OMEGA-3-FATTY-ACIDS ATTENUATE GLOMERULAR CAPILLARY HYDRAULIC PRESSUREIN RATS WITH RENAL ABLATION

To clarify the emerging role of omega-3 fatty acids (FAs) in the regul ation of the renal microcirculation, we recently performed micropunctu re studies in normal rats maintained on diets enriched with omega-3 FA s. Although those studies suggested that omega-3 FAs alter the renal m icrocirculation in normal rats, it was not apparent whether this dieta ry maneuver could modulate intrarenal hemodynamics in the setting of r enal disease. Therefore, the present renal micropuncture studies were performed in nephrectomized rats maintained on control diets or diets enriched with omega-3 FAs. omega-3 FAs abrogated glomerular capillary (56.2 +/- 0.8 vs. 63.9 +/- 2.0 mm Hg) and transcapillary hydraulic pre ssure (40.9 +/- 1.4 vs. 50.6 +/- 1.3 mm Hg) compared to untreated rats , This effect was attributable to (1) a reduction in mean arterial pre ssure (138 +/- 3 vs. 163 +/- 2 mm Hg) and (2) a decrease in efferent a rteriolar resistance (0.43 +/- 0.06 vs. 0.98 +/- 0.19 dyn x seconds x cm(-5) x 10(10)). Sclerosis index and albuminuria were also lessened b y this dietary maneuver. To further characterize the mechanism of alte red renal arteriolar resistance, we then explored the effects of omega -3 FAs on renal prostaglandin synthesis and angiotensin II-stimulated phospholipid turnover. A significant decrease in the urinary excretion of the renal vasoconstrictor, TXA(2) (12.8 +/- 2.3 vs. 35.1 +/- 14.0 ng/24 hr), was induced by treatment with omega-3 FAs. Moreover, angiot ensin II-stimulated phospholipid turnover was attenuated in intact glo meruli pretreated with omega-3 FAs. We conclude that omega-3 FAs exert favorable effects on experimental renal injury by eliciting a salutar y effect on the renal microcirculation of rats subjected to subtotal r enal ablation. Moreover, the similarities between these findings and t hose obtained with sustained inhibition of angiotensin II converting-e nzyme suggest that these compounds act through parallel pathways of in hibition.