[The effect of chemical sympathectomy with 6-hydroxydopamine on the activity of the sodium-potassium pump and on the contractile responses of the mesenteric artery and vein]. / Vliianie khimicheskoi desimpatizatsii 6-gidroksidofaminom na aktivnost' natrii-kalievogo nasosa i sokratitel'nye otvety bryzheechnykh arterii i veny.

After chemical sympathectomy of mesenteric arteries and veins, different increase of responsiveness to noradrenaline, potassium chloride and ouabain was found. Stronger changes occurred in the vein which seems to be due to different adrenergic innervation of arteries and veins.

[The reactivity of the mesenteric arteries and vein to exposure to endogenous noradrenaline in normal rats and rats with DOCA-salt hypertension]. / Reaktivnost' bryzheechnykh arterii i veny na vozdeistvie éndogennogo noradrenalina u krys v norme i s DOKA-solevoi gipertenziei.

The DOCA-salt hypertension was shown to induce changes of different types in reactivity of the mesenteric artery and vein, acting on the contractility of the vessels rather than on the sensitivity of their receptor apparatus. The observed heterogeneity of the alpha-adrenoreceptors in the artery and the vein suggests that the artery's reactivity is under the control of both humoral and neurogenic factors, whereas the vein's reactivity is neurogenically controlled rather.

[Structural changes in the vascular wall in vasoconstrictor and vasodilator exposures]. / Strukturnye izmeneniia stenki sosudov pri vazokonstriktornykh i vazodilatornykh vozdeistviiakh.

Noradrenaline vasoconstriction of the tail artery decreased external, internal diameters and the cross-section area of all the elements of the blood vessel wall. Papaverine vasorelaxation of the same artery increased the diameters but reduced the endothelium and adventitia areas. The data obtained suggest a close relation between the blood vessel tonus and the morphology of all the elements of the vessel wall.

[The significance of rhythmic contractile activity of the arteries for the regulation of the rate of blood flow]. / O znachenii ritmicheskoi sokratitel'noi aktivnosti arterii dlia reguliatsii skorosti krovotoka.

The effect of rhythmic contractile activity of the rat mesenteric arteries upon the blood flow velocity, was studied. The vasomotion was induced both by a direct stimulation of vascular motor nerves and a nociceptive stimulation. The wave of the vasomotion was shown to spread towards the periphery of the arterial bed irrespective of the way of influencing. The mathematical model of the vessel as a peristaltic pump working against the background of a constant shifting of the pressure with the contraction wave's parameters measured during the experiments, revealed that the blood flow velocity equally depended on the amplitude and the velocity of spreading of the rhythmic contractions. The experiments suggest involvement of the sympathetic nervous system in the control of the vasomotion's parameters and, consequently, of the blood flow velocity in the vessels during latters' rhythmic contractile activity.

[The activity of the sodium-potassium pump of the mesenteric arteries and veins in normal rats and in DOCA-salt hypertension]. / Aktivnost' natrii-kalievogo nasosa bryzheechnykh arterii i ven u krys v norme i pri DOKA-solevoi gipertenzii.

The activity of sodium-potassium pump was studied in mesenteric arteries and veins of rats, as well as its inhibition effect upon catecholamine-induced contractile responses and the time of relaxation of these vessels in normal rats and in those with DOCA-salt hypertension. The activity was measured by 86Rb [correction of 86Rh] up-take. A difference in the ouabain-sensitive take-up was found between arteries and veins. It was higher in normotensive rats' veins than in arteries; in hypertension, the activity of the pump tended to decrease in arteries and sharply increased in veins. Inhibition of the pump with ouabain reduced arteries' contractile responses to noradrenaline and phenylephrine in normotensive animals, whereas in hypertension the effect involved all the types of stimulation leaving intact the contractions of venous vessels. Ouabain increased the period of relaxation of arteries and veins in some types of stimulation in normal as well as in hypertensive rats.

Adrenergic innervation of blood vessels in Dahl rats with salt hypertension.

