The effect of ethyzine on the conditioned reflexes of dogs

Summary The author studied the effect of ethyzine on the salivatory food and protective respiratory conditioned reflexes in 4 dogs. There is evidence that the disturbance of the cerebral cortex function sets in when ethyzine is administered in a dose of 0.5 mg/kg. This weakens the process of internal inhibition but has no effect on the excitation process. Positive conditioned reflexes become increased differentiation—disinhibited, while the inhibitory phase of the delayed reflex is shortened. 1–25 mg/kg of ethyzine provokes a progressive weakening of the cortical processes with the conditioned reflexes dropping to zero. The conditioned reflexes become less intense when higher doses of the preparation (1–10 mg/kg) are given.Presented by Active Member AMN SSSR V. V. ParinEthyzine is N-(2-dimethylaminoethyl)-phenothiazine hydrochloride, or phenethazine.     

Reflex regulation of vascular tone when the brain is isolated and cooled

Summary When a dog's head was isolated humorally and cooled to 24–26° while the rest of the body remained at normal temperature, no significant depression of control over vascular tone was observed.We showed that the vascular reflexes elicited by stimulating the central end of the vagus nerve were normal, or even somewhat augmented. The reflex reactions of the vessels of the trunk remained normal when the perfusion pressure in the vessels to the head was changed; the direct sensitivity of the brain centers to the action of the humoral stimulants adrenalin and acetylcholine either remained normal or was somewhat increased; depression of the vascular reflexes was observed only when the brain temperature was reduced to 20° or less.These facts indicate that within certain limits, cold does not exert any direct depressant effect on the nerve centers controlling vascular tone. Depression of vasomotor centers, which always occurs in general hypothermia, is evidently caused by the numerous interoceptors of the cooled body tissues.Presented by Active Member AMN SSSR N. N. Gorev Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 53, No. 1, pp. 7–11, January, 1962     

Effect of amphetamine and gutimin on adaptive changes in blood pressure during skeletal muscular contraction

The effect of amphetamine and gutimin on the arterial pressure reflex to skeletal muscular contraction in response to stimulation of spinal ventral roots was investigated in acute experiments on decerebrate, unanesthetized cats. Doses of the drugs increasing locomotor activity and physical working capacity were used. Amphetamine in a dose of 0.1 mg/kg raised the systemic arterial pressure and the amplitude of the pressor reflexes. If the dose of amphetamine was increased to 1–11 mg/kg the pressor reflex was inhibited and the arterial pressure began to fall. Gutimin (5–50 mg/kg) raised the arterial pressure but did not affect the amplitude of the pressor response to skeletal muscular contraction.Department of Pharmacology, I. P. Pavlov First Leningrad Medical Institute. Department of Physical Education, Leningrad Shipbuilding Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR S. V. Anichkov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 80, No. 12, pp. 41–44, December, 1975.     

The Effects of Systemic Administration of Selective Antagonists of Dopamine D1 and D2/D3 Receptors on Food-Related and Defensive (escape responses) Conditioned Paw-Placing Responses in Cats

Experiments were performed on cats to study the effects of systemic administration of antagonists of dopaminergic transmission on food-related and defensive (an escape response) operant conditioned reflexes acquired on the basis of the innate response of placing the forepaw on a support. Selective blockade of D1 receptors with SCH23390 (0.005–0.1 mg/kg) completely and selective blockade of D2/D3 receptors with raclopride (0.1–0.25 mg/kg) partially suppressed both reflexes. At these doses, both blockers had stronger actions on the defensive conditioned escape reflex than the food-related reflex: SCH23390 had significantly stronger inhibitory effects on both reflexes than raclopride.Translated from Zhurnal Vysshei Nervnoi Deyatel’nosti, Vol. 54, No. 4, pp. 489–494, July–August, 2004.     

Changes in body temperature and oxygen consumption in rabbits following the administration of sodium amytal

Summary In comparing the changes of body temperature and of oxygen intake in rabbits after sodium amytal injection no direct relationship was noted between the changes of the BMR level and body temperature (Fig. 1).Sodium amytal given in a dose of 40 mg/kg reduces the oxygen intake by 19–38% with respect to the inital level. The highest reduction occurred in 1–2 (at times in 3–4) hours. With increase of the dose of this narcotic (100, 200 mg/kg) there are seen hypothermia and a drop of oxygen intake (Fig. 3).Body temperature dropped in 4–6 hours by 3.6–7.8°C, whereas oxygen intake-by 43–58% already in 1–4 hours.Oxygen intake decreases in the majority of experiments earlier than body temperature. This leads to a conclusion that reduction of body temperature under the action of sodium amytal is to some extent the result of primary BMR reduction.(Presented by AMN SSSR Active Member S. V. Anichkov) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 52, No. 7, pp. 48–53, July, 1961     

The action of sarcolysin on regeneration in amphibia and on tumors in mice under slight hypothermia

Summary A comparative effect of the action of sarcolysin, novoembichin and TEM on the regeneration of the tadpole tail was studied both at the optimal and at subnormal temperatures (3–6° lower). Slowing of the metabolism provoked by the temperature reduction intensified the inhibitive action of sarcolysin on the tail regeneration, but weakened the effect of novoembichin and TEM. The author also investigated the action of sarcolysin and TEM on Ehrlich's tumor (transplanted into mice intramuscularly)-both on the usual strain and a strain subjected to prolonged chilling at 4°C. The inhibitive effect of sarcolysin on the tumor growth of the chilled strain was 3–4 times greater than on that of the normal strain. Conversely, the inhibitive effect of TEM on the growth of the normal strain tumors was double that exercised on the chilled tumors.The combined effect of sarcolysin and chlorpromazine on a normal strain Fhrlich's tumor was also investigated. In this case the inhibitive effect of sarcolysin on the tumor was also intensified by the pharmacological hypothermia.(Presented by Active Member AMN SSSR V. V. Zakusov) Translated from Byulleten' èksperimental' noi biologii i meditsiny Vol. 49 No. 3, pp. 97–101, March, 1960The experiments on tadpoles were conducted at the biological station of the Laboratory of Growth and Development (Head — Prof. L. D. Liozner) of the Institute of Experimental Biology (Dir.-Prof. I. N. Maiskii) of the AMN SSSR.     

The blockade of bulbospinal inhibition by 5-hydroxytryptamine antagonists

Summary Histochemical evidence suggests that neurons in the brain stem raphé nuclei which contain serotonin (5-HT) project to the spinal cord. Stimulation of the raphé nuclei facilitated and inhibited spinal reflexes: the conduction velocity calculated for the bulbospinal inhibitory pathway was 10 m/sec. Antagonists of 5-HT were without effect on facilitation, but readily blocked raphé-evoked inhibition of the monosynaptic reflex. The antagonists also blocked the inhibition evoked from the ventral medial reticular formation. Blockade of bulbospinal inhibition was observed after LSD (0.25 mg/kg), methysergide (0.5 mg/kg), BOL (1–1.5 mg/kg) and cinanserin (4 mg/kg) but not cyproheptadine (5 mg/kg). The 5-HT antagonists were more effective when injected into the arterial supply of the spinal cord than when injected into the arterial supply of the brain stem. Thus, the antagonists appear to act at the spinal level, presumably blocking the effect of a 5-HT-releasing interneuron intercalated in the bulbospinal inhibitory pathway.This work was supported in part by the National Institutes of Health Grant NB 05611. Additional support was received for B. V. C. through Grant NB 05262.     

The ammona-glutamic acid-glutamine system of the brain in the combined effect of hypothermia and elevated oxygen tension

Summary A study was made of the ammonia-glutamic acid-brain glutamine system in combined action of hypothermia (body temperature-20–19°C) and hyperoxia (4 atmospheres). The system studied showed no significant differences from that in animals in the state of hypothermia: the ammonia content was 3.22 and 3.16 mg percent, glutamine 6.27–6.27 mg percent glutamic acid-150–156 mg percent, respectively. There were no characteristic oxygen convulsions in hypothermic animals.Investigation of combined action of hypothermia and hyperoxia demonstrated that ammonia was not the cause of various functional states of the brain, but the result of chemical processes in the dicarboxylic acid-brain protein system.(Presented by Active Member AMN SSSR V. N. Orekhovich) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 57, No. 5, pp. 42–45, May, 1964     

Effect of hypothermia on metabolism in the liver during preservation

The effect of hypothermia to different depths (18–20°C and 4–6°C) on carbohydrate metabolism and the degree of solubilization of the enzymes in the liver (lactate and glutamate dehydrogenases, urocaninase, deoxyribonuclease, glucose-6-phosphatase) during preservation of the unperfused organ was studied in 20 experiments on dogs. The effectiveness of preservation was assessed during subsequent normothermic perfusion for 2 h. After preservation of the liver at 18–20°C marked solubilization of the above-mentioned enzymes was observed, indicating a disturbance of the integrity of the cell membranes during preservation. After preservation of the liver at 4–6°C moderate utilization of the glycogen reserves in the liver and of sugar in the perfusion fluid was observed, suggesting uniform depression of metabolism in the liver and predominance of normal tissue respiration over glycolysis on restoration of the circulation in the organ.Department of Experimental Surgery, Central Research Laboratory, Riga Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR V. A. Negovskii.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 86, No. 8, pp. 179–182, August, 1978.     

