[NEPHROPROTECTIVE PROPERTIES OF 5-HT3 RECEPTOR BLOCKER RU-63 IN EXPERIMENTAL ACUTE RENAL FAILURE UNDER HYPERGRAVITY CONDITIONS].

The effective diuretic dose of 5-HT3 receptor blocker RU-63 (1 mg/kg) was found in experiments on white rats. It is established that the diuretic and saluretic effects of compound RU-63 increase on the background of impact of the gravitational factor. Compound RU-63 (1 mg/kg, subcutaneously) administered daily under hypergravity conditions (3 g in the direction of centrifugal force toward the kidneys) in animals with model ischemic acute renal failure increased excretory function of kidneys, glomerular filtration rate, and creatininuresis (on average by 180%; p < 0.05), and decreased serum creatinine, urinary excretion of protein, lactate dehydrogenase, and g-glutamyl transferase (on average by 49%; p < 0.05) as compared to the untreated control. Under similar conditions, the diuretic hydrochlorothiazide (in a dose of 20 mg/kg, intragastric) produced a more pronounced creatininuretic action than that of RU-63 (by 358%; p < 0.05).

Comparative Study of Diuretic Activity of Hydroalcoholic Extracts from Medicinal Plants Containing Flavonoids.

Cherula and sticklewort tinctures exhibit rapid and short-lasting diuretic effect. Tinctures of tansy and immortelle are featured by rapid onset of the effect and prolonged action, while the tincture of common bearberry has a long latency period and prolonged action. Under normal conditions of gravity, flavonoid rutin stimulates diuresis only through tubular component; under hypergravity, simultaneously via glomerular and tubular components.

[The reactions of breathing and of the respiratory neurons in the rat to electrical stimulation of sciatic nerve afferents]. / Reaktsii dykhaniia i dykhatel'nykh neironov krysy na elektricheskoe razdrazhenie afferentov sedalishchnogo nerva.

A short-term stimulation of the ventral respiratory neurons shortened the respiratory cycle in anesthetised rats. The electrical activity of inspiratory as well as expiratory neurons increased.

[The mechanism of the anti-ischemic protection of the kidneys by diuretics]. / O mekhanizme protivoishemicheskoi zashchity pochek diuretikami.

The review presents the literature data on the mechanism of the protective action of diuretics in ischemic damage of the kidneys. The role of changes in the renal blood flow, glomerular filtration, oxidative metabolism of the kidney epithelium in the increase of resistance of the kidneys to circulatory hypoxia is analyzed. Great importance of sodium excretion and the corresponding change in hydrodynamics of nephrons in prevention of the damage of the specialized structures of the kidney cells, nephrons, in normalization of the kidney function in the postischemic period is emphasized.

[Mechanism of the anti-ischemic protection of the kidneys by diuretics]. / Mekhanizm protivoishemicheskoi zashchity pochek diuretikami.

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.

[Effect of furosemide on the permeability of the wall of intact and ischemic nephrons in the rat]. / Vliianie furosemida na pronitsaemost' stenki intaktnykh i ishemizirovannykh nefronov pochek krys.

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.

[Effect of furosemide on intact and ischemic rat kidney cortical structures]. / Deistvie furosemida na intaktnye i ishemizirovannye kortikal'nye struktury pochek krys.

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.

[Effect of several diuretics on ischemic damage to the kidneys]. / Vliianie nekotorykh diuretikov na ishemicheskoe povrezhdenie pochek.

Furosemide, etacrynic acid and mannitol administered to the survival of rats. However, these drugs prove ineffective in the event they are indicated after the action of the ischemic factor is discontinued. Etacrynic acid and novurit inhibit the functional activity of isolated mitochondria incubated under hypoxia and at a temperature of 37 degrees C.

[Kidney function and mitochondrial metabolism in excluded renal blood flow against a background of diuretic action]. / Funktsiia pochek i metabolizm mitochondrii pri vykliuchenii pochechnogo krovotoka na fone deistviia diuretikov.

Single administration of furosemid, etacrine acid and mannitol prior to switching off circulation in the only kidney for 2.5 hrs preserves the renal tissue from ischemic lesion, aids to normalizing the excretory processes on the 2nd--4th days of postischemic period, reduces duration of the oligo--anuric phase in acute renal insufficiency, and raises survival rate in the rats. The above substances are ineffective if administered after cessation of the ischemic period. Etacrin acid and novurit suppress functional activity of isolated mitochondria incubated in hypoxia at 37 degrees. Furosemid and mannitol in these conditions exert no effect. Preliminary administration of furosemid aids to preservation of lumen in proximal tubules of superficial nephrones both during cessation of the renal circulation and in the postischemic period.

[Anti-ischemic action of diuretics]. / O protivoishemicheskom deistvii diuretikov.

Rat experiments were conducted for comparative study of the effect of diuretics, injected into the organism in a single dose prior to two-and-a-half-hour ischemia of an only kidney and after it, on the extent of the kidney affection and survival of the animals. It was established that furosemid, etacryn acid and mannitol exert a preventive protective effect in ischemia of the kidneys and considerably increase the survival of rats as compared to the control-group. Analysis of the renal function in the first five days of the postischemic period testifies to the property of the above-mentioned diuretics for normalizing excretory processes on the 2nd-4th days of the action of the injuring agent, and for relieving or shortening the oligoanuric phase of acute renal failure. The significance of metabolic shifts, intratubular hydrodynamics and vascular microcirculation in the mechanism of the protective effect of diuretics in ischemia of the kidneys is discussed.