HETEROLOGOUS EXPRESSION OF SPECIFIC K-LYMPHOCYTES - FUNCTIONAL CONSEQUENCES FOR VOLUME REGULATION( CHANNELS IN T)

It has been postulated that the K+ channel isoform Kv1.3 plays a role in regulatory volume decrease (RVD) in response to hypotonic shock. We show that a mouse cytotoxic T-lymphocyte line, CTLL-2, is devoid of v oltage-dependent K+ channels and is unable to volume regulate. Transie nt transfection of these cells with Kv1.3 reconstitutes their ability to volume regulate. As predicted by our model, this ability depends cr itically on volume-induced changes in membrane potential and the isofo rm of the K+ channel used. When the cells were transfected with Kv3.1, an isoform believed to be expressed in a specific subclass of mouse t hymocytes, the CTLL-2 cells did not show RVD. The difference in the ab ility of the two isoforms to confer the capacity for RVD is expected f rom differences in the voltage dependence of activation of the channel s, according to our proposed model for RVD. The experimental approach that we use, transient transfection and panning to select positive tra nsfectants, is highly effective; it has a >95% efficiency. This method , and this cell line, may be important tools in studying lymphocyte K channels and their function in situ.