Persistent proximal tubule dysfunction late in Heymann nephritis.

To determine whether proximal tubule function returned to normal after cessation of active immunological injury in Heymann nephritis, we compared kidney function in an acute stage of the disease, when antibodies were being deposited on the brush border, to a later, chronic stage. Renal blood flow measurements via a flow probe, along with clearance and micropuncture techniques, were used to measure renal plasma flow, glomerular filtration rate, protein and albumin excretion, organic ion (PAH and TEA) extraction and tubule fluid inulin concentration. Proximal tubule fluid reabsorption, which was depressed in the acute stage of injury, returned to normal in chronic Heymann nephritis, but both PAH and TEA extraction continued to be depressed. PAH extraction was also decreased in isolated perfused kidneys from rats with Heymann nephritis. A three fold increase in PAH content of these perfused kidneys indicated that there was a defect in luminal PAH transport. Reconstitution of the proximal tubule brush border in chronic Heymann nephritis was not accompanied by functional recovery of secretory processes.