[Stretch-activated channels in renal tubule].

The mechanosensitive (MS) ion channels have been identified in various tissue, including muscle, neuron, egg, kidney cells. The MS channels can be classified into 4 subtypes, i. e. stretch-activated (SA), curvature-sensitive, stretch-inactivated, and shear-stress activated. Channel activity of SA channels was increased in proportion to tension of the patch-membrane, but not to negative pressure of the patch-pipette. Potassium- and cation-selective (SA) channels were found in renal tubules, which were activated by cell-swelling and membrane-stretch. SA potassium channel may be responsible for a K exit pathway from cell. Ca-permeable (SA) cation channel may allow Ca into the cell. They can play an important role for the cell volume regulation.