Influence of long-term supplementation with alpha-linolenic acid on myocardial lipid peroxidation and antioxidative capacity in spontaneously hypertensive rats.

The ischaemic vulnerability of the heart of spontaneously hypertensive rats (SHR) is enhanced after feeding an alpha-linolenic acid (LNA) enriched diet. Because oxygen radical-induced reactions (e.g. lipid peroxidation) are involved in the ischaemic damage, an increased susceptibility of the SHR heart to such damaging reactions might be the reason. As a sign of the enhanced susceptibility to lipid peroxidation of LNA-fed SHR, we found (measured as TBARS) higher plasma and heart lipid peroxide levels (3.84 +/- 0.50 micromol/l vs 2.98 +/- 0.78 micromol/l and 507 +/- 127 nmol/g prot. vs 215 +/- 80 nmol/g prot., respectively) after feeding LNA. Using Fe2+/Vit. C to induce lipid peroxidation in myocardial 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 higher peroxidation index (PI 227 vs. 170) and the loss in myocardial activities 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.