NBD-TMA: a novel fluorescent substrate of the peritubular organic cation transporter of renal proximal tubules.

摘要: Traditionally, the measurement of transport activity has employed radiolabeled compounds. The resulting experimental procedures do not measure in real time and are limited temporal spatial resolution. use epifluorescence microscopy provides ability to with high Using we characterized fluorescent organic cation, [2-(4-nitro-2,1,3-benzoxadiazol-7-yl)aminoethyl]trimethylammonium (NBD-TMA+, MW 266). NBD-TMA+ structural characteristics common other secreted cations is (λex=458 nm; λem=530 nm). excitation emission spectra insensitive changes [Cl–] minimally sensitive pH physiologically relevant range (pH 5.0–7.4). A microscope equipped a photon-detection system was used accumulation by isolated rabbit renal proximal tubules. Accumulation tubules dependent saturable (Michaelis-Menten constant K m 12 µM). Proximal tubule inhibited tetraethylammonium (TEA+) (apparent inhibitory app TEA 134 µM), cimetidine, N 1-methylnicotinamide (NMN). Our results provide strong evidence that transported one or more basolateral cation transporters involved secretion this chemical class compound. This substrate means investigating transport.