[The characteristics of the effect of mediator substances on the dynamic oxygen tension in the gastric mucosa].

The studies on rats were carried out to determine dynamics of pO2 in the mucous membrane of the stomach under the effect of acetylcholine, norepinephrine, serotonin, histamine, prostaglandin E2 and ATP. As to the changes in pO2 the mediator substances were arranged as follows (from more intensive effect to less pronounced one): serotonin, acetylcholine, prostaglandin E2, norepinephrine, histamine and ATP. As to the duration of the action--PGE2 acetylcholine, serotonin, norepinephrine, ATP and histamine.

[The cholinomimetic activity of alkyltrimethylammonium compounds in experiments on the isolated mollusk neuron and on frog and chicken skeletal muscle].

As revealed by contractile reaction of frog and chick muscles and by changes in the membrane current of isolated molluscan neurone, cholinomimetic activity of alkyltrimethylammonium compounds (ATMC) in the highest in drugs with 4 and 5 methylene groups in a molecule. The decrease in the activity with the decrease in the number of methylene groups was more evident in chick muscle; the decrease in the activity due to the increase in the number of these groups was most significant in experiments on molluscan neurone. Analysis of membrane current fluctuations showed that elementary current does not depend, whereas channel open time only slightly depends on the number of methylene groups in ATMC.

[Determination of the Hill coefficient in the action of various agonists on the N-cholinoreceptors of the isolated mollusk neuron].

The Hill coefficient (2.07-2.23) of the response to low concentrations of acetylcholine and its analogues was unrelated to their cholinomimetic activity and molecular structure.

[The reaction of the N-cholinoreceptors of the isolated neuron of the mollusk Planorbarius corneus to polymethylene-bis-trimethylammonium compounds].

Experiments have been made on isolated giant neurones of the mollusc Planorbarius corneus using clamp technique at temperatures 10 and 20 degrees C. The effect of polymethylene-bis-trimethylammonium compounds with 7-18 methylene groups in the molecule (C7..

[Factors affecting the cholinomimetic activity of alkyltrimethylammonium compounds in experiments on isolated neurons of the mollusk Planorbarius corneus].

It has been shown that the elementary current is independent whereas the duration of channel opening is slightly dependent on the number of methylene groups (from 1 to 9) in the molecule of alkyltrimethylammonium compounds. However, substances with more than 4 methylene groups exhibit lower cholinomimetic activity (i.e.

[Status of the electrolyte balance of the gastric juice during stimulation of secretion by histamine].

The content of electrolytes (Na+, K+, Ca2+) in human basal secrete has been determined before and after injection of histamine in gastric juice and insoluble mucus in healthy people. Electrolytes in the mucous membrane of the stomach, gastric juice and insoluble mucus have been determined in dogs with stomach fistula after Basow. Species peculiarities have been marked in electrolyte content change during gastric secretion.

[Presynaptic action of tubocurarine during frequent stimulation of a motor nerve].

The dependence of the end-plate potentials inhibition upon the prevention of the muscle twitches either by tubocurarine, or alpha-neurotoxin, or cutting of the fibers was studied during nerve tetanization in the frog isolated cutaneous pectoral muscles. The decrease in end-plate potentials in the course of tetanization was the strongest under the effect of tubocurarine. The latter seems to inhibit the quantum release of acetylcholine during the nerve tetanization.

[The cytoprotective effect of prostaglandin E2 in duodenal ulcers].

Intragastric administration of a synthetic analog of prostaglandin E2 to patients with duodenal ulcers results in depression of the gastric acid production and in reduction of potassium level, leads to an elevation of the sialic acid debit and a rise of sodium concentration, not essentially changing calcium, chlorides, and pepsin levels. A combined analysis of gastric acid production and measurements of sialic acids, sodium and potassium detect the imbalance of the mucoid and bicarbonate secretion in peptic ulcers, this helping predict the disease course.

[Effect of tubocurarine on the quantum release of acetylcholine during the infrequent stimulation of a motor nerve].

The effect of d-tubocurarine on quantal release of acetylcholine elicited with nerve pulses 0.5 to 1 Hz was studied in the frog isolated cutaneous pectoris muscle. The muscle twitches were prevented either by lowering Ca++ and raising Mg++ or by cutting the muscle fibers.

[Characteristics of the combined effect of serotonin and histamine on the secretory function of the gastric glands].

The effect of serotonin, its combined effect with histamine on the gastric glands secretory function, and the morpho-functional condition of the mucous membrane of stomach were studied in dogs with the stomach fistula. The secretory response of gastric glands induced with histamine depended on the dose of serotonin. In combined action of serotonin and histamine, both the content of pepsin in gastric juice and the concentration of sodium and potassium ions increased.

[Quantitative patterns of tubocurarine action on the synaptic potentials of frog muscle].

The dependence of amplitude of synaptic potentials (EPP and mEPP) upon the d-tubocurarine concentration was studied in the frog cutaneous pectoral muscle. In the presence of d-tubocurarine up to 5 x 10(-7) M, the amplitude of EPP and mEPP decreased to the extent which strictly followed competitive action of d-tubocurarine. At a higher concentration, the inhibition of synaptic potentials was stronger than would be expected assuming that d-tubocurarine can only act as a competitive antagonist.

[Cholinoreceptor sensitivity of the mollusk neuron and frog skeletal muscle to acetylcholine and tetramethylammonium analogs].

Studies have been made on the sensitivity of cholinoreceptors in identified isolated neuron from the pedal ganglion of the snail Planorbarius corneus and cholinoreceptors of m. rectus abdominis of the frog Rana temporaria to drugs which differ from acetylcholine by the structure either in cationic group, methylene chain, or ester group. Snail cholinoreceptors were found to be less sensitive to changes in the structure of cationic group and more sensitive to the increase in methylene chain from 3 to 4 groups, as compared to frog cholinoreceptors.

[Reaction of cholinoreceptors from an isolated molluskan neuron with analogs of acetylcholine and tetramethylammonium].

The effect of 13 acetylcholine and tetramethylammonium derivatives on cholinoreceptors of isolated neurone on the pond snail has been investigated by the analysis of membrane current fluctuations at 10 and 20 degrees C. The elementary current was independent from the agonist structure. The channel open time and its Q10 coefficient were found to be maximum for acetylcholine.

[Effect of prostaglandin E2 on the secretory function of the stomach].

The effect of prostaglandin E2 (PgE2) injected with histamine in dogs with stomach fistula, involved a decrease of volume of secreted gastric juice, production of hydrochloric acid and pepsin lessening as compared with the findings obtained in the effect of histamine alone. The inhibition of gastric secretion increases in combined injection of PgE2 with histamine and acetylcholine. After intramuscular injection of PgE2 the content of sodium ions in the blood serum of rats decreases, the concentration of potassium becoming higher.

[Effect of acetylcholine on gastric secretory function and its vascular tonus].

Depending on doses, acetylcholine can produce the same effects in respect to activation of the stomach gland secretion either in hypodermic or intramuscular administration or acting from the surface of the stomach mucosa. Combination of acetylcholine and histamine produces the same secretory effect as food irritation. In acute experiments on dogs i.