Tubular permeability maintained in post-ischemic acute renal failure

Abstract

The effect of nearly total renal ischemia during a two hour period on glomerular filtration and urine composition was studied in relation to tubular permeability and tubular obstruction, two mechanisms that could explain renal insuficiency after iscehmia. Studies on creatinine clearance, micropuncture and microinjection of 14C-inulin into the proximal tubules by means of a hydraulic system were performed before and after the period of ischemia. Thirty minutes after the withdrawal of arterial obstruction, the animals exhibited a maintained diuresis, 50 per cent reduction in glomerular filtration in the superficial nephrons and in the total kidney, a reduction in the proximal fractional absorption of water, and also an increase in the urinary elimination of sodium. The glomerular filtrate of cortical nephorns obtained by micropuncture in anterior areas of the proximal tubules did not differ significantly from the one obtained by micropuncture in more distal areas. The inulin injected into the proximal tubules of a kidney was entirely eliminated by it.