TRANSPORT OF ORGANIC ANION IN THE OK KIDNEY EPITHELIAL-CELL LINE

Transport of an organic anion, p-aminohippurate (PAH), was investigate d in an established cell line derived from the American opossum kidney (OK). Transepithelial transport and accumulation of PAH were measured in OK cells cultured on permeable supports. Specifically mediated tra nscellular transport of PAH across OK cell monolayers occurred only fr om basal to apical side, and the accumulation of PAH in the cells was much larger from basal side than from apical side. Both the transcellu lar transport of PAH from basal to apical side and the accumulation fr om basal side were temperature dependent, saturable, and inhibited by organic anions such as probenecid but not by organic cations. In contr ast, such a specific transport of PAH was not observed in LLC-PK1, ano ther epithelial cell line derived from pig kidney. These findings sugg est that OK cells can transport PAH by the organic anion transport sys tem unidirectionally from basal to apical side across the cell monolay ers and that OK cells might be a useful model for the study of organic anion secretion in the renal proximal tubules.