[2-Amino-2-thiazoline derivatives--a novel chemotype possessing muscarinomimetic effect].

Derivatives of 2-amino-2-thiazoline exhibit muscarinomimetic properties in model experiments with isolated rat ileum. The activity of compounds strongly depends on the nature of substituents in 5-position of thiazoline ring. The most active spasmogenic compound is 5-iodomethyl-2-amino-2-thiazoline hydroiodide (EC50 = 13 +/- 2 microM).

[The pharmacological selectivity of cholinesterase inhibitors is due to their antagonism with calcium ions].

The inhibitory activity of O-carbamoyl acylhydroxymoylchlorides was studied on the purified specimens of acetylcholinesterase from human erythrocytes and butirylcholinesterase from the horse blood serum. The pharmacological activity of these compounds was studied on isolated organs of rats. It was shown that introduction of N-aryl substituent in carbamate molecule increases the anticholinesterase activity and efficacy of blocking the neuromuscular conductivity.

[The hypoazotemic and diuretic action of lespeflan in acute kidney failure].

Hypoazotemic and diuretic effects of a new bioflavonoid drug lespephlan made in Russia have been tested in a dose 2 ml/kg to treat acute renal failure induced by mercury bichloride solution (a dose 2 mg/kg). The data were obtained on lespephlan ability to reduce blood levels of urea, creatinine and activate their renal elimination, to enhance diuresis, sodium clearance, glomerular filtration. Water and electrolyte release were also changeable by angiotensin aldosterone system.

[The mechanism of action of the bioflavonoid lespeflan and the antihypoxant TB-4 on nitrogen metabolism in animals with acute kidney failure].

The changes in the levels of urea and creatinine caused by the new native preparation lespeflanum and the antihypoxant TB-4 were studied in animal experiments. The agents tested produced a significant hypoazotemic effect in acute renal failure. Lespeflanum showed diuretic and natriuretic effects in healthy animals, elevated plasma aldosterone levels and decreased hepatic arginase activity.

[Effect of a natriuretic factor of hepatic origin on the indices of water-salt metabolism and blood circulation].

The influence of natriuretic factor inhibiting the Na--K--ATPase, on the volume-regulating function of kidneys and the hemodynamics was studied in dogs. A single administration of natriuretic factor in a dose increasing the renal excretion of water, sodium and osmotically active substances, affected the hemodynamics. The changes of both the central hemodynamics and of the renal blood circulation were of a shorter duration compared with the changes in renal functions.

[Effect of the natriuretic factor on the transport of electrolytes and energy metabolism in kidney cortex sections].

The peptide material of the 2nd and 3rd fractions of the natriuretic factor did not affect the passive sodium transport while inhibiting the active transport in slices of the rat kidney cortex. This inhibition was accompanied by a decrease of both the succinic dehydrase system and Na+, K+-activated ATPase activities in the slices. The natriuresis caused by the natriuretic factor seems to be due to the inhibition of the active sodium transport.

[Role of the liver in formation of the natriuretic factor].

A response to an increase in the liquid volume and the level of the natriuretic factor in the blood were studied 30 h, 3, 7, 14 and 28 days after removal of 2/3 of the liver mass in rats. The state of the liver was studied in parallel in the same periods. Volumetric natriuresis in rats and the NUF level in the blood after partial hepatectomy decreased sharply and increased gradually by the 28th day, i.

[Effect of natriuretic factor on sodium secretion in the small intestine].

In dogs with Tiri-Vella fistula, the natriuretic factor increases the secretion of the intestinal fluid and its content of sodium. In rats with increased content of natriuretic factor, the water and sodium absorption diminishes in the intestine whereas the secretion of 22Na into the intestine lumen is increased.

[Influence of lithium carbonate on the effects of the natriuretic factor].

It has been shown in rat experiments that administration of lithium carbonate for 3 days (100 mg/kg) enhances renal excretion of water and electrolytes following an increase in the volume of extracellular fluid. In this case renal excretion of natriuretic factor rises, whereas its concentration in blood plasma does not ascend. Lithium carbonate raises the sensitivity of the kidneys to natriuretic factor and reduces its effect on transport activity in the small intestine.

[Mechanism of delayed electrolyte excretion as affected by phenobarbital].

Phenobarbital in a dose of 20 mg/kg administered for 3 days lowered renal sodium excretion after an increase in the amount of extracellular liquid induced by different methods: by intravenous injection chloride isotonic solution in an amount of 3% of body mass, by warmed tap water or salt (0.45% solution) loads given in the same quantity. The drug exerted no marked effect on renal sensitivity to natriuretic factor.

[Method of quantitative determination of natriuretic factor in biological fluids].

The natriuretic factor was determined quantitatively on the isolated rat jejunum segmens turned inside out. After addition of the test blood plasma into the incubation medium the changes in fluid absorption by the intestinal epithelium were recorded. The amount of the natriuretic factor capable of complete blocking the transport activity of the intestinal epithelium was accepted as 1 intestinal unit of the natriuretic factor.

[Effect of glucocorticoids on electrolyte excretion after expansion of the extracellular space].

The influence of glucocorticosteroids (cortisone, hydrocortisone, prednisone, dexamethasone, and triamcinolone) on the volumetric natriuresis was studied in experiments on rats. Natriuresis proved to increase considerably after the widening of the extracellular space, and exceeded sodium excretion in control animals after a similar increase of the fluid volume in control animals. Intensification of the natriuretic response to the increase of the extracellular fluid volume against the background of glucocorticoids apparently occurred as a result of production or activation under the influence of these hormone of the natriuretic factor.

[Effect of aldosterone, vasopressin and natriuretic factor on the process of absoprtion in the rat small intestine].

Experiments were conducted on rat jejunum pouches turned inside-out. On addition of blood plasma containing the natriuretic factor there was a reverse relationship between the natriuretic factor concentration and the processes of absorption in the jejunum. No such effect was noted under the effect of aldosterone and vasopressin.