21] Measurements of volume and shape changes in isolated tubules

Abstract

This chapter describes the techniques designed specifically for measuring cell volume in isolated and perfused renal tubules using a combination of video and optical techniques. The methods allow access to both apical and basolateral solutions and provide excellent time resolution. It may be important to change both apical and basolateral solutions simultaneously. Because of inherent differences in lumenal and bath perfusion systems, it is necessary to determine the time from the initial switching of the valve to the time when the solution actually contacts the tubule by placing a dye in one of the perfusion solutions. The tubule is viewed through an inverted microscope modified to include differential interference optics (DIC). Although DIC is commercially available for most inverted microscopes, it may not be possible to adapt the commercial DIC for use with the isolated perfused tubule preparation. If this is the case, a DIC system, which works well with isolated and perfused tubules, can be constructed.