[The vasomotor effects of the enzymes of the fibrinolytic system in rats]. / Vazomotornye éffekty fermentov fibrinoliticheskoi sistemy krys.

Human plasmin (Pm) caused a rapid dose-dependent relaxation of norepinephrine-preconstricted isolated aortic ring and vascular net in the Wistar rat hindlimbs. Neither atropine, nor obsidan or indomethacin suppressed the Pm-induced vasodilatation of the aortic ring. Mechanical removal of endothelium and NO-blocker N-Nitro-L-Arg almost completely abolished the Pm-induced relaxation. DIP-Pm, AN-Pm and Glu-plasminogen did not change the vascular tone of the preconstricted rings. Both aprotinin and E-aminocapronic acid inhibited the relaxing effect of the Pm. Besides the circulating Pm, the enzyme forming on the endothelial surface from plasminogen under the action of urokinase, produced the vascular dilatation as well.

[The role of the sympathetic cholinergic pathway in the neurogenic control of the release of tissue-type plasminogen activator into the blood]. / Rol' simpaticheskogo kholinergicheskogo puti v neirogennom kontrole vydeleniia v krov' aktivatora plazminogena tkanevogo tipa.

In anesthetized cats, electric stimulation of the sympathetic chain induced vasoconstriction and release of t-PA from the vascular wall into the blood. Efferent stimulation of the sympathetic chain against the background of alpha-adrenoceptor blockade increased the blood flow and the t-PA activity. Atropin suppressed both the vascular relaxation and the t-PA release into the blood. A neurogenous mechanism controlling t-PA release from the vascular wall caused by activation of sympathetic cholinergic pathway and associated with excitation of vascular M-cholinoreceptors by acetylcholine, has been suggested.

[An analysis of the components of the hyperosmotic vasomotor effect]. / Analiz komponentov giperosmoticheskogo vazomotornogo éffekta.

The vessels of the rats hindlimbs were perfused by the Tyrode solution with the constant outflow. The efficacy of vasoconstrictor effects produced by short-time infusion of exogenous norepinephrine or by the electrostimulation of sympathetic chain while increasing osmotic pressure of the perfusion solution was studied. The hyperosmolarity suppressed both vasoconstrictory reactions, but in the different degree and velocity. The comparison of osmolarity effects on maximally relaxed and precontracted vessels permitted distinguishing several phases of the reaction. It can be supposed that an increase in osmolarity of the blood flowing induced a decrease in the vascular wall sensitivity to the vasoconstrictor effects of norepinephrine followed by depression of norepinephrine secretion from nerve terminals. The relationship of these compounds determines vasomotor response to an increase of osmolarity in different moments of time.

[The role of heparin and tissue-type plasminogen activator in the adaptation of the hemostatic system to high altitude]. / Rol' geparina i aktivatora plazminogena tkanevogo tipa v adaptatsii sistemy gemostaza k usloviiam vysokogor'ia.

The role of endogenous heparin and tissue-type plasminogen activator in the middle-period (25 days) adaptation of haemostasis to high altitude (altitude 3200 m) and formation or "high-altitude hypocoagulation" was studied in the experiments on white rats. It was observed that the formation of "high-altitude hypocoagulation" is connected with an increase of heparin and tissue-type plasminogen activator level due to its release from must and endothelial cells to the bloodstream. Histochemical analysis showed that at the course of adaptation to high altitude the increase in blood heparin level was caused by the stimulation of must cells secretory activity. The endothelium of lung vessels is the main source of tissue-type plasminogen activator release into the blood. The existence of interconnection between the changes in haemostasis and stimulation of angiogenesis at high altitude is proposed.

[The stimulation of fibrinolysis during cholinergic vasodilating reactions]. / Stimuliatsiia fibrinoliza pri kholinergicheskikh sosudorasshiriaiushchikh reaktsiiakh.

Changes in the fibrinolytic activity of blood flowing from the skeletal muscles during electrostimulation of the peripheral end of the cut-off sympathetic chain at the blockade of alpha-adrenoceptors have been studied in the acute experiments on cats. It is stated, that this action induces not only an increase of vascular conductivity but also fibrinolysis stimulation relating to the secretion of plasminogen activators to the blood. The effect of fibrinolysis stimulation was reproduced during intraarterial infusion of acetylcholine and was blocked by atropine. The vasodilating reactions on sodium nitroprusside and papaverine similar by intensity to the cholinergic reactions induce no plasminogen activator release. The existence of the specific regulation mechanism of plasminogen activator secretion, mediated by M-cholinoceptors is suggested.

