
id metabolism. In Experiment 1, rats were fed for 5 wk diets with or w
ithout 0.2 g/kg L-N(omega)nitroarginine (L-NNA), a specific inhibitor
of nitric oxide synthase, that were or were not supplemented with 40 g
/kg L-arginine. Rats fed L-NNA had significantly higher concentrations
of serum triglyceride and total cholesterol, lower concentrations of
serum nitrate, and a lower ratio of HDL-cholesterol to total cholester
ol than rats fed the basal diet. These alterations were suppressed by
supplementing L-arginine to the L-NNA-containing diet. In Experiment 2
, rats were fed diets with or without 0.2 g/kg L-NNA. Dietary L-NNA el
evated serum concentrations of free fatty acids without affecting thos
e of ketone bodies. L-NNA lowered the activity of hepatic carnitine pa
lmitoyltransferase, the rate-limiting enzyme of fatty acid oxidation,
but did not affect activities of hepatic glucose-6-phosphate dehydroge
nase and fatty acid synthase which are lipogenic enzymes. These result
s suggest that the lower nitric oxide level in rats fed L-NNA leads to
hyperlipidemia and that the elevation in serum triglyceride might be
due to reduced fatty acid oxidation.