Phrenic nerve-diaphragm preparations in relation to temperature and hibernation

1961 ◽  
Vol 200 (3) ◽  
pp. 565-571 ◽  
Author(s):  
Frank E. South
Keyword(s):  
Mechanical Properties ◽  
Neuromuscular Blockade ◽  
Phrenic Nerve ◽  
Neuromuscular Transmission ◽  
Incubation Temperature ◽  
Diaphragm Muscle ◽  
Muscle Tissues ◽  
Contraction And Relaxation ◽  
Incubation Temperatures ◽  
And Control

Electrical and mechanical properties, as correlates of incubation temperature, of phrenic nerve-diaphragm preparations obtained from hibernating and control hamsters and from rats were examined. Six incubation temperatures, ranging from 5° to 38°C, were used. Nerves of rats evidenced much steeper temperature functions than did either hamster group, with respect to irritability, spike voltage and conduction velocity such that they were inexcitable at 5°C. The hibernating and control hamster groups behaved quite similarly to each other in these respects. Neuromuscular blockade occurred at 10°C in the rat preparations and at 5°C of the control hamster preparations but in no case did it occur among those of hibernating animals. Similar or analogous differences were apparent in diaphragm muscle tissues insofar as irritability, tension production and rates of contraction and relaxation are concerned. These observations were taken to demonstrate the existence of phylogenetic adaptations correlated with the ability of hamsters to hibernate as well as the probable necessity for a prehibernal acclimatization of such mechanisms as neuromuscular transmission on the part of these animals.

scholarly journals The influence of lidocaine and racemic bupivacaine on neuromuscular blockade produced by rocuronium: a study in rat phrenic nerve-diaphragm preparation

2009 ◽  
Vol 24 (3) ◽  
pp. 211-215 ◽  
Author(s):  
Vanessa Henriques Carvalho ◽  
Angélica de Fátima de Assunção Braga ◽  
Franklin Sarmento da Silva Braga ◽  
Yolanda Christina S. Loyola ◽  
Daniele Ribeiro de Araújo ◽  
...  
Keyword(s):  
Neuromuscular Blockade ◽  
Phrenic Nerve ◽  
Local Anesthetics ◽  
Neuromuscular Transmission ◽  
Membrane Potentials ◽  
Diaphragm Muscle ◽  
Muscle Response ◽  
End Plate ◽  
Indirect Stimulation

PURPOSE: To evaluate in vitro lidocaine and racemic bupivacaine effects in neuromuscular transmission and in neuromuscular blockade produced by rocuronium. METHODS: Rats were distributed in 5 groups (n = 5) in agreement with the studied drugs: lidocaine, racemic bupivacaine, rocuronium, separately (Groups I, II, III); rocuronium in preparations exposed to local anesthetics (Groups IV, V). The concentrations used were: 20 µg/mL, 5 µg/mL and 4 µg/mL, for lidocaine, bupivacaine and rocuronium, respectively. It was evaluated: 1) amplitude of diaphragm muscle response to indirect stimulation, before and 60 minutes after separately addition of lidocaine, racemic bupivacaine and rocuronium and the association of local anesthetics - rocuronium; 2) membrane potentials (MP) and miniature end-plate potentials (MEPP). RESULTS: Lidocaine and bupivacaine separately didn't alter the amplitude of muscle response and MP. In preparations previously exposed to lidocaine and racemic bupivacaine, the rocuronium blockade was significantly larger (90.10 ± 9.15% and 100%, respectively), in relation to the produced by rocuronium separately (73.12 ± 9.89%). Lidocaine caused an increase in the frequency of MEPP, being followed by blockade; racemic bupivacaine produced decrease being followed by blockade. CONCLUSIONS: Local anesthetics potentiated the blockade caused by rocuronium. The alterations of MEPP identify presynaptic action.

