Oxygen free radical regulation of rat splanchnic blood flow.
BACKGROUND
The role of oxygen-derived free radicals on splanchnic prostaglandin (PGI2) synthesis and superior mesenteric artery (SMA) blood flow was examined during acute hemorrhage.


METHODS
Sprague-Dawley rats were hemorrhaged to 30 mm Hg for 5, 30, or 45 minutes without (SK5, SK30, and SK45) or with (SK5 + R, SK30 + R, and SK45 + R) blood reperfusion. The SK30 + R and SK45 + R groups were treated with or without superoxide dismutase (10,000 units/kg intravenously). In vivo SMA blood flow was measured continuously for 100 minutes by a transonic flow probe, or in other groups the in vitro-perfused SMA and its end-organ intestine (SV+SI) were assayed for release of PGI2 by radioimmunoassay after 15 and 30 minutes of perfusion.


RESULTS
Acute hemorrhage at all time periods increased SV+SI PGI2 release twofold to threefold compared with sham animals (p less than 0.01), which was abolished after blood reperfusion. SMA blood flow was decreased by 79.6% +/- 3.3% and 88.2% +/- 1.4% in the SK30 + R and SK45 + R groups compared with the sham animals (p less than 0.01). Superoxide dismutase treatment restored both SV+SI release of PGI2 after SK and SMA blood flow to control levels.


CONCLUSIONS
Oxygen-derived free radicals locally produced during SK30 + R and SK45 + R inhibited splanchnic PGI2 synthesis, which contributed to decreased splanchnic blood flow.
Myers
S I
SI
Department of Surgery, University of Texas Southwestern Medical School, Dallas 75235.
Hernandez
R
R
D000208:Acute Disease; D000818:Animals; D001775:Blood Circulation; D011464:Epoprostenol / Q000378:metabolism; D005609:Free Radicals; D006470:Hemorrhage / Q000503:physiopathology; D007413:Intestinal Mucosa / Q000378:metabolism; D008638:Mesenteric Arteries / Q000378:metabolism; D010100:Oxygen / Q000502:physiology*; D011863:Radioimmunoassay; D051381:Rats; D011919:Rats, Inbred Strains; D013152:Splanchnic Circulation / Q000187:drug effects / Q000502:physiology*; D013482:Superoxide Dismutase / Q000494:pharmacology
D005609:Free Radicals; D011464:Epoprostenol; D013482:Superoxide Dismutase; D010100:Oxygen