EFFECTS OF HYPOTHERMIA ON THE INDUCTION OF NO SYNTHASE EVOKED BY CYTOKINE IN VASCULAR SMOOTH MUSCLE

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The purpose of this study was to clarify the effect of hypothermia on IL-1β evoked iNOS induction in vascular smooth muscle.Exposure of rat aortic rings without endothelium to IL-1β for 5h in 37℃ Krebs Ringer solution significantly attenuated the contractile responses to phenylephrine and KCl. These attenuations were reduced when exposed to IL-1β for 5h in 27℃ Krebs Rnger solution. Exposure of the endothelium-denuded rat aorta to IL-1β for 5 h in 37℃ Krebs Ringer solution caused an increase in the tissue cGMP contents. The levels of cGMP measured in aortic strips that were exposed to IL-1β for 5h in 27℃ Krebs Ringer solution were significantly lower than those in 37℃. The expressions of iNOS mRNA and iNOS protein evoked by the exposure to IL-1β for 5h in 37℃ Krebs Ringer solution were attenuated by the exposure to IL-1β in 27℃.The present study demonstrated that hypothermia attenuated the IL-1β evoked iNOS induction in vascular smooth muscle. These results suggest that iNOS induction may participate in the mechanism of ischemic brain damage and that the attenuation of iNOS induction may contribute the brain protection with hypothermia.