Angiotensin Converting Enzyme 2 (ACE2) is an important player of the Renin-Angiotensin-System (RAS) and has recently been shown by our group to be necessary for the expression of various amino acid transporters in murine intestine. ACE2 expression has been shown in different tissues to be up-regulated when RAS-active antihypertensive drugs such as ACE-inhibitors or angiotensin II AT1 receptor blockers where administered. The aim of the present study is to characterize in human subjects treated or not treated with RAS-active antihypertensive drugs the intestinal distribution and expression of RAS proteins and of AA-, peptide and glucose transporters potentially influenced by the local RAS. The mRNA level will be tested by quantitative real time PCR (qPCR), and the protein expression by immunofluorescence and Western blot analysis. Preliminary results show in human duodenal bulb mRNA expression of various AA-, peptide- and glucose transporters as well as of RAS components. Furthermore, immunofluorescence images show a co-localization of the two luminal AA transporters of the SLC6 family B⁰AT1 (broad neutral amino acid transporter 1, SLC6A19) and SIT1 (sodium dependent imino transporter 1, SLC6A20) with ACE2 along human intestinal villi. When co-expressed in X. laevis oocytes human ACE2 increases the transport rate of SIT1 and B⁰AT1 10- and 15-fold, respectively, suggesting a functional interaction of ACE2 and these transporters. Our preliminary results indicate that ACE2 interacts with the two luminal AA transporters B⁰AT1 and SIT1 and suggest the possibility that a local human intestinal RAS might regulate the expression and function of specific AA transporters.