In Vitro Proximal Tubule Perfusion Preparation

Isolation and perfusion of single nephron segments was first described by Burg et al. (1 ) in 1966. This technique has allowed us to study both transepithelial and transmembrane transport in individual nephron segments, including the proximal tubule, under carefully controlled circumstances. This has obvious advantages for experiments that require the epithelium and its junctional complexes to remain intact, but removed from the influences of endogenous neural or humoral mediators, including angiotensins. In addition, control of bath and luminal perfusate compositions and flow rates allows peptides to be added independently to each side of the epithelium. This has particular relevance in the case of angiotensin, which binds to luminal and basolateral receptors and initiates intracellular signal transduction pathways that may differ between the two sites (2 ).