Table 1.

Aquaporin (AQP) types in astrocytes.

AQP Type	AQP Isoforms	Permeability to Water	Permeability to Small Solutes (i.e., Glycerol, Urea, Monocarboxylates)	Ability to Form OAPs in the Plasma Membrane
AQP1	AQP1	Yes	No	No
AQP4	AQP4a (M1)	Yes	No	Only together with AQP4c
	AQP4c (M23)	Yes	No	Yes
	AQP4e	Yes	No	Only together with AQP4c
	AQP4b	?	No	N/A
	AQP4d	?	No	N/A
	AQP4f	?	No	N/A
AQP9	AQP9 ~32 kDa (is AQP9 ~30 kDa its splicing isoform?)	Yes	Yes	No
	AQP9 ~25 kDa	Yes	Yes	No

?, not yet definitely determined; N/A, not applicable; OAPs, orthogonal arrays of particles.