The question was addressed whether dietary phosphorus-induced nephrocalcinosis in rats is associated with impaired kidney function. Weanling female rats were fed purified diets containing either 0.4 or 0.6% (wt/wt) phosphorus for 28 d. The diet containing 0.6% phosphorus produced marked kidney calcification, as determined both by chemical analysis of kidney calcium and histological examination in kidney sections. Histological examination did not show calcification in stomach, lung, heart or thoracic aorta, which are predisposition sites of metastatic calcification in secondary renal hyperparathyroidism. In rats fed the 0.6% phosphorus diet, phosphorus retention and urinary excretion were greater compared with rats fed the 0.4% phosphorus diet. The following indicators of kidney function were examined: water intake, urinary volume, urine and plasma osmolality, urine and plasma creatinine, urine and plasma urea, urea and creatinine clearance and urinary albumin excretion. Of these indicators, only urinary albumin excretion was significantly increased in rats fed the nephrocalcinogenic diet. In a further experiment, the increase of urinary albumin was reproduced. After pooling the results of the two experiments, in individual rats fed the 0.6% phosphorus diet, the concentration of kidney calcium was found to be positively related with kidney weight expressed relative to body weight (r = 0.82, n = 22) and with albumin excretion in urine (r = 0.79, n = 28). The increased weight of calcinotic kidneys was mainly due to both calcium deposition and tubular hyperplasia. It is concluded that dietary phosphorus-induced nephrocalcinosis is associated with impaired kidney function in rats.

The optimal length of the adaptation period after transportation of rats, to be used in nutritional studies, was investigated in this study. After intracontinental transportation of rats by car and by air to and from the laboratory for a total period of 15 h, measurements were carried out for a period of 3 weeks after transport. Control and transported animals were housed in the same laboratory before and after transportation. During transport the animals had access to food and water. As blood collection could also cause stress, a factorial design was carried out with transport and blood collection as main factors. Transport or blood collection did not cause significant effects on the following parameters: body weight, growth, clinical observation, and blood enzyme activities of LDH and ASAT. Water intake was significantly increased after transport. Food intake did not show consistent effects after transport or blood collection. Unexpectedly, blood corticosterone levels were significantly lower in the transported animals at day 1 after transport. After 3 days these levels were back to normal. Blood glucose, blood free fatty acids and blood urea nitrogen concentrations were incidentally decreased, whereas total cholesterol levels showed an incidental rise in the transported rats. The open-field behaviour test revealed no clear-cut results concerning the effects of transport or blood collection on faeces production, rearing and ambulation. Our results indicate that after intracontinental transport, an adaptation period of 3 days appears to be sufficient for rats to be used in nutritional studies.

The effects of intake of dietary amounts of carrot or corresponding amounts of (-)-(3R)-falcarinol from carrots on development of azoxymethane (AOM)-induced colon preneoplastic lesions were examined in male BDIX rats. Three groups of eight AOM-treated rats were fed the standard rat feed Altromin supplemented with either 10% (w/w) freeze-dried carrots with a natural content of 35 mug falcarinol/g, 10% maize starch to which was added 35 mug falcarinol/g purified from carrots, or 10% maize starch (control). After 18 weeks, the animals were euthanized and the colon was examined for tumors and aberrant crypt foci (ACF), which were classified into four size classes. Although the number of small ACF was unaffected by the feeding treatments, the numbers of lesions as a function of increasing size class decreased significantly in the rats that received one of the two experimental treatments, as compared with the control treatment. This indicates that the dietary treatments with carrot and falcarinol delayed or retarded the development of large ACF and tumors. The present study provides a new perspective on the known epidemiological associations between high intake of carrots and reduced incidence of cancers.