The effects of oxygen on regional hemodynamics in hemorrhagic
shock.
Bitterman, Haim, Vera Brod, Giora Weisz, Daniel Kushnir, & Noemi
Bitterman.
Department of Internal Medicine A, Carmel Medical Center, Rappaport
Family Institute for Research in the Medical Sciences. Faculty of
Medicine. Technion-Israel Institute of Technology, Haifa, 34362, and
Israel Naval Medical Institute, Medical Corps, Israel Defense Forces,
Israel
APStracts 2:0567H, 1995.
This study investigated mechanisms of the hemodynamic effects of
oxygen in hemorrhagic shock induced by bleeding 30% of the total
blood volume in anesthetized rats. Ultrasonic flowmeter was used to
monitor regional blood flow. Changes in tissue perfusion were
assessed by the laser doppler technique. The inhalation of 100%
oxygen induced a significant increase in MABP and vascular resistance
in the hind quarters, with a concomitant decrease in blood flow in
the distal aorta and the biceps femoris muscle. In contrast, oxygen
did not change vascular resistance in the SMA and renal beds, and
induced a significant increase in blood flow to the renal artery, SMA
and small bowel in hemorrhaged rats. L-arginine (100 mg/kg i.v.) but
not D-arginine or the vehicle (0.9% NaCl) completely abolished the
effects of oxygen on blood pressure and reversed its effects on blood
flow and resistance in the hind quarters and biceps femoris muscle.
Administration of the NO-synthase inhibitor L-NAME (50 mg/kg i.v.)
significantly increased MABP and the resistance in the three vascular
beds. Pre-treatment of hemorrhaged rats with superoxide dismutase
(SOD) mimic, the nitroxide stable radical 2,2,6,6,-tetramethyl
-piperi-dinoxil (TEMPO 5mg/kg i.v.) resulted in significantly
diminished effects of oxygen on hind quarter hemodynamics. These
results demonstrate a differential effect of oxygen, which increases
vascular resistance in the hind quarters without a significant effect
in the splanchnic and renal beds, thus favoring an increase in
splanchnic and renal perfusion. It is suggested that inactivation of
NO by reactive oxygen species may underlie the effects of oxygen on
hind quarter vascular tone during shock.
Received 5 July 1995; accepted in final form 1 December 1995.
APS Manuscript Number H610-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 23 December 95