[Seasonal changes in the acetylcholine and noradrenaline content and the sensitivity to these substances in the smooth musculature of the small intestine in the rat]. / Sezonnye izmeneniia soderzhaniia atstilkholina i noradrenalina i chuvstvitel'nost' k étim veshchestvam gladkoi muskulatury tonkoi kishki krysy.

Sensitivity of the rat intestine's smooth muscle to acetylcholine (A) and noradrenaline (NA) changes in opposite directions during the year. Starting from the end of November the sensitivity to A grows gradually whereas the sensitivity to NA decreases, the maximum of the former coinciding with the minimum of the latter by the end of winter and in spring, whereas the minimum of A sensitivity coincides with the maximum of NA sensitivity in September-November. Study of the season-related changes of A and NA contents in the small intestine tissue revealed the greatest amount of A (8.0-11.5 X 10(-5) M/g) during the spring months and the least amount (3.7-5.9 X 10(-5) M/g) during the autumn and winter months. The maximal contents of NA (603-700 mg/g) occurs in autumn and the minimal that (271-390 mg/g) in spring and summer time. Like the A and NE sensitivity, the A and NA contents in the small intestine tissue changes during the year in opposite directions.

[Effect of adaptation to the altitude hypoxia on catecholamine metabolism in rats with spontaneous hereditary hypertension]. / Vliianie adaptatsii k vysotnoi gipoksii na nekotorye pokazateli obmena katekholaminov pri spontannoi nasledstvennoi gipertonii u krys.

An increase in the noradrenaline concentration in the myocardium and vas deferens was revealed in 11- and 15-week-old spontaneous hypertensive rats (SHR), this increase being less marked in 15-week-old SHR. On the contrary, catecholamine metabolic changes in the adrenals were more pronounced in 15-week-old SHR and consisted in an appreciable reduction of the content of noradrenaline and adrenalin. The concentration of noradrenaline was inversely proportional to the magnitude of arterial pressure. Adaptation to the daily 6-hour action of hypoxia (5000 m above sea level) by the 4th day prevents the development of hypertension in SHR and related changes in catecholamine metabolism in the adrenals.

[Adaptation of the peripheral organs of rats to noradrenaline deficiency following chronic desympathization]. / Adaptatsiia perifericheskikh organov krys k nedostatku noradrenalina pri khronicheskoi desimpatizatsii.

In 3--week guanetidine--desympathized rats, the noradrenaline (NA) concentration in myocardium, small intestine and ductus deferens constituted 1, 6 and 3% of the control, resp., whereas release of the NA from the ductus deferens on transmural stimulation dropped to 3%. From 4 to 16--week age the NA content in myocardium and small intestine reached 30 and 23%, resp., and its release was equal to control. The diminishing of NA content was followed by augmented adrenaline--sensitivity and diminished cholinosensitivity of the organs under study. Significance of local adaptive mechanisms for normalizing of activity of the adrenergic nervous system under conditions of desympathization, is considered.

[Functional status of the sympatho-adrenal system of rats during emotional-painful stress]. / Funktsional'noe sostoianie simpato-adrenalovoi sistemy krys pri émotsional'no-bolevom stresse.

Within 2-24 hrs after cessation of the 5-hr emotional-nociceptive stress the content of noradrenaline decreases in myocardium, small intestine, striatum, hypothalamus. The neuronal uptake of H3-NA and its synthesis decreased in atria. The compensatory response of small intestine to the lack of the adrenergic transmitter involves an increase of its sensitivity to NA and simultaneous decrease of its sensitivity to acetylcholine. Starting from the 2nd day after cessation of the stress the sympatho-adrenal system begins its normalizing and practically restores by the 5th day.

[Protection of the rat adrenergic system with gamma-hydroxybutyric acid during emotional-painful stress]. / Zashchita adrenergicheskoi sistemy krys gamma-oksimaslianoi kislotoi pri émotsional'no-bolevom stresse.

The anxiety neurosis decreased the catecholamine concentration in the rat striatum, hypothalamus, adrenal cortex, heart and small intestine. The decrease in noradrenaline concentration during the stress was followed by activation of the synthesis and suppression of the transmitter binding in the heart as well as enhancement of the adreno- and cholino-reactivity in the small intestine. Absence of noradrenaline content changes during stress in the seminal duct was followed by no changes of adreno-reactivity in this organ. Preliminary administration of 75 mg/kg of GABA prevented the above changes during the stress. This defensive action of the GABA seems to be based on limiting the activation of sympathetic-adrenal system and decrease of the respective transmitter release.

[Noradrenaline concentration in peripheral organs and their adrenosensitivity following chemical desympathization]. / Soderzhanie noradrenalina v perifericheskikh organakh i ikh adrenochuvstvitel'nost' pri khimicheskoi desimpatizatsii.

The rats desympathised with guanetidine developed a 58% decrease of the noradrenaline content in the myocardium, 37% - in the deferent duct, and 82% - in the small intestine. No significant changes of the catecholamines content occurred either in adrenal glands or in the hypothalamus. Sensitivity of the deferent duct's adrenoreceptors increased by 9 times. Sensitivity of the small intestine to noradrenaline increased by 3.4 times whereas the sensitivity to the antagonistic transmitter acetylcholine decreased by 2.4 times. Local adaptation mechanisms maintaining functioning of the organism in chronic desympathisation, are regarded.

