Fast accumulation of basement membrane material and the rate of morphological changes in acute experimental diabetic glomerular hypertrophy.

Renal glomerular structures have been studied during the initial phases of renal and glomerular hypertrophy in streptozotocin diabetic rats. -- After four days of diabetes significant increases were found in the following absolute structural quantities: the tuft volume (25%), the surface area (42%) and volume (46%) of peripheral basement membrane, and capillary luminal volume (29%). No further changes in these quantities took place over the succeeding 47 days. The geometry of the capillaries, however, changed over this period: at 4 days the total capillary length had increased significantly (32%) with an unchanged average cross sectional area, whereas at 47 days the length had reverted to normal, but average cross sectional area had increased (30%). The increased surface of filtering area may be the morphological counterpart of increased glomerular filtraton rate. The changes in glomerular volume were thus accompanied by changes in glomerular structural composition which after a few weeks returned to normal, in balance with the increased volume.