Susceptibility of the proximal tubular brush border to acute obstructive injury.

The purpose of this investigation was to determine the susceptibility of proximal renal tubular epithelial cells to the effects of acute urinary tract obstruction. Brush border derived-renal tubular epithelial antigens (RTE) were quantitated in urine by radioimmunoassay both before and after the induction of bilateral ureteral obstruction of 15-150 minutes duration in anesthetized diuretic rats. Glomerular filtration rates (GFR) before and after obstruction were determined by calculating renal clearances of Na iothalamate 125I. Light microscopic examination of renal tissue was performed. Post obstructive renal function was well preserved in all rats with GFRs ranging from 76-100 per cent of control values. However, in the immediate post-obstructive period RTE excretion increased dramatically in all rats. Up to 10 fold increases in urine antigen concentrations were observed under conditions of isosthenuria and stable urine flow rates. The degree of elevation correlated with the length of obstruction and with the severity of histologic changes in the proximal tubules (progressive proximal tubular dilatation and brush border loss). It is concluded that proximal tubular cells are highly susceptible to obstructive insults as brief as 15 minutes in duration. The mechanism of this injury and its effect on post-obstructive renal function remain to be clarified.