Changes in cranial and rectal temperature, blood pressure and arterial blood gas during and after unilateral and bilateral forebrain ischemia in Mongolian gerbils

Transient forebrain ischemia was produced by occluding the common carotid arteries, either unilaterally or bilaterally, in Mongolian gerbils under halothane anesthesia. After 20-min ischemia, the cranial temperature measured in the temporal muscle decreased compared to the preischemic level, the decrease being larger after the bilateral than after the unilateral occlusion. After recirculation, cranial temperature recovered promptly to the preischemic level in the unilateral group, while it was elevated to above the preischemic level in the bilateral group. The rectal temperature also decreased with a similar time course. During 30-min ischemia, the blood pressure of both groups increased to above the preischemic level, the increase being larger in the bilateral group than in the unilateral group. After recirculation, blood pressure of the unilateral group recovered promptly to the preischemic level, while that of the bilateral group decreased to below the preischemic level. When forebrain ischemia was produced immediately after cessation of halothane inhalation, blood pH, PaO 2 or PaCO 2 did not change significantly from the control level. However, these values showed larger variation in the bilateral group than in the unilateral group. Unilateral occlusion in preselected gerbils provided a good model of transient brain ischemia, giving rise to uniform experimental results.