PICROTOXIN (Picrotoxinum; synonym: Cocculin) — stimulator of the central nervous system; active beginning of seeds of a tropical liana of Anamirta cocculus (L.) Wight et Am., this. Menispermacea. Represents mix of a pikrotoksinin (C 15 H 16 O 6 ) and pikrotina (C 15 H 18 O 7 ). Prismatic crystals or fine-crystalline powder, inodorous, bitter taste. On light collapses, it is slightly soluble in water; t ° pl 198 — 200 °. Solutions are stable at pH 6,1 — 6,7.
The item has exciting effect on c. N of page. On activity concerning c. the N of page pikrotoksinin is about 50 times more active than a pikrotin. Due to the central action stimulates breath, raises the ABP, causes bradycardia. In high doses causes the kloniko-tonic spasms which are followed by emergence of sharp-pointed high-amplitude biopotentials in a cerebral cortex, average, oblong and then and in a spinal cord. Due to the analentichesky effect of P. sometimes use at poisoning with substances, the oppressing c. N of page, napr, barbiturates (see). At alcoholic poisonings and morphine P. it is ineffective.
On influence on processes of synoptic transfer of nervous impulses of P. consider as the antagonist of GAMK — piperidic acid (see). Exciting influence of P. national. in N of page according to modern representations it is caused by blockade of postsynaptic GAMK-ergichesky receptors and easing thereof brake action of GAMK on neurons. Antagonism between picrotoxin and GAMK at the level of a postsynaptic receptor is shown on drugs of nervous tissue of invertebrates and on various nervous formations of mammals. It is suggested that P.'s ability to influence ionophores of chlorine in a postsynaptic membrane is the possible reason of non-competitive antagonism.
The item is widely used by hl. obr. in experimental medicine in quality pharmakol, the analyzer. P.'s use along with bikukulliny (alkaloid phthalide - isoquinolinic structure) allows to identify GAMK-ergichesky neurons. One of the main criteria for evaluation of neurons as GAMK-ergichesky is existence of the brake reaction of neyronalny categories registered in the conditions of electrophysiologic experiments which is weakened at system or micro-ionoforetichesky introduction of P. or a bikukullin. The spasms caused by P. are used as model at pharmakol, screening of anticonvulsant substances.
The item is a part of analeptical mix of the domestic combined drug used in medical practice as an analeptic.
Analeptical mix (Mixtura analeptica, SP. A) contains in 1 ml caffeine-sodium benzoate of 0,01 g, Corazolum of 0,01 g, strychnine of nitrate and picrotoxin on 0,00005 g. Apply at asphyxia of newborns and poisonings with barbiturates, and also to acceleration of awakening after an anesthesia. The newborn enter into an umbilical vein 0,5 — 1 ml in mix from 5 ml of isotonic solution of sodium chloride or 5% of solution of glucose; the adult — in a vein on 1 ml 2 — 3 times.
Form of release: ampoules on 1 ml. Keep in the place protected from light.
See also Neural activity stimulators .
Bibliography: Andrews P. R. a. Johnston G. A. R. GABA agonists and antagonists, Biochem. Pharmacol., v. 28, p. 2697, 1979; GABA in nervous system function, ed. by E. Roberts a. o., N. Y., 1976; Neurotransmitters, ed. by P. Simon, p. 43, Oxford a. o., 1979.
P. U. Ostrovskaya.