A STUDY IN THE MAINTENANCE PHASE OF ISCHEMIC ACUTE-RENAL-FAILURE IN THE RAT

The fate of the trapped deformed erythrocytes seen in the early recirculation phase after ischaemia and the generation of long Tamm-Horsfall (TH) cylinders in the renal medulla during the first week after recirculation was studied in rats. In an in-vitro study the effects of different concentrations of TH protein on the permeability to Na+ of a semipermeable membrane were also investigated. The trapping of erythrocytes was found to be a reflow phenomenon, as there was no increase in the capillary area of the medulla in kidneys subjected to ischaemia but with no recirculation. This area increased to a maximum of 34.6 ± 2.07% 20 min after recirculation and decreased to a normal value of 3.3 ± 0.74% 1 day after the primary ischaemia. The area occupied by cylinders increased to a maximum of 19.2 ± 1.4% 2 days after the primary damage and was as large as 16.7 ± 1.47% after 1 week. It was also shown that the diffusion half-time of Na+ ions across a semipermeable membrane increased from 11.4 ± 0.45 min to a maximum of 32.2 ± 2.19 min with a protein concentration of 1 mg ml-1. It was concluded that the trapping of erythrocytes alone could not explain the decrease in renal function 1 week after the primary damage, but that the blockade of the tubules by the long homogeneous TH cylinders could be responsible for this decrease.