[Experimental hemorrhagic stroke].

The authors propose the technique of experimental haemorrhagic stroke of a hypertensive type in non-narcotized rats produced by means of gravity overload in the caudocranial vector with the use of a special centrifuge.

[Effect of ketamine on cerebral circulation of intact and ischemic animals].

The influence of ketamine on the local cerebral circulation was studied in intact rats and under the conditions of global brain ischemia. The drug increased the local blood flow in intact rats. Despite pronounced hypotension accompanying the global brain ischemia, ketamine helped maintenance of the cerebral circulation.

[Brain ischemia induced by gravitational overload].

It is suggested that radial gravitational overloads in craniocaudal direction, during which the pressure in meningeal arteries drops to zero, can be used to model the ischemic state. The post-ischemic period is characterized by increasing content of lipid peroxidation products in the venous blood and by violation of the neurological state in rats. This ischemia model, requiring no anaesthesia for the experimental animals, can be used in the directed search for new neuroprotectors and their characterization.

[The action of emoxipin, lithium oxybutyrate and pikamilon on the blood circulation of the ischemic brain].

Acute experiments were conducted on rats under nembutal anesthesia to compare the efficacy of emoxipin with that of lithium oxybutyrate and picamilon in the postischemic period after preventive and therapeutic injections in various doses. Emoxipin proved to be most effective in prevention of postischemic non-restoration of the flow of blood in the brain and in preservation of the autoregulation responses of the cerebral vessels. The possible mechanisms of the effect of the drug are discussed.

[The anti-ischemic effects of 3-hydroxypyridine derivatives in cerebrovascular pathology].

The effect of the antioxidant mexidol and two new derivatives of 3-oxypyridine, namely LBK-10 and LBK-39 on the circulation of blood and metabolism of the brain in the postischemic period was studied in acute experiments on narcotized cats under conditions of autohemoperfusion of the cerebral vessels with a stable volume of blood. Therapeutic injection of mexidol and LBK in a dose of 20 mg/kg inhibited the development of the no-flow phenomenon and restored the ischemia damaged metabolism in the brain tissues. LBK-10 reduced the lactate content in the blood flowing from the brain and contributed to constriction of the cerebral vessels.

[The effect of 3-hydroxypyridine derivatives on postischemic disorders in the autoregulatory reactions of the cerebral vessels].

Acute experiments on nembutal anesthetized rats showed improvement of cerebral blood flow autoregulation in the postischemic period under the effect of mexidol and the new 3-hydroxypyridine (3-HOP) derivatives LBK-10 and LBK-38 administered for prophylactic and therapeutic, purposes. The role of dopaminergic activity, solubility in lipids, and other factors in the mechanism of the activity of 3-HOP derivatives is analysed.

[The effect of cytochrome c preparations on the autoregulation of the cerebral blood flow in ischemia].

The effect of animal cytochrome C (Ca), biotechnological cytochrome (Cb) and its hemtetradecapeptide (HTDP) on cerebral blood flow autoregulation during rapid decrease of systemic arterial pressure (SAP) was studied in acute experiments on rats. Cytochrome C preparations caused no effect on the autoregulatory responses of the cerebral vessels in animals with normal cerebral circulation. Injection of 5 mg/kg Ca and Cb and 0.

[The effect of lithium derivatives of GABA on blood circulation and metabolic indices in the brain under ischemia].

In acute experiments on anesthetized cats with cerebral ischemia in conditions of autohemoperfusion of cerebral and peripheral vessels with a stable volume of blood we found that lithium oxybutirate and new GABA derivatives: LOS 1-84 and LOS 5-79 affect the cerebral blood flow and metabolism in the brain. Prophylactic intravenous injection of lithium oxybutirate did not affect the development of postischemic hyperperfusion but inhibited postischemic hyperperfusion. The compounds prevent the development of postischemic phenomena and promote the recovery of metabolism in the brain.

[The effect of cytochrome c preparations on the cerebral circulation in cerebral ischemia].

Biotechnological cytochrome c, heme-tetradecapeptide (HTDP) and animal cytochrome c were studied for their effects on intact and brain ischemic rats. In the latter case, the compounds were administered before ischemia induction and 15 min after artery ligation. It was found that the cytochrome c preparations did not virtually affect the cerebral circulation in intact rats.

[Cerebral blood circulation during angiotensin-converting enzyme inhibition].

The inhibitor of angiotensin-converting enzyme captopril does not change the tone of the brain vessels but decreases the blood pressure and the tone of peripheral vessels, increases the oxygen and glucose demand in the brain in intact cats. In animals with brain ischemia, captopril decreased the tone of the brain vessels and promoted normalising of metabolic and transcapillary exchange in the brain.

[The comparative characteristics of the hemodynamic and biochemical indices of the postischemic period in relation to the regimens of brain autohemoperfusion].

In anesthetized cats, comparative characteristics of hemodynamics and biochemical indications of postischemic period in respect to autohemoperfusion with stable blood volume and perfusion pressure, were determined. Cerebral ischemia was caused by the 15-min stop of the perfusing pump or flowmeter and a decrease of systemic arterial blood pressure to 40 ml Hg. In the autohemoperfusion of brain vessels in stable volume or stable arterial pressure, a phasic postischemic phenomenon becomes obvious.

[The role of dopamine in regulating the cerebral circulation in extreme conditions].

In acute experiments on anesthetized cats, the perfusion of dopamine (100 micrograms/kg.min) during 35 minutes after cerebral ischemia inhibited the development of postischemic phenomena. Dopamine was found to exert a considerable effect on the oxidative metabolism in the brain.

