GASTRIC NA(-ROTUNDUS()K(+)ATPASE ACTIVITY AND INTESTINAL UREA HYDROLYSIS OF THE COMMON VAMPIRE BAT, DESMODUS)

The blood diet of the vampire bat represents an extraordinarily high r atio of protein to other nutrients and the highest water consumption p er body weight of any other mammal. This bat has a unique gastrointest inal morphology that is characterized by a reduced small intestine, ab sence of a large intestine and intestinal cecum and the presence of a water-absorptive gastric fundus. The present study demonstrates that t he gastric fundus has a greater Na(+)K(+)ATPase activity for active io n transport compared with Other equally sized mammals; This activity i s believed to be necessary to establish a gradient favoring water abso rption across what would otherwise be an osmotic disequilibrium. The a bsence of a large intestine and intestinal cecum may reflect a reduced urea hydrolysis by the vampire bat. The present study demonstrated th at the vampire bat does not hydrolyze urea as does an equally sized no n-sanguinivorous mammal. These data suggest that the blood diet and th e relocation of water-absorptive tissue from the lower intestinal trac t to the stomach is associated with an active ion transport mechanism in the gastric tissue and a reduced capacity for ureolytic microbes to hydrolyze urea in the intestine. Both processes are specializations f or a diet high in protein and water. (C) 1997 Elsevier Science Inc.