EFFECT OF TEMPERATURE IN FOCAL ISCHEMIA OF RAT-BRAIN STUDIED BY P-31 AND H-1 SPECTROSCOPIC IMAGING

P-31, H-1 and lactate spectroscopic imaging was used to evaluate the e ffects of hypothermia on focal cerebral ischemia produced by middle ce rebral artery occlusion, The effects on high energy phosphate metaboli sm, pH, lactate and NAA were investigated in 24 spontaneously hyperten sive rats subjected to either permanent or transient ischemia. Under e ither normothermic (37.5 degrees C) or hypothermic (32 degrees C) cond itions, with permanent 6-h occlusion, there was little difference betw een groups in either the NMR measurements or the volume of infarction. In animals that underwent 3 h of ischemia followed by 12 h of reperfu sion, the ischemic changes in lactate, pH, NAA, and high-energy phosph ate returned toward control values, and there was a protective effect of hypothermia (infarct volume of 211 +/- 26 and 40 +/- 14 mm(3) in no rmothermic and hypothermic groups, respectively), Thus, hypothermia di d not ameliorate the changes in lactate, pH, NAA, or high energy phosp hate levels occurring during ischemia, however, during reperfusion the re was an improvement in both the recovery of these metabolites and pa thological outcome in hypothermic compared with normothermic animals.