Thirteen-week dietary intake of rapeseed oil or soybean oil as the only dietary fat in Wistar Kyoto rats - change in blood pressure

Wistar Kyoto (WKY) rats were fed a diet containing 10% rapeseed (canola) oi l or soybean oil as the only dietary fat for 13 weeks. From week 5 of feedi ng, systolic blood pressure of the canola oil group became higher than that of the soybean oil group. The 13-neek canola oil intake increased plasma l evels of Na+ and lipids, and decreased the level of K+ compared to those in the soybean oil group. The canola oil group also showed a high density of neutrophils and a low density of platelets compared to the soybean oil grou p. Moreover, the activities of catalase and superoxide dismutase in the hep atic cytosol were depressed in the canola oil group. The mechanisms for the higher blood pressure are unclear, However, an increase in body fluid via activation of Na+ pump or Na+, K+-ATPase and/or a blunt endothelium-depende nt vasodilation by increased superoxide might have relevance to the elevate d blood pressure. The increased plasma lipids and the changes in the densit ies of platelets and neutrophils appear not to be critical in WKY rats. How ever, these would tend to promote peripheral vascular lesions in the strain s, such as spontaneously hypertensive rats and stroke-prone spontaneously h ypertensive rats, which are prone to present atheroscrelotic vascular injur y. (C) 2000 Elsevier Science Ltd. All rights reserved.