From Big Medical Encyclopedia

CALCITONIN (synonym thyrocalcitonin) — peptide hormone, a physiological role to-rogo consists in regulation of exchange of calcium and phosphorus. It was found in extracts from a thyroid gland, edges is the main source of its education at mammals.

By the chemical nature To. represents peptide about a pier. weighing 3600; primary structure is deciphered To. pigs, bull; sheep, salmon, and also person. Molecules K., differing in details, have the general scheme of a structure — consist of 32 amino-acid remains with semi-cystine on the N-end, the disulfide bridge (S — S-communication) between the 1st and 7th amino-acid remains and amide of proline on the C-end; To. the following structure has the person:

Are synthesized To. person, pig and salmon.

At the majority of mammals To. cosecretes parafollicular cells, or K-cells, a thyroid gland; at some mammals, including at the person, To. it is developed not only in thyroid, but also in thymic and parathyroids. Secretion To. it is regulated by the content of calcium in blood: increase in content of calcium in blood strengthens, and reduction — K.

Radioimmunol suppresses secretion, by method it is established that datum level To. in a blood plasma of the person makes 0,002 — 0,4 ng/ml.

Primary place of influence To. — a target organ — is the bone tissue. The main effect To. it is shown in a hypocalcemia and a hypophosphatemia.

To. — antagonist parathormone (see), it biol, action consists in braking of resorptive processes in a bone tissue. Gipokaltsiyemichesky and gipofosfatemichesky effects To. are caused by its ability to suppress a resorption of bone mineral. To. influences also organic structure of bones, suppressing disintegration of collagen that is shown by reduction of excretion with urine of oxyproline (see. Prolin ). Introduction To. to animals and the person is followed by increase in a diuresis and excretion with urine of phosphate, calcium, potassium and especially sodium at reduction of excretion of magnesium. However a question of a possibility of direct action To. on kidneys it is not solved yet.

Rather convincing evidence is obtained that To., it is similar to others to proteinaceous and peptide hormones (see), can carry out the action in effector cells of a bone tissue and kidneys in the same way, activating adenyl cyclase and, thus, stimulating education in cells cyclic 3', 5 '-AMF.

In need of definition To. in fabrics and biol, liquids methods are used biol, and radioimmunol. Biol, a method is based on ability To. at introduction by his animal (rats are more often used) to lower the content of calcium in blood, and in culture of fabric to suppress a bone resorption. With the help radioimmunol, the method based on ability of not marked hormone to compete with the iodated hormone for its linkng with specific antibodies it is established that at patients with the medullary carcinoma developing from parafollicular cells of a thyroid gland, contents To. sharply increases in tumoral fabric and peripheral blood.

Drugs of a calcitonin receive from thyroid glands of pigs («Calcitare») and way of chemical synthesis (salmon To.). Standardization biol, activities of drugs K. it is carried out by its comparison to activity of standard drug of hormone; activity is expressed in conventional units of action — MRC of PIECE (Medical Research Council).

Drug K. it can be recommended at hypercalcemias (see) different origins, for treatment osteoporosis (see), first of all senile, and also at Pedzhet's disease (see. deforming ). There are data on efficiency» uses of drugs K. in case of the slowed-down consolidation of bones at changes and operative measures.

Drugs K. are entered subcutaneously, intravenously and intramusculary. For prolongation of action To. as its solvent use 16% solution gelatin. Doses To. select empirically; special schemes of use do not exist.

In the USSR the method of receiving drug K is developed. from thyroid glands of cattle.

Bibliography: Alyoshin B. V. New data on thyrocalcitonin, Usp. sovr, biol., t. 69, century 1, page 158, 1970, bibliogr.; Biochemistry of hormones and hormonal regulation, under the editorship of N. A. Yudayev, page 126, M., 1976, bibliogr.; Migunovan. And., etc. Thyrocalcitonin and its clinical use, Owls. medical, No. 4, page 34, 1973, bibliogr.; Avramides A. and. lake of Paget's disease of the bone, J. clin. En-docr., v. 42, p. 459, 1976; Calcium, parathyroid hormone and the calcitonins, ed. by R. Y. Talmage a. P. L. Manson, Amsterdam, 1972; Cooper C, W. Recent advances with thyrocalcitonin, Aiin. clin. Lab. Sci., v. 6, p. 119, 1976; Human calcitonin and Paget’s disease, ed by I. MacIntyre, Bern 1977.

A. A. Bulatov.