EXCHANGE OF VARIOUS CALCIUM FORMS IN ORGANISM OF RATS WITH PREDNISOLONE OSTEOPOROSIS

Abstract

Relevance. In order to reduce osteopenic condition, as well as risks of osteoporotic fractures in patients who are on long glucocorticoid therapy, additional intake of calcium-containing medications is required. Application of preparations of natural origin for prevention of osteoporosis and increase of treatment efficiency is relevant, with mollusc shells being likely to be considered as promising raw material for production of calcium-containing medications.The aim of the work was to carry out comparative research of efficiency of metabolising in organisms of rats calcium obtained from Rapana shells (carbonate) or shells treated with citric acid (citrate) at the background of long-terms intake of prednisolone.Materials and methods. The research was performed on white rats of outbred breeding, which for two months were modelled prednisolone (5 mg/kg) osteoporosis with addition to the diet of non-treated (calcium carbonate) and treated with citric acid (calcium citrate) crashed Rapana shells for prophylaxis. Rapana shells were analysed for content of zinc, lead and cadmium by method of flameless atomic absorption photometry, of calcium – by method of titration with murexide, of phosphorus – spectrophotometrically. The research also included determination of day amount of calcium obtained by a rat organism and excreted with urine and feces. In femur of rats bone mineral density, content of calcium and activity of phosphatases were determined.Results and conclusions. Comparative study of preventive introduction of calcium carbonate and citrate from Rapana shells found certain advantages of impact of calcium citrate on rat organism. Thus, in spite of the fact that when given citrate, rats received 3.5 times less calcium than with carbonate, the former contributed to achievement of more efficient reduction of calcium excretion with urine and inhibition of bone AP activity at the background of considerable activation of osteogenesis and inclusion of calcium into composition of bone tissue hydroxyapatite, as well as more expressed increase of mineral density of femur of rats which experienced long-term introduction of prednisolone.In case of preventive intake of calcium citrate by rats the amount of calcium in their organism was 2.9 times lower than in case of carbonate intake, but that calcium had more positive effect on the condition of bone system of rats with osteoporosis, which might be explained by higher bioaccessibility of the said form of calcium, as well as expressed ability of citrate to regulate metabolism, namely to slow down prednisolone-induced destructive processes in bone tissue. Moreover, with equal introduced dose of both forms of calcium (300 mg/kg), rats which received carbonate preserved a higher level of calcium, which can have negative consequences for functioning of kidneys, liver and cardiovascular system. An important conclusion of the research is the fact of considerable reduction of the level of heavy metals in the process of treating Rapana shell with citric acid.Key words: osteoporosis; calcium citrate; calcium carbonate; Rapana.