Generation of nitric oxide and superoxide during reperfusion after
focal cerebral ischemia in rats.
Kumura, Eiji, Toshiki Yoshimine, Ko-Ichi Iwatsuki*, Kazunori Yamanaka,
Satonori Tanaka, Toru Hayakawa*, Takeshi Shiga, and Hiroaki Kosaka.
Departments of Physiology and Neurosurgery, Osaka University
Medical School, Osaka 565, Japan
APStracts 2:0341C, 1995.
We investigated the levels of nitrosyl hemoglobin (HbNO) in rat
jugular blood by electron spin resonance (ESR) spectroscopy during
and after middle cerebral artery occlusion. The levels of plasma
nitric oxide (NO) end products, nitrite+nitrate, were compared with
the levels of HbNO. Small amounts of HbNO were detected in sham
-operated (n = 4) rats and those subjected to 2 h occlusion (n = 4),
while nitrite + nitrate was increased only in the latter
(p<0.01; vs. sham). Upon reperfusion after 2 h occlusion, both
HbNO and nitrite + nitrate clearly increased after 15 min (n = 4) and
30 min (n = 6) reperfusion (p<0.01; vs. occlusion).
Administration of superoxide dismutase (5 mg/kg) significantly
increased HbNO (p<0.05), but not plasma nitrite + nitrate (n =
5). The increase in HbNO and nitrite + nitrate after 30 min
reperfusion was suppressed by administration of NG-nitro-L-arginine
methyl ester (20 mg/kg) (n = 4, p<0.01), and this suppression
could be reversed by L-arginine (200 mg/kg) (n = 4). The present
study clearly showed that the L-arginine-NO synthase pathway was
activated during reperfusion after focal cerebral ischemia, and
indicated the involvement of a reaction between NO and superoxide
during early reperfusion.
Received 16 May 1995; accepted in final form 13 September 1995.
APS Manuscript Number C280-5.
Article publication pending Am. J. Physiol. (Cell Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 31 October 95