CONSECUTIVE IN-VIVO MEASUREMENT OF NITRIC-OXIDE IN TRANSIENT FOREBRAIN ISCHEMIC RAT UNDER NORMOTHERMIA AND HYPOTHERMIA

The effects of hypothermia on production of nitric oxide (NO) in ische mic brain were investigated by using in vivo microdialysis. Male Wista r rats were randomly divided into three groups; saline-treated normoth ermic group (37 degrees C, n = 6), 30 mg/kg N-nitro-L-auginine methyl ester(L-NAME)-treated normothermic group (n = 6), and saline-treated h ypothermic group (30 degrees C, n = 6). Transient forebrain ischemia w as produced by bilateral common carotid artery occlusion combined with hypotension (MABP = 50 mmHg). Saline-treated normothermic animals res ulted in a reduction of LCBF to 9% of baseline. Saline-treated hypothe rmic rats revealed the similar changes of LCBF. In contrast, L-NAME ad ministration reduced the basal CBF to 85% of saline-treated group and to 8% after ischemia. NO products were decreased during ischemia and t ransiently increased after reperfusion in saline-treated groups. Howev er, the increase of NO products after reperfusion was less significant in the hypothermia. L-NAME-treated group showed a constant reduction of NO production during ischemia and after reperfusion. (C) 1998 Elsev ier Science B.V. All rights reserved.