Fatty acid metabolism during hypothermic perfusion of the isolated dog kidney.

Perfusion of isolated dog kidneys was performed at 8--12 degrees C using an albumin solution containing caprylic acid (about 6 mmol/l) and long-chain fatty acids (about 0.5 mmol/l). During 48 h the amounts of caprylic acid in the perfusate fell by about 3 mmol, whereas long-chain FFA increased by 0.2--0.3 mmol and small amounts of arachidonic acid appeared. [14C]palmitate or [14C]linoleate--when added--decreased by about 10% in the perfusate. The decrease was mainly due to exchange with kidney phospholipid fatty acids. Only about 0.4% was recovered as [14C]CO2. The amounts of total phospholipids in kidney tissue decreased by up to 10% during the perfusion (when 10% kidney weight gain was taken into account), whereas lysophospholipids, cholesterol, triglycerides and free fatty acids remained essentially unchanged. The distribution of fatty acids in the total phospholipid fraction was strikingly altered. The relative amounts of arachidonic acid increased, whereas all other major fatty acids decreased. Synthesis of arachidonic acid by chain elongation of perfusate [14C]linoleic acid could not be demonstrated, and no evidence was found for a significant increase of the total amounts of arachidonic acid. The possibility that arachidonic acid-containing phospholipids in the kidney are preferentially preserved during the hypothermic conditions is discussed.