[Importance of tubulo-interstitial changes in glomerular excretory and urine concentrating function of the kidney]

Results are presented for morphologic investigations on the correlation between structural and functional alterations in various inflammatory and non-inflammatory glomerular and extraglomerular renal diseases. The role of the glomeruli in the excretion of substances excreted exclusively by the urinary tract is dependent, to a degree not previously appreciated, on the condition of the postglomerular vasculature as well as on the functional status of the tubular epithelium. All processes which result in damage to the post-glomerular vasculature negatively influence glomerular excretory function by limiting the flow of blood out of the glomeruli and reducing glomerular perfusion. It is further assumed that all processes which negatively influence tubular reabsorption will also be detrimental to glomerular function as a result of increased pressure in the proximal renal tubule as well as via the Thurau mechanism. Finally it is suggested that the kidney's concentrating ability is partially dependent on tubular interstitial factors: with increasing width of the renal cortical interstitium and increasing atrophy of the renal tubule (as measured by the proximal tubules) the kidney's concentrating ability steadily diminishes.