MECHANISMS OF CEREBROSPINAL FLUID SECRETION

For further details on individual transporters click on the box below.

Cerebrospinal fluid (CSF) is secreted by the epithelial cells of the choroid plexuses. These cells like those of other secretory epithelia are polarised so that the properties of their apical membrane (ventricle facing) differ from those of the basolateral membrane (blood facing). Both membranes have a greatly expanded area (apical membrane is made up of numerous micovilli, and the basolateral membrane has many infoldings), so that the total area available for transport is similar to that of the blood- brain barrier.

The free cellular surface of the rat lateral ventricle choroid plexus. Note numerous microvilli (asterisk). Bar = 1 µm.

Basolateral

K+-Cl¯ cotransporter

Na+- HCO₃¯ cotransport

Cl¯-HCO₃¯ anion exchanger

Na+/ H+ exchanger

Aquaporins

Expression of transport proteins in choroid plexus epithelial cells

H₂0, Na⁺, HCO₃¯, Cl¯

Follow the appropriate link to find out more about individual transporters.

Apical

K channels

Na+/K+ ATPase

Na+-K+-2Cl¯ Cotransport

Anion channels

CSF secretion involves the transport of ions ( Na⁺, Cl¯ and HCO₃¯) across the epithelium from blood to CSF. The movement of these ions creates an osmotic gradient that drives the unidirectional transport of ions across an epithelium. Secretion can occur because of the polarised distribution of specific ion transporters in the apical or basolateral membrane of the epithelial cells. The diagram summarises our knowledge of ion transporters involved in CSF secretion by the mammalian choroid plexus. Information on each transporter and evidence of a role in CSF secretion can be obtained by clicking on the appropriate links.

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