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Results for “Paralysis, Hyperkalemic Periodic”

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At least 19 recordsLinked to original sources
PubMed1979

Regulation of plasma potassium in hyperkalemic periodic paralysis.

Hyperkalemic periodic paralysis is frequently considered a disorder in which episodes of weakness and an attendant rise in plasma potassium interrupt a baseline of normal strength and potassium. We studied venous potassium throughout a 36-hour period in two patients with hyperkalemic periodic paralysis and in nine normals under rigidly controlled conditions. At no time did the patients with periodic paralysis have an attack of weakness, but their mean potassium concentrations were above the normal range for 33 to 36 hours. In hyperkalemic periodic paralysis, the postprandial change in potassium relative to insulin release exceeded normal. There appears to be a continuous alteration in potassium regulation in our patients with hyperkalemic periodic paralysis.

Female↗
PubMed1999

A global defect in scaling relationship between electrical activity and availability of muscle sodium channels in hyperkalemic periodic paralysis.

Hyperkalemic periodic paralysis (HyperPP) is a hereditary disorder characterized by alternate episodic attacks of muscle weakness and muscle myotonia. The most common mutation associated with HyperPP is a T704M substitution in the skeletal-muscle sodium channel. This mutation increases sodium persistent currents, alters voltage dependence of activation and impairs slow inactivation. The present study shows experimental evidence in support of a potentially important global defect caused by the T704M mutation. While the effective rate of recovery from slow inactivation, in both normal and mutated channels, is related to the duration of past activity by a power law function, the scaling power of the mutated channel is significantly greater. This difference between the channels offers a clue for an explanation to the wide range of time scales, history dependence, and the mixed myotonic/paralysis effect, which mark the clinical picture of HyperPP.

Cell Line↗
PubMed1993

Functional consequences of a Na+ channel mutation causing hyperkalemic periodic paralysis.

Hyperkalemic periodic paralysis (HYPP), one of several inheritable myotonic diseases, results from genetic defects in the human skeletal muscle Na+ channel. In some pedigrees, HYPP is correlated with a single base pair substitution resulting in a Met replacing Thr704 in the fifth transmembrane segment of the second domain. This region is totally conserved between the human and rat channels. We have introduced the human mutation into the corresponding region of the rat muscle Na+ channel cDNA and expressed it in human embryonic kidney 293 cells. Patch-clamp recordings show that this mutation shifts the voltage dependence of activation by 10-15 mV in the negative direction. The shift results in a persistent Na+ current that activates near -70 mV; this phenomenon could underlie the abnormal muscle activity observed in patients with HYPP.

Amino Acid Sequence↗
PubMed1997

Hyperkalemic periodic paralysis.

Hyperkalemic periodic paralysis is an autosomal codominant genetic disease of horses who are descendants of the quarter horse sire Impressive. It produces a muscular phenotype that has been selected by show judges, which has resulted in the rapid dissemination of this disease. Clinical attacks are characterized by muscle fasciculation and spasm, and they respond to treatments for the concurrent hyperkalemia.

Animals↗
PubMed1994

Sodium channel mutations in acetazolamide-responsive myotonia congenita, paramyotonia congenita, and hyperkalemic periodic paralysis.

Hyperkalemic periodic paralysis (hyperKPP) and paramyotonia congenita (PC) are genetic muscle disorders sharing the common features of myotonia and episodic weakness. In hyperKPP, patient symptoms and signs are worsened by elevated serum potassium, whereas in PC, muscle cooling exacerbates the condition. There are patients in whom features of both hyperKPP and PC are present. These diseases result from molecular alterations in the adult skeletal muscle sodium channel. This report summarizes our sodium channel mutation analysis in 25 families with hyperKPP and PC. We also report the putative disease-causing mutation in acetazolamide-responsive myotonia congenita, a related disease in which myotonia is worsened by potassium but in which episodic weakness does not occur. This missense mutation (I1160V) occurs at a very highly conserved position in the sodium channel, cosegregates with the disease, and was not present in any of a large panel of normal DNAs. Electrophysiologic characterization of specific mutations will lead to better understanding of the biophysics of this voltage-gated ion channel.

