Adenosine triphosphatases of rat cerebral microvessels. Effect of age and diabetes mellitus.

To determine the effect of age and diabetes mellitus on the activity of 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 indicate that diabetic rats have reduced ATPase inhibition by N-ethylmaleimide (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 had reduced NEM sensitive ATPase activity. Sodium-potassium (Na(+)-K(+)-) or magnesium ATPase activity of cerebral microvessels was not altered with diabetes or aging. The changes in cerebral microvessels were distinct from those found in synaptosomal membranes indicating cell specificity of the findings. The results indicate that the age-related and diabetes-related changes in the activity of ATPases in cerebral microvessels are similar but not identical. These changes may contribute to the altered blood-brain barrier functions found in diabetic and aged rats.