INFLUENCE OF LONG-TERM SUPPLEMENTATION WITH ALPHA-LINOLENIC ACID ON MYOCARDIAL LIPID-PEROXIDATION AND ANTIOXIDATIVE CAPACITY IN SPONTANEOUSLY HYPERTENSIVE RATS

zThe ischaemic vulnerability of the heart of spontaneously hypertensiv e rats (SHR) is enhanced after feeding an alpha-linolenic acid (LNA) e nriched diet. Because oxygen radical-induced reactions (e.g. lipid per oxidation) are involved in the ischaemic damage, an increased suscepti bility of the SHR heart to such damaging reactions might be the reason . As a sign of the enhanced susceptibility to lipid peroxidation of LN A-fed SHR, we found (measured as TBARS) higher plasma and heart lipid peroxide levels (3.84 +/- 0.50 mu mol/l vs 2.98 +/- 0.78 mu mol/l and 507 +/- 127 nmol/g prot. vs 215 +/- 80 nmol/g prot., respectively) aft er feeding LNA. Using Fe2+/Vit. C to induce lipid peroxidation in myoc ardial tissue homogenates, we demonstrated the enhanced susceptibility to lipid peroxidation of the LNA-fed SHR heart (68 +/- 12 nmol/min x g prot. vs 40 +/- 8 nmol/min x g prot.) also in vitro. The myocardial enrichment of n-3 polyunsaturated fatty acids (PUFA) resulting in a hi gher peroxidation index (PI 227 vs. 170) and the loss in myocardial ac tivities of the antioxidative enzymes (SOD: 76 +/- 24 U x 10(3)/g prot . vs 235 +/- 150 U x 10(3)/g prot.; GSH-Px: 32 +/- 5 U/g prot. vs 110 +/- 30 U/g prot.) by feeding LNA could be the cause of the increase in myocardial susceptibility to lipid peroxidation of PUFA supplemented SHR.