Chronic experimental study of natural activity of the dog splanchnic nerve by the pulsed coherent component separation method

Natural electrical activity in the left greater splanchnic nerve during feeding was studied in chronic experiments on dogs. The method of separation of coherent components in pulsed form was used to analyze the discharges: Recording from the nerve was carried out at two points; activity was delayed by the time for its conduction along the nerve between the channels, in the channel which received it first, and it was then led from both channels to the coincidence unit. Spontaneous afferent impulsation was shown to spread among a group of nerve fibers with conduction velocities of between 3.7 and 20 m/sec, and with a mean velocity for the maximum of activity of 9.2±1.0 m/sec. Efferent spontaneous activity was not detected. During feeding with meat, besides spontaneous activity, activity of a group of afferent fibers with conduction velocities within the range 3.7–9.2 m/sec also was found (the mean velocity for the maximum of activity was 5.8±0.7 m/sec), and also activity of a group of efferent fibers with conduction velocities within the range 2.5–9.8 m/sec (mean value for maximum 3.5±0.5 m/sec).A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 13, No. 6, pp. 636–642, November–December, 1981.     

Investigation of the frequency distribution of natural activity in a mixed nerve trunk by the colliding impulse method

the theory of the colliding impulse method of determining the discharge frequency spectrum and the distribution of fibers by frequency in a mixed nerve trunk is examined. Using the double impulse method, a modification of the colliding impulse method, afferent A-fibers of the aortic nerve in the cat were investigated. Only 61% of these fibers were found to be activated in the initial phase of cardiac ejection when the arterial pressure was 120 mm Hg. Most of the active fibers functioned with a frequency of about 115 spikes/sec.M. V. Lomonosov Moscow State University. Translated from Neirofiziologiya, Vol. 6, No. 3, pp.318–327, May–June, 1974.     

Adenosine triphosphatase activity of cutaneous nerve fibers

Summary The histochemical study of Mg⁺⁺-activated adenosine triphosphatase (Mg⁺⁺-ATPase) activity was carried out on the peripheral nerves of mouse digital skin by light and electron microscopy. Under the light microscope, the ATPase activity was clearly demonstrated on the nerve fibers as a fine network in the subepidermal regions. Under the electron microscope, the reaction product of enzyme activity was located in the interspace between axolemma and the surrounding Schwann cells of the unmyelinated nerve fibers. No reaction product was observed in the space between the axolemma and the Schwann cells associated with myelinated nerve fibers. Demonstrable activity was absent at the nodes of Ranvier as well as on the para- and internodal regions of these myelinated axons. The part of the axolemma lacking a Schwann cell sheath failed to show a reaction product. The perineural epithelial cells surrounding the nerve fibers displayed reaction product in the caveolae. These results suggest a functional difference in the axon-Schwann interface of myelinated as compared to unmyelinated nerve fibers. The function of the perineural epithelial cell would be expected to be a regulatory one in transferring materials across the epithelium to keep the proper humoral environment around nerve fibers.     

Adaptation of motor nerve fibers to physical activity

The effects induced by training on the H-reflex of soleus and lateral gastrocnemius muscles have been studied on 19 adult male volunteers; out of these, 10 were non-trained subjects and the remaining 9 were top level athletes engaged in sports requiring very rapid and intense contractions (sprinters and volley-ball players). It has been observed that the latency of the M response is significantly higher in the athletes than in the non-trained subjects. Instead, no significant differences were observed between these two groups, concerning the latency of H response. The increase of M response latency is likely due to a decrease of nerve conduction velocity in the terminal part of motor fibers. The possibility that this conduction speed decrease could be dependent on sprouting and/or terminal branching growth of the motor nerve ending is discussed.     

Suffocation of nerve fibers by living nanovesicles: a model simulation

A model using nanospheres to allow the simulation of the nonspecific interaction of nanobacteria (NB), one with another or with body tissues, is established. Depending primarily on their concentrations and stress levels, these apatite nanovesicles may nucleate thrombogenic conglomerates in blood, or self-assemble to dense nanoclay layers on surfaces in the body. Partial or total encapsulation of nerve fiber bundles by such mineral layers may interrupt the metabolic exchanges between the surrounded tissue and its immediate environment and may restrict signaling processes. The presented model could provide detailed insight into plaque formation triggered by NB, and the parameters encouraging it.     

Renal sympathetic nerve activity modulates afferent renal nerve activity by PGE2-dependent activation of alpha1- and alpha2-adrenoceptors on renal sensory nerve fibers

Increasing efferent renal sympathetic nerve activity (ERSNA) increases afferent renal nerve activity (ARNA). To test whether the ERSNA-induced increases in ARNA involved norepinephrine activating alpha-adrenoceptors on the renal sensory nerves, we examined the effects of renal pelvic administration of the alpha(1)- and alpha(2)-adrenoceptor antagonists prazosin and rauwolscine on the ARNA responses to reflex increases in ERSNA (placing the rat's tail in 49 degrees C water) and renal pelvic perfusion with norepinephrine in anesthetized rats. Hot tail increased ERSNA and ARNA, 6,930 +/- 900 and 4,870 +/- 670%.s (area under the curve ARNA vs. time). Renal pelvic perfusion with norepinephrine increased ARNA 1,870 +/- 210%.s. Immunohistochemical studies showed that the sympathetic and sensory nerves were closely related in the pelvic wall. Renal pelvic perfusion with prazosin blocked and rauwolscine enhanced the ARNA responses to reflex increases in ERSNA and norepinephrine. Studies in a denervated renal pelvic wall preparation showed that norepinephrine increased substance P release, from 8 +/- 1 to 16 +/- 1 pg/min, and PGE(2) release, from 77 +/- 11 to 161 +/- 23 pg/min, suggesting a role for PGE(2) in the norepinephrine-induced activation of renal sensory nerves. Prazosin and indomethacin reduced and rauwolscine enhanced the norepinephrine-induced increases in substance P and PGE(2). PGE(2) enhanced the norepinephrine-induced activation of renal sensory nerves by stimulation of EP4 receptors. Interaction between ERSNA and ARNA is modulated by norepinephrine, which increases and decreases the activation of the renal sensory nerves by stimulating alpha(1)- and alpha(2)-adrenoceptors, respectively, on the renal pelvic sensory nerve fibers. Norepinephrine-induced activation of the sensory nerves is dependent on renal pelvic synthesis/release of PGE(2).     

Study of total activity of natural lipid antioxidants by chemiluminescence method

The total antiradical activity of lipid antioxidants extracted from organs and tissues of fish Coregonus peled (Gmelin) was investigated using chemiluminescence method. It has been established that lipids contain antioxidants of two types. The bioantioxidants of the first type have a comparatively high efficiency constant K7eff. = (2.4-3.2) 10(6) M-1.s-1, whose value is 100 times more than that of the constant of the second type inhibitors K7eff. = (3.5-5.0) 10(4) M-1.s-1. Using the method of thin-layer chromatography such individual antioxidants of lipids as tocopherol, ubiquinon, ubichromenol were separated and quantitatively studied, as well as recorded in the presence of vitamin K, A, cholesterol. It is shown that the quantitative content of high-activity antioxidants in lipid of different kinds substantially varies (0.5-17.1) 10(-4) M; the low level of their content has been recorded for internal fat and brain lipids, the high one--for the lipids present in immature eggs, red muscles and liver.     

Spontaneous rhythmic activity of single nerve fibers of the cervical sympathetic nerve trunk of the rabbit

In experiments on rabbits anesthetized with urethane, we recorded spontaneous sympathetic activity of single nerve fibers. The activity was recorded from fine filaments dissected from the cervical sympathetic nerve trunk (CSNT). Conduction velocities in CSNT fibers and action-potential amplitude of single B-fibers were measured during recording of whole nerve trunk. Spectral analysis of the activity recorded was carried out. It was shown that unmyelinated CSNT fibers are under stronger baroreceptor control than myelinated fibers. Also, a periodic component of 2–3 Hz, noted by a number of authors after denervation of baroreceptors, was detected in intact animals along with a rhythm at the pulse rate. This component was found equally often in the activity of B- and C-fibers. Cross-correlation analysis of the simultaneously recorded activities of 24 pairs of CSNT single fibers was carried out. A correlation due to synchronization of the activities of pairs of fibers with a physiological rhythm (respiration, pulse) was found in five pairs. The correlation in one pair suggests the presence of a common excitatory synaptic input into two distinct preganglionic neurons.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 23, No. 3, pp. 259–266, May–June, 1991.     

Suffocation of nerve fibers by living nanovesicles: a model simulation--part II

Nanobacteria may cause peripheral neuropathy by adhesion to the perineurium. This hypothesis receives support from five independent observations: (1) identification of perineurial apatite in diabetic patients with peripheral neuropathy, (2) massive presence of nanobacteria in a diabetic patient, (3) beneficial effect of lasers on peripheral neuropathy, (4) model simulation indicating that perineurial deposition and attachment of nanobacteria is encouraged by both their size and chemical nature, and (5) transient inhibition of neural function by apatite. Initial deposition of (stressed) nanobacteria is promoted by a slime thought to consist of proteins, calcium, and phosphate, and is most likely followed by an immobilization phase, mediated by a bioadhesive capacity of the apatite. Proteomics may hold the key to control both attachment processes.     

Acetylcholinesterase activity of motor and sensory nerve fibers in the spinal nerve roots of the rat

Summary The histochemical and cytochemical distribution of acetylcholinesterase activity in the anterior and posterior spinal nerve roots and ganglia of the rat was demonstrated by the Karnovsky method using acetyl and butyrylthiocholine as substrates and eserine and DFP as inhibitors. Light and electron microscopic examination of transverse frozen sections enabled the simultaneous visualization of end product in relationship to the various fiber components of each nerve root. While the enzymatic activity of the anterior roots was consistantly observed in the large extrafusal and small intrafusal motor fibers a relatively greater amount of precipitate occurred in aggregates of myelinated and unmyelinated fibers believed to represent preganglionic sympathetic nerves. In contrast, no significant enzymatic activity could be demonstrated in the myelinated nerve fibers of the posterior root. In the sensory sytem, the limited enzymatic precipitate was largely restricted to the unmyelinated afferent fibers and to their small cell bodies in the dorsal root ganglia. The ultrastructural distribution of enzymatic activity was located in the granular endoplasmic reticulum and perinuclear spaces of the ganglion cells. Within peripheral nerves this end product occurred between the apposing axonal and Schwann cell membranes and along the membranous aspect of occasional axoplasmic vesicles of both myelinated and unmyelinated nerve fibers.This study was supported by grants NB 04161-04 and NB 04161-05 of the National Institute of Neurological Diseases and Blindness. — The author would like to thank MissMaria C. la Valle for her skillful technical assistance.