The collecting duct epithelium is fine tuning the water balance of the body. Pathophysiological states like diabetes can drive regulation capacity out of range - resulting in a long term hypotonic challenge of the cells. We mimicked this situation in vitro using primary cells from rat inner medulla collecting duct (IMCD). They were stressed hypotonically for three days. After this period, they were fixed and subjected to atomic force microscopy (AFM). Topographical data revealed the cell junctions to be considerably distorted. Nanomechanical analysis of living cells demonstarted a significant stiffening of the cells through generation of a fibrous meshwork. The network does not consist of actin. Penotypically, cells produce mechanical stress in response to hypotonic stress; underlying molecular mechanisms will be discussed.

Figure 1