IMMORTALIZATION AND CHARACTERIZATION OF PROXIMAL TUBULE CELLS DERIVEDFROM KIDNEYS OF SPONTANEOUSLY HYPERTENSIVE AND NORMOTENSIVE RATS

Epithelial cell lines from the proximal tubule of SHR and WKY rats wer e generated by microdissection, cell growth on 3T3 cell feeder layers, and transduction of the SV40 large T-antigen gene. The cell lines tha t formed confluent, electrically-resistive monolayers (basal conductan ce 1 to 20 mS/cm(2)) were selected for further study. Of these, cell l ines generated from one rat did not show evidence of T-antigen express ion or integration, and apparently immortalized spontaneously. Cell li nes from three other rats expressed high levels of T-antigen, and show ed evidence of integration of one or more copies of T-antigen. All cel l lines formed polarized monolayers with apical microvilli, tight junc tional complexes, and convolutions of the basolateral plasma membrane. Most cell lines grew in the absence of extracellular glucose indicati ng a capacity for gluconeogenesis. Sodium succinate cotransport and P- 2-purinergic receptor mediated signaling were demonstrated in all line s tested. The cell lines also showed that Na/H exchanger activity is r egulated by angiotensin II. The results indicate that these cell lines express a proximal tubular phenotype, and are morphologically and fun ctionally similar to primary cultures. These rat cell lines represent a new, potentially useful cell model for elucidating the cellular and molecular mechanisms of genetic differences in proximal tubule Na+ rea bsorption.