Dry weight as a point of reference in studies of renal papillary composition

Abstract

The effects of chronic K deprivation and acute hydration on the weight and density of dry solids in the renal papilla of the laboratory rat were examined. When the papillary region of the kidney was identified by its anatomical boundaries and examined in toto, significant variations were found both in the weight and in the density of its non-aqueous materials. Under some conditions the differences in dry weight were sufficient to mask the magnitude and/or direction of differences in absolute papillary water and solute contents when dry weight was used as a point of reference and comparisons were made between normal and kaliopenic or dehydrated and hydrated papillae. From these observations it was concluded that the use of dry weight as a reference base should be limited in comparative studies of renal papillary composition, at least in the rat.