No Effect of Dietary Fish Oil on Renal Hemodynamics, Tubular Function, and Renal Functional Reserve in Long-Term Renal Transplant Recipients1 Jesper Meichior Hansen,2 Hans L#{248}kkegaard, Carl-Erik H#{248}y,Niels Fogh-Andersen, Niels Vidlendal Olsen, and Svend Sfrandgaard supplementation with fish oil in these patients did not J.M. Hansen, N.y. Olsen, Department of Clinical improve renal function. Physiology, Herlev Hospital, University of Copenhagen, Key Words: Amino acids, cyclosporin A, GFR, lithium clear- Herlev, Denmark once, renal circulation H. L#{248}kkegaard, S. Strandgaard, Department of Nephrology, Herlev HospItal, University of Copenha- T he use of cyclosporin A (CsA) in clinical immuno- gen, Herlev, Denmark suppression is associated with nephrotoxlcity, characterized by a dose-dependent, initially reversible N. Fogh-Andersen, Department of Clinical Chemistry, decline in the GFR and RBF (1 ,2). The renal hemody- Herlev Hospital, University of Copenhagen, Herlev, namic changes are most likely due to a direct CsA- Denmark induced constriction of the afferent arteriole (3). The C.-E. H#{248}y,Department of Biochemistry and Nutrition, precise mechanism of this vasoconstriction is still Technical UniversIty of Denmark, Lyngby, Denmark unclear, but some evidence does suggest a CsA-in- (J. Am. Soc. Nephroi. 1995; 5:1434-1440) duced alteration in the synthesis of the eicosanoids (4-6). In addition to the renal functional changes, prolonged treatment with CsA may cause structural ABSTRACT lesions in the kidney with arteriolopathy and intersti- Dietary supplementation with fish oil rich In n-3 poly- tial fibrosis (7). unsaturated fatty acids has been suggested to pro- Previous studies in CsA-treated animals (4,8) and humans (9-1 1) have demonstrated that a dietary tect the kIdney agaInst cyclosporin A (CsA) toxicity. supplement of fish oil rich in n-3 polyunsaturated This study Investigated the effects of a 10-wk dietary fatty acids (n-3 PUFA) improves renal function, possi- supplementation with fish oIl on renal function and bly by reducing the synthesis of the vasoconstricting renal functional reserve in healthy volunteers (N = 9) elcosanoid thromboxane (4). DUssing and coworkers and two groups of stable long-term kldney-frans- demonstrated that fish oil also may decrease renal planted patients freated with maintenance low-dose vascular resistance and increase GFR in healthy CsA (3.0 ± 0.6 mg/kg; N = 9) or without CsA (N = 9). young volunteers (12), suggestIng that the effect of After an overnight fast, the subjects were water fish oil on renal hemodynamics is nonspecific and not loaded, and clearance studies were performed, post- restricted to CsA-induced nephrotoxicity. poning morning medication. GFR and effective RPF In normal kidneys, GFR increases in response to an were measured as the renal clearances of (Tc)DTPA oral protein load or iv infusion ofamino acids (13,14). This renal functional reserve has been shown to be and (1311)hippuran, respectively. Renal tubular function absent or blunted in CsA-treated kidney-transplanted was evaluated by use of the renal clearance of lithium patients (15, 16). It has not previously been studied and the urinary excretion of 3-microgIobulin. Fish oil whether treatment with fish oil has any effect on the did not change baseline values of effective RPF, GFR, renal functional reserve in stable CsA-treated kidney- lithium clearance, and urinary excretion of f32-mlcro- transplanted patients. globulin in any of the groups. The infusion of amino In this study, we have therefore investigated the acids induced a comparable Increase in GFR, lithium effect ofa 10-wk daily dietary supplement with 3.5 g of clearance, and the urinary excretion rate of 13-micro- n-3 PUFA on renal function and renal functional globulin in all three groups with no additional effect of reserve in healthy volunteers and in two groups of fish oil. Thus, long-term renal franspiant recipients stable, long-term, renal transplant recipients treated with and without low-dose CsA. freated with a low maintenance dose of CsA had a well-preserved renal functional reserve, and dietary METHODS 1 Psc.ivd March 22, 1994. Accepted Juno 29, 1994. Subjects 2 coisspondonc. to Dr. J.M. Hanson, Depa,tment 01 Nephrology, Honey Hospl- The study was approved by the scientific ethical committee sal. Hodov Rlngvej, DK-2730 Honey, Denmark. of Copenhagen County. and all subjects gave Informed con- 1046’6673/0507-1434$03.OO/O Journal ol Wi. American Society of Nephrology sent in accordance with the Helsinki Declaration. The study Copyright 0 1995 by the American society of Nephroiogy included 9 normal volunteers, aged 31 to 55 yr. and 18 1434 Volume 5’ Number 7 ‘ 1995 Hansen et al nondlabetic renal transplant recipients, aged 32 to 65 yr with investigated before and on the last day with fish oil supple- a well-functioning graft (serum creatinine below 160 pxnol/D mentation. The protocols for the two study days were iden- for more than 22 months before the study. None had expe- tical, and each study was done in the morning after an rienced any episodes ofacute rejection since the Initial period overnight fast. A 24-h urine sample was collected from 8:00 after transplantation, and none had signs of chronic rejec- a.m. on the day before each study. Lithium clearance (Ca) tion. Nine of the transplanted patients had received immu- was used to estimate the proximal tubular outflow of sodium nosuppressive therapy with prednisone, azathioprine Wa), and water (17). A test dose oflithium carbonate (300 mg. 8.1 and CsA for more than 22 months; at the time of inclusion, mmol) was given orally at 8:00 p.m. the evening before each the dose of CsA was at a low maintenance level (3.0 ± 0.6 study day. On the study days, morning medication was mg/kg; CsA group). Nine had never received CsA. but only withheld and the subjects abstained from smoking and from prednisone and azathioprine Wa group). Four patients in caffeine-containing beverages. Renal function was measured both groups received no antihypertensive medications. The during eight 30-mM clearance periods. Except for briefly last dose of immunosuppressive and antihypertensive med- standing when voiding every 30 mm. the subjects were ication was taken by the patients around 6 p.m. the day investigated in a supine resting position. A urine flow of before the study. Patients receiving dthydropyridlne calcium approximately 500 mL/h was maintained by the oral intake antagonists were not included in the study. The demographic of water starting 2 to 2.5 h before the first clearance period and clinical characteristics ofthe normal subjects and of the with an initial load of 750 mL, followed by 250 mL eveiy 30 two groups ofrenal transplant recipients are shown in Table ruin. After two consecutive 30-mm control periods, the infu- 1 . Two additional subjects were excluded from the study- sion of amino acids (2.5 ml/h per kilogram) was started and one normal subject because of incomplete bladder emptying maintained during six consecutive 30-mm periods. during the renal clearance studies, and one transplant re- Effective RPF (ERPF) and GFR were measured by a con- cipient because of noncompliance (changing to a vegetarian stunt infusion technique with I’31llhippuran and (#{176}‘‘TcJ- diet). D’fl’A in a total dose of 0. 10 mCi (3.6 MBq) and 0.73 mCI (27.0 M8i), respectively. After an equilibration period of at Experimental Protocol least 1 h, renal clearances of L’31llhlppuran. t’TcJDTPA, lithium, and sodium (CNa) were calculated by the urinary For 10 wk, each subject daily received six capsules of excretion rates and plasma samples drawn in the middle of marine, long-chain n-3 PUFA (each containing 1 g of 35% each period. The urinary excretion rate of -micmglobuim eicosapentaenoic acids 1C20:5 n-31, 23% docosahexaenoic was measured in the last control period, in the third last, and acids (C22:6 n-31, and 3 IU ofvitamln E as an antioxidant; in the last period during amino acid infusion. Arterial blood Plkasol, Lube A/S. Hadsund, Denmark). Patient compliance pressure and heart rate were measured once in each clear- was verified by pifi counting and measurements of the ance period by a semiautomatic blood pressure monitor plasma composition offatty acids. Changes in medication or (‘Fakeda Medical, A & D Company, Tokyo, Japan). intake of nonsteroidal anti-inflammatory drugs were not allowed during a period of 1 month before and until the Analytical Methods termination of the study. Subjects were Instructed not to change their diet and level of physical activity during the Activities of I’31llhlppuran and [#{176}FcIDTPA were deter- study period. mined in a well scintillation counter. Uthium in plasma and Renal function and the renal response to the i.v. infusion of urine was measured by atomic absorption spectrophotome- amino acids (Vamin#{176};Pharmacla, Linioges, France; electro- try (Model 403; Perkln Elmer, Norwalk, fl. Plasma sodium lyte free; 18 g of nitrogen/L; 114 g of amino acids/U were was measured with a Technicon RA 1000, and urinary sodium was measured with a Technicon RA-XT (Tarrytown, NY). -MIcmglobu11n in plasma and urine was measured by TABLE 1. Demographic and clinical characterlstlcsa an enzyme-linked immunosorbent assay (DAKO, Copenha- gen. Denmark). Urine samples for p-micmglobuha were Normal CsA Aza stored at pH >6. 6-Keto-prostaglandln F1,, and thromboxane Characteristic Subjects Groupb Groupb B2 in urine were measured by radloimmunoassay, with (N=9) (N=9) (N=9) specific antisera (Amersham, Little Challont, United King- dom), and iodlnated 6-keto-prostagJandln F1,, and throm- Sex (F/M) 5/4 2/7 5/4 boxane B2 were used as tracers.