Acetazolamide↗
PubMed1998

Phenytoin alters transcript levels of hormone-sensitive lipase in muscle from horses with hyperkalemic periodic paralysis.

In equine hyperkalemic periodic paralysis (HyperPP), there is evidence suggesting that the primary defect in the sodium channel is associated with a secondary alteration in triacylglycerol-associated fatty acid metabolism (TAFAM) in skeletal muscle. Furthermore, TAFAM may be involved in the therapeutic action of phenytoin. The effects of phenytoin treatment on the transcript levels of three key proteins in TAFAM, hormone sensitive lipase (HSL), carnitine palmitoyltransferase (CPT), and fatty acid binding protein (FABP), were examined. These transcripts were quantitated by competitive reverse transcription polymerase chain reaction in undifferentiated and differentiated primary cultures of equine skeletal muscle from control, heterozygous HyperPP, and homozygous-affected HyperPP horses. There was a 10-fold lower level of HSL transcript in both undifferentiated and differentiated cultures from homozygous-affected horses than from horses of the other genotypes. Phenytoin selectively increased the HSL transcript in homozygous-affected differentiated cultures to levels similar to those of the other genotypes. The levels of CPT and FABP transcripts were unaffected by genotype, differentiation, and phenytoin treatment. These results suggest that the primary defect in HyperPP may secondarily decrease HSL transcript levels and that the therapeutic action of phenytoin may include regulation of mRNA transcripts in skeletal muscle.

Animals↗
PubMed1995

Sodium channel inactivation is impaired in equine hyperkalemic periodic paralysis.

1. Equine hyperkalemic periodic paralysis (E-HPP) is a dominantly inherited disorder of muscle that causes recurrent episodes of stiffness (myotonia) and weakness in association with elevated serum K+. Affected horses carry a mutant allele of the skeletal muscle isoform of the Na channel alpha-subunit. To understand how this mutation may cause the disease phenotype, the functional defect in Na channel behavior was defined physiologically by recording unitary currents from cell-attached patches on normal and affected equine myotubes. 2. The presence of the mutation was confirmed in our cell line by restriction digest of polymerase chain reaction (PCR)-amplified genomic DNA. Myotubes from the affected horse were heterozygous for the point mutation that codes for a Phe to Leu substitution in S3 of domain IV. This assay provides a rapid technique to screen for the mutation in horses at risk. 3. The primary physiological defect in mutant Na channels was an impairment of inactivation. This defect was manifest as bursts of persistent activity during which the channel closed and reopened throughout a maintained depolarization. Disrupted inactivation slowed the decay of the ensemble-averaged current and produced an eightfold increase in the steady-state open probability measured at the end of a 40-ms pulse. This point mutation identifies a new region of the alpha subunit that is important for rapid inactivation of the channel. 4. The persistent Na current was produced by a distinct mode of gating. Failure of a mutant channel to inactivate was infrequent and occurred in groups of consecutive trials.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1993

Use of corticotropin-induced potassium changes in the diagnosis of both hypo- and hyperkalemic periodic paralysis.

Both hypo- and hyperkalemic periodic paralysis may be difficult to diagnose conclusively when patients are not seen during attacks. Since paralysis of both types can be induced with ACTH, we have determined the frequency of this response in small groups of patients. Weakness or paralysis with appropriate changes in serum K concentration resulted from ACTH gel administration, in 4 of 5 patients with known hypokalemic periodic paralysis and in 3 of 3 patients with hyperkalemic paralysis. No adverse effects of the test were observed, but hospitalization and careful monitoring were necessary. The response to ACTH appears to be a sensitive, useful aid to the diagnosis of both hypo- and hyperkalemic periodic paralysis.

Adolescent↗
PubMed1980

Progressive supranuclear palsy and hyperkalemic periodic paralysis.

A patient with hyperkalemic periodic paralysis experienced the gradual onset of additional and unexpected neurologic abnormalities in middