Expression of I-sK protein mRNA in cultured rat strial marginal cells

A cell culture system of marginal cells (MC) of the rat stria vascularis wa s established by the explant method. When grown on plastic dishes, cultured MC showed a polygonal "cobblestone-like" appearance. Dome formation, compo sed of several hundreds to thousands of cells, occurring after confluence s uggested that vectorial transport of ion(s) with accompanying fluid develop ed in the cultured MC. Transmission electron microscopy demonstrated juncti onal complexes formed of right junctions and desmosomes at the upper latera l membranes. The polymerase chain reaction (PCR) product, amplified with pr imers made from the cDNA reverse transcribed from cultured MC, yielded a di stinct band compatible with the expected size of the PCR products amplified from cDNA of positive control groups containing I-sK protein, indicating t hat cultured MC expressed the I-sK protein mRNA. The results show that cult ured MC can Form large domes and express the most characteristic I-sK prote in, indicating that they maintain their vectorial electrolyte transport Fun ction and, possibly, the ability to secrete K+; in this condition.