Aquaporins: Their role in cholestatic liver disease

Table 1 Cellular and subcellular localization and permeability characteristics of hepatic AQPs

Cell type	Aquaporin	Subcellular localization	Permeability	Ref.
Hepatocytes	AQP0	ICV	Water	[16]
	AQP8	ICV-CPM-Mitochondria-SER	Water/NH3/H2O2	[9,16-20,28,29,32]
	AQP9	BLM	Water/glycerol/urea/certain small uncharged molecules	[16,21,22,30,31]
	AQP11	ND	ND	[6]
Cholangiocytes	AQP1	APM-BLM-ICV	Water	[23,25,36]
	AQP4	BLM	Water	[26]
Gallbladder epithelia	AQP1	APM-BLM	Water	[27]
	AQP8	APM	Water/NH3/H2O2
Peribiliary vascula endothelia	AQP1	APM-BLM	Water	[24]

ICV: Intracellular vesicles; CPM: Canalicular plasma membrane; BLM: Basolateral plasma membrane; APM: Apical membrane; SER: smooth endoplasmic reticulum; NH₃: Ammonia; H₂O₂: Hydrogen peroxide; ND: Not determined.

Table 2 Molecular and functional expression of AQPs in cholestasis

Experimental model	AQP8			AQP9			Ref.
	Protein	mRNA	CPM Pf	Protein	mRNA	BLM Pf
Obstructive cholestasis
BDL	↓↓	↑	ND	↓↓↓	↓	↓	[57,58]
Intracellular cholestasis
EE-induced cholestasis	↓↓↓	↑	↓	↔	ND	ND	[59]
LPS-induced cholestasis	↓↓↓	↑	↓	↔	ND	ND	[64]
CLP-induced cholestasis	↓↓↓	ND	ND	↔	ND	ND	[66]

Arrows depict significant protein and mRNA changes in treated rats compared with controls: ↑, increased; ↓, decreased; ↔, without change. ND: Not determined; P_f: Osmotic membrane water permeability; CPM: Canalicular plasma membrane; BLM: Basolateral plasma membrane; BDL: Bile duct ligation; EE: 17α-ethinylestradiol; LPS: Lipopolysaccharide; CLP: Cecal ligation and puncture.