| Potassium channels in the proximal tubule epithelial cells (PTECs) play a pivotal physiologic roles in the generation of the cell-negative potential, the regulation of the volume of tubule cells and ultimately in the mechanism by which tubule cells maintain fluid and electrolyte equilibrium. The proximal tubule is likely to be affected by hypoxia and poisoning. Despite this pivotal physiological role, the properties of this kind of channels have been incompletely characterized.The immunosuppressive drug cyclosporine A has been successfully used in several diseases with immunological basis and in transplanted patients. Nephrotoxicity is the main secondary effect of CsA treatment. Although the mechanisms of nephrotoxicity are not completely defined, we have found out that CsA-induced tubular injury and haemodynamic disturbances contribute to CsA nephrotoxicity independently. There are some evidences suggest that CsA treatment do result in the change of proximal tubule from morphous to function, but little to know about CsA-induced ion channels change of proximal tubular injury.In our study, we established a method for primary culture, passage and identification of mouse proximal tubule epithelial cells, and studied the properties of the potassium channels in the apical membrane of mouse PTECs using the cell-attached and inside-out mode of the patch-clamp technique. In addition, we evaluated the effect of cyclosporine A on the potassium channels, and also explored the probable mechanism of its effect. The results were as follows:1. The modified method of collagenase enzyme digestion-density gradient centrifugation procedure yielded a preparation primarily consisting of cells nearly the same volume with ~95% viability as assessed by exclusion of the vital dye trypan blue. The unattached cells were round, smooth and glossy with good stereo, and the diameter range from 8.5μm to 10.5μm. Attached cells were Fusiform shape, with increased clarity and...
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