odon degus, a South American desert rodent. Am J Physiol

todon degus is a desert rodent of northern Chile, adapted to survive with a limited supply of water. This rodent has a high degree of fecal dehydration, related to colon water absorp-tion. With the hypothesis that aquaporins (AQPs) might be present in the colon epithelium of O. degus and involved in fluid absorption, we studied colon water absorption in vivo and the distribution of AQPs and Na transporters by im-munocytochemistry. AQP-1 was found in apical and basolat-eral membranes of surface-absorptive and crypt epithelial cells. AQP-8 was found in the cytoplasm of enterocytes of surface colon. AQP-3 immunolabeling, on the other hand, was absent from the epithelium but present in a subepithe-lial fibroblast layer, pericryptal cells, and muscularis muco-sae. The hydration state did not modify the amount of im-munostaining for any of the AQPs. Colon water absorptio