Blood pressure reflexes to stimulation of tibial nerve a fibers in mesencephalic and bulbar cats

The role of the various subgroups of A fibers of the tibial nerve (pulse frequency of electrical stimulation 10/sec) in the formation of reflex changes in blood pressure (BP) was investigated in unanesthetized cats with total transection of the brain stem at the level of the pontomedullary junction (bulbar animals) or at the rostral border of the mesencephalon (mesencaphalic animals), and also in anesthetized cats with an intact brain. The lowest thresholds for the reflexes were found in anesthetized animals with an intact brain, the highest in bulbar cats. Excitation of A fibers in anesthetized cats with an intact brain evoked only depressor reflexes. In some bulbar and mesencephalic animals only pressor reflexes appeared. In the experiments of this group excitation of fibers with a conduction velocity of over 15 m/sec in mesencephalic cats evoked reflexes of near maximal strengths, whereas in bulbar cats excitation of thinner A fibers also was necessary. In unanesthetized animals disconnection of the suprabulbar structures thus lowers the sensitivity of the central mechanisms of vasomotor regulation to impulses in lowthreshold A fibers. No such effect was found in another group of experiments in which depressor reflexes appeard in response to stimulation of fast-conducting A fibers only. In these experiments, if slower A fibers also were stimulated, the reflexes became pressor but the difference between their magnitude in the bulbar and mesencephalic cats was not signicant.Laboratory of Biophysics and Pathophysiology of the Circulation, Institute of General Pathology and Pathological Physiology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR A. M. Chernukh.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 84, No. 10, pp. 393–396, October, 1977.     

Role of GABA and glycine in the formation of somato-sympathetic reflexes

The action of strychnine and picrotoxin, synaptic antagonists of glycine and GABA, on the components of somato-sympathetic reflexes evoked by stimulation of cutaneous and intercostal muscular afferents was studied in experiments on intact or cordotomized cats. Evoked potentials were recorded in the white ramus communicans of the 3rd thoracic segment. Strychnine and picrotoxin produced different changes in the magnitude of the various components of the reflex, indicating differences in the localization of the inhibitory action of GABA and glycine in the central link of the somato-sympathetic reflex arc.Department of Pharmacology, Volgograd Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR V. V. Zakusov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 82, No. 11, pp. 1342–1344, November, 1976.     

Effect of tactivin on formation of conditioned and manifestation of unconditioned avoidance reflexes in august rats

Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 113, No. 4, pp. 397–399, April, 1992.     

Depressor responses to stimulation of the nerve to the gastrocnemius muscle in intact unanesthetized cats

Changes in the blood pressure, heart rate, and respiration rate during stimulation of the nerve to the gastrocnemius muscle before and after intravenous injection of noradrenalin were studied in chronic experiments on unanesthetized cats. Stimulation of the nerve to the gastrocnemius muscle in intact animals caused an increase in the blood pressure and the heart and respiration rates. Similar stimulation of the nerve against the background of noradrenalin-induced hypertension led to a fall of blood pressure and quickening of the heart beat. The depressor response was unchanged by -adrenergic receptor blockade but it disappeared after blockade of muscarinic cholinergic receptors by methylatropine. In unanesthetized decerebrate animals the phase of the fall of blood pressure did not take place. It is suggested that the depressor response of the latter is due to strong cholinergic vasodilatation arising by a reflex mechanism in response to stimulation of the motor nerve in the intact cat.Department of Pharmacology, I. P. Pavlov First Leningrad Medical Institute. Department of Physical Education, Leningrad Shipbuilding Institute. (Presented by Academician S. V. Anichkov of the Academy of Medical Sciences of the USSR.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 83, No. 4, pp. 395–399, April, 1977.     

