Uptake of fluorescent albumin in MDCK cells.

<p>MDCK-I cells were grown on permeable support to confluency. Fluorescence-tagged albumin was added for 24 hours to the lower chamber and the cells were fixed and imaged by confocal microscopy. A) Top view of the stack of images with internalized albumin (green) and rhodamine peanut agglutinin as a luminal surface marker (red). B & C) Oblique views of the same data set showing albumin-fluorescence inside the cells (green). D) Similar uptake of albumin after 24-hours exposure (control for E and F). E) Representative micrograph of albumin uptake after 24 hours in the presence of an inhibitor of clathrin-mediated endocytosis (chlorpromazine), F) a parallel experiment performed in the presence of an inhibitor of dynamin-dependent endocytosis (dynasore). G) 24 hours uptake of aldosterone conjugated albumin, where aldosterone (green) was visualized by immunostaining after fixation and permeabilization. The red signal is peanut agglutinin against the apical membrane.