TITLE

Chronic clofibrate administration prevents salineinduced endothelial dysfunction and oxidative stress in young Sprague-Dawley rats

AUTHOR(S)
Sankaralingam, Sowndramalingam; Desai, Kaushik M.; Wilson, Thomas W.
PUB. DATE
April 2008
SOURCE
Clinical & Investigative Medicine;Apr2008, Vol. 31 Issue 2, pE62
SOURCE TYPE
Academic Journal
DOC. TYPE
Article
ABSTRACT
Purpose: High salt intake causes hypertension and endothelial dysfunction in young Sprague-Dawley rats. Clofibrate (clof) prevents this salt induced hypertension. We asked whether clof can prevent salt-induced endothelial dysfunction, and if so, its mechanism. We also questioned whether high salt intake can induce endothelial dysfunction without hypertension in older animals. Methods: Young (Y, 5 weeks) and old (O, 53 weeks) male Sprague-Dawley rats were given either vehicle (Con, 20 mM Na2CO3) or 0.9% NaCl (Sal) to drink for three weeks. Some young rats received clof (80 mg/d) in their drinking fluid. After three weeks, we measured mean arterial pressure (MAP), endothelial function, by comparing hypotensive responses to acetylcholine (ACh, endothelium dependent) and sodium nitroprusside (SNP, endothelium independent), plasma total nitrite+nitrate levels (PNOx), by the Griess reaction, and aortic superoxide production by lucigenin chemiluminescence. Results: Carotid artery MAP did not change in O. Sal-Y developed hypertension: 133±3 vs. 114±2 mmHg, P<0.001, which was prevented by clof: 105±2 mmHg . ACh induced a similar dose dependent hypotensive response in Con-O and Sal-O that was inhibited by L-NAME (100mg/kg i.v.). Responses to ACh were blunted in Sal-Y but not in Con-Y. Further, L-NAME inhibited ACh responses only in Con-Y. The response to SNP was similar in all animals. Importantly, the ACh-induced hypotensive reresponse was potentiated in clof+Sal-Y, an effect which was attenuated by blocking calcium-activated potassium channels (KCa) with a combination of apamin (50 μg/kg i.v.) + charybdotoxin (50 μg/kg i.v.), but not by L-NAME. PNOx was reduced in Sal-Y compared to Con-Y (2.09±0.26 vs. 4.8±0.35 ??M, P<0.001), but not in Sal-O. Aortic superoxide production was higher (P<0.001) in Sal-Y (2388±40 milliunits/mg/min) than Sal-O (1107±159 milliunits/mg/min), but was reduced by clof (1378±64 milliunits/mg/min; P<0.001). Conclusions: High salt intake increases oxidative stress in young animals, leading to impaired nitric oxide activity and endothelial dysfunction. Clofibrate prevents endothelial dysfunction partly through reduced O2∙- formation but mainly via selective activation of KCa channels. Older animals are resistant to both salt induced hypertension and oxidative stress.
ACCESSION #
31872260

 

Related Articles

Share

Read the Article

Courtesy of THE LIBRARY OF VIRGINIA

Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics