Effects of dietary cod liver oil on fatty-acid composition and calcium transport in isolated adult rat ventricular myocytes and on the response of isolated hearts to ischemia and reperfusion

Abstract

Three-week-old male and female rats were placed either on standard rat chow or chow supplemented with 10% cod liver oil for 12 weeks. Animals fed cod liver oil demonstrated reduced body weights. Cod liver oil feeding produced a significant reduction in the ratio of (n−6)/(n−3) fatty acids in phospholipids of the isolated myocytes. The primary changes included a significant decrease in archidonic acid (20:4, n−6) and elevations in eicosapentaenoic acid (20:5, n−3) and docosahexaenoic acid (22:6, n−3). Furthermore, isolated myocytes from cod liver oil fed rats exhibited an enhanced ⁴⁵Ca²⁺ uptake, although ⁴⁵Ca²⁺ release was unaffected. Dietary cod liver oil had little effect on cardiac response to ischemia and reperfusion. Thus, neither developed force or resting tension was significantly affected by diet, although the latter tended to be elevated in hearts from cod liver oil fed animals. Release of creatine kinase was unaltered by diet. The release of 6-ketoprostaglandin F_1α from isolated hearts was significantly reduced by dietary cod liver oil, likely due to the reduced levels of arachidonic acid. Our study indicates that dietary cod liver oil and subsequent changes in phospholipid fatty-acid content are accompanied by changes in Ca²⁺ transport in isolated cardiac myocytes. However, this diet produces little effect on the cardiac response to acute ischemia and reperfusion.