LACTIC ACID

From Big Medical Encyclopedia

LACTIC ACID — alpha and hydroxy-propanoic to - that [CH 3 CH(OH)COOH], the representative carboxylic to - the t, is an end product of anaerobic glycolysis and a glycogenolysis, and also substrate of a gluconeogenesis; to a crawl of that, a part milk to - you from blood are absorbed by a cardiac muscle where it is used as power material. M.'s maintenance to. in blood can be additional diagnostic test. At patol. the states which are followed by the strengthened muscular contractions (epilepsy, a tetany, tetanus and other convulsive states), as a rule, M.'s concentration to. in blood raises. Increase in maintenance of M. to. in blood note also at a hypoxia (heart or pulmonary failure, anemias and so forth), malignant new growths, at an acute hepatitis, in an end-stage of cirrhosis, at toxicoses. Increase in concentration of M. to. in blood it is connected generally with strengthening of its education in muscles and decline in the ability of a liver to turn M. to. in glucose (see) and glycogen (see). At a decompensation of a diabetes mellitus in blood M.'s concentration also increases to., what is result of blocking of a catabolism pyroracemic to - you and increases in a ratio NAD-N / OVER . As a rule, strengthening of M. to. in blood is followed by reduction of an alkaline reserve (see. Acid-base equilibrium ) and increase in quantity ammonia (see) in blood. Hereditary lactacidemia (see) it is shown at early children's age by heavy acidosis (see) with the expressed respiratory disturbances. At sick children note a delay of psychomotor development, a hypomyotonia. A consensus whether the hereditary lactacidemia is true enzymopathy (see) or it is caused by overdue maturing of the corresponding fermental systems, not so far. With age there occurs improvement, however in literature also lethal outcomes are described.

Vapors of lactic acid have bactericidal properties, in particular in relation to hemolitic stafilo-and streptococci therefore they are used for ensuring bacterial purity of rooms for medical procedures and hospital chambers. Lactic acid is applied also as a caustic.

M to. improves organoleptic properties of various foodstuff. In composition of fungicidal drugs, to-rymi process fabrics in the textile industry, M. also enters to.

For the first time M. to. it was found in muscles of animals. Later it was found as well in seeds of plants. M to. is a product of exchange of many anaerobic microorganisms.

In blood of the person is normal at muscular rest M.'s maintenance to. fluctuates within 9 — 16 mg of %. At hard muscular work M.'s maintenance to. in blood sharply increases — by 5 — 10 times in comparison with norm.

M to. — optically active connection: in muscles of animals it is found L-milk to - that (dextroizomer), microorganisms and plants contain DL milk to - that. M to. (racemate) forms colourless hydroscopic crystals, t ° pl 18 °, t ° kip 119 ° at 12 mm of mercury. Well a rastvorima in water and organic solvents. Has chemical properties of aliphatic alpha oxyacids.

Commercially M. to. receive fermentation of carbohydrates.

In the analytical purposes M. to. allocate from blood serum and urine with ion-exchange chromatography and determine colorimetric by Barker's method — Sammersona (see. Barker-Sammerson method ); also euzymatic method of definition based on M.'s dehydrogenation to is used. lactate dehydrogenase (see), by quantity of the formed NAD-N 2 , defined spektrofotometrichesk. In a gastric juice of M. to. determine by qualitative methods, napr, using konts. salt to - you and 30% of ferric chloride (see. Berg methods ). M to. define also by means of columnar and gas-liquid chromatography (see).



Bibliography: Lenindzher A. Biochemistry, the lane with English, page 55, etc., M., 1974; Barker S. Century of Preparation and colorimetric determination of lactic acid, in book: Meth. enzymol., ed. by S. P. Colowick a. N. O. Kaplan, v. 3, p. 242, N. Y., 1957, bibliogr.; N o r d m a n n J. N o r d m a n n R. Organic acids in blood and urine, Advanc, clin. Chem., v. 4, p. 53, 1961, bibliogr.


H. V. Prokazova; V. P. Fisenko (pharm.).

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