Peripheral nerve at extreme low temperatures 1: Effects of temperature on the action potential

doi:10.1016/j.cryobiol.2009.01.003

Cryobiology

Volume 59, Issue 1, August 2009, Pages 1-11

https://doi.org/10.1016/j.cryobiol.2009.01.003 Get rights and content

Abstract

Hypothermia is an important means of neuroprotection. Understanding the effects of temperature on a physiologic measurement such as the nerve action potential (NAP) is important in monitoring its effects. The effects of hypothermia on the NAP amplitude, conduction velocity, and response to paired pulse stimulation were quantified in a rat sciatic nerve preparation from 37 to 10 °C. The time course of temperature related changes and the effect of repeated cycles of cooling and rewarming are explored using the following measures of the NAP: peak-to-peak amplitude, conduction velocity, duration, area under the curve and response to paired pulse stimuli. The NAP amplitude initially increases as temperature is reduced to 27 °C and then drops to roughly 50% of its baseline value by 16 °C while the area under the curve increases gradually until it begins to decline at 16 °C. Permanent loss of the NAP appears only after cooling below 10 °C for extended periods. Although the dependence of amplitude on temperature is approximately sigmoidal, the conduction velocity declines linearly at a rate of 2.8 m/s/°C. The response to paired pulse stimulation is strongly dependent on both temperature and the interstimulus interval with the responses at shorter interstimulus intervals being more temperature sensitive. With repetitive cycles of cooling and rewarming, the NAP amplitude declines by roughly 4% with every cycle without changes in the temperature at which the NAP amplitude reaches 50% of baseline. Only minor differences in conduction velocity are seen during cooling and rewarming.

Section snippets

Nerve harvests/stimulation

After a euthanizing dose of pentobarbital, under a protocol approved by the Weis Center for Research ACUC (protocol# 124-00), both sciatic nerves from adult Sprague–Dawley rats were quickly and carefully dissected. Initially, the harvests were performed with continuous EMG recording so that any stretch injury during the harvest would be detected immediately and the surgical procedure modified. With experience, this was no longer required as negligible EMG activity was recorded. The harvests

Stability

Prior to other studies, the period of time over which the preparation was stable was investigated. For these investigations, seven nerves were perfused at a fixed temperature of 37 °C and seven nerves at 25 °C while NAP’s were continuously recorded. Since it was expected that the amplitude of the NAP might decline exponentially a linear regression of the logarithm of the NAP amplitude on time was carried out with the result: $Normalized NAP Amplitude = \{\begin{matrix} e^{- 0.000048 t + 0.25}; T = 37 ° C \\ e^{- 0.000011 t + 0.03}; T = 25 ° C \end{matrix}\}$

Discussion

The ability to study a number of simultaneous parameters of the nerve action potential under various conditions in the same model system allows a better understanding of the temperature dependent behavior of peripheral nerve. There are three observations of primary importance in this paper. The first was the quantitation of the variation of NAP amplitude, area under the curve, duration, conduction velocity and amplitude ratio with temperature. The second was the demonstration of hysteresis in

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In order to enhance our knowledge of insulin’s effects on whole nerves, this paper will study how insulin changes the peripheral nerve NAP (nerve action potential) in-vitro system, where the effects of insulin can be separated from those of glucose and anoxia. A more detailed description of the methods is given in previous papers (Baylor & Stecker, 2009; Stecker & Baylor, 2009; Stecker & Stevenson, 2013, 2015). Under a protocol approved by the IACUC (Winthrop University Hospital Protocol, WUH-MS#1), a total of 148 nerves from 74 Sprague–Dawley rats (Hilltop, Scottdale, PA) were studied.
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^☆: Statement of funding: This research was funded by the Department of Neurology at the Geisinger Medical Center.

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Peripheral nerve at extreme low temperatures 1: Effects of temperature on the action potential☆

Abstract

Section snippets

Nerve harvests/stimulation

Stability

Discussion

Biophys. J.

Bull. Math. Biol.

J. Vasc. Surg.

J. Neurol. Sci.

Electroencephalogr. Clin. Neurophysiol.

Electroencephalogr. Clin. Neurophysiol.

Ann. Thorac. Surg.

Ann. Thorac. Surg.

J. Neurol. Sci.

The effects of temperature on human compound action potentials

J. Neurol. Neurosurg. Psychiatry

Regional hypothermia with epidural cooling for spinal cord protection during thoracoabdominal aneurysm repair

Semin. Vasc. Surg.

Nerve conduction velocity during hypothermia in man

Anesthesiology

Effects of age, temperature, and disease on the refractoriness of human nerve and muscle

J. Neurol. Neurosurg. Psychiatry

AAEM minimonograph #14: the influence of temperature in clinical neurophysiology

Muscle Nerve

The influence of temperature on conduction block

Muscle Nerve

Conduction failure in myelinated and non-myelinated axons at low temperatures

J. Physiol. (Lond.)