Influence of the phospholipid n-6:n-3 polyunsaturated fatty acid ratio on the oxidative phosphorylation of isolated cardiac mitochondria (part 11). DISCUSSION
Liedtke et al showed that an excess fatty acid supply enhanced the oxygen cost of contractility in the open-chest working swine heart. On the other hand, stunned myocardium exhibits a reduced metabolic efficiency. Mitochondrial free calcium concentration is known to increase during ischemia and to be maintained for a long period during reperfusion. This could result in decreased cardiac metabolic efficiency in a way similar to that reproduced in vitro in the isolated mitochondria. We reported an increased fatty acid oxidation to oxygen consumption ratio in stunned myocardium. This excess fatty acid oxidation might result in acetate accumulation and oxygen wasting in the whole heart.
The effect of dietary PUFA on mitochondrial function was the main focus of the present stuy. Substituting n-6 PUFA with n-3 PUFA in the diet did not modify the amounts of saturated, monounsaturated and polyunsaturated fatty acids. Conversely, the n-6:n-3 PUFA ratio of mitochondrial phospholipids was noticeably decreased. These changes in membrane fatty acid composition were associated with some changes in mitochondrial function. Whatever the free calcium concentration, the n-3 rich mitochondria exhibited a lower rate of oxygen consumption. This is in agreement with other studies, showing that high levels of n-3 PUFA in the phospholipids decreases mitochondrial oxidative capacities. This phenomenon remains unexplained. In the present study, the n-3 PUFA-induced decrease in oxidative capacity was associated with lower CP production. A higher ADP content in the buffer devoid of free calcium during the first minute of incubation and a lower ATP level in the presence of 0.50 |jM free calcium were also noticed in the n-3-rich mitochondria. This suggests that the n-3-rich mitochondria displays a lower creatine production through the creatine kinase system because of decreased oxidative and phosphorylation capacities. This could be due to changes in the membrane lipid environment. Find out more about your chance to visit the most trusted pharmacy you could ever find to get in the amounts required, without any need to see your health care provider first or get a prescription.