Effect of lithium hydroxybutyrate on cortical and subcortical excitability in rabbits

Microinjections of lithium hydroxybutyrate (10 g/l) had a depriming action on spontaneous cortical and subcortical electrical activity. The compound reduced the excitability of the motor cortex, hippocampus, caudate nucleus, thalamus, posterior hypothalamus, and mesencephalic reticular formation; the excitability of the amygdala was increased. In its depriming effect, lithium hydroxybutyrate surpassed lithium chloride.Department of Pharmacology, Tomsk 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. 88, No. 11, pp. 574–576, November, 1979.     

Inhibition of serotonin uptake by synaptosomes and glial cells induced by certain drugs

Uptake of [¹⁴C]serotonin by glial cells and synaptosomes in the rabbit cerebral cortex was studied. The value of K_m for serotonin uptake was the same (0.083±0.02 M) for both synaptosomes and glial cells. Cortical synaptosomes took up serotonin twice as fast as glial cells (the rates of uptake were compared as protein). Of the psychotropic drugs tested, the most active inhibitors of both synaptosomal and glial serotonin uptake were the tricyclic antidepressant imipramine and the psychostimulant cocaine which, in concentrations of 50 M, inhibited uptake of [¹⁴C]serotonin in synaptosomes by 90% and in glial cells by 75–80%.Laboratory of Neurochemical Pharmacology, Institute of Pharmacology, Academy of Medical Sciences of the USSR, Moscow. Department of Biochemistry, Tbilisi University. (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. 564–566, November, 1979.     

Dynamics of reactivity of mesenteric microvessels in rats with experimental renal and hormonal hypertension

Reactivity of mesenteric arterioles 10–30 in diameter to application of histamine (100–500 g) adrenalin, and noradrenalin (1–10 g) was studied in rats with experimental renal and hormonal hypertension. The sensitivity of the microvessels to the vasoactive substances was shown to vary with the stage of development of experimental hypertension.Laboratory of General Pathophysiology and Experimental Therapy, 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. 81, No. 2, pp. 150–152, February, 1976.     

Replication time of human chromosomes studied with the AID of 5-bromodeoxyuridine

Cultures of peripheral blood lymphocytes from normal persons of both sexes were treated with 5-bromodeoxyuridine (BDU; 20 g/ml), 5-fluorodeoxyuridine (FDU; 0.1 g/ml), and uridine (2 g/ml). Chromosome preparations were obtained 5 h later, incubated in a solution of the fluorochrome Hoechst 33258, and then stained with a 2% solution of Giemsa's stain in phosphate buffer, pH 5.0. Segments of the chromosomes that incorporated BDU stained weakly with Giemsa's stain, as a result of which the late-replicating regions showed up in each chromosome as weakly stained segments. The late replication pattern of DNA in all human chromosomes was described on the basis of this method. The method is much superior in resolving power to autoradiography.Laboratory of General Cytogenetics, Institute of Medical Genetics, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR N. A. Kraevskii.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 81, No. 1, pp. 76–78, January, 1976.     

Enhancement of activity of an epileptogenic focus in the frog hippocampus by kynurenins and its depression by serotonin

Experiments on frogs with an epileptogenic focus produced by injection of 1000 units penicillin (0.4 l) into the primordial hippocampus showed that preliminary injection of two kynurenins — quinolinic acid (QA, 0.1 g) and kynurenin itself (K, 1 g) — into the region of the focus or their injection into an already functioning epileptogenic focus led to an increase in the frequency of interictal epileptiform discharges and of electrographic correlates of fits on the EEG. Anthranilic acid (AA, 5 g) had no effect on activity of the focus whereas serotonin (S, 1 g) and 5-methoxytryptamine (1 g) substantially depressed it. The provoking action of the kynurenins on epileptically predisposed brain neurons, it is suggested, may play an important role in the pathogenesis of epilepsy.Department of Pharmacology, Leningrad Pediatric 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. 87, No. 2, pp. 158–160, February, 1979.     

Effect of thyrotropin releasing hormone and thyroxine on cytochrome oxidase activity in the rat adenohypophysis

Thyrotropin releasing hormone (TRH), in a dose of 0.01 and 1.0 g/ml, sharply increased cytochrome oxidase activity in the adenohypophysis of rats fed for 6 weeks with methylthiouracil. This effect of TRH on enzyme activity was blocked by thyroxine (T₄), if added to the incubation medium in a concentration of 20 g/ml. Actinomycin D (20 g/ml) prevented the blocking of cytochrome oxidase by T₄. TRH in a concentration of 0.01 g/ml and T₄, in a dose of 2.0 g/ml, caused no change in cytochrome oxidase activity in the adenohypophysis of intact and partially thyroidectomized rats.Laboratory of Biological Standardization of Hormones, Institute of Experimental Endocrinology and Hormone Chemistry, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR N. A. Yudaev.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 84, No. 11, pp. 559–562, November, 1977.     

