Differential expression of KCNQ1 K(+) channel in tubular cells of frog kidney

The aim of this study was to evaluate KCNQ1 K(+) channel expression in the frog kidney of Rana esculenta. KCNQ1 K(+) channel, also known as KvLQT1, is the pore forming α-subunit of the I(Ks) K(+) channel, a delayed rectifier voltage-gated K(+) channel, which has an important role in water and salt transport in the kidney and gastrointestinal tract. The expression of KCNQ1 K(+) channel along tubular epithelium differs from species to species. In the present study the expression of KCNQ1 K(+) channel in the frog kidney has been demonstrated by immunohistochemistry. The presence of KCNQ1 K(+) channel was demonstrated in the epithelial cells of distal convoluted tubule and collecting duct. However, the pattern of expression of KCNQ1 K(+) channel differs between distal convoluted tubules and collecting duct. All epithelial cells of distal convoluted tubules revealed basolateral expression of KCNQ1 K(+) channel. On the contrary, only the single cells of collecting duct, probably intercalated cells, showed diffuse cell surface staining with antibodies against KCNQ1 K(+) channel. These findings suggest that KCNQ1 K(+) channel has cell-specific roles in renal potassium ion transport.