Effect of exogenous ascorbic acid on experimental hypertension and mineral balance in rats fed low- and high-fat diets.

The effects of exogenous ascorbic acid on the development of experimental hypertension and on calcium, sodium, and potassium metabolism have been studied. The investigation was carried out in 90 4-mo-old male Wistar rats fed high- and low-fat diets. Hypertension was induced by administering a 1.5% solution of NaCl orally. Some rats received 0.1% ascorbic acid in distilled water orally for the first 7 wk of the experiment, then 0.3% for the next 5 wk. The results showed that the amount of fat, NaCl, and ascorbate in the diet may play a role in the etiopathogenesis of hypertension. A high-fat high-NaCl diet increased blood pressure more than a low-fat high-NaCl diet. Additional intake of 0.3% ascorbate solution reduced experimentally induced hypertension by 4% with a low-fat diet and by 14% with a high-fat diet. Also, 0.3% ascorbate solution had a blood-pressure-lowering effect in rats fed a high-fat diet without NaCl. Supplementation with ascorbate diminished urine calcium output with a high-fat diet and increased the urine PGE2/PGF2 ratio with both low- and high-fat diets.

Effect of dietary fats on experimental hypertension.

In an experiment on 95 Wistar rats weighing 330 g the effect was studied of partially hydrogenated marine oil and cod-liver oil as well as sunflowerseed oil and animal fat on arterial hypertension induced with administration of 1.5% NaCl in drinking water. During 5 weeks the animals received diets containing 37.8 kcal% derived from the studied fats. After the first week of 1.5% NaCl solution administration a significant rise of the systolic blood pressure and heart rate was observed in all animals without regard to the fat received by them with the diet. The rise of the blood pressure was greatest in the group of rats kept on the diet with animal fat, while in the groups of rats receiving diets with sunflowerseed oil or marine oils this rise was significantly smaller, especially with cod-liver oil. The hypotensive effect of marine oils, particularly cod-liver oil, was more pronounced than that of sunflowerseed oil. The hypotensive effect of partially hydrogenated fish oil was less pronounced than that of cod-liver oil. Our experiments demonstrated a significant effect of the amount of dietary fat on the development of experimental hypertension. Greater intake of salt and animal fats in human diet may be one of the causes of essential hypertension.

Effect of long-term diet enrichment with selenium, vitamin E and vitamin B15 on the degree of fatty infiltration of the liver.

In a two-year experiment on 190 Wistar rats the effects were studied of the aging process and diet enrichment with selenium, vitamin E and vitamin B15 (pangamic acid) on the degree of fatty infiltration of the liver determined histochemically with Oil Red O. The degree of fatty infiltration of the liver was assessed by the method of quantitative analysis using a computer image analyser Quantimet 720. System 30 (Cambridge Instruments). The process of aging of the animals was associated with increasing fatty infiltration of the liver. Selenium had a two-phase effect on the degree of fatty infiltration: in the first 12 months of selenium administration (0.1 ppm of sodium selenite per 100 g of the diet) fatty infiltration of the liver was decreasing, and after 18 months of the experiment this effect disappeared and the degree of fatty infiltration was not different from that in the control group. Contrary to this, vitamin E administration 6 mg/100 g of the diet increased the degree of fatty infiltration during the first 12 months. After 18 months a reverse effect appeared with inhibition of the progression of fatty infiltration. Thus the two-phase effect of vitamin E was a reverse of selenium effect. Addition of vitamin B15 to the diet (2.5 mg/100 g of diet) increased the degree of fatty infiltration of the liver which was maintained at a stable level throughout the whole experiment, i.e. 12-18 months.