ADENOSINE TRIPHOSPHATASES OF RAT CEREBRAL MICROVESSELS - EFFECT OF AGE AND DIABETES-MELLITUS

To determine the effect of age and diabetes mellitus on the activity o f various adenosine triphosphatases (ATPases) of cerebral microvessels , streptozotocin-induced diabetic rats, and aged rats (26 months old) were compared to young control rats (4 months old) The results indicat e that diabetic rats have reduced ATPase inhibition by N-ethylmaleimid e (NEM), a vacuolar proton (H+)-ATPase inhibitor (98.7 +/- 0.81% vs 78 .9 +/- 4.3% of buffer, p<0.05). Aged rat cerebral microvessels also ha d reduced NEM sensitive ATPase activity. Sodium-potassium (Na+-K+-) or magnesium ATPase activity of cerebral microvessels was not altered wi th diabetes or aging. The changes in cerebral microvessels were distin ct from those found in synaptosomal membranes indicating cell specific ity of the findings. The results indicate that the age-related and dia betes-related changes in the activity of ATPases in cerebral microvess els are similar but not identical. These changes may contribute to the altered blood-brain barrier functions found in diabetic and aged rats .