Table 1.

Transporters supposed to be involved in CSF secretion in CPE cells.

Molecules	Apical Side	Basal Side
H2O	AQP1	AQP1
Na+, K+	Na+−K+−ATPase
Na+, K+, 2Cl−	NKCC1
Na+, H+	NHE1
Na+, HCO3−	NBCe2	NBCn1
Na+, Cl−, HCO3−		Ncbe
Cl−, HCO3−		AE2
Cl−	Clir, VRAC
K+	Kir7.1, Kv

Localization of transporters suggested to be involved in CSF secretion in CPE cells is shown. The water channel AQP1, Na⁺-K⁺-ATPase, Na⁺, K⁺, 2Cl⁻ cotransporter NKCCl, acid/base transporters NHE1 and NBCe2, Cl⁻ channels Clir and VRAC, and K⁺ channel Kir7.1 and Kv are expressed in the luminal membrane. Some acid/base transporters are expressed in the basolateral membrane: the Na⁺-dependent HCO₃⁻ transporter NBCn1, Na⁺-dependent Cl⁻/HCO₃⁻ exchanger Ncbe, and the anion exchange protein AE2. AQP1 is expressed in large quantities in the luminal membrane, whereas it is also in the basolateral membrane with a lower abundance.