The adrenergic innervation of major arteries and veins was examined in Dahl salt-sensitive (DS) and salt-resistant (DR) rats using a histochemical fluorescent technique to detect the intraneuronal catecholamine content. Under the conditions of low salt intake the density of adrenergic plexus tended to be higher in DR than in DS rats. A decrease of catecholamine content with a subsequent reduction in the density of visible adrenergic plexus was observed in mesenteric and renal but not in femoral vascular beds of salt hypertensive DS rats. The adrenergic innervation was more altered in veins than in respective arteries. Pronounced alterations of vascular sympathetic innervation induced by high salt intake in DS rats contrasted with negligible changes occurring in DR animals. Observed changes of adrenergic innervation in particular vascular beds of salt hypertensive DS rats could reflect the enhanced catecholamine turnover and sympathetic hyperactivity which is important for the pathogenesis and/or maintenance of salt hypertension in Dahl salt-sensitive rats.

[Determination of productive conformations of acetylcholinesterase substrates using theoretical conformational analysis]. / Opredelenie produktivnykh konformatsii substratov atsetilkholinésterazy s pomoshch'iu teoreticheskogo konformatsionnogo analiza.

All equilibrium conformations of twenty-three acetylcholinesterase effectors were calculated by the molecular mechanics method, nonbonded interactions, torsion energy and energy of bond angles deformation being taken into account. In a series of conformationally flexible derivatives of acetylcholine the correlation was found between hydrolysis rate and population of the completely extended tt-conformation. In a series of cyclic analogues of acetylcholine the high hydrolysis rate occurs only for substrates sterically corresponding to tt-conformation of acetylcholine with regard to disposition of ammonium group, carbonyl oxygen and carbonyl carbon. The hydrolysis rate of acetylcholine derivatives with elongated chain between acetyl and cationic groups is directly proportional to the population of the conformations similar to tt-conformation of acetylcholine. It is concluded that tt-conformation of acetylcholine is productive for acetylcholinesterase hydrolysis.

[Versatility of arterial and venous responses to the action of physiologic stimuli in rats with DOCA-salt hypertension]. / Mnogoobrazie reaktsii arterii i ven na deistvie fiziologicheskikh stimulov u krys s DOKA-solevoi gipertenziei.

The reactivity of the rat popliteal, mesenteric and renal arteries and veins to electrical stimulation, noradrenaline, serotonin and potassium chloride in the DOCA-salt hypertension, was studied. The data obtained reveal the organ heterogeneity of the blood vessels contractile responses and the changes of arterial and venous responses in the hypertension, the character and extent of these changes depending on a particular vascular bed and the type of stimulation. Functional changes in hypertensive veins were stronger than in arteries. The artery and vein contractile responses were found to be associated with the external calcium altered in the hypertension. A direct influence of the DOCA and the salt overload on vascular reactivity was studied as well.

[Functional effects of subthreshold stimulation of smooth muscle cells of the blood vessel]. / Funktsional'nye éffekty subporogovoi stimuliatsii gladkomyshechnykh kletok krovenosnogo sosuda.

The effect of subthreshold electrical stimulation of smooth muscle cells of the vessel wall upon the level of tonic tension developed by the smooth muscle in response to distention, was studied in isolated segments of the rat tail artery. Low concentrations of catecholamines--30-300 times lesser than those ordinarily observed in the blood--as well as subthreshold electrical stimuli were shown to affect functional properties of the blood vessel's smooth muscles, potentiating the tonic tension developed by the vessel in response to distention. Calcium ions are necessary for the development of potentiating effect of the subthreshold stimuli upon the tone of the blood vessels.

[Disorders of the endothelial pavement of the vascular bed caused by denervation]. / Narusheniia éndotelial'noi vystilki krovenosnogo sosuda, vyzyvaemye denervatsiei.

