Influences of dietary omega-3 polyunsaturated fatty acids on the recovery of cardiac and renal functions after preservation in hyperlipidemic rats.

BACKGROUND

The effects of a soybean oil diet and a high-cholesterol oil (HC) diet, and an HC diet with eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) supplementation, on basal and postpreservative cardiac function of the hearts and on postpreservative renal function of the kidneys from older rats were examined.

METHODS

Groups 1 through 4 of 100-week-old rats were fed either soybean oil, HC, HC with EPA, or HC with DHA, respectively, for 12 weeks. Blood was collected for analysis of plasma fatty acids, and the heart and left kidney were removed from the rat. In experiment 1, the heart was perfused on a Langendorff apparatus. After evaluation of the cardiac function of each rat, the heart was stored in histidine-tryptophan-ketoglutarate solution for 8 hr at 4 degrees C. The heart was reperfused and the recovery of cardiac function was evaluated. The coronary perfusate during reperfusion was collected to measure 6-keto prostaglandin F1alpha and thromboxane B2. Coronary flow (CF) perfused with Krebs-Henseleit bicarbonate (KHB) solution containing 5-hydroxytryptamine (5-HT) and nitroglycerin were evaluated in the Langendorff mode with atrial pacing (330 beats/min). In experiment 2, the excised left kidney was immediately flushed and preserved with University of Wisconsin solution for 8 hr at 4 degrees C. The kidney was then reperfused with KHB solution and renal function was evaluated.

RESULTS

The plasma and cardiac EPA levels in group 3 were significantly higher than the levels found in the other groups. The plasma and cardiac ratios of EPA to arachidonic acid were significantly higher in groups 3 and 4 than in groups 1 and 2. There were no significant differences in basal cardiac function among any of the diet-fed rats. The percentage values of the recovery of aortic flow, cardiac output (CO), and left ventricular max dp/dt in group 3 and CO in group 4 were significantly higher than in group 2. In addition, the recovery of CF in group 3 tended to be higher than in group 2 (P=0.07). The percentage values of the recovery of aortic flow, CF, CO, and left ventricular max dp/dt in group 1 were significantly lower than in the other dietary groups. CF reperfused with KHB solution containing 5-HT was significantly higher in group 3 than in groups 1 and 2. CF reperfused with KHB solution containing 5-HT was significantly higher in group 4 than in group 1. CF reperfused with KHB solution containing nitroglycerin in group 3 tended to be higher than in groups 1 and 2 (P=0.07). The thromboxame B2 concentrations in the coronary perfusate during reperfusion in groups 3 and 4 were significantly lower than in groups 1 and 2. Fractional sodium reabsorption in group 3 was significantly higher than in group 2. Inulin clearance in groups 3 and 4 was significantly higher than in group 1. The postpreservative urinary flow in group 3 was significantly higher than in groups 1 and 2. The urinary flow was significantly higher in group 4 than in group 1.

CONCLUSIONS

These results suggest that EPA administration may attenuate preservation and reperfusion injury and improve the recovery of cardiac and renal functions in hyperlipidemic and older rats. DHA administration may also show beneficial effects on kidney preservation in hyperlipidemic rats.