Effect of dietary alpha-linolenic acid on functional characteristic of Na+/K(+)-ATPase isoenzymes in whole brain membranes of weaned rats.
The influence of dietary fatty acids on Na+ sensitivity and ouabain affinity of Na+/K(+)-ATPase isoenzymes of whole brain membranes were studied in weaned rats fed for two generations with diets either devoid of alpha-linolenic acid (sunflower oil diet) or rich in alpha-linolenic acid (soya oil diet). The (n--3) deficiency induced by the sunflower oil diet led to an increase in the (n--6)/(n--3) molar ratio in whole brain membranes. Na+/K(+)-ATPase isoenzymes were discriminated on the basis of their differential affinities for ouabain. In rats fed sunflower oil diet, the ouabain titration displayed three inhibitory processes with markedly different affinities: low affinity (alpha 1); high affinity (alpha 2); and very high affinity (alpha 3). Membranes of rats fed soya oil diet exhibited only two inhibitory processes, i.e., low affinity (likely alpha 1+ alpha 2) and high affinity (likely alpha 2+ alpha 3) with the low affinity form intermediate between the sunflower alpha 1 and alpha 2 forms, and the high affinity form intermediate between the sunflower alpha 2 and alpha 3 forms. In fact, the Na+ response shows that the three isoenzymes have different Na+ sensitivities. Regardless of the diet, alpha 1 has a similar Na+ sensitivity (less than 1 mM), whilst alpha 2 and alpha 3 are more sensitive in soya oil membranes compared to sunflower oil membranes (5.1 vs. 7.2 mM and about 11 vs. 22.5 mM, respectively). Thus, sodium appears to be a better criterion of heterogeneity than ouabain.
INSERM U26 Hôpital Fernand Widal, Paris, France.
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Gerbi
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Zerouga
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Debray
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Durand
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Chanez
J M
JM
Bourre
D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000201:enzymology; D004042:Dietary Fats, Unsaturated / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D005227:Fatty Acids / Q000032:analysis; D007527:Isoenzymes / Q000378:metabolism*; D008042:Linolenic Acids / Q000172:deficiency / Q000494:pharmacology*; D008566:Membranes / Q000187:drug effects / Q000201:enzymology; D010042:Ouabain / Q000494:pharmacology; D010938:Plant Oils / Q000008:administration & dosage; D051381:Rats; D017208:Rats, Wistar; D012964:Sodium / Q000494:pharmacology; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D013024:Soybean Oil / Q000008:administration & dosage; D000074242:Sunflower Oil
D004042:Dietary Fats, Unsaturated; D005227:Fatty Acids; D007527:Isoenzymes; D008042:Linolenic Acids; D010938:Plant Oils; D000074242:Sunflower Oil; D010042:Ouabain; D013024:Soybean Oil; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase