Expression And Functional Characterization Of AQP1 Water Channel In Gastrointestinal System

With development of RT-PCR, in situ hybridization andimmunohistochemistry technique, we have realized water channelprotein distributed widely in digestive system though glands to colon.Physiologically, the protein was closely related to secretion andabsorption of water. Water transepithelial transportation played animportant role in secretion and absorption of digestive system. Waterchannel protein was discovered as special porous located widely incellular membrane of procaryotic cell and eucaryotic cell in the earlyof 1990's. Presently, the important role of water channel protein inbody fluid transportation had been proved. As body fluidtransportation of organs in digestive system was active, histiocytelocation expression and fuction study of water channel protein indigestive system played an important role in comprehension ofphysiopathology of digestive system body fluid and direction ofclinical treatment of digestive system disease.The article systematicly studied the expression of AQP1 inhuman digestive gland and gastrointestinal tract and conformed theexpression of AQP1 in salivary microvascular endodermis, biliaryducts endepidermis in liver confluens and central veins endodermis.Moreover, APQ1 expressed widely in blood vessel and lympgaticvessel endodermis of human gastrointestinal tract, especially theexpression in chyle vessel endodermis of villi of small intestine,which was similar to previous reports on rat and mouse digestivetract. The study discovered firstly that the wide expression of AQP1in nervous system of gastrointestinal tract and pancreatic gland.AQP1 mainly spread supportive cell-satellite cell surroundingganglia in nerve plexus by special immunostaining. AQP1 showedstrong membrane staining in these cells, but no expression of AQP1in nerve cell in nerve plexus. Meissner's plexus and myenteric nerveplexus of all gastrointestinal tract, from esophagus to intestinumrectum, showed the high expression of AQP1. No expression ofAQP1 in nerve plexus in salivary gland and liver.Special hypso-expression in nerve plexus of gastrointestinaltract and pancreatic gland suggested water channel may played a rolein regulating the function of nerve signal transduction in stomachintestine and pancreatic gland. The hypothesis was confirmed bysecretion, absorption and motion function, external secretion andendocrine secretion function of pancreatic gland in AQP1-/-mouse.However, the study on immunolocalization of AQP1 ingastrointestinal tract in the experiment indicated that no expressionof AQP1 because of the rare structure of satellite cells surroundednerve cells in. No expression of AQP1 in pig gastrointestinal tractcould been seen, which was similar to human gastrointestinal tract instructure and physiological function. These results indicated that thestructure of satellite cells in nerve plexus of gastrointestinal tract andthe expression of AQP1 were special to human, which the functionand physiological function were worthy to further study.