Biophysics of domes formed by the renal cell line Madin-Darby canine kidney

When cultured on an impermeable substratum, the renal epithelial cell line Madin-Darby canine kidney (MDCK) forms domes. From a knowledge of dome shape, radius, and hydrostatic pressure difference delta P, from within to outside the domes, biophysical properties of the epithelium can be determined. By microscopy, circular based domes were found to be section of spheres with a constant height-to-radius ratio h/r of 0.684. By using the Laplace equation derived for this geometry and measurements of delta P and r, the values of the tension of cell dish adhesion Ta and dome wall tension Tw were found to be constants of 6.60 and 7.08 torr, respectively. By combining constants, Ta, and h/r, and because domes are section of spheres, delta P and dome volume were shown to be known functions of radius alone. The modulus of elasticity of the epithelium was calculated to be 4.82 X 10(3) dyn/cm2.