Segmental reciprocal reflexes of the thoracic portion of the spinal cord

Under ordinary experimental conditions stimulation of the central end of a divided intercostal nerve causes reflex discharges simultaneously in several intercostal nerves on the same and opposite sides of the chest. No reciprocity is observed between these reflexes. It is shown as a result of this investigation that mechanical stimulation of the parietal pleura of unanesthetized spinal cats facilitates reflex discharges in the intercostal nerves on the side of stimulation of the pleura and inhibits them on the opposite side. The presence of reciprocal segmental reflxes between the left and right halves of the chest was thus established for the first time.Laboratory of Restoration and Compensation of Disturbed Functions, Institute of General Pathology and Pathological Physiology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR A. M. Chernukh.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 84, No. 10, pp. 400–402, October, 1977.     

Role of nitric oxide in modulation of afferent impulses in cutaneous branches of somatic nerves by polarized light

Subcutaneous injection of L-NAME inhibited afferent impulse activity inn. ischiadicus andn. saphenus and abolished the increase in this activity induced by stimulation of mechanoreceptors after skin irradiation with polarized light with various spectral characteristics. Subsequent subcutaneous injection of sodium nitroprusside restored the pattern of afferent impulse activity in these nerves during repeated skin irradiation with polarized light. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 130, No. 8, pp. 140–143, August, 2000     

The brain stem and the very late reflex response of vasoconstrictor neurons to impulses of somatic A-afferents

Single stimulation of A-fibers of the tibial nerve evoked not only a late response — a discharge of the latent period 60–140 msec — in the renal nerve of unanesthetized decrebrate cats, but also a very late response (VLR), with a latent period of about 0.35 sec. This response was easily elicited in nearly all experiments on mesencephalic animals, but after division of the brain stem at different levels of the pons, including the region of the pontobulbar junction and the most rostral portions of the medulla, it was discovered in only 1 of 18 animals. After division of the brain stem rather more caudally (in bulbar animals) VLR was found in 10 of 11 animals. In the region of the pontobulbar junction there are thus structures which tonically inhibit the activity of the system generating the VLR. It is shown that the activity of this system is potentiated by two types of summation processes: Some taking place during long (seconds) and others taking place during short (milliseconds) time intervals.Laboratory of Biophysics and Pathophysiology of the Circulation, Institute of General Pathology and Pathological Physiology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR A. M. Chernukh.) Translated from Byulleten' Éksperimental'noi Biologii Meditsiny, Vol. 88, No. 10, pp. 390–393, October, 1979.     

Structural features of acute focal metabolic injuries to somatic muscle fibers caused by dimethylparaphenylenediamine

The pathological picture of an acute disorder of cell metabolism caused by dimethylparaphenylenediamine consists of typical focal reactions of striated muscles to injury: myofibril contractures and intracellular myocytolysis. Analysis of the pathological process demonstrates the time course of contracture injuries as a succession of overcontracture (first-third degree contractures) and necrobiotic phases (fourth degree contracture), followed by lump degradation and macrophagal resorption. Two polar types of contractures are clearly differentiated by the size, shape and structural and metabolic characteristics of target fibers: “ribbons“ and ”medallions”. Disappearance of Z strips, disaggregation, disorientation, and fragmentation of myofibrils are typical of intracellular myocytolysis. The observed changes form the morphological basis for acute disease of striated muscles. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 127, No. 6 pp. 700–705, June, 1999     

Effects of different stress techniques and adaptation on behavioral and somatic indices in rats

We developed a model of stress (free swimming in a cage) which allows to assess the immediate and long-term effects of emotional stress. This stress induced typical changes in the open field test and ulceration of gastric mucosa. Unlike standard immobilization stress the proposed technique excludes a traumatic factor, it is well reproducible and simple. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 128, No. 8, pp. 157–160, August, 1999     

Effect of adaptation to high-altitude hypoxia in early ontogeny on higher nervous activity

Newborn male and female Wistar rats were adapted to hypoxia in a pressure chamber. Adaptation began at an altitude of 1000 m for 1 h daily, after which the duration and intensity of exposure were gradually increased so that, starting from the 17th day, the animals were adapted to an altitude of 5000 m for 5 h on 5 days a week. After adaptation for two months, a conditioned active avoidance reflex was produced in the animals. In the adapted males a tendency was observed for the reflex to be formed more rapidly and for it to be preserved to a much greater degree than in the control animals. In females adapted to hypoxia under similar conditions no changes were observed in the formation and preservation of the reflex.Laboratory of Pathophysiology of the Heart, Institute of General Pathology and Pathophysiology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR A. M. Chernukh.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 82, No. 8, pp. 902–903, August, 1976.     