[Neurogenic cholinergic dilation observed in isolated vessels of the skeletal muscles of cats (the caudal femoral artery)]. / Neirogennoe rasshirenie kholinergicheskoi prirody, nabliudaemoe v izolirovannykh sosudakh skeletnykh myshts koshki (kaudal'naia bedrennaia arteriia).

Neuromediated behaviour of feline caudal femoral arteries was studied in vitro. Transmural stimulation of arteries, previously constricted by noradrenaline, caused an up to 58% relaxation of the induced tone. Atropine (10(-5) g/ml) blocked this response by 93%. The removal of endothelium did not affect the magnitude of the response. It is suggested that the caudal femoral artery is an example of a blood vessel which has muscarinic receptors located directly on its smooth muscles.

[Effect of acetylcholine on the tail artery reaction in rats]. / Vliianie atsetilkholina na reaktsii khvostovoi arterii krysy.

The response to acetylcholine (10(-5) g/ml) was studied on the rat tail artery perfused with Krebs buffer. Perfusion with acetylcholine produced vasodilation (by 69%) in arteries pre-constricted with transmural nerve stimulation. Atropine (10(-6) g/ml) blocked more than 95% of this response. Acetylcholine had a vasodilating effect on arteries pre-constricted with norepinephrine.

[Changes in osmolarity of arterial blood in intensive muscle exercise]. / Izmenenie osmoliarnosti arterial'noi krovi pri intensivnoi myshechnoi rabote.

Acute experiments in cats demonstrated that a prolonged rhythmic muscle contraction of four limbs induced by stimulation of transected motor nerve endings is concomitant with an increase in osmotic pressure of arterial and venous blood plasma both in blood vessels and in the heart. The increase in osmolarity is parallel to an increase in the minute volume of the heart, a fall in the arterial pressure and an enhanced blood flow through the exercising limbs. Muscle hyperemia is related to osmotic shifts in venous blood and the increased minute volume of the heart--to those in arterial blood. The osmotic factor seems to be involved in adaptation of the cardiovascular system to intensive physical exercise.

[Effect of monoiodoacetate and ouabain on cholinergic vasodilation in cat skeletal muscles]. / Vliianie monoiodatsetata i uabaina na kholinérgicheskii rasshiritel'nyi éffekt v sosudakh skeletnykh myshts koshki.

The effects of a glycolysis blocking agent monoiodoacetate and of the sodium pump blocker ouabain, on cholinergic vasodilatation in skeletal muscle were studied. In acute experiments on cats, i. v. administration of monoionoacetate eliminated both the cholinergic vasodilation and the increase in the osmotic pressure of the venous blood. I. v. injections of ouabain also abolished the vasodilatative effect of the sympathetic chain stimulation and of intraarterial injection of acetylcholine. Ouabain had no effect on the development of a sympathetic vasoconstrictive response and the vasodilative effect caused by intraarterial injection of papaverine. The data obtained indicate that cholinergic vasodilative response is due to activation of anaerobic metabolism in skeletal muscle and that hyperosmolarity resulting from the enhanced Na+ transport is a key link between tissue metabolism and vascular tone.

[Changes in plasma composition resulting in an increase in the osmotic pressure of venous blood during the cholinergic dilatation effect]. / Izmeneniia sostava plazma, privodiashchie k uvelicheniiu osmoticheskogo davleniia venoznoi krovi pri kholinergicheskom rasshiritel'nom éffekte.

Stimulation of the sympathetic chain in the presence of alpha-receptor blocking agents caused cholinergic vasodilatation of the cat hind-limb vessels. The arterial-venous difference with respect to osmotic pressure (Posm), as well as to the content of K+, Na+, Ca2+, lactate, total protein, and inorganic phosphate was determined in blood samples collected during vasodilatation. Sympathetic stimulation in the presence of alpha-receptor-blocking agents agents increased the conductance of the hind-limb vessels and Posm of the venous blood (7.6 +/- 0.8 mOsm/l); both effects were abolished by atropine. During vasodilatation the content of K+, Na+ and lactate in venous blood plasma was increased, while that of total protein, inorganic phosphate and Ca2+ remained unchanged. The increase in Posm (73.7%) was found to be due to the rise in Na+. The data obtained suggest an increased intensity of metabolism in skeletal muscle during cholinergic vasodilatation.