The level of cerebrospinal fluid (CSF)
protein is elevated in diseases and disease models that are associated with circulating
immune complexes such as
serum sickness. Circulatory
immune complexes are known to deposit in the basal lamina of fenestrated capillaries and may, as a result, affect both capillary bed and parenchymal function. Since the brain has both fenestrated and unfenestrated capillaries and
immune complexes deposit to a varying extent in the fenestrated capillaries in chronic
serum sickness, cerebral capillary permeability to
protein may be altered in some brain areas and lead to the elevation of CSF
proteins. In addition various other cerebrovascular and metabolic functions may also be affected by this condition. In this study either
radio-iodinated serum albumin (RISA) or 2-[14C]
deoxyglucose (14C-2DG) was intravenously injected into control Wistar rats and Wistar rats with chronic
serum sickness; subsequently the tissue levels of radioactivity were measured by quantitative autoradiography in 4 brain areas with fenestrated capillaries and 11 brain areas with unfenestrated capillaries. The 2-min distribution of RISA, which demarcates the volume of circulating plasma in perfused microvessels and is generally proportional to local plasma flow, was the same in control and experimental rats. The passage of RISA from blood into brain over 30 min was negligible in both groups; thus cerebral capillary permeability to
albumin was not detectably increased in any of these 15 brain areas by chronic
serum sickness. The rate of local cerebral
glucose utilization, an
indicator of local metabolic and neural activity, was calculated from the 14C-2DG data and was virtually identical in control and experimental rats.(ABSTRACT TRUNCATED AT 250 WORDS)