Measurement of the vasoconstrictive substances endothelin, angiotensin II, and thromboxane B2, in cold storage solution can reveal previous renal ischemic insults

In a rat model, the left kid ney was subjected to 60 min of normothermic ischemia followed by 15 min of reperfusion, whereas the right kidney, serving as a paired control, was not rendered ischemic. Both kidneys were then perfused in situ with either Euro-Collins (EC) solution (n=12) or University of Wisconsin (UW) solution (n=6) for 10 min. Each kidney was then harvested and stored at 4°C in its respective solution. After 24 and 48 h of cold storage, the following vasoactive substances were measured in the preservation media: endothelin (ET), angiotensin II (A-II), thromboxane (B2) (TxB2), and prostaglan-din I2 (PGI2). After 24 h in EC solution, left kidneys uniformly produced significantly higher concentrations of each vasoactive substance than right kidneys: ET 1.64 ± 0.3 pg/ml vs 0.82 ± 0.1 pg/ml (P 0.009); A-II 20.8 ± 6.2 pg/ml vs 7.75 + 2.3 pg/ml (P 0.007); TxB2, 100.8 ± 17.7 pg/ml vs 40.1 f 11.7 pg/ml (P 0.04); PGI2, 638.3 ± 41.1 pg/ml vs 318.3 ± 36.4 pg/ml (P 0.001), respectively. At 48 h, a similar pattern of results was obtained as the kidney continued to produce TxB2 and prostacyclins during the 24–48 h period. In the UW solution, basal levels of ET and A-II were lower than those in EC solution, but similarly increased after initial ischemia. At 24 h, the concentrations produced by the left and right kidneys were as follows: ET 0.66 ± 0.1 pg/ml vs 0.48 ± 0.1 pg/ml (P 0.14); A-II 10.36 f 3.7 pg/ml vs 2.14 ± 0.7 pg/ml (P 0.006); TxB2 178 ± 53 pg/ml vs 52 ± 23.1 pg/ml (P 0.001); and PGI2 448.3 ± 49 pg/ml vs 323 ± 44.3 pg/ml (P 0.01), respectively. After 48 h, the range of concentrations of each substance was similar to that obtained after 24 h. In further studies, the concentrations of ET and A-II were measured in solution previously used to preserve human kidneys (n=7). The mean concentration of ET and A-II in these samples was 3.82 ± 1.14 pg/ml and 21.3 ± 9.2 pg/ml, respectively, whereas in control media both substances were below the limits of detection. These results demonstrate that vaso-constrictive substances can be measured in the preservation media after a kidney has been stored cold and that higher concentrations are found when the organ has been subjected to prior normothermic ischemia. The measurement of these vasoactive substances before transplantation may reveal that the kidney has been subjected to previous ischemic events. Moreover, these vasoactive substances could be involved in the early recovery of renal function after kidney transplantation.