Changes of blood pressure in spontaneously hypertensive rats dependent on the quantity and quality of fat intake

The effect of diets rich or deficient in polyunsaturated fatty acids (PUFA) on blood pressure of spontaneously hypertensive rats (SHR) and normotensive Wistar rats (WR) was studied. The diets contained either sunflower oil (PUR-SOL), linseed oil (PUR-LIN), cod-liver oil or hydrogenated palm-kernel oil (PUFA-deficient) amounting to 15 or 3 weight percent of fat. They were started at weaning (4 weeks of age) for 22 weeks or prenatally one week before mating of the parents. During the development of hypertension in SHR, systolic blood pressure was decreased in animals of all dietary groups fed 15% fat when compared to SHR on normal food (pellets), i.e. independent of the various diets loaded, all diets containing 15% fat led to a marked delay in the onset of high blood pressure as compared to SHR on normal pellet food. After manifestation of hypertension, obviously a more differentiated effect on blood pressure could be shown in SHR in dependence on different amounts of PUFA loaded. In normotensive Wistar rats (WR) after feeding linseed oil or sunflower oil also a significant lowering in blood pressure could be observed in comparison to controls fed pellets. But after feeding cod-liver oil there was no decrease in blood pressure of normotensive Wistar rats, whereas palm-kernel oil resulted in a blood pressure lowering effect only at the later age of normotensive Wistar rats. Moreover, in SHR after prenatal feeding of a LA-rich, but also a PUFA-deficient diet the blood pressure lowering effect was more pronounced as compared to postnatal feeding of the diets. SHR fed a 15% fat diet showed a significantly lower body weight in comparison to SHR fed a 3% fat diet. In both dietary groups SHR were significantly smaller than SHR fed pellets. In WKY fed a 3% or a 15% fat diet the same body weight could be confirmed. Food intake in SHR fed a 3% fat diet ad libitum appeared higher than in SHR fed a 15% fat diet ad libitum. However, considering the uptake of energy no differences between the groups could be seen. Therefore, in SHR fed a 15% fat diet, body weight and blood pressure were lowest when compared with the other groups of SHR indicating that body weight in SHR might be nearly connected with blood pressure level.(ABSTRACT TRUNCATED AT 400 WORDS)