Conducting pathways of the dog solar plexus

Conducting pathways of the dog solar plexus were studied by recording action potentials from its nerves. The splanchnic nerves are composed of two groups of fast-conducting afferent A fibers (with conduction velocities of 12–15 and 25–56 m/sec), slowly conducting afferent C fibers (0.4–2.0 m/sec), and preganglionic B and C fibers (1.0–12.0 m/sec). Afferent A and C fibers from peripheral nerves run without interruption through the ganglia of the solar plexus, splanchnic nerves, and sympathetic chain and they enter the spinal cord in the composition of the dorsal roots. Cell bodies of A fibers are located in the spinal ganglia, those of the C fibers below the ganglia of the solar plexus, evidently in the walls of the internal organs. Peripheral nerves contain A fibers only with very low conduction velocities (13–20 m/sec) and no fast-conducting A fibers (25–56 m/sec) were found. Preganglionic fibers terminate synaptically on neurons of the ganglia of the solar plexus whose axons run in the peripheral nerves to the internal organs. Synaptic pathways run from some peripheral nerves of the solar plexus into others through its ganglia; in all probability these pathways participate in peripheral reflex arcs.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 8, No. 1, pp. 76–83, January–February, 1976.     

Neuronal organization of the left celiac ganglion in the cat

Unit responses of the isolated left celiac ganglion to stimulation of various nerves of the solar plexus were studied by intracellular microelectrode recording in cats before and after degeneration of the preganglionic fibers. The resting potential of the ganglionic neurons was ?62.2±2.9 mV and the amplitude of the spike potential 72.4±3.2 mV. The spike was followed by after-hyperpolarization with a mean amplitude of 24% of the spike amplitude and a duration of between 25 and 180 msec. A characteristic feature of the ganglion was the presence of orthodromic unit responses to stimulation of peripheral nerve fibers of the solar plexus. The higher threshold of activation of the neurons by peripheral fibers than by preganglionic fibers and the preservation of orthodromic unit responses to stimulation of peripheral nerves after degeneration of the preganglionic fibers are evidence that the peripheral reflex arc is closed in this ganglion. Neurons of the left celiac ganglion are divided into three groups. Only preganglionic fibers of the splanchnic nerve with different properties converge on the neurons of the first group (the most numerous); only afferent fibers of peripheral nerves converge on the neurons of the third group (the least numerous); both types of fibers terminate on neurons of the second group. This convergence may lie at the basis of the mechanism of the centrifugal and peripheral reflex interaction in the ganglion for coordinated visceral activity.     

Neuronal organization of ganglia in the lumbar sympathetic chain in cats

The study of the neuronal organization of ganglia L₃–L₆ of the sympathetic chain in cats by intracellular recording showed that neurons of the ganglion can be divided into three main groups on the principle of sympathetic preganglionic fibers of different types converging on them. The most numerous group (66%) consists of neurons on which sympathetic preganglionic fibers of the B₁, B₂, and C groups (with conduction velocities of 12.0±0.7, 4.4±0.3, and 1.0±0.1 m/sec respectively) simultaneously converge, while the least numerous group (10%) is formed by neurons with only sympathetic preganglionic fibers of the C-group converging on them; an intermediate group (24%) consists of neurons activated by sympathetic preganglionic fibers of the B₁ and B₂ groups. The preganglionic fibers to the ganglionic neurons can mainly be traced from the rostral segments of the spinal cord through the white rami communicantes. Sympathetic preganglionic fibers activating the neurons also enter the ganglion through their own and caudally situated white rami communicantes. Neurons of the ganglion were found to receive a preganglionic (C input) run in the composition of the gray ramus communicans and caudal commissure; the remaining neurons send their axons evidently into visceral branches.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. I. P. Pavlov Institute of Physiology, Academy of Sciences of the USSR, Leningrad. Translated from Neirofiziologiya, Vol. 9, No. 5, pp. 518–526, September–October, 1977.     

Isolation and properties of flight muscle mitochondria of the bumblebee Bombus terrestris (L.)

This report describes the isolation procedure and properties of tightly coupled flight muscle mitochondria of the bumblebee Bombus terrestris (L.). The highest respiratory control index was observed upon oxidation of pyruvate, whereas the highest respiration rates were registered upon oxidation of a combination of the following substrates: pyruvate + malate, pyruvate + proline, or pyruvate + glutamate. The respiration rates upon oxidation of malate, glutamate, glutamate + malate, or succinate were very low. At variance with flight muscle mitochondria of a number of other insects reported earlier, B. terrestris mitochondria did not show high rates of respiration supported by oxidation of proline. The maximal respiration rates were observed upon oxidation of α-glycerophosphate. Bumblebee mitochondria are capable of maintaining high membrane potential in the absence of added respiratory substrates, which was completely dissipated by the addition of rotenone, suggesting high amount of intramitochondrial NAD-linked oxidative substrates. Pyruvate and α-glycerophosphate appear to be the optimal oxidative substrates for maintaining the high rates of oxidative metabolism of the bumblebee mitochondria.     

Diagnostics of Polymerus Hahn (Heteroptera,Miridae) Species Group Including Agricultural Pests in the East European Forest-Steppe,Based on Morphological and Molecular Characters

Entomological Review - The paper presents an improved key to the co-occurring species of Polymerus Hahn, 1831 (Heteroptera, Miridae) based on morphological characters and our new data on the...     

Convergence of preganglionic fibers on vasomotor neurons of the sympathetic ganglia in cats

Convergence of different preganglionic fibers on antidromically identified vasomotor neurons was studied by intracellular recording from neurons of ganglia L3 and L4 of the sympathetic chain, isolated from their rostral and caudal commissures, white ramus communicans, and muscular and cutaneous (mixed) twigs of the ventral branch and dorsal branch of the mixed nerve, in cats. Neurons activated antidromically by stimulation of these twigs were confidently considered to be vasomotor. Preganglionic fibers of only the B₂ and C groups were shown to converge on the vasomotor neurons, by contrast with the rest. Discharges of neurons were evoked only by excitation of preganglionic fibers of the B₂-group, arising mainly from higher segments of the spinal cord and entering through the rostral commissure. Vasomotor neurons also differ from the remaining ganglion cells in the properties of their axons, which conduct excitation at a significantly slower velocity (0.95±0.05 m/sec) than axons of other neurons (1.30±0.15 m/sec).I. P. Pavlov Institute of Physiology, Academy of Sciences of the USSR, Leningrad. A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 9, No. 6, pp. 592–597, November–December, 1977.     

Unique features of flight muscles mitochondria of honey bees (Apis mellifera L.)

Honey bees Apis mellifera L. are one of the most studied insect species due to their economic importance. The interest in studying honey bees chiefly stems from the recent rapid decrease in their world population, which has become a problem of food security. Nevertheless, there are no systemic studies on the properties of the mitochondria of honey bee flight muscles. We conducted a research of the mitochondria of the flight muscles of A. mellifera L. The influence of various organic substrates on mitochondrial respiration in the presence or absence of adenosine diphosphate (ADP) was investigated. We demonstrated that pyruvate is the optimal substrate for the coupled respiration. A combination of pyruvate and glutamate is required for the maximal respiration rate. We also show that succinate oxidation does not support the oxidative phosphorylation and the generation of membrane potential. We also studied the production of reactive oxygen species by isolated mitochondria. The greatest production of H₂O₂ (as a percentage of the rate of oxygen consumed) in the absence of ADP was observed during the respiration supported by α‐glycerophosphate, malate, and a combination of malate with another NAD‐linked substrate. We showed that honey bee flight muscle mitochondria are unable to uptake Ca²⁺‐ions. We also show that bee mitochondria are able to oxidize the respiration substrates effectively at the temperature of 50°С compared to Bombus terrestris mitochondria, which were more adapted to lower temperatures.     

Tritium diagnostics in a fusion reactor

Methods for controlling tritium in a fusion reactor are reviewed. The characteristic features of the interaction of tritium with surfaces are considered, as well as its diffusive properties and its levels and saturation depths for a number of radioactive materials. New properties of boundary layers and new diffusive properties in the polycrystalline structure of metals are revealed. Unique measurements of the diffusive properties of tritium in stainless steel at room temperature are carried out. It is found that the main contribution to the diffusion process comes from the intergranular tritium flux. The capture of tritium by metals in the ITER device is calculated.