[The role of the dopaminergic component in the autoregulatory reaction of the cerebral vessels].

Cerebral blood flow was measured in anesthetised white rats with the hydrogen clearance technique under different levels of arterial blood pressure before and after cerebral ischemia induced with the occlusion of the common carotid arteries during 12 min. The continuous i.v.

[Effect of dopamine on the blood circulation and metabolism in the brain during ischemia].

In acute experiments on anesthetized cats under blood autoperfusion of cerebral and peripheral vessels with a stable volume of blood during cerebral ischemia there was revealed the vascular and metabolic effects of dopamine on cerebral circulation. Administration of dopamine by perfusion in a dose of 100 micrograms/kg/min for 35 min after ischemia inhibited the development of postischemic hypoperfusion of the brain and also eliminated postischemic hypotension. A significant effect of dopamine on oxidative metabolism of the brain was observed.

[The participation of dopamine in the vascular reactions and metabolic processes of the brain].

The dopamine effect on the tension of perfused vessels and the arterial BP depended on its doses in acute experiments on anesthetized cats. Dopaminergic vasodilatory components in perfused vessels responses and the BP were determined with joint blockade of alpha- and beta-receptors. Oxygen and glucose consumption increased in the brain during continuous i.

[Autoregulation of the cerebral blood flow in normo- and hypertensive rats under beta-adrenoreceptor blockade].

A disorder in the autoregulation of cerebral blood flow due to a drop of arterial blood pressure (shift to the right) occurred earlier in hypotensive rats than in normotensive ones. A beta-adrenergic blockade (obsidan) improved the autoregulation (shift to the left) in both normo- and hypertensive animals.

[Effect of komplamin and nikoshpan on brain circulation and metabolism in the postischemic period].

Intravenous administration of komplamin to anesthetized cats before the brain ischemia or in the early period following ischemia prevents the development of the postischemic phenomenon of the cerebral blood flow nonrecovery and beneficially influences the cerebral metabolism: restores oxygen and glucose consumption by the brain, decreases pyruvic acid level in the arterial and venous blood, attenuates the phenomenon of acidosis. Nikoshpan improves the blood supply to the brain, restores oxygen and glucose consumption by the brain in the postischemic period only if administered before the brain ischemia.

[Effect of euphylline and no-shpa on cerebrovascular resistance and the survivability of animals after cerebral ischemia].

In acute experiments on anesthetized cats with total ischemia of the brain (15-minute arrest of blood autoperfusion of the cerebral vessels by a stable blood volume) it was shown that euphylline and no-shpa administered before ischemia or in the early period after ischemia inhibit or prevent the development of the postischemic phenomenon of non-recovery of the cerebral blood flow. The two drugs contributed to survival of albino rats following the brain ischemia produced by ligation of both carotid arteries.

[Effect of dibasol and several of its imidazo-analogs on the resistance of animals to gravitational overloading and the dynamics of the development of post-ischemic cerebrovascular phenomena].

Anesthetized and nonanesthetized animals (white rats and cats) were used to study the effect of dibasol and its new imidazo analogs (designated AKS-67 and AKS-87) on animal tolerance to gravitational effects and cerebral ischemia (ligation of both carotid arteries) as well as on systemic arterial pressure and tone of cerebral and peripheral vessels (resistographically) in the postischemic period. The drugs were administered 30-90 min before exposure. It was found that in nonanesthetized rats dibasol and AKS-87 increased tolerance to cranio-caudal acceleration and decreased it to caudo-cranial acceleration, whereas AKS-67 produced a distinct protective effect regardless of the vector.

[Use of gravitational loads as a screening method in research on new biologically active substances].

The application of longitudinal gravitational overloads in white rats in craniocaudal and caudo-cranial directions modelled on a centrifuge is suggested for the screening of bioactive agents. The time and value of the overload are selected in such a way, as to kill 50% of animals in the control experiments. The same overload is given to animals that have previously received the tested agents.

[Role of the autoregulatory component in the vascular reaction of the brain to euphylline].

The method of hydrogen clearance used for the registration of cerebral blood flow in acute experiments on anesthetized white rats with artificial respiration has shown that aminophylline had a biphasic effect (dilatation-constriction) on cerebral vessels, particularly with stable blood pressure. Systemic hypotension provoked an increase in dilatation response. With blood pressure reduced, autoregulation levels lowered.

[Effect of complamine and nicospan on the cerebral blood flow and its regulation in changes in blood pressure].

Acute experiments on anesthetized cats under the conditions of artificial respiration were made to study the action of intravenous injection of complamine (75 mg/kg) and nicospan (0.5 ml/kg) on the cerebral blood flow (CBF), arterial blood pressure in venous vessels of the head (VP) and autoregulatory reactions (AR) of cerebral vessels at different levels of arterial blood pressure. The results of experiments indicate that both drugs provoke phasic (dilatation-constriction) responses of cerebral vessels, reduction of the CBF and a decrease in BP and VP.

[Effect of clofelin and apressin on blood circulation and metabolic indices of the brain].

Experiments on cats were made to study the effects of clopheline (5-6 and 10 micrograms/kg) and apressin (1 mg/kg) on the time-course of changes in the cerebral circulation, total arterial and venous pressures, oxygen and glucose concentrations, pH in the arterial and venous blood. It was discovered that clopheline and apressin appreciably reduce the total blood pressure and minimize the volumetric velocity of the cerebral circulation. Brain oxygen and glucose consumption was found to be reduced under the effect of these drugs.