This study was performed to characterize the transport of the endogenous photosensitizer delta-aminolevulinic acid in tumor cells of the extrahepatic biliary duct. Uptake of [(3)H]delta-aminolevulinic acid into human cholangiocarcinoma SK-ChA-1 cells was linear for up to 10 min, independent of a Na(+) gradient, but stimulated 3- to 4-fold by an inwardly directed H(+) gradient. Uptake of delta-a...