[Peripheral regulation of the adrenergic mediator process in the smooth muscles of the rat small intestine]. / Perifericheskaia reguliatsiia adrenergicheskogo mediatornogo protsessa v gladkikh myshtsakh tonkoi kishki krysy.

Under the effect of noradrenaline a physiologically active substance (A-factor) is released from smooth fibres of rat's intestine. A-factor enhances spontaneous activity of an isolated piece of rat's intestine. The A-factor is thermostable, its stimulating action is blocked neither with alpha- nor with beta-adrenolytics which indicates a non-catecholamine nature of this substance. Blocking of the intramural nervous system with novocain does not stop the release of the A-factor which shows that this system is not responsible for the A-factor release. Metabolic adrenoreceptors rather than the functional ones are responsible for the release of this substance. Experiments with metabolic poisons (2,4-dinitrophenol) and sodium fluoride have shown that the release of the A-factor is due to the effect of noradrenaline on glycolysis. The A-factor increases sensitivity of the intestine piece to noradrenaline. Participation of the A-factor in the regulation of the activity of smooth muscle adrenoreceptors of rat's intestine on the principle of positive feedback, is discussed.

[Adrenosensitivity of isolated rat organs after a change in their noradrenaline content]. / Adrenochuvstvitel'nost' izolirovannykh organov krys pri izmenenii v nikh soderzhaniia noradrenalina.

The 30-day dynamics of noradrenaline contents after a single administration of guanitidine (50 mg/kg) was similar in the heart and small intestine but different in the vas deferens. The decrease of the noradrenaline content in the small intestine and vas deferens duct was followed by an increase of their adrenosensitivity, and the restoration of noradrenaline level--by a decrease of the adrenosensitivity, which reveals an invert relationship between these parameters (the correlation coefficient for small intestine being 0.78 and for vas deferens duct--0.61). The role of the catecholamine level near the adrenoreceptors in regulation of the adrenosensitivity of effectors is discussed.

[Peripheral regulation of the cholinergic mediator process in the smooth muscles of the rat small intestine]. / Perifericheskaia reguliatsiia kholinergicheskogo mediatornogo protsessa v gladkikh myshtsakh tonkoi kishki krysy.

A physiologically active substance (X-factor) is released from smooth muscle fibers of rat's small intestine-donor under the effect of acetylcholine. This substance which seems to be a macroergic nature strengthens the spontaneous activity of isolated piece of rat's small intestine-recipient and increases its sensitivity to acetylcholine almost twofold. Participation of the X-factor in the control of cholinoreceptor activity of smooth muscle fibers of rat's small intestine following the pattern of positive feedback, is discussed.

[Role of nucleoside triphosphatase in the formation of factor-X in frog myocardium following exposure to acetylcholine]. / Rol' nucleozidtrifosfatazy v obrazovanii X-faktora v miokarde liagushki pri deistvii atsetilkholina.

Under the effect of acetylcholine and vagal stimulation on the donor frog myocardium, a uridine polyphosphate-like substance (X-factor) is released. It intensifies contractions of the isolated heart-recipient and decreases the heart's sensitivity to acetylcholine and vagal stimulation. Acetylcholine (1-10(-4)-1-10(-5 g/ml) decreases UTPase activity (by 20-25%) and ATPase activity (by 15%) in isolated ventricle of the frog heart. When acetylcholine is washed away, UTPase activity is almost completely restored. Suppression of UTPase activity by acetylcholine seems to be one of the mechanisms responsible for the accumulation and release and uridine polyphosphates in the heart muscle.

[Effect of ATP on the sensitivity of the from heart to adrenaline]. / Vliianie ATP na chuvstvitel'nost' serdtsa liagushki k adrenalinu

Adenosinthreephosphoric acid (ATP) in concentration 1-10(-6)--1-10(-5) g/ml decreases sensitivity of the frog heart muscle to adrenaline by half. It is suggested that ATP present in the specific granules of adrenals, c. n. s. and adrenergic axons together with catecholamines and excreted with the mediator during excitation of adrenergic nerve, alters the sensitivity of postsynaptic membrane to adrenaline.

[Possible participation of lactic acid in formation of a non-mediator agent stimulating the heart during exposure of the myocardium to sympathetic influences]. / O vozmozhnom uchastii molochnoi kisloty v obrazovanii stimuliruiushchego serdtse nemediatornogo agenta pri simpaticheskom vozdeistvii na miokard

Release of A-factor, the physiologically active substance of a non--mediatory nature under sympathetic stimulation, depends upon the glycolytic process. To examine the assumption that A-factor may be a glycolytic product, lactic acid was studied in particular, and it was shown that A-factor is not identical to lactic acid. However it was found out that lactic acid participates in the release of A-factor in the heart. It was shown that under the effect of lactic acid a substance having high cardiostimulating activity was released in the frog heart muscle. This cardiostimulating substance as well as A-factor increases the amplitude of contractions of A-factor, was not abolished with beta-sympathicolytic inderal. The ability of both substances to stimulate heart activity was preserved after 20 min heating in a water bath. The cardiostimulating substance similar to A-factor increases heart sensitivity to sympathetic and decreases it to parasympathetic stimulations. It may be suggested that the cardiostimulating substance released in the heart under the effect of lactic acid is identical to A-factor released in the myocardium under the action of catecholamines and stimulation of the sympathetic nerve.