| Popis: |
The blood-brain barrier and the blood-cerebrospinal fluid (CSF) barrier are terms that are deeply entrenched in the literature of neurobiology. The concept of a permeability barrier between the blood and the nervous system evolved from observations of Ehrlich that the brain did not become stained after intravenous injection of aniline dyes (e.g., trypan blue). Goldmann later showed that the brain became stained after injection of trypan blue into the CSF. For many years, the barrier was considered to be an anatomical one that absolutely restricted the passage of certain substances into the brain. When tracer methodology became available, it became clear that most substances were not absolutely restricted from the brain, but rather that their rates of entry or ultimate ability to accumulate were reduced with respect to other organs. In this way, the chemical environment of the brain could be carefully guarded and exquisitely regulated. This chapter provides a brief account of the mechanisms that contribute to the regulation of concentrations of various classes of solutes in the brain and CSF. It seems likely that no fundamental differences exist in the mechanisms of transport at the blood-brain and blood-CSF interfaces. Several monographs expand the subject for interested readers.11,35,48,52,53,81 |
