Decreased Blood-Brain Barrier Permeability to Sodium in Early Experimental Diabetes Free

Blood-brain barrier (BBB) permeability to ²⁴Na^+ 36CI⁻, and [³H] sucrose was studied in rats after 2 wk of streptozocin-induced diabetes. The PS (permeabilitysurface area product) for Na⁺ in the cortex of the frontal lobes was 5.4 ± 0.6 (105 cm³ g⁻¹ · s⁻¹; ± SD) in diabetic rats compared with 7.1 ± 1.7 in control rats. In the occipital cortex, the values were 7.6 ± 1.5 and 9.9 ± 1.6, respectively. In contrast, BBB permeability to Cl⁻ and sucrose remained unchanged. We conclude that a selective alteration in BBB permeability to Na⁺ unrelated to changes in brain capillary surface area is present in experimental diabetes.