Low Lead Doses and Atherogenic Diet in Rabbits: Biochemical Results in Blood

Abstract

Changes in concentrations of blood lead, cholesterol, tnacylglycerols, GOT and GPT enzymes, phosphorus, proteins, plasma calcium and magnesium, and erythrocyte magnesium were studied for 25 weeks in 4 groups of 6 rabbits each receiving different diets: I (controls), II (water with 9.66 µmol/l of lead), III (atherogenic) and IV (atherogenic + 9.66 µmol/l of lead). Differences observed, with respect to the diets, for lead, cholesterol, enzymes, proteins and erythrocyte magnesium were evident from the 42nd day on. Low lead doses raised the levels of cholesterol and tnacylglycerols in group II, whereas triacylglycerols were lower in the plasma of group IV in comparison with group III and were accumulated in the aorta. The elevation of enzymes in groups III and IV indicated heart and liver dysfunctions. There was a significant drop in erythrocyte magnesium in groups III and IV, which was especially marked in the latter group, with an interaction between the two diets.

Concentrations of Lead, Magnesium, Calcium, Zinc and Cadmium in Twenty Rabbit Tissues after Exposure to Low Lead Doses and Atherogenic Diet

“…Our investigations demonstrate signifi cant metabolic changes, with respect to diets, in the tissues as well as in the blood of rabbits [10], and indicate little significant interaction between the two diets. Extrapolation from the rabbit, an herbivore, to man would be inadvisable.…”

“…The study concerned 4 groups of 6 young grey rabbits (3 males, 3 females), showing no early mineral contamination [10]. They were kept in our air-conditioned animal laboratory with a 12:12 light/dark cycle, and housed individually in plastic cages.…”

“…Group 1 (normal diet): lOOg/day and animal of rabbit feed 'Lapins entreticn 112 UAR' [10] and 250 ml of soft tap water (the lead level of the water remained below 25 nmol/1 throughout the experiment and the cadmium level below 1 nmol/1).…”

“…Among the factors likely to be in volved are the bulk nutrients (sodium, mag nesium and calcium) and the nonessential trace metals (cadmium and lead) [1,2], Higher concentrations of lead have been found in the blood and aortas of atherogenic patients than in those of persons not afflicted with this disease [1]. Experimental studies have tentatively correlated long-term expo sures to low level cadmium or lead with the appearance of abnormal cardiovascular sys tem changes [2], For these reasons, and as a continuation of our previous work [5][6][7][8][9], we have determined lead, magnesium, calcium, zinc and cadmium levels in 20 tissues of rab bits subjected over a 25-week period to very low lead doses and/or an atherogenic diet after having observed changes in biochemical values in the blood in the same circum stances [ 10], As far as the rabbit is concerned, there have been few reports on the content of trace metals in tissues [11], Moreover, Schlick et al [12] have shown in mice that, after administration of low lead doses, organ lead contents were measurably increased but not blood lead levels. The determination of blood lead level alone would seem to be inad equate for reliable detection of long-term lead accumulation.…”