Pushing, pulling, dragging, and vibrating renal epithelia by using atomic force microscopy

Renal physiologists focus on events that take place on and around the surfa ces of cells. Various techniques have been developed that follow transport functions at the molecular level, but until recently none of these techniqu es has been capable of making the behavior of molecular structures visible under physiological conditions. This apparent gap may be filled in the futu re by the application of atomic force microscopy. This technique produces a n image not by optical means, but by "feeling" its way across a surface. At omic force microscopy can, however, be modified in a number of ways, which means that besides producing a high-resolution image, it is possible to obt ain several types of data on the interactions between the ultrastructural c omponents of cell membranes (such as proteins) and other biologically activ e molecules (such as ATP). In this review we describe the recent use of the atomic force microscope in renal physiology, ranging from experiments in i ntact cells to those in isolated renal transport protein molecules, include examples of these extended applications of the technique, and point to use s that the microscope has recently found in other areas of biology that sho uld prove fruitful in renal physiology in the near future.