Molecular and ultrastructural basis of the blood-brain barrier function. Immunohistochemical demonstration of Na+/K+ ATPase, alpha-actin, phosphocreatine and clathrin in the capillary wall and its microenvironment.

Cerebral capillaries represent the responsible structure for the establishment of the BBB. We have demonstrated the presence within both pericytes and endothelial cells of abundant cytoplasmic vesicles. We have noticed the presence of Na+/K(+)-ATPase-, alpha-actin-, phosphocreatine- and clathrin-like molecules within cerebellar capillaries and their microenvironment. These facts suggest the importance of the contractile and transport mechanisms in the blood-brain barrier. We have also demonstrated the close contact between different nervous components of the cerebellar cortex with the basement membrane that surrounds capillary wall. We suggest that these observations represent the morphological evidence of neurogenic control of brain circulation.