Postischemic renal failure. Intrarenal blood flow and functional characteristics in the recovery phase.

Intrarenal blood flow, nephron function and whole kidney function were studied in the recovery phase of acute failure induced by 45 min of warm ischemia. Analyses were made 24 h, 7 days and 28 days after the ischemic insult. At 24 h the total renal blood flow was 4.0 ml . min-1 . g-1, decreasing to 1.2 within one week. After four weeks it was normalized to 3.4 ml . min-1 . g-1. The intrarenal blood flow distribution, studied with the 86-Rb extraction method, showed the same pattern of response, with no signs of a persistent heavy reduction in the deeper parts, as was found 10 min after recirculation (Karlberg et al. 1982 a). The contralateral, nonischemic kidney responded with hyperemia in all areas 24 h after the trauma, but after 7 days the values were normal. The function of the superficial nephrons was studied with the micropuncture technique. In the initial phase mainly obstructed nephrons were found, but after four weeks the nephrons were essentially normal. After 24 h the postischemic kidneys were anuric but at 7 days urine production had started and the GFR was 0.1 ml . min-1; this improved to 0.55 ml . min-1 after 4 weeks.