CHOLINE UPTAKE INTO RENAL PHOSPHOLIPIDS FOLLOWING RENAL ISCHEMIA IN RATS

Renal phospholipid metabolism was studied after ischemia was induced by occlusion of the left renal artery in the rat. There was no change in the rate of cellular [14C]choline uptake after 25 or 60 min of ischemia. However, [14C]choline incorporation into phospholipid was 2 to 3 times greater in slices from the ischemic kidney than in slices from the contralateral control kidney. The increase occurred after 25 min of ischemia plus 15 min of reflow, and after 60 min of ischemia with or without reflow. When [14C]choline was injected into rats after a 60-min period of renal ischemia, the rate of incorporation into phospholipid in the ischemic kidney was almost twice that of the control kidney. These results were similar to those of the in vitro experiments. Since virtually all of the cellular phospholipids of the kidney are present in cellular membranes, renal ischemia affects membrane metabolism. The mean distribution ratio of α-aminobutyric acid in slices of kidneys ischemic for 60 min was similar to that of control slices: 4.11 ± 0.2 (SEM) vs. 4.30 ± 0.30. The normal uptake of α-aminobutyric acid indicates that the increased incorporation of choline is associated with functional integrity of the membrane.