ABSTRACT
BACKGROUND: The effect of arterial carbon dioxide tension (PaCO2) during ischemia and reperfusion has been a controversial issue. In this study, the effect of PaCO2 during ischemia and reperfusion was evaluated by 31P magnetic resonance spectroscopy (MRS). METHODS: Incomplete global cerebral ischemia was induced by ligation of carotid artery under lowered mean blood pressure (mean blood pressure= 40 mmHg) for 30 minutes followed by 2 hours of reperfusion. Eighteen cats were divided into 3 groups: For group 1 (n=6) (control group), animals were subjected to normocarbia (PaCO2=28~33 mmHg) during ischemia and reperfusion, for group 2 (n=6), animals were subjected to hypocarbia (PaCO2=18~23 mmHg) during ischemia and reperfusion, and for group 3 (n=6), animals were subjected to normocarbia during ischemia and hypocarbia during reperfusion. RESULTS: For group 1, the energy metabolism measured by [PCr/Pi] was recovered about 74.7 6.4%. For group 2, the energy metabolism failed to be completely recovered by 120 minutes of reperfusion (69.3 7.3%), whereas for group 3, the energy matabolism was completely recovered by 120 minutes of reperfusion (97.6 2.4%). There were statistically significant differences between group 1 and group 3 (p<0.05). The changes in pH were not significantly different among the groups. CONCLUSION: In this study, a condition of hypocarbia during reperfusion seems better for the energy metabolism after incomplete global ischemia of cats.