Effect of neuromediators on the antinociceptive effect of mesencephalic stimulation in rats

The action of L-tryptophan (25 mg/kg, intraperitoneally) and microinjection of serotonin (20 g), dopamine (10 g), and neostigmine (5 g) into the circum aqueductal gray matter on the antinociceptive effect of stimulation of the same points of the mesencephalon was studied in rats with implanted cannula-electrodes. L-tryptophan, serotonin, and neostigmine (after preliminary injection of methylatropine) potentiated the effect of subthreshold antinociceptive stimulation, tested with respect to changes in thresholds of appearance of individual components of the complex nociceptive response to electrical stimulation of the rat's tail. Dopamine did not possess this action. The potentiating effect of serotonin is not abolished by naloxone.Department of Pharmacology, First Leningrad Medical Institute. Institute of Pharmacology, Academy of Medical Sciences of the USSR, Moscow. Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 88, No. 11, pp. 551–553, November, 1979.     

Dependence of cytogenetic action of TEPA on its concentration in human lymphocyte cultures

The cytogenetic action of TEPA [tris(2-methyl-1-aziridinyl)-phosphine oxide; mol. wt. 173.154] on cultures of human lymphocytes was investigated. With an increase in concentration of the mutagen from 0.125 to 16.0 g/ml the cytogenetic effect increased: the proportion of aberrant metaphases rose from 6.0 to 61.0% and the total number of breaks from 7.96 to 116.3. A method of finding the smallest effective concentration of a test substance compared with a control is suggested, and for TEPA its value is 0.120 g/ml. The fraction of chromatid breaks remained constant at 51.72% when different TEPA concentrations were used. The distribution of chromosome breaks among the cells is satisfactorily described by a geometric distribution.Laboratory of Mutagenesis, Institute of Medical Genetics, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician N. P. Dubinin.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 82, No. 10, pp. 1265–1267, October, 1976.     

Effect of nerve growth factor and benactyzine on survival and metabolism of spinal ganglia in culture

Spinal ganglia of a 9-day chick embryo were cultured by the floating raft method in ordinary medium (control) and in medium containing benactyzine (100 g/ml) or nerve growth factor (50 g/ml). Under the influence of benactyzine the number of surviving neurons, most of which contained monoamine oxidase, increased, as also did NAD-diaphorase, lactate dehydrogenase, and isocitrate dehydrogenase activity. Under the influence of nerve growth factor the number of nerve cells with acetylcholinesterase increased, NAD-diaphorase activity rose, lactate dehydrogenase activity became maximal, malate dehydrogenase activity increased a little, but succinate dehydrogenase activity was depressed.Morphological Group, Central Research Laboratory, Leningrad Pediatric Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR A. P. Avtsyn.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 85, No. 2, pp. 212–215, February, 1978.     

Role of injury in the appearance of “activated” smooth muscle cells

In experiments on rats the ultrastructure of the muscle tissue of the inferior vena cava after disturbance of the outflow of blood, of the muscular coat of the stomach after resection of 50% of its fundus, and of the muscular coat of the cecum after constriction of its ascending portion was studied. Activation of smooth muscles was shown to reflect the phase of injury to the ultrastructure of the cells, followed by processes of intracellular regeneration. Analysis of the ratio between DNA-synthesizing and activated cells showed the local origin of the latter from differentiated myocytes.Institute of General Pathology and Pathological Physiology, Academy of Medical Sciences of the USSR. No. 4 Main Board, Ministry of Health of the USSR. Institute of Human Morphology, Academy of Medical Sciences of the USSR. Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR A. P. Avtsyn.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 84, No. 7, pp. 112–115, July, 1977.     

