A mechanism of oxygen free radical production in the Dahl hypertensive rat.
OBJECTIVE
To determine if oxygen free radicals derived from xanthine oxidase are involved in the development of salt-induced hypertension. Enhanced production of oxygen free radicals may play a role in hypertension by affecting vascular smooth muscle contraction and provide a mechanism for lesion formation.


METHODS
Dahl salt-sensitive (Dahl-S) and salt-resistant (Dahl-R) rats were fed either a low-salt, high-salt or high-salt + tungsten diet for 4 wk. In vivo production of superoxide (O2-) was detected by the reduction of a tetranitroblue tetrazolium (TNBT) dye in the rat mesentery, while plasma hydrogen peroxide (H2O2) production levels were determined using a modified electrochemical electrode technique.


RESULTS
The tungsten diet lowered the blood pressure of Dahl-S rats compared to high-salt-treated Dahl-S rats, but had no effect on blood pressure in Dahl-R rats. Light absorption of formazan deposits revealed that tungsten-treated Dahl-S rats had reduced TNBT staining along the endothelium of arterioles and venules compared to hypertensive, high-salt-treated Dahl-S rats. In addition, tungsten-treated Dahl-S rats had a lower plasma H2O2 concentration compared to hypertensive, high-salt-treated Dahl-S rats.


CONCLUSIONS
These findings indicate that xanthine oxidase-derived oxygen free radicals are involved in the pathogenesis of salt-induced hypertension.
Swei
A
A
Department of Bioengineering and Institute for Biomedical Engineering, University of California at San Diego, La Jolla 92093-0412, USA.
Lacy
F
F
Delano
F A
FA
Parks
D A
DA
Schmid-Schönbein
G W
GW
D000818:Animals; D001794:Blood Pressure; D004032:Diet; D006861:Hydrogen Peroxide / Q000097:blood; D007202:Indicators and Reagents; D008297:Male; D018482:Muscle, Skeletal / Q000201:enzymology; D051381:Rats; D020303:Rats, Inbred Dahl / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism*; D013481:Superoxides / Q000378:metabolism; D013778:Tetrazolium Salts; D017973:Tungsten Compounds / Q000378:metabolism; D014969:Xanthine Oxidase / Q000037:antagonists & inhibitors / Q000378:metabolism
D007202:Indicators and Reagents; D017382:Reactive Oxygen Species; D013778:Tetrazolium Salts; D017973:Tungsten Compounds; D013481:Superoxides; C025399:sodium tungstate(VI); D006861:Hydrogen Peroxide; D014969:Xanthine Oxidase