A model for acute carbon monoxide poisoning in conscious rats

These experiments were designed to establish an animal model of acute carbon monoxide (CO) poisoning in awake habituated rats. On the day before exposure, under a brief anesthesia, a Levine preparation (unilateral common carotid artery occlusion) was performed on group 1 (n = 8) and 2 (n = 28), but not on group 3 rats (n = 8). Group 1 rats were exposed to air as control. Groups 2 and 3 rats were exposed to 0.27% CO in air for 60 min [carboxyhemoglobin (HbCO) = 70%] followed by a 2-day recovery in air. The Levine preparation per se did not induce any detectable physiologic effects on group 1 rats. Identical cardiovascular and metabolic responses to CO occurred in groups 2 and 3. After the CO exposure, all group 3 rats lived for 2 days with normal neurologic index (NI). In group 2 (n = 25 post-CO), 84% of the rats showed increased NI and edema of the ipsilateral cerebral hemisphere, and 76% of the rats died 8.7 +/- 1.7 h after the CO exposure. NI correlated with the brain edema (rs = 0.748, P < 0.001) and inversely correlated with the survival time after the CO exposure (rs = -0.777, P < 0.001). We therefore may conclude that exposure of the Levine-prepared rats to 0.27% CO in air for 60 min will provide a valuable model for testing of different treatments for CO poisoning.