The role of ascorbic acid in the mechanism of artificial hypothermia development

Summary The change of ascorbic acid content was studied in adrenal glands and blood of rabbits during the development of artificial hypothermia; changes occurring in the weight of adrenal glands were recorded as well. A reduction of ascorbic acid content in the adrenal glands takes place in conditions of moderate hypothermia at temperatures ranging from 31 to 26°C; there was also a moderate increase in the weight of the glands and a rise of ascorbic acid content in the blood. With intensification of hypothermia at temperatures ranging from 26 to 25°C a marked drop of ascorbic acid content in adrenal glands is accompanied by a reduction of their weight and discharge of ascorbic acid into the blood. In deep hypothermia (25–23°C) the amount of ascorbic acid in adrenal glands rises, their weight increases, while the blood ascorbic acid content declines.(Presented by AMN SSSR Active Member N. A. Kraevskii) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 52, No. 7, pp. 54–57, July, 1961     

The reflex control of vascular tone during hypothermia

Summary The vascular reflexes were studied in dogs, cats, and rabbits during stimulation of the receptors of carotid sinus, lungs, and urinary bladder; the reflexes were also investigated during stimulation of the sensory nerves (vagus, aortic, sciatic). A marked reduction of all vascular reflexes was noted during hypothermia; they disappeared almost completely when the body temperature dropped below 20°C.Depressor reflexes were subjected to more rapid and profound depression than pressor. To investigate the role of the receptor link in the changes mentioned, experiments were carried out with the local application of cold upon the carotid sinus receptors. It was found that when cooled to a temperature of 20–26°C the carotid sinus receptors showed no reduction of their sensitivity either to various chemical stimulants or to changes in the intravascular pressure. On the contrary, within this temperature range the excitability of the receptor formations was even higher than normal.(Presented by Active Member AMN SSSR, N. N. Gorev) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 50, No. 9, pp. 65–69, September, 1960     

The local reflex component in the cardiac response to raised intrapulmonary pressure and to increased pressure in the vena cava

Summary Experiments were performed on canine heart-lung preparations. Injections were given into the coronary circulation of 0.1–2 mg/kg body weight of arphonade, a ganglion-blocking agent which depresses local viscerovisceral reflexes; it was found that cardiac reactions to increased blood pressure in the vena cava (Starling's Law) and to a rise of intrapulmonary pressure were depressed. Injecting 5–10 mg/kg body weight of cysteine, which is a sulfhydryl-group donor partially restored the initial reactions. The results obtained indicate that local reflexes play an important part in the reactions described.(Presented by Academician V. N. Chernigovskii) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 50 No. 12, pp. 11–14, December, 1960     

The effect of training on the resistance of chilled rats to anemia of the brain

Summary Occlusion of two carotid, right subclavicular and left vertebral arteries at normal body temperature leads to the death of albino rats in 3–5 min. Application of deep artificial hypothermia (13–15°C) prolongs the possible periods of arterial occlusion. However, arrest of cerebral blood supply for 30–40 min in these conditions is also incompatible with the life of almost half of the animals. Resistance of rats to cerebral anemia may be raised by preliminary training to hypoxia, hypercapnia and chilling, as well as by placing the animals in conditions of cold for 1–1 1/2 months. Complete restoration of the viability of such rats was observed after the arrest of cerebral circulation at a temperature of 13–15°C for 60–75 min, and in individual experiments — for 90 min.(Presented by Active Member of the Akad. Med. Nauk SSSR I. R. Petrov) Translated from Byulleten Éksperimental'noi Biologii i Meditsiny, Vol. 55, No. 8, pp. 44–45, December, 1963.     

A role for 5-hydroxytryptamine in descending inhibition of spinal sexual reflexes

Summary Neurons in the region of the rostral nucleus paragigantocellularis (nPGi) mediate the inhibition of spinal sexual reflexes. Anatomical and pharmacological evidence is presented supporting a role for 5-hydroxytryptamine (5-HT) in this inhibition. Neurons in the rostral nPGi project to the ventral horn in the vicinity of the pudendal motoneurons. A significant number (78% ipsilateral) of these neurons contain 5-HT. Anterograde tracing with Phaseolus leucoagglutinin (PHA-L) confirmed the nPGi projection to pudendal motoneuron and interneuronal areas of the lumbar cord. 5-HT immunoreactive fibers and presumptive terminals surround the pudendal motoneurons. Urethral stimulation, in the anesthetized male rat, elicited penile erections, ejaculation and rhythmic contractions of the perineal muscles, we have used the term coitus reflex to describe this response. Intrathecal injection of 5-HT (4–50 µg) abolished the coitus reflex. Methysergide (1–10 mg/kg i.v.) prevented the 5-HT induced blockade of the coitus reflex. These data support the hypothesis that 5-HT is involved in the descending inhibition of spinal sexual reflexes.     

