Peculiarities of zone migration and band broadening in gradient reversed-phase high-performance liquid chromatography of proteins with respect to membrane chromatography.

The peculiarities of zone migration and band broadening in the reversed-phase gradient HPLC of proteins were investigated. In the isocratic mode a critical composition of the mobile phase was found at which all proteins regardless of their molecular mass migrate with equal velocity and have a capacity factor equal to the phase ratio (VP/V0), i.e., the same capacity factor as a marker of total accessible volume would have in steric exclusion chromatography. It is shown that steric exclusion conditions are never achieved in gradient HPLC. In the first (adsorption stage) of gradient elution where the separation takes place the velocity of a protein increases until it becomes equal to the velocity of the desorbing solvent front at a critical distance X0 from column entrance. Strong broadening is characteristic of this stage. In the second (critical) stage the protein travels the remaining distance (L-X0) with the velocity of the solvent. A definition of X0 is given allowing one very simple calculation of the minimum permissible column length as a function of gradient steepness, mobile phase velocity and protein adsorption parameter. When x = X0 the protein zone has the smallest dispersion. Making L < X0 is especially disadvantageous, as it leads to anomalous bandspreading. The theory of gradient HPLC was refined on this basis and the usefulness of this approach in high-performance membrane chromatography is demonstrated.

[Effect of adrenoblockaders on vascular reactions in sinocarotid baroreflexes]. / Vliianie adrenoblokatorov na sosudistye reaktsii pri sinokarotidnykh barorefleksakh.

Blood pressure in the common carotid artery, the tone of the cerebral and femoral vessels were recorded by resistography in acute experiments on nonanesthetized cats (local anesthetics, listenon) with artificial respiration. The increased pressure in isolated carotid sinuses was accompanied by a decrease in arterial pressure and in the tone of the cerebral and femoral vessels. In both cases the reaction of the cerebral vessels was less pronounced as compared to that shown by the femoral vessels. The blocking of alpha-adrenoreceptors with phentolamine reduced or abolished completely the reactions noted. After beta-adrenergic blockade with obsidan these reactions persisted. The role of carotid baroceptors in the regulation of cerebral circulation under orthostatic collapse is discussed.

[Cerebral circulatory autoregulation in the presence of orthostatic stimuli]. / Autoreguliatsiia mozgovogo krovoobrashcheniia pri ortostaticheskikh vozdeistviiakh.

Autoregulation of cerebral blood flow (ACBF) under orthostatic tests (OT) was estimated in acute experiments on rabbits and cats under local anesthesia according to changes of perfusion pressure (PP) in carotid arteries, cerebral blood flow, pressure in the venous system of the brain, and resistance of cerebral vessels. OT was modeled by turning a special table with animal fixed stop of it from horizontal position to head up or down position for 40--80 degrees. In most experiments ACBF correlated with the changes of PP. Different variations of ACBF and its possible mechanisms are discussed.

[Effect of adrenergic blockade on autoregulation of cerebral blood flow during orthostatic tests]. / Vliianie adrenergicheskoi blokady na autoreguliatsiiu mozgovogo krovotoka pri ortostaticheskikh vozdeistviiakh.

The effect of phentolamine and anapriline on the cerebral blood flow autoregulation (CBFA) under the orthostatic test (OT) was studied in experiments on locally anesthetized rabbits. Cerebral blood flow (CBF) in the carotids, venous pressure in the cerebral vessels, perfusion pressure (PP) in the carotid arteries were measured, the resistance of cerebral vessels was calculated. OT was modeled by tilting a special table with the animal (with its head upwards or a special table with the animal (with its head upwards or downwards) by 40--80 degrees from the horizontal level. The results showed adrenergic block in most of OT cases to disturb CBFA; phentolamine promoted passive increase of CBF when PP was increased; on the contrary, anapriline promoted passive CBF reduction when PP was decreased.

[Effect of phentolamine on cerebral circulation]. / Vliianie fentolamina na mozgovoe krovoobrashchenie.

The influence of phentolamine hydrochloride on the volumentric circulation rate of the cerebral blood flow, the tone of the cerebral vessels and oxygen tension in the cerebral tissue was studied in acute experiments on anesthetized and nonanesthetized cats. Injected intravenously, phentolamine hydrochloride was found to lower the intra- and extracranial vessels for a long time, the latter to a greater extent. The circulation rate of the cerebral blood flow decreased under conditions of a significant hypotension caused by phentolamine hydrochloride and increased with a stable perfused pressure; pO2 changes in the cerebral tissue corresponded mostly to the blood flow. Preliminary atropinization of the animals and denervation of the carotid regions failed to influence the effect of phentolamine hydrochloride. The latter decreased or prevented the vasoconstrictor action of norepinephrine and phenylephrine hydrochloride (mesatone) on the cerebral vessels.

[Effect of beta-adrenoreceptor blockade on cerebral circulation and extracranial vascular tone]. / Vliianie blokady beta-adrenoretseptorov na mozgovoe krovoobrashchenie i tonus vnecherepnykh sosudov.

The influence of anapriline (propranolol) on the cerebral circulation rate, tone of the cerebral and femural vessels, pO2 in the cerebral tissue, was studied. I. v. administration of anapriline decreased the arterial blood pressure. The changes of tone of the vessels are often of the two-phase character: a decrease followed by an increase. The lowering of the arterial pressure is the most probable cause of the lowering cerebral circulation rate. pO2 decreases accordingly to the blood flow. The effect of anapriline was greater in anesthetized animals.

[Method of resistography]. / K metodike rezistografii.

To eliminate the error of the resistograph connected with the animal's arterial pressure fluctuation an automatic stabilizer of the entrance pressure provided with an electromagnetic valve is proposed. To switch off the resistograph pump automatically when the blood flow into the apparatus is either hindered or stopped the following device is proposed: the pressure stabilizer and the servo system are controlled by electro-contact Hg manometers connected with the admission channel of the resistograph.