Effect of leucine-enkephalin on cerebral cortical unit activity

Experiments on unanesthetized rats immobilized with flaxedil showed that leucineenkephalin (150 g), if injected into the lateral cerebral ventricle, caused heterogeneous changes in the activity of 21 sensomotor cortical units tested. Spike discharges of five neurons were reduced and those of 11 neurons increased. Naloxone (2 mg/kg, intravenously) prevented both the inhibitor and the activating effect of leucine-enkephalin in the case of repeated injections of this pentapeptide. Leucine-enkephalin did not change the activity of five units.Department of Pharmacology, Faculties of Internal Medicine and Hygiene, 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. 88, No. 7, pp. 42–44, July, 1979.     

Kinetics and properties of cortisolresistant lymphocyte population from guinea pig lymph nodes during protein sensitization

Lymphocytes from the cervical lymph nodes of guinea pigs were incubated in medium No. 199 for 24 h in the presence of cortisol in concentrations of 20 and 100 g/100 ml. The survival rate of the lymphocytes and their cortisol metabolism were determined and their nucleic acid concentration was estimated cytophotometrically. In intact and sensitized guinea pigs progesterone, in a concentration of 10^–5 M, inhibited both the lytic action of cortisol and its metabolism. A marked decrease in cortisol metabolism by the lymphocytes was found from the sixth day after sensitization, and it did not recover until the 90th day. On the 17th-30th day the cortisol-resistant lymphocyte population was increased. In a concentration of 100 g/100 ml cortisol reduced the nucleic acid concentration in lymphocytes both of the intact guinea pigs and also of the sensitized animals on the 17th-30th day, when the cortisol-resistant cell population was increased.Department of General Pathology, N. I. Pirogov Second Moscow Medical Institute. Allergologic Scientific-Research Laboratory, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR A. D. Ado.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 83, No. 1, pp. 68–71, January, 1977.     

Blood-flow distribution at branches of arterial microvessels in the frog mesentery

The blood-flow distribution was studied in 49 bifurcations of arterial trunks 25.7 in diameter into branches 0.9 in diameter in the mesentery ofR. temporaria. The flow was calculated as the product of the linear velocity of blood flow and the area of cross-section of the vessel. The linear velocity was measured by impulse digital chronometry of the erythrocyte transit time, and the geometry of the bifurcation was studied in intravital photographs. The asymmetrical structure of the bifurcation was established: One branch had a lumen 2.2 times greater than the other, and a smaller angle of turn (29° and 59°). The flow into branch I was 3 times greater than the flow into branch II, as the result of its larger lumen and the greater linear velocity of the blood flow. According to calculations, the specific resistance of turn of the branch was negligible compared with the total resistance to its blood flow; hence it follows that the angle of turn of the branches is not an important regulator of the blood volume flowing through it. The correlation found experimentally between the blood flow in the branches, their radius, and their angle of turn is well described by equations of an optimal model of vascular ramification.Institute of Physiology, Academy of Medical Sciences of the USSR, Siberian Branch, Novosibirsk. (Presented by Academician of the Academy of Medical Sciences of the USSR A. M. Chernukh.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 81, No. 3, pp. 307–309, March, 1976.     

Effect of natural inhibitors of free radical reactions on adrenalin autoxidation

Water-soluble antioxidants (1 M reduced glutathione, 3 M cysteine, 1 M ascorbate), in the presence of EDTA, inhibit the adrenalin autoxidation reaction at pH 10.2, whereas their oxidized forms, and also -tocopherol (40 M), have no such effect. The inhibiting power of superoxide dismutase is many times greater than that of the substances tested. Adrenochrome formation during free-radical oxidation of adrenalin takes place without the participation of the hydroxyl radical.Department of Biochemistry, Second Moscow Medical Institute. (Presented by Academician of the Academy of Medical Sciences of the USSR V. N. Orekhovich.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 81, No. 1, pp. 33–35, January, 1976.     

Reversible inhibition of cellular aggregation by cytochalasin B and colcemid

Aggregation of normal mouse fibroblast-like cells, placed on the surface of a Millipore filter, was investigated quantitatively. The addition of 10 g/ml of cytochalasin B (a substance blocking active cell movements) or 0.1 g/ml of colcemid (a substance disturbing polarization processes in cells and, consequently, interfering with directional cell movements) completely inhibits such aggregation. The inhibition is reversible—after removal of the agents the cells again aggregate. It is concluded that aggregation of cells in this experimental system requires active cell movement and cellular polarization.Laboratory of Mechanisms of Carcinogenesis, Institute of Experimental and Clinical Oncology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR L. M. Shabad.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 81, No. 1, pp. 49–51, January, 1976.     

