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Isolation of the TRPV4 Osmoreceptor from the Avian Lower Gastrointestinal Tract
Author(s) -
Warner Paige C,
Braun Eldon J
Publication year - 2012
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.26.1_supplement.1070.10
Subject(s) - cloaca , trpv4 , peristalsis , biology , osmotic concentration , anatomy , gastrointestinal tract , medicine , transient receptor potential channel , endocrinology , receptor , biochemistry
Avian osmoregulation differs from mammals in that not only do the kidneys regulate water and electrolyte levels but the lower gastrointestinal tract as well. Urine from the kidneys is conveyed to the cloaca where a reverse peristalsis brings the urine in contact with epithelial tissues of the colon and digestive ceca where its composition can be further modified. Brummermann and Braun (AJP, 268, 1995) have shown not only do changes in osmolarity within the lumen of the cloaca have a direct effect on reverse peristalsis, but also that this occurs independent of central osmoreceptors, suggesting local regulation of the reverse peristalsis. It is believed that the sensor of osmolarity is a member of the vanilloid‐receptor subfamily of transient receptor potential channels (TRPV4). TRPV4 has been shown to respond to osmotic stimuli in a variety of mammalian tissues. Cloacal and colonic tissues were harvested from mourning doves and homogenized for analysis using Gel Electrophoresis, Western blotting, and Immunohistochemistry. TRPV4 was localized to the area where the ureters enter the cloaca, but not found in other regions of the cloaca. In addition, TRPV4 was not found in the colon suggesting that the osmotic potential of the urine is monitored as it enters the cloaca. We used rat renal tissue where TRPV4 has been previously shown, as a control and clearly demonstrated the presence of TRPV4 in the medullary region of the kidney.