Purpose: To study the effect of diet and aging in ventricular myocardium. Methods: We studied ventricular lipid composition and electrical activity of 6 groups of rats: 6, 14, 20 months aged rats fed a standard diet, and 25 months fed either standard, saturated fat or fish oil supplemented diet. Biochemical, chromatographic analyses were used for tissue cholesterol (C) and phospholipid (PL), fatty acid of phosphatidylcholine (PC), phosphatidylethanolamine (PE). Ventricular refractory period (VRP) was obtained. Results: C/PL ratio increased along age due a major increase in C than PL (0.24±0.01 at 6,0.34±0.02 at 25 months). In outer membrane PL (PC, PE) unsaturated fatty acids 18:2 and 22:6 decreased, 16:0, 18:0, 18:1 increased along aging. Degree of unsaturation decreased along age by 30% (p<0.05). VRP increased from 91±6 at 6 to 112±6 msec at 25 months (p<0.001). In the aged rats those fed with a saturated diet showed similar but quantitatively more marked changes than those caused only by age while fish oil diet attenuated aging: C/PL ratio 0.36±0.02 in saturated, 0.30±0.02 in fish oil diet (p<0.05 vs normal); saturated diet increased 18:0, 20:4, 22:6 while fish oil diet decreased 18:1, 18:2 20:4, but increased much more 22:6 (p<0.05). Degree of unsaturation did not change with diet in aged rats. Saturated diet further increased VRP in aged rats but fish oil diet did not significantly decreased it (122±7, 111±6 msec, p<0.05). Conclusions: Thus increased ratio C/PL and minor PL unsaturation of the aged myocardium is associated to longer VRP, probably due to a decreased membrane fluidity induced by the lipid changes. A saturated diet exaggerated, while a fish oil attenuated, the aging changes. Clinical implications: When assessing aging process some others factors such as diet lipids must be considered.
|Issue number||4 SUPPL.|
|Publication status||Published - 1 Oct 1996|