Inhibition of transformation of phytohemagglutinin-stimulated lymphocytes by neutral SH-dependent splenic proteinase

The effect of neutral SH-dependent splenic proteinase on the intensity of transformation of human peripheral blood lymphocytes was studied. Proteinase (1–10 g ml) was shown to inhibit transformation of phytohemagglutinin (PHA)-stimulated lymphocytes but to have no effect on spontaneous transformation. Proteinase did not change the mitogenic properties of PHA and had no cytotoxic action. Consequently, inhibition of transformation of the stimulated lymphocytes either was the result of the direct action of proteinase on the cell or was connected with the formation of a suppressor factor.Laboratory of Immunogenetics, Institute of Organ and Tissue Transplantation, Ministry of Health of the USSR. Laboratory of Biochemistry and Chemical Pathology of Proteins, Institute of Biological and Medical Chemistry, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR V. N. Orekhovich.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 88, No. 9, pp. 324–326, September, 1979.     

Nature of the longitudinal differential staining of metaphase chromosomes

Patterns of differential longitudinal spiralization of chromosomes induced by the addition of 5-bromodeoxyuridine (200 g/ml) for 5–7 h before fixation of the cells were compared with the differential staining of normally spiralized chromosomes with Giemsa stain in chromosomes of lymphocytes in human blood cultures. The patterns of differentiation of both types were found to coincide for all chromosomes of the normal karyotype; areas of incomplete spiralization corresponded to areas staining intensively with the Giemsa stain. The significance of these results in connection with the mechanisms of differential staining of metaphase chromosomes is discussed.Laboratory of General Cytogenetics, Institute of Medical Genetics, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR N. A. Kraevskii.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 78, No. 7, pp. 106–108, July, 1974.     

α-Adrenergic activation of the muscarinic K+ channel is mediated by arachidonic acid metabolites

Phenylephrine (10 M), added in the bathing solution, stimulated the cardiac muscarinic K⁺ channel (I_K.ACh) in the cell-attached patch. The pipette solution contained 10 M atropine and 100 M theophylline to block the muscarinic acetylcholine and adenosine receptors, respectively. The channel activation induced by phenylephrine was blocked by prazosin, an ₁-antagonist, indicating that ₁-adrenergic receptor mediates the response. Phenylephrine-induced activation was prevented by nordihydroguaiaretic acid, a lipoxygenase inhibitor, and AA-861, a 5-lipoxygenase inhibitor, but was not affected by indomethacin, a cyclooxygenase inhibitor. These observations suggest that 5-lipoxygenase metabolites of arachidonic acid may be involved in the -adrenergic activation of I_K.ACh.On leave from Kyowa Hakko Kogyo Co., Pharmaceutical Research Laboratories; Nagaizumi-cho, Sunto-gun, Shizuoka 411, Japan     

Action of a cytotoxin from the venom of a central asiatic cobra on rat liver mitochondrial function

The action of various concentrations of cytotoxin (C), free from contamination with phospholipase A, on respiration and oxidative phosphorylation of rat liver mitochondria and their ghosts and also on the permeability of their internal membranes for various ions was studied. Low concentrations of C (10–25 M) do not affect functional parameters of intact mitochondria but increase the permeability of the internal membranes for monovalent ions sharply. The uncoupling action of C on mitochondrial ghosts is evidently due to the formation of nonspecific channels of conductance in the membrane with low selectivity for size and charge of the ion.Laboratory of Biophysics, Institute of Biochemistry, Academy of Sciences of the Uzbek SSR, Tashkent. (Presented by Academician of the Academy of Medical Sciences of the USSR S. E. Severin.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 85, No. 4, pp. 422–424, April, 1978.     

Uptake of tryptophan by glial cells and synaptosomes of the rabbit cerebral cortex

The uptake of L-[¹⁴C]tryptophan by glial cells and synaptosomes of the rabbit cerebral cortex was investigated. The assimilation system of the glial cells exhibits high affinity for tryptophan (K_m=0.8 M). Tryptophan uptake by the synaptosomes has lower affinity (K_m=50 M). The psychotropic drugs chlorpromazine and imipramine inhibit glial uptake. The leading role of the glial cells in the nutrition of the neurons and the normal course of neurodynamic processes is confirmed.Laboratory of Neurochemical Pharmacology, Institute of Pharmacology, Academy of Medical Sciences of the USSR, Moscow. Department of Biochemistry, Tbilisi University. (Presented by Academician of the Academy of Medical Sciences of the USSR V. V. Zakusov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 85, No. 2, pp. 172–174, February, 1978.