Effect of local action of heat and cold on arterial and venous pressures,lymph flow and respiration

Summary Forty-one acute experiments were conducted on adult dogs. The inguinal region, abdomen, and back were heated to a temperature of 40–50°C or cooled to temperatures between –2° and 15°.The observations were made while breathing was carried out naturally or by artificial respiration. It was found that local thermal stimulation provoked a reflex change of lymph flow and an increase in the venous pressure of the femoral and portal veins. However, lymph flow and venous pressure may depend to a certain ext ent upon various extra-cardial factors such as muscular tension, etc.Presented by Active Member of the AMN SSSR, V. N. Chernigovskii     

The effect of ganglion-blocking drugs on the conduction velocity of nervous excitation in the sympathetic ganglia

Summary Experiments were performed on cats under urethanechloralose anaesthesia. The author studied the effect of ganglioblocking drugs, novocain and barbamyl on the condition velocity (latency) of excitation in the superior cervical and stellate ganglia. Discharges from postganglionic fibers were recorded in response to a single supramaximal electric stimulation of the preganglionic trunk.All the preparations investigated viz. tetraethylammonium (0.5–10 mg/kg), hexonium (0.5–7 mg/kg) pentamine (0.5–10 mg/kg), mecamine (0.5–6 mg/kg), novocain (15–20 mg/kg) and barbamyl (10–20 mg/kg) provoked a lengthening of the interval between the artifact of the exciting stimulus and the response discharge by 0.5–4 milliseconds, which was parallelled by a decrease of the discharge amplitude. Reduction of the synaptic conduction velocity in the ganglia occuring under the effect of the substances under investigation is regarded as a consequence of decreased functional mobility of the ganglionic neurons; it is viewed as a general manifestation of the action of gangliotics, irrespective of the mechanism of their depressive effect.(Presented by Active Member AMN SSSR V. V. Zakusov) Translated from Byulleten' èksperimental' noi biologii i meditsiny Vol. 49 No. 3, pp. 61–64, March, 1960     

Changes of conditioned reflexes in dogs during inhalation of ether in low concentrations

Summary The object of study was the dynamics of conditioned secretory food reflexes in dogs during 20–60 min inhalation of a 1–2% ether-oxygen mixture. It was found that a 1% ether mixture, without causing a change in general dogs' behavior, provokes a reduction of the conditioned reflex to a weak stimulation and disinhibition of the capacity for differentiation. The total intensity of conditioned reflexes usually declines by 4–65% below the control level. Upon inhalation of a 2% ether mixture, dogs develop a motor unrest. The conditioned reflexes are reduced in all dogs, the capacity for differentiation is disinhibited, and the ultraparodoxical and paradoxical phases come on the scene. The restoration of conditioned reflexes following inhalation of ether in small concentrations occurs on the 2nd-15th day.(Presented by Active Member of the Academy of Medical Sciences of the USSR V. V. Parin) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 61, No. 1, pp. 63–65, January, 1966     

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.     

The effect of a fall of the temperature on regeneration in the amphibia and on the resistance of the regenerating tissue under these conditions to the cytotaxic action of novembichin and TEM

Summary The average velocity of growth of the tail regenerate inRana temporaria andR. ridibunda tadpoles of the II and III stage (according to Blacher) was studied at various temperatures. It was demonstrated that the average 24-hours temperature of 18–20°C is the optimal for the growth of the regenerate. By decreasing the water temperature by 2–4°C the velocity of the regenerate's growth is retarded by 60% (in comparison with the growth at the optimal temperature). The author studied the effect of colchicin, novembichin and 2, 4, 6 triethyleneimio 1, 3, 5-triazine (TEM)on the regeneration of the tail at optimal temperature (type A), as well as in its regeneration at decreased temperatures (type B). The technique of administration of these preparations into the tadpole body cavity was developed and LD 100% determined. The process of regeneration in type B revealed the resistance to the effect of novembichin and TEM.Presented by Active Member AMN SSSR V. N. Chernigovskii