Myotonia not aggravated by cooling

Ricker, K.; Hertel, G; Langscheid, K.; Stodieck, G.

doi:10.1007/bf00312810

Cited by 28 publications

(11 citation statements)

References 15 publications

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“…Thus, in the presence of a concentration of 9-AC known to reduce Ga to values of 10% or less of control, the appearance of myotonic activity is reversibly controllable by altering the external Ca++ concentration or the environmental temperature. A recent clinical study has demonstrated a temperature dependency similar to that reported here for myotonic activity in patients with myotonia congenita [26].…”

supporting

confidence: 82%

The pathophysiology of myotonia produced by aromatic carboxylic acids

Furman

Barchi

1978

Annals of Neurology

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A series of nine related aromatic monocarboxylic acids (ACAs) previously shown to inhibit muscle membrane chloride conductance (GCl) selectively in the rat were studied for their ability to produce myotonia. All nine induced characteristic repetitive electrical activity and delayed relaxation in isolated muscle, although the concentrations required for this action varied widely. In each case, myotonia was observed at concentrations that correlated closely with previously determined half-maximal concentrations for inhibition of GCl. Intracellular recordings from muscle made myotonic with ACA revealed prolonged latencies at rheobase, multiple driven spikes, and self-sustaining repetitive activity similar to that previously reported in hereditary goat myotonia. Phase-plane diagrams of membrane action potentials recorded after exposure to the most effective of these compounds suggested little effect on the voltage-dependent sodium system. The changes seen could be duplicated by simple removal of chloride ion. The expression of repetitive electrical activity in the presence of low membrane GCl depends on ambient temperature and on the concentration of calcium ion. Increasing temperature and decreasing Ca++ predispose toward myotonic activity; converse conditions inhibit myotonia. Myotonia induced by ACA is inhibited by concentrations of diphenylhydantoin that are clinically effective in controlling hereditary myotonia in humans.

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supporting

confidence: 82%

The pathophysiology of myotonia produced by aromatic carboxylic acids

Furman

Barchi

1978

Annals of Neurology

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“…In view of the results of Simoncini and Stuhmer [15], it is likely that depolarization prevents the development of myotonic contractions by inactivating the voltagedependant Na+ channels. The failure of 9-AC-induced myotonia to develop at low temperatures supports the results of Ricker et al [4] obtained in human myotonic patients, which showed that myotonic contractions of the adductor pollicis muscle reverted to normal when the muscle temperature was lowered. Myotonia was alleviated in humans at 20"C, but in the present study it was not possible to identify the precise temperature at which myotonia failed to develop.…”

Section: Discussionsupporting

confidence: 86%

“…Furthermore, the low temperatures referred to were not quantified. It may be for these reasons that they are in conflict with the results of the only objective study done in humans [4] and our own results reported here, both of which are the outcome of quantitative measurements.…”

Section: Normal Krebscontrasting

confidence: 83%

“…Likewise, in myotonic goats, the myotonia was observed to worsen in cold weather, while application of heat to the thighs of the goats appeared to improve the myotonia [6]. It is possible that the conflicting results are related to the fact that quantitative measurements were only made in the study of Ricker et al [4]. In the other two studies [5, 61, the results were based on observation or subjective sensation, either or both of which could be unreliable.…”

Section: Introductionmentioning

confidence: 96%

“…There is confusion in the literature about the precise effect of muscle cooling on myotonic contractions in myotonia congenita. In humans suffering from recessive generalized myotonia congenita, Ricker et al [4] recorded tetanic contractions in the adductor pollicis muscle when the muscle temperature was 33°C and after it had been maintained at 20°C for 30 min by fixing the hand and arm in a vessel of iced water. At a temperature of 33"C, measured using an EMG thermo needle, the recordings showed an after contraction typical of myotonia, whereas at 20°C the after-contraction no longer appeared, indicating that myotonia was alleviated at low temperature.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Temperature Reduction on Myotonia in Rat Skeletal Muscles in vitro

Fanning

MacDermott

1997

Clinical Science

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1. The objective of the study was to determine the effect of temperature reduction on the response of rat skeletal muscles to myotonia-inducing agents. 2. A model myotonia was induced in the muscles in vitro, using either the chloride channel blocker anthracene-9-carboxylic acid or chloride-free Krebs solution. This model is similar in its characteristics to the myotonia which occurs in autosomal recessive generalized myotonia congenita in humans. 3. Isometric twitch contractions were recorded in the muscles in Krebs solution before and after the addition of the myotonia-inducing agent. The presence of myotonia was confirmed when the half-relaxation time of the twitch contraction after the addition of the agent was significantly greater than that before its addition. 4. Recordings were made at 37 degrees C, 30 degrees C, 25 degrees C and 15 degrees C. Myotonia developed at 37 degrees C, 30 degrees C and 25 degrees C, but not at 15 degrees C, indicating that at a temperature between 25 degrees C and 15 degrees C, anthracene-9-carboxylic acid-induced myotonia failed to develop. This supports the results obtained in humans suffering from myotonia congenita where myotonic contractions in the adductor pollicis muscle disappeared when the muscle temperature was cooled to 20 degrees C. 5. The myotonia which developed at 37 degrees C could be significantly reduced by exposure to 1 x 10(-4) mol/l ouabain or by elevation of the K+ concentration of the Krebs solution to 7.5 mmol/l. 6. Measurements made using microelectrodes showed that the conditions under which myotonia either did not develop or was significantly reduced, i.e. a temperature of 15 degrees C, exposure to 7.5 mmol/l K+ at 37 degrees C or exposure to 1 x 10(-4) mol/l ouabain at 37 degrees C were each associated with membrane depolarization. The results are discussed in terms of a possible role for depolarization in preventing/reducing the myotonic response.

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Channelopathies of Skeletal Muscle Excitability

Cannon

2015

Comprehensive Physiology

176

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Familial disorders of skeletal muscle excitability were initially described early in the last century and are now known to be caused by mutations of voltage-gated ion channels. The clinical manifestations are often striking, with an inability to relax after voluntary contraction (myotonia) or transient attacks of severe weakness (periodic paralysis). An essential feature of these disorders is fluctuation of symptoms that are strongly impacted by environmental triggers such as exercise, temperature, or serum K+ levels. These phenomena have intrigued physiologists for decades, and in the past 25 years the molecular lesions underlying these disorders have been identified and mechanistic studies are providing insights for therapeutic strategies of disease modification. These familial disorders of muscle fiber excitability are “channelopathies” caused by mutations of a chloride channel (ClC-1), sodium channel (NaV1.4), calcium channel (CaV1.1) and several potassium channels (Kir2.1, Kir2.6, Kir3.4). This review provides a synthesis of the mechanistic connections between functional defects of mutant ion channels, their impact on muscle excitability, how these changes cause clinical phenotypes, and approaches toward therapeutics.

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Myotonia not aggravated by cooling

Cited by 28 publications

References 15 publications

The pathophysiology of myotonia produced by aromatic carboxylic acids

The pathophysiology of myotonia produced by aromatic carboxylic acids

Effect of Temperature Reduction on Myotonia in Rat Skeletal Muscles in vitro

Channelopathies of Skeletal Muscle Excitability

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