Levels of high‐energy phosphates in crayfish nerve during prolonged repetitive impulse activity.

Smith, Dean O.

doi:10.1113/jphysiol.1980.sp013204

Cited by 10 publications

(3 citation statements)

References 27 publications

(35 reference statements)

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“…At a concentration of 0-2 mm, this has been shown in this preparation to reduce the concentration of ATP by about 70-85% within 30 min (Smith, 1980b); similar drops also occur in arginine phosphate levels. With the preparation in normal saline, the number of stimulus pulses delivered repetitively at 50 impulses/sec before conduction block was measured.…”

Section: Effects Of Metabolic Inhibitorsmentioning

confidence: 95%

Mechanisms of action potential propagation failure at sites of axon branching in the crayfish.

Smith¹

1980

The Journal of Physiology

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134

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SUMMARY1. The phenomena leading to action potential conduction block during repetitive stimulation of the excitor axon of the opener muscle in the crayfish walking leg were studied.2. Action potentials, recorded extracellularly with micro-electrodes, failed to propagate past sites of axonal bifurcation following at least 3000 impulses; reduction of the rate or brief cessation of stimulation resulted in restored conduction.3. Failure occurred initially at branch points located most peripherally and then more centrally as stimulation continued; this centripetal progression of the site of block resulted in a stepwise reduction of the number of synaptic terminals from which transmitter was released.4. Prior to conduction failure, the conduction velocity and the sodium inward current of the action potentials decreased.5. Local application of hyperpolarizing current or of physiological saline with low [K+] in the vicinity of a block can restore propagation; thus depolarization of the membrane most probably causes failure.6. Soaking the preparation for as long as 2 hr in the metabolic inhibitor 2,4-dinitrophenol had no effect on the number of stimulus impulses before initial conduction block; however, the time required for recovery from the failure was prolonged.7. The number of impulses prior to block was related directly to the temperature of the preparation; this had a Q10 calculated to be about 1*3.8. It is suggested that during repetitive activity, the K + gradient across the membrane is reduced, resulting in depolarization and eventually in conduction failure.

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Section: Effects Of Metabolic Inhibitorsmentioning

confidence: 95%

Mechanisms of action potential propagation failure at sites of axon branching in the crayfish.

Smith¹

1980

The Journal of Physiology

Self Cite

134

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“…This was associated with a 50% reduction in energy substrates. With intact blood circulation the ATP concentration was unchanged during stimulation with 30 Hz for 30 min ( Smith, 1980 ) . Ischemia increased the incorporation of the glucose analog 2‐deoxyglucose in nerves, indicating a compensatory shift to less efficient glycolysis ( Sladky et al, 1987 ) resulting in decreased excitability and amplitude caused by a lowered pH or lack of energy substrates per se.…”

Section: Discussionmentioning

confidence: 99%

Effect of ischemia and cooling on the response to high frequency stimulation in rat tail nerves

Andersen

Nielsen

Sørensen

et al. 2000

J Peripheral Nervous Sys

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In normal rat tail nerves the effect of temperature and ischemia on the response to long-term high frequency stimulation (HFS) (143 Hz) was studied. The effect of temperature was studied in two consecutive tests at 14 degrees C and 35 degrees C. Prior to the HFS the peak-to-peak amplitude (PP-amp) of the compound nerve action potential was 139 +/- 20 microV (mean +/- SD) and 127 +/- 37 microV at 35 degrees C and 14 degrees C, respectively (NS). After 15 min of HFS the PP-amp was reduced to 45.3 +/- 20.5% of baseline level at 14 degrees C as compared with 80.8 +/- 10.2% at 35 degrees C (p < 0.001). Applying ischemia to the rat tail, an additional fall of the PP-amp was seen after 15-20 min of HFS at both low (20 Hz) and high (143 Hz) stimulation frequencies. In conclusion, ischemia and cooling result in an impaired ability to transmit high frequency impulses.

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“…In the presence of ouabain, AaK was larger and was maintained consistently at its maximum value. Altered Na+ and K+ gradients may further increase Na+-K+-ATPase activity during prolonged stimulation (Rang & Ritchie, 1968;Smith, 1980c), precluding more substantial build-up.…”

Section: Discussionmentioning

confidence: 99%

Extracellular potassium levels and axon excitability during repetitive action potentials in crayfish.

Smith¹

1983

The Journal of Physiology

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SUMMARY1. Changes in extracellular K+ levels were measured during repetitive stimulation of the excitor axon of the opener muscle of the crayfish walking leg.2. Mesaxon channels, through which K+ might diffuse away from the periaxonal ('Frankenhaeuser-Hodgkin') space, were examined in electron micrographs; they were seen every 2-10 jam along the axon, and their average (± S.D.) length and width were 3 0 (± 1-6) gsm and 19'8 (± 8 9) nm, respectively.3. Intracellular recordings revealed a 40 ms after-depolarization following an action potential; this was attributed to elevated levels of extracellular K+. During stimulation at 50 Hz, this resulted in a depolarizing shift of the membrane potential between impulses; the average depolarization was 9-3 mV, which corresponds to a 4-3 mM increase in extracellular K+.4. Using K+-selective micro-electrodes, changes in extracellular K+ activity, AaK, were measured at distances ranging from 10 to 50 ,um from the axon; during 50 Hz stimulation, AaK rose within 15 s to a maximum value of 1 1 mm which was maintained at a steady level in most preparations.5. Conduction failure occurred in several preparations after at least 90 s of stimulation; levels of AaK were not abnormally high in these cases.6. Soaking the axon for at least 15 min in saline with extracellular K+ levels at least 18 mm above normal values was necessary to cause blockage in unstimulated nerves.7. Soaking the preparation for 30 min in 10-3 M-ouabain resulted in a 48 % increase in the maximum values of AaK during 50 Hz stimulation.8. It is concluded that K+ accumulates extracellularly during axon stimulation and that the extent of this accumulation is reduced by active uptake mechanisms; however, this accumulation probably cannot directly block action potential conduction, for neither the magnitude nor the kinetics of K+ build-up approach values shown to reduce excitability.

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Levels of high‐energy phosphates in crayfish nerve during prolonged repetitive impulse activity.

Cited by 10 publications

References 27 publications

Mechanisms of action potential propagation failure at sites of axon branching in the crayfish.

Mechanisms of action potential propagation failure at sites of axon branching in the crayfish.

Effect of ischemia and cooling on the response to high frequency stimulation in rat tail nerves

Extracellular potassium levels and axon excitability during repetitive action potentials in crayfish.

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