Studies of Cerebral Capillary Endothelial Membrane

Abstract

The movement of nutrients from blood to brain, at the exclusion of many other blood-born substances, ranks high in significance among the unique properties of cerebral capillaries identified thus far. The presence and the activity of transport systems for glucose, amino acids, and various other metabolic substrates clearly demonstrates the role of this endothelia in supplying brain cells with fuel for energy metabolism and biosynthetic pathways. The dynamics of water and ion permeability (1) of the cerebral microvasculature, as well as its involvement in blood flow regulation (2), further indicate an important role for endothelial cells in cerebral metabolic homeostasis. The mechanisms by which capillary functions are energized and regulated are most certainly related to capillary cell metabolism. Therefore, the metabolic activity of the endothelium is of major significance. Based on current information about the enzymatic and metabolic activities of isolated cerebral microvessels (3,4), it appears that brain endothelial cells have versatile substrate requirements and possess a significantly high metabolic capability.