Sensitivity of the respiratory system to pulmonary mechanoreceptor impulses during GABAergic system activation

Acute experiments on narcotized cats show that systemic administration of the GABA receptor agonist sodium hydroxybutyrate and fenibut (phenylbutyrate) during periodic apneustic breathing and subsequent engine-like breathing reduces sensitivity of the respiratory system to afferentation from lung stretch receptors. Preliminary vagotomy does not promote the transformation of periodic apneustic breathing to engine-like breathing in response to injection of GABA agonists. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 127, No. 3, pp. 265–269, March, 1999     

Role of interoceptive impulses in the modulation of emotional and behavioral responses

Chronic experiments on rabbits with a gastric fistula and electrodes implanted into deep brain structures showed that stimulation of the gastric receptors leads to modulation of emotional and behavioral responses evoked by electrical stimulation of the hypothalamus, amygdala, and hippocampus. The effect depends on the intensity of interoceptive stimulation and on nature of the emotional response, which has its own cerebral control systems.Department of Physiology, Ivan-Frankovsk Medical Institute. (Presented by Academician V. N. Chernigovskii.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 81, No. 3, pp. 264–266, March, 1976.     

General pathological processes in somatic muscles in W/SSM rats with genetically determined metabolic myopathy

Hypertrophy, atrophy, and dystrophy, which reflect the balance between alterative and compensatory-adaptive processes at all levels of structural organization, predominate among structural changes in W/SSM rats with metabolic myopathy under conditions of progressive chronic disorders of cellular homeostasis. Primary universal reactions of striated muscles to damage (myofibril contractures and intracellular myocytolysis) are observed at the ultrastructural level. Increased incidence of focal changes and the time course of morphological and stereological parameters in a constantly functioning organ (diaphragm) indicate that working muscle fibers are most susceptible to injury. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 126, No. 8, pp. 228–233, August, 1998     

Cutaneous reflexes during rhythmic arm cycling are insensitive to asymmetrical changes in crank length

The neural control of a movement depends upon the motor task performed. To further understand the neural regulation of different variations of the same type of movement, we created three dissimilar bilateral rhythmic arm cycling tasks by unilaterally manipulating crank length (CL). Modulation in the amplitude and sign of cutaneous reflexes was used as an index of neural control. Neurologically intact subjects performed three bilateral cycling trials at ∼1 Hz with the ipsilateral crank arm at one of three different lengths. Cutaneous reflexes were evoked during each trial with trains (5 × 1.0 ms pulses at 300 Hz) of electrical stimulation delivered to the superficial radial nerve at the ipsilateral wrist. EMG recordings were made bilaterally from muscles acting at the shoulder, elbow, and wrist. Analysis was conducted after phase-averaging contingent upon the timing of stimulation in the movement cycle. CL variation created an asymmetrical cycling pattern and produced significant changes in the range of motion at the ipsilateral shoulder and elbow. Background EMG amplitude in muscles of the contralateral arm generally increased significantly as CL decreased. Therefore at a given phase in the movement cycle, the background EMG was different between the three cycling trials. In contrast, cutaneous reflex amplitudes in muscles of both arms were similar at each phase of the movement cycle between the different CLs trials at both early and middle latencies. This was particularly evident in muscles ipsilateral to nerve stimulation. We suggest that variations of arm cycling that primarily yield significant changes in the amplitude of muscle activity do not require significant task-specific change in neural control.     

