EFFECT OF HYPOCAPNIA, HYPERCAPNIA, AND BLOOD PRESSURE ON NADH FLUORESCENCE, ELECTRICAL ACTIVITY, AND BLOOD FLOW IN NORMAL AND PARTIALLY ISCHEMIC MONKEY CORTEX

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Abstract
NAD fluorescence, cortical reflectance, cortical blood flow and EEG were recorded from squirrel monkey [Saimiri sciureus] brains before, during and after focal transient cerebral ischemia produced by the temporary clipping of the middle cerebral artery. After release of the occluding clip the monkeys were followed through an N2-breathing cycle and then to death from anoxia. The effects of controlled variations in arterial CO2 tensions (PaCO2) and mean arterial blood pressures (MABP) were investigated in normal and in ischemic brain. In normal brain with preserved autoregulation, NADH fluorescence was constant through a wide range in PaCO2, MABP and cortical blood flow. In ischemic brain NADH levels increased, correlated closely with decreased cortical blood flow and EEG abnormalities, and became dependent on MABP. Artifacts in fluorescence measurements were reduced by monochromators for excitation, emission and reflected light; low intensity vertical excitation energy and high sensitivity recording instrumentation; and a small avascular (123 .mu.m) field.