Effect of varying concentrations of linoleic acid on α-adrenoceptor responses in spontaneously hypertensive rats

Abstract The effect of increased intake of linoleic acid on the α-adrenergic system was assessed by safflower oil supplementation to spontaneously hypertensive rats. Linoleic acid-enriched intake at 5%, 15% and 30% by weight of total food intake for 12 wk was associated with a reduction in resting arterial blood pressure, while heart rate and heart to body weight ratios were similar to control group values. A dose-response analysis to norepinephrine bitartrate administered intravenously indicated a significant reduction in the vascular reactivity to this α-adrenergic agonist in all groups given linoleic acid. Direct assessment of α-adrenoceptor number (Bmax) and affinity (K D ) in cardiac sarcolemma with [ 3 H]-prazosin indicated that receptor binding properties were not affected by linoleic acid intake. Our results suggest that short-term linoleic acid supplementation in the established hypertensive state may lower blood pressure through effects upon α-adrenergic reactivity in vascular tissue, without associated effects in cardiac tissue.