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Biomedical subjects

A A Lebedev

Publications and source records attributed to A A Lebedev.

At least 145 records · Page 8Linked to original sources
PubMedDate not supplied

[Mechanism of the anti-ischemic protection of the kidneys by diuretics].

Experiments on rats showed that single doses of diuretics furosemide, ethacrynic acid, mannitol, hypertonic solution of sodium chloride administered subcutaneously 30 and 60 min and intravenously 10 and 20 min before complete arrest of the blood flow in the single kidney for 2.5 hours decrease creatinine content in the blood and increase survival rate of the animals. The anti-ischemic protection occurs provided that the natriuretic effect of the drugs coincides with the ischemic factor action. Morphometry revealed the ability of furosemide to prevent the development of hyperhydration of the epithelial cells, to increase lumina of the proximal and distal tubules. The role of hydrodynamic factors in the mechanism of anti-ischemic protection of the kidneys with diuretics is discussed.

Animals↗
PubMedDate not supplied

[Behavioral reactions to stimulation of the emotiogenic zones of the brain in the rats with different individual experience].

Emotional reactions evoked by electric stimulation of the hypothalamus and amygdala were studied in white outbred rats, grown either in conditions of isolation or in community. The method of self-stimulation in shuttle box was used. The values of self-stimulation reaction were significantly lower and those of avoidance reactions were higher in animals bred in isolation. Their food-procuring behaviour disappeared faster at stimulation of the negative emotiogenic zones. The observed differences are due to plastic reorganization of the brain reinforcing systems.

Amygdala↗
PubMedDate not supplied

[Determination of the specific activity and biological availability of Soviet-made furosemide].

Experiments on mice, rats and dogs showed that furosemide manufactured in the USSR is not inferior by its specific activity to furosemide manufactured abroad. Furosemide manufactured in the USSR and furosemide-substance made in Finland were compared at three doses--1, 5 and 25 mg/kg. The bioavailability of furosemide tablets manufactured in the USSR and that of "Polfa" production tablets studied on rats (5 and 25 mg/kg) and dogs (40 mg) appeared to be identical.

Animals↗
PubMedDate not supplied

[Pharmacological activity of the furfuryl amine salt of 4-chloro-N-(2-furylmethyl)-5-sulfamoyl anthranilic acid].

Furfuryl amine salt of 4-chloro-N-(2-furylmethyl)-5-sulfamoyl anthranilic acid was shown to exert more pronounced diuretic and saluretic action in rats, mice and dogs than that of furosemide. The previous administration of furfuryl amine salt of furosemide promoted normalization of the excretory processes of the kidney and increased survival rate of rats in ischemia of the single kidney. The antiedema activity of the drug was found to be much more pronounced than that of furosemide.

Acute Kidney Injury↗
PubMedDate not supplied

[Effect of furosemide on the permeability of the wall of intact and ischemic nephrons in the rat].

It has been established in acute experiments on rats that furosemide reduces the supply of uranine from the lumen of renal tubules to the interstitial space and systemic blood flow. Complete disconnection of the renal blood flow for 1 h dramatically raises the permeability of the epithelial barrier of the tubules. Administration of furosemide before disconnection of the renal circulation is accompanied by an increase of uranine transport from the nephron lumen to the blood as compared with the control. However, this response is less pronounced than in experiments with renal ischemia without the use of the diuretic.

Animals↗
PubMedDate not supplied

[Mechanism of action of diuretics studied by a fluorescent probe method].

The mercuric-xanthine diuretic novurit, ethacrynic acid and furosemide reduced the fluorescence of 1,8-anilinonaphthalene-8-sulfonate (1,8-ANS) in a suspension of phospholipid liposomes and human serum albumin solution. Ethacrynic acid and furosemide eliminated the fluorescence of 1,8-ANS in a suspension of non-energized mitochondria of rat kidney, while novurit provoked fluorescence intensification. The constants of novurit and ethacrynic acid binding with kidney mitochondria determined by the degree of changes in 1,8-ANS fluorescence variation appeared significantly higher than the constants of binding with phospholipids and serum albumin. However furosemide did not show a predominant binding with kidney mitochondria.

Alkylmercury Compounds↗
PubMedDate not supplied

[Effect of diuretics on electrolyte and non-electrolyte penetration of intercellular spaces].

The effect of novurit, mannitol and furosemide on permeability of the intercellular interstice of the frog urinary bladder by inulin, saccharose, iodide, lithium cation and fluorescein moving against a concentration gradient was examined. Novurit (0.5--6 mM/l) raised permeability of the intercellular interstice by all test substances and ions. Mannitol (210 mM/l) increased permeability of the intercellular interstice by lithium cation and fluorescein, while furosemide failed to exert any effect on permeability. The character of asymmetrical ionic flows moving in opposite directions across the wall of the frog urinary bladder is discussed.

Alkylmercury Compounds↗
PubMedDate not supplied

[Interaction of catecholamines and the renin-angiotensin system in regulating sodium reabsorption in the rat kidney].

It has been established that the catecholamine-induced increase in renin secretion by juxtaglomerular apparatus cells and sodium reabsorption stimulation in the rat kidney are consequent on the excitation of renal beta-adrenoreceptors. Strophanthin K interferes with the renin-secreting action of adrenaline and perverts its activating effect on sodium transport by renal tubules. When given in a dose inhibiting angiotensin II formation and renin-secreting effect of catecholamines, heparin also diminishes their activating effect on tubular sodium transport. It is suggested that the renin-angiotensin system may be directly involved into the mechanism of catecholamine-stimulated sodium reabsorption by the rat kidney.

Absorption↗
PubMedDate not supplied

[Effect of furosemide on intact and ischemic rat kidney cortical structures].

Biomicroscopy and microphotography of cortical structures of rat kidneys have shown that furosemide produces a significant increase in the internal and external diameters of the tubules without substantial change in the wall thickness and width of intertubular space. In renal ischemia, the wall thickness and external diameter of the tubules progressively increase. The majority of the tubules show the disappearance of the lumen. In the course of the blood flow recovery, the wall thickening remains unchanged. Ligation of the renal vessels in the presence of furosemide administration also leads to the collapse of the tubules. However, the thickness of the tubular wall decreases while the lumen rises during ischemia. The role of the hydrodynamic effect in the mechanism of anti-ischemic action of furosemid is discussed.

Animals↗
PubMedDate not supplied

[The effects of dopaminergic agents on the self-stimulation of the lateral hypothalamus and on dopamine metabolism in the brain of isolated rats with a disrupted ventral tegmental area].

Male Wistar rats were socially isolated from the 17th day of birth. Ventral tegmental area (VTA) of a half of the 17th-day rats was unilaterally damaged with intrastructural administration of kainic acid. In adult rats (both raised in groups and in isolation) amphetamine (1 mg/kg) facilitated self-stimulation of the lateral hypothalamus (by 37%). Social isolation increased the sensitivity of dopaminergic system only in rats with VTA lesions which was manifested in promoting self-stimulation after administration of amphetamine, though the level and turnover of tegmental dopamine was decreased. 6-Hydroxydopamine (75 mcg intracisternally), a catecholaminergic neurotoxin, significantly inhibited self-stimulation in isolated rats and decreased catecholamine levels in the lateral hypothalamus. The neurotoxic effect of 6-hydroxydopamine was abolished by amphetamine, probably, owing to enhancement of the functional activity of parabiotically living neuronal structures of the mesocorticolimbic dopaminergic system of the brain.

Amphetamine↗