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Aquaporin‐1 as a NO transporter.
Author(s) -
Herrera Marcela,
Garvin Jeffrey Lawrence
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.5.a1219-d
Subject(s) - aquaporin , chemistry , transfection , aquaporin 1 , transporter , biophysics , vesicle , water transport , lipid bilayer , ion transporter , permeability (electromagnetism) , membrane , biochemistry , water channel , water flow , biology , gene , mechanical engineering , environmental engineering , engineering , inlet
NO is thought to diffuse freely across cell membranes without need for a specific transporter. The water channel aquaporin‐1 (AQP‐1) transports CO 2 and NH 3 in addition to water and is highly expressed in cells that produce and are targets for NO. Consequently, we hypothesized that AQP‐1 transports NO across lipid bilayers. We transfected CHO cells with an AQP‐1‐expressing vector or a control vector and measured NO influx with DAF2‐DA. NO influx was initiated by creating a 5 μM NO gradient. When using a NO donor to create the gradient, AQP‐1 increased NO influx from 10.2±3.4 to 32.5±6.9 fluorescence units (F.U)/sec ( p <0.03) and NO correlated with water permeability ( r = 0.70, n = 71). DMSO and HgCl 2 , inhibitors of AQP‐1, blunted AQP‐1‐stimulated NO influx by 64±11% and 71±3% respectively ( p <0.001). When using 5 μM NO gas, AQP‐1 increased NO influx from 13.7±0.9 to 37.8±3.3 F.U/sec ( p <0.03) and DMSO blunted this effect by 49±11% ( p <0.03). AQP‐1‐dependent NO transport was concentration dependent with a K 1/2 of 0.54μM. Influx saturated at 3 μM NO. Reconstituted purified AQP‐1 in lipid vesicles increased NO influx from 5.3±1.1 to 22.1±6.2 F.U/sec ( p <0.024). We conclude that AQP‐1 transports NO across lipid bilayers. NO transport by AQP‐1 may allow cells to control intracellular NO levels and their effects.