To determine whether purified ω-3 and ω-6 fatty acids influence the progression of hypertensive renal failure in salt-loaded stroke-prone spontaneously hypertensive rats (SHRSP) with established hypertension of during the developmental stage of their hypertension.
Groups of eight SHRSP aged 1 or 4 months were fed, for 12 weeks, synthetic diets containing 2% sodium (wt:wt) and either 5% olive oil or 4.5% γ-linolenic acid (ω-6), eicosapentaenoic acid (ω-3) or docosahexaenoic acid (ω-3).
Urinary protein excretion and blood pressure were measured after 6, 9 and 12 weeks. The rats were killed and their tissues were collected for fatty acid and eicosanoid analysis.
Young rats (aged 1 month) fed diets containing γ-linolenic acid or olive oil developed marked proteinuria by 9 weeks, whereas no change was observed after 12 weeks in rats fed docosahexaenoic acid or eicosapentaenoic acid. Blood pressure was lower in those fed docosahexaenoic acid or eicosapentaenoic acid than in the γ-linolenic acid or olive oil groups. Adult rats (Aged 4 months) fed the docosahexaenoic acid diet had significantly lower proteinuria than those fed γ-linolenic acid, eicosapentaenoic acid or olive oil, but there were no differences in blood pressure among the groups. Kidneys from rats fed ω-3 fatty acids had increased levels of docosahexaenoic acid or eicosapentaenoic acid, or both, whereas those from rats fed γ-linolenic acid and olive oil contained virtually no ω-3 fatty acids. Thromboxane B2 and 12-hydroxyeicosatetraenoic acid production in renal cortex extracts was lowest in rats fed docosahexaenoic acid and eicosapentaenoic acid.
Dietary ω-3 fatty acids retard the development of hypertension-induced proteinuria. This may be caused by a favorable influence on fatty acid and eicosanoid metabolism and reduction of blood pressure.