Fatigue of isolated rat diaphragm: role of impaired neuromuscular transmission

1986 ◽  
Vol 61 (3) ◽  
pp. 1077-1083 ◽  
Author(s):  
T. K. Aldrich ◽  
A. Shander ◽  
I. Chaudhry ◽  
H. Nagashima
Keyword(s):  
Neuromuscular Blockade ◽  
Phrenic Nerve ◽  
Neuromuscular Transmission ◽  
Low Frequency ◽  
Rat Diaphragm ◽  
Direct Stimulation ◽  
Low Frequency Stimulation ◽  
Before And After ◽  
Frequency Stimulation ◽  
Isolated Rat

We compared the contributions of impaired neuromuscular transmission (transmission fatigue) and impaired muscle contractility (contractile fatigue) to fatigue of the isolated rat diaphragm. To make this comparison, we measured the differences in active tension elicited by direct muscle stimulation and by indirect (phrenic nerve) stimulation before and after fatigue induced by indirect supramaximal stimulation at varying frequencies and durations. Transmission fatigue was observed after all experimental protocols. Although significant contractile fatigue was not demonstrated after brief periods of low-frequency stimulation (6 min, 15 Hz, 25% duty cycle), it was present after longer or higher frequency stimulation. We repeated the direct stimulation in the presence of neuromuscular blockade with 6 microM d-tubocurarine to demonstrate that a reduced response to stimulation of intramuscular branches of the phrenic nerve during direct stimulation was not responsible for the apparent contractile fatigue. Since we found significant decreases in the response to direct stimulation even after neuromuscular blockade, we could verify the presence of contractile fatigue. We conclude that both contractile and transmission fatigue can occur in the isolated rat diaphragm and that transmission fatigue is a much more important factor after brief periods of fatiguing contractions.

scholarly journals Diaphragm neuromuscular transmission failure in aged rats

2019 ◽  
Vol 122 (1) ◽  
pp. 93-104 ◽  
Author(s):  
Matthew J. Fogarty ◽  
Maria A. Gonzalez Porras ◽  
Carlos B. Mantilla ◽  
Gary C. Sieck
Keyword(s):  
Nerve Stimulation ◽  
Phrenic Nerve ◽  
Neuromuscular Transmission ◽  
Motor Units ◽  
Diaphragm Muscle ◽  
Muscle Stimulation ◽  
Transmission Failure ◽  
Old Rats ◽  
Motor Neuron Loss ◽  
Fast Twitch

In aging Fischer 344 rats, phrenic motor neuron loss, neuromuscular junction abnormalities, and diaphragm muscle (DIAm) sarcopenia are present by 24 mo of age, with larger fast-twitch fatigue-intermediate (type FInt) and fast-twitch fatigable (type FF) motor units particularly vulnerable. We hypothesize that in old rats, DIAm neuromuscular transmission deficits are specific to type FInt and/or FF units. In phrenic nerve/DIAm preparations from rats at 6 and 24 mo of age, the phrenic nerve was supramaximally stimulated at 10, 40, or 75 Hz. Every 15 s, the DIAm was directly stimulated, and the difference in forces evoked by nerve and muscle stimulation was used to estimate neuromuscular transmission failure. Neuromuscular transmission failure in the DIAm was observed at each stimulation frequency. In the initial stimulus trains, the forces evoked by phrenic nerve stimulation at 40 and 75 Hz were significantly less than those evoked by direct muscle stimulation, and this difference was markedly greater in 24-mo-old rats. During repetitive nerve stimulation, neuromuscular transmission failure at 40 and 75 Hz worsened to a greater extent in 24-mo-old rats compared with younger animals. Because type IIx and/or IIb DIAm fibers (type FInt and/or FF motor units) display greater susceptibility to neuromuscular transmission failure at higher frequencies of stimulation, these data suggest that the age-related loss of larger phrenic motor neurons impacts nerve conduction to muscle at higher frequencies and may contribute to DIAm sarcopenia in old rats. NEW & NOTEWORTHY Diaphragm muscle (DIAm) sarcopenia, phrenic motor neuron loss, and perturbations of neuromuscular junctions (NMJs) are well described in aged rodents and selectively affect FInt and FF motor units. Less attention has been paid to the motor unit-specific aspects of nerve-muscle conduction. In old rats, increased neuromuscular transmission failure occurred at stimulation frequencies where FInt and FF motor units exhibit conduction failures, along with decreased apposition of pre- and postsynaptic domains of DIAm NMJs of these units.

Effect of hypoxia on neuromuscular transmission in the developing diaphragm

1994 ◽  
Vol 76 (2) ◽  
pp. 708-713 ◽  
Author(s):  
A. R. Bazzy
Keyword(s):  
Nerve Stimulation ◽  
Phrenic Nerve ◽  
Neuromuscular Transmission ◽  
Ringer Solution ◽  
Diaphragm Muscle ◽  
Control Force ◽  
Force Response ◽  
Direct Stimulation ◽  
Frequency Of Stimulation ◽  
Predominant Effect

To study the effects of hypoxia on neuromuscular transmission in the developing diaphragm, phrenic nerve-hemidiaphragm preparations were obtained from newborn (4–9 days) and older (22–30 days) rats. Diaphragms were stimulated directly or indirectly (via the nerve) for 1 s at frequencies of 10–80 Hz. Force generated in response to stimulation was measured during perfusion of oxygenated Ringer solution (control) and Ringer solution bubbled with 95% N2–5% CO2 (hypoxia). After 45 min of hypoxia, the force response of the older diaphragms to direct stimulation had decreased to approximately 50% of control at > or = 40 Hz; however, when stimulation occurred via the nerve at these frequencies only 15–20% of control force was generated. In the newborn diaphragms, the force decrement after similar or longer periods of hypoxia (< or = 90 min) was 30– 40% irrespective of the route or frequency of stimulation. After 15 min of reoxygenation, the force response to both muscle and nerve stimulation recovered completely in the older diaphragms but only partially in the newborn diaphragms (range 77% of control at 50 Hz to 95% of control at 10 Hz). These data suggest that in the newborn diaphragm 1) neuromuscular transmission is more resistant to the effects of hypoxia than the older diaphragm and 2) the predominant effect of hypoxia is peripheral in the diaphragm muscle fibers, whereas in the older diaphragm the effect is before or at the neuromuscular junction.

Diaphragmatic failure during loaded breathing: role of neuromuscular transmission

1993 ◽  
Vol 74 (4) ◽  
pp. 1679-1683 ◽  
Author(s):  
A. R. Bazzy ◽  
D. F. Donnelly
Keyword(s):  
Phrenic Nerve ◽  
Neuromuscular Transmission ◽  
Diaphragm Muscle ◽  
Plateau Phase ◽  
Nerve Activity ◽  
Transdiaphragmatic Pressure ◽  
M Wave ◽  
Arterial Pco2 ◽  
Loaded Breathing

To determine whether central or peripheral mechanisms are responsible for diaphragmatic failure during loaded breathing, phrenic nerve activity (iENG), diaphragm muscle electromyogram (iEMG), and transdiaphragmatic pressure (Pdi) were measured in unanesthetized chronically instrumented sheep during inspiratory flow-resistive (IFR) loaded breathing. After placement of the IFR load, Pdi increased initially and remained relatively stable for 10–30 min [Pdi = 69.9 +/- 6.3 (SE) cmH2O, n = 6]; arterial PCO2 also increased from baseline (35.8 +/- 0.9 Torr) to 55.1 +/- 4.7 Torr. During IFR loading, iEMG and iENG also increased from baseline, but during the plateau phase of Pdi, iENG continued to increase at the same time while iEMG was stable, and the M wave, evoked by phrenic nerve stimulation, decreased during this period. After the plateau phase, Pdi decreased and arterial PCO2 increased, at which point the study was terminated (at 82.1 +/- 20.6 min). The observation that iENG increased while Pdi and iEMG were stable demonstrates a reduced efficiency of neuromuscular transmission and suggests that the neuromuscular junction is an important site of diaphragmatic failure in unanesthetized sheep during IFR loaded breathing.

scholarly journals Diaphragm Neuromuscular Transmission Failure in a Mouse Model of an Early-Onset Neuromotor Disorder

2020 ◽  
Author(s):  
Matthew J. Fogarty ◽  
Joline E. Brandenburg ◽  
Gary C. Sieck
Keyword(s):  
Motor Neurons ◽  
Nerve Stimulation ◽  
Phrenic Nerve ◽  
Early Onset ◽  
Neuromuscular Transmission ◽  
Postnatal Period ◽  
Diaphragm Muscle ◽  
Phrenic Nerve Stimulation ◽  
Transmission Failure ◽  
S Period

The spa transgenic mouse displays spasticity and hypertonia that develops during the early postnatal period, with motor impairments that are remarkably similar to symptoms of human cerebral palsy. Previously, we observed that spa mice have fewer phrenic motor neurons innervating the diaphragm muscle (DIAm). We hypothesize that spa mice exhibit increased susceptibility to neuromuscular transmission failure (NMTF) due to an expanded innervation ratio. We retrogradely-labeled phrenic motor neurons with rhodamine and imaged them in horizontal sections (70 µm) using confocal microscopy. Phrenic nerve-DIAm strip preparations from wildtype and spa mice were stretched to optimal length, and force was evoked by phrenic nerve stimulation at 10, 40 or 75 Hz in 330 ms duration trains repeated each s (33% duty cycle) across a 120 s period. To assess NMTF, force evoked by phrenic nerve stimulation was compared to force evoked by direct DIAm stimulation superimposed every 15 s. Total DIAm fiber number was estimated in hematoxylin and eosin stained strips. Compared to wildtype, spa mice had over two-fold greater NMTF during the first stimulus train that persisted throughout the 120 s period of repetitive activation. In both wildtype and spa mice, NMTF was stimulation-frequency dependent. There was no difference in neuromuscular junction morphology or the total number of DIAm fibers between wildtype and spa mice, however there was an increase innervation ratio (39%) in spa mice. We conclude that early-onset developmental neuromotor disorders impair the efficacy of DIAm neuromuscular transmission, likely to contribute to respiratory complications.

Effects of Low Frequency Magnetic Fields on Chick Embryos. Dependence on Incubation Temperature and Storage of the Eggs

1986 ◽  
Vol 41 (11-12) ◽  
pp. 1111-1116 ◽  
Author(s):  
Jukka P. Juutilainen
Keyword(s):  
Magnetic Field ◽  
Magnetic Fields ◽  
Incubation Temperature ◽  
Low Frequency ◽  
Chick Embryos ◽  
The Difference ◽  
Incubation Temperatures ◽  
And Control ◽  
And Storage ◽  
The Magnetic Field

Abstract Chick embryos were exposed to sinusoidally oscillating 100 Hz magnetic fields during their first two days of development. The magnetic field strength was 1 A/m. Incubation temperatures of 36.3, 37.0, 38.0 and 38.5 °C were used and the duration of the storage of the eggs before incuba­tion was varied from 1 hour to 4 days. After the incubation, the embryos were examined for abnormalities. When the temperature was 36.3 or 37.0 °C and the eggs were stored for one day or less, the effect of the magnetic field was statistically significant. In these conditions, the percent­ age of abnormal control embryos was low, 8% in 36.3 °C and 5% in 37.0 °C. In the exposed groups the corresponding percentages were 23% (36.3 °C) and 25% (37.0 °C). However, higher temperature and storage of the eggs for 3 to 4 days increased the percentage of abnormal embryos in both the exposed and control groups. The difference between the exposed and control embryos was not significant in these conditions. The results demonstrate the importance of the handling of the eggs in this kind of experiments.

Phytotoxic Effect of Decaying Quackgrass (Agropyron repens) Residues

Weed Science ◽  
1979 ◽  
Vol 27 (6) ◽  
pp. 595-598 ◽  
Author(s):  
T. V. Toai ◽  
D. L. Linscott
Keyword(s):  
Incubation Temperature ◽  
Soil Surface ◽  
Water Soluble ◽  
Water Extracts ◽  
Phytotoxic Activity ◽  
Phytotoxic Effect ◽  
Effects Of Temperature ◽  
Incubation Temperatures ◽  
Toxin Formation ◽  
Agropyron Repens

We studied the effects of temperature (5, 10, 20, and 30 C) on the phytotoxic activity of decaying quackgrass [Agropyron repens (L.) Beauv.] leaves and rhizomes that were incubated in soils for 0, 1, 2, 4, and 6 weeks. Alfalfa (Medicago sativa L.) seeds were grown for 96 h in water, water extracts of control soils, and water extracts of soil with quackgrass rhizomes or leaves. Dried quackgrass rhizomes and leaves contained water-soluble toxins that inhibited alfalfa seedling development and growth. There was a strong interaction between incubation time and temperature on the development of additional toxins by decomposing quackgrass. High incubation temperature (30 C) accelerated toxin formation and ultimate decay. Intermediate temperature (20 C) delayed toxin formation and decay. Low incubation temperatures (5 C and 10 C) prevented formation of additional toxin. In all extracts of quackgrass and soil that had been incubated for 6 weeks, normal alfalfa seedling number equaled that in water. However, seedling growth varied with incubation temperatures.Treatment of quackgrass with glyphosate [N-(phosphonomethyl) glycine] in the greenhouse did not influence the toxicity of decaying quackgrass leaves. The highest toxic effect was noted after 1 week of decay on the soil surface.

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