Isolation of a Putative Osmoreceptor from the Avian GI Tract

Abstract

Avian osmoregulatory physiology has certain distinctions from that of mammals. Birds exhibit a very interesting reverse peristalsis mechanism in the lower GI tract which allows for modification of the fluid and electrolytes of the urine. Previous studies by Brummermann and Braun (AJP, 268, 1995) have shown not only does change in osmolarity within the lumen of the GI tract have a direct effect on reverse peristaltic activity, but also that this occurs independent of central osmoreceptors in the hypothalamus, suggesting local regulation. The nature of this local regulation is not known at this time and it is the goal of our study to identify the mechanism(s) by which this regulation takes place. A possible candidate for the sensing of osmolarity is a vanilloid-receptor subfamily member of the transient receptor potential channels (TRPV4). TRPV4 has been shown to respond to osmolarity stimuli in mammals and other animals, and we hope to identify and localize this channel within the avian GI tract. Using Gel electrophoresis and Western blotting, these receptors will be separated and characterized. In addition, localization of these proteins will be determined with the use of Immunohistochemistry.