Diabetes, Vol 42, Issue 6 891-900, Copyright © 1993 by American Diabetes Association
Structure and segmental localization of glycogen in the diabetic rat kidney
P Holck and R Rasch
Department of Cell Biology, University of Aarhus, Denmark.
Pathological accumulations of glycogen were studied in the kidney tubular
epithelium in untreated STZ-induced diabetic rats of 50 days diabetes
duration. Blood glucose concentrations were approximately 17 mM, and the
animals had no ketonuria. At the termination of the experiment, the kidneys
were perfusion-fixed, and serial sections were cut from the renal capsule
to the tip of the papilla and stained with toluidine blue and periodic acid
Schiff. By tracing tubular profiles from section to section in a light
microscope, the outlines of nephrons were reconstructed, and abnormal
glycogen accumulations were mapped in accordance with the outlines. The
exact segmental localization, character, and extension of the glycogen
accumulations were determined. The predominant location of the pathological
glycogen accumulations was in the thick ascending limb of Henle's loop.
Dot-shaped and diffuse-appearing glycogen accumulations were discretely
distributed throughout the segment, and large confluent cytoplasmic
accumulations of glycogen were also present. On a continuous basis,
glycogen was present only in the cortical thick ascending limb of Henle's
loop and the macula densa segment excluding the macula densa cells. In the
distal convoluted tubule and the cortical collecting duct system, scattered
dot-shaped and diffuse glycogen accumulations were discretely distributed.
Furthermore, glycogen appeared as confluent, cytoplasmic accumulations in
the initial part of the descending thin limb of Henle's loop. In addition,
glycogen accumulations were found in nuclei within a narrow stripe of the
outer stripe of the outer medulla in the medullary thick ascending limb of
Henle's loop.