Effect of droperidol on corticofugal influences in food motivation reflexes

The effect of droperidol, a butyrophenone derivative, on the food reflex to electrical stimulation of the hypothalamic food center was studied in experiments on freely moving rabbits. Intravenous injection of droperidol (0.3 mg/kg) lowered the threshold of the evoked food response. Inhibitory influences of the anterior neocortical zones on food responses were absent but facilitatory influences of the caudal regions of the cortex were preserved or even somewhat increased. The effects observed can be explained by the dopamine-negative action of droperidol and by disturbance of the brain inhibitory system.Department of Normal Physiology, I. M. Sechenov First Moscow Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR V. V. Zakusov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 81, No.3, pp. 267–269, March, 1976.     

Effect of antidromic impulses of the afferent flow in the Aδ fibers of a cutaneous nerve

Afferent activity in myelinated A fibers was analyzed by a modified colliding impulses method. Frequency characteristics of the orthodromic flow without preliminary electrical stimulation of A fibers and after stimulation of the nerve were compared. Antidromic impulses arising during electrical stimulation of the nerve were found to produce an increase in the spike frequency in the afferent flow during adequate stimulation of the skin receptors.Department of Biocybernetics, Scientific-Research Institute of Applied Mathematics and Cybernetics, N. I. Lobachevskii Gor'kii University. (Presented by Academician V. N. Chernigovskii.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 83, No. 4, pp. 390–392, April, 1977.     

Depression of presynaptic inhibition of spinal reflexes by ammonium acetate

In experiments on cats ammonium acetate (AA), injected intravenously (2–4 moles/kg), depresses primary afferent depolarization (PAD), which is associated with presynaptic inhibition of spinal reflexes. Depression of PAD develops parallel with depression of postsynaptic inhibition of monosynaptic reflexes and is reversible in character. Depression of PAD is not connected with blocking of negative postsynaptic dorsal cord potentials or of reflex electrical discharges in ventral roots. It is concluded that one of the mechanisms of the convulsant action of AA is its depression of presynaptic inhibition. It is suggested that depression of PAD by AA may be the result of blocking of the chloride pump which operates in afferent terminals and creates the emf for the outward transmembrane chloride current producing PAD.Department of Pathological Physiology, N. I. Pirogov Second Moscow Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR A. D. Ado.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 84, No. 10, pp. 428–431, October, 1977     

Morphological study of somatic muscles in alimentary-toxic paroxysmal myoglobinuria

The development of acute focal metabolic lesions of somatic muscles is shown in alimentary-toxic paroxysmal myoglobinuria. Two principal universal reactions of striated muscles are traced in the genesis of this pathological process, namely, contracture damage and intracellular myocytolysis. The functional asynchronism and structural-metabolic heterogeneity of muscle fibers are reflected in the stagewise and typical heterogeneity of the morphological picture, which preserves the entire spectrum of stereotypical pathological reactions regardless of the severity of the illness. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 121, N ^o 2, pp. 228–233, February, 1996 Presented by D. S. Sarkisov, Member of the Russian Academy of Medical Sciences     

Effect of sodium hydroxybutyrate on the cerebral circulation and regional vasomotor reflexes

Experiments on cats in which electromagnetic and resistographic methods were used showed that sodium hydroxybutyrate (100 mg/kg) considerably increases the cerebral circulation. It also increases the blood flow into the brain during the period of formation of pressor blood pressure reflexes. An increase in blood flow also is observed in the system of the femoral arteries, whereas in the intestinal artery, on the other hand, the increase in the blood flow is reduced during vasomotor reflexes. Reflex changes in the resistance of the regional vessels also differ in character: depression of pressor reflexes in the cerebral vessels accompanied by facilitation in the intestinal and femoral arteries and potentiation of the dilator phase of the reflex in the limb vessels. These differences are evidently based on differences in the sensitivity of sympathetic formations in the central components of the different regional vasomotor reflexes to hydroxybutyrate.Laboratory of Pharmacology of the Nervous System, Institute of Pharmacology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR V. V. Zakusov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 88, No. 11, pp. 555–557, November, 1979.