The changes of endothelial surface in a tail artery at its denervation provoked by the removal of a part of adventitia have been studied with the help of scanning electron microscopy. It has been shown that the innervation didn't occur in a distal part of a vessel 10-days after the operation, there were considerable changes in the endothelial cover resulting in the protrusion of nuclear region of endothelial cells into the vessel lumen and in occurrence of spindle-like cells with long, thin projections while in the proximal part of the vessel the innervation was retaining, the endothelial surface changes being not significant. It can be concluded that the endothelial surface change is due to the switching off vascular nerve influences on a vascular wall, being not result of a postoperative injury.

Sympathetic innervation of blood vessels in rats with aortic constriction hypertension.

The adrenergic innervation of blood vessel wall was studied in various vascular beds of adult rats with experimental hypertension induced by the constriction of the aorta between the origins of both renal arteries. A moderate expansion of body fluids was demonstrated in this hypertensive model. The decrease of the density of adrenergic plexus in the vessel wall as well as the diminished catecholamine fluorescence were found only in renal vessels. These changes were pronounced in the left renal artery and vein even if the left kidney was not subjected to elevated blood pressure. Thus the alteration of vascular adrenergic innervation in hypertensive rats is not a consequence of high blood pressure but it seems to be a part of neurohumoral pathogenetic mechanisms.

[Adrenergic innervation and reactivity of the blood vessels of different organs]. / Adrenergicheskaia innervatsiia i reaktivnost' krovenosnykh sosudov razluchnoi organnoi prinadlezhnosti.

The structural and functional heterogeneity in rat mesenteric and hind leg arteries has been established. The results of histochemical, biochemical and physiological studies showed the change of adrenergic plexus density, content and ratio of catecholamines and contractility of smooth muscle cells along the superior mesenteric artery. The proximal part of the artery is sparsely innervated and contains only traces of noradrenaline. It demonstrates small contractile response to nerve stimulation, noradrenaline and potassium chloride. Increased nerve density, noradrenaline content and responsiveness has been revealed in the distal part of the artery. The same correlation between the nerve density and vessel reactivity was obtained in hind leg arteries: the more innervated popliteal artery demonstrates more strong contractile response than the femoral artery. It has been also revealed the organ heterogeneity. In general, hind leg arteries are best innervated, contain more catecholamines and demonstrate increased maximal contractility in comparison to mesenteric arteries. The femoral and popliteal arteries have not phasic contractile activity which is very well expressed in the mesenteric ones.

[Ultrastructural characteristics of branch sphincters and precortical arteries in the rabbit pial arterial system]. / Ul'trastrukturnye osobennosti sfinkterov otvetvlenii i prekortikal'nykh arterii v pial'noi arterial'noi sisteme u krolikov

Structural peculiarities of pial arteries and their active microvascular segments-sphincters in offshoots and precortical arteries have been investigated, using electron and light microscopy. Our studies have revealed that these vascular segments, which can independently change their lumen, possess multiple myoendothelial junctions, as well as neuro-muscular contacts. This gives evidence of their independent responses that might be determined by structural peculiarities and innervation of their walls.

[Effect of blood movement on the reactivity of blood vessels]. / Vliianie dvizheniia krovi na reaktivnost' kovenosnykh sosudov.

The influence of electrokinetic phenomena arising from blood movement on reactivity of blood vessels has been studied. The potential difference, as it has been established, occurs during blood movement along a vessel between its internal and external surfaces, being dependent upon the rate of blood movement, and the internal one becomes negatively charged. Blood movement facilitates penetration of molecules of dye with a positive charge into a vessel wall. The contractile response of a vessel to the stimulation of vasomotor nerves gradually increases with a start of blood movement and decreases after a blood stop. Artificially applied potential difference between the internal and external vessel surfaces results in the changes of contractile response and vessel tone. The role of electrokinetic phenomena in regulation of contractile ability and vessel tone is discussed.

The adrenergic innervation of arteries and veins in rats with DOCA-NaCl hypertension: the role of sodium and chloride overload.

The adrenergic innervation of major arteries and veins was examined in DOCA-NaCl hypertensive rats using a histochemical fluorescent technique to detect the intraneuronal catecholamine content. The possible role of sodium and chloride ions was studied in DOCA-treated rats which were fed a low-salt diet which was supplemented with sodium bicarbonate instead of sodium chloride. Focal defects of adrenergic innervation were observed in blood vessels of DOCA-NaCl hypertensive rats. Nevertheless, the degree of these changes differed according to the vascular bed examined. A maximum decrease of the catecholamine content in varicosities of adrenergic terminals was found in the femoral vessels while there were nearly no changes in tail arteries and veins. Adrenergic innervation was usually more impaired in veins than in corresponding arteries of hypertensive animals. Pronounced changes in blood vessels of rats with DOCA-NaCl hypertension contrasted with the maximum alterations observed in those hypertensive DOCA-treated animals which were fed a NaHCO3-supplemented diet. Thus a chloride overload seems to be more important for alteration of adrenergic innervation than the degree of blood pressure elevation or the sodium overload per se.

[Functional significance of the instability of neuromuscular relations in the vascular wall]. / Funktsional'noe znachenie nepostoianstva nervno-myshechnykh otnoshenii v sosudistoi stenke.

In isolated preparations of the rabbit ear artery, the contractile response to a single electrical stimulus and its latency were studied at different degrees of stretching. Contractile responses were compared in direct and indirect stimulations of the vessel's smooth muscle at different temporal interrelationships between the stimulus and the stretching process. The contractile response was found to augment in indirect stimulation within a certain stretch area of the vascular ring whereas its latency was found to shorten. The direct stimulation of the desympathised vessel left latency the same whereas the contractile response started to diminish at a lesser stretching. The comparison of contractile responses of the artery's smooth muscle in indirect and direct stimulations suggests that, with reduction of neuro--muscular distances, an automatic increase of adrenergic effects on the vascular wall occurs. The significance of this phenomenon for vascular tone control is discussed.

The importance of sodium and chloride ions for the development of DOCA-NaCl hypertension: a haemodynamic study.

The role of sodium and its accompanying anion for the development of DOCA-salt hypertension was studied in uninephrectomized DOCA-treated weanling Wistar rats which were fed a diet containing either sodium chloride or sodium bicarbonate (170 mmol/kg). The blood pressure was increased in both groups of rats with sodium overload as compared to rats fed a low-salt diet only. A decreased cardiac output and substantially elevated systemic resistance were demonstrated in both groups of rats with high sodium intake in comparison with rats kept on a low-salt diet. However, these haemodynamic changes were more pronounced in rats with sodium chloride overload than in animals with a high sodium bicarbonate intake. On the other hand, the rigidity of major arteries which was estimated as the pulse pressure/stroke volume ratio, was increased only in rats fed a diet with sodium chloride but not in rats with sodium bicarbonate overload. Thus high sodium intake was responsible for the changes of systemic resistance in DOCA-treated animals and its action was only slightly augmented by a high chloride intake. In contrast to this, the chloride overload seemed to be essential for the induction of increased arterial rigidity.

[Functional status and ultrastructure of the smooth muscle coat of arteries]. / Funktsional'noe sostoianie i ul'trastruktura gladkomyshechnoi obolochki arterii.

The ultrastructure of smooth-muscle sheath of the rabbit ear artery was studied in situ with the blood flow preserved both in contracted and in relaxed states. In the latter state a decrease in the volume of smooth-muscle cells and a relative increase of interfellular space were revealed. These findings suggest a redistribution of fluid in the artery wall during contraction and relaxation which can be important for transport of substances in the vascular wall. In relaxation of smooth-muscle cell such phenomena as desaggregation of thick myosin myofilaments, considerable reduction of the micropinocytose apparatus, shifting of contractile elements to the cell's central zone, partial discomplexation of the endoplasmatic reticulum, were revealed. Possible mechanisms of the ultrastructural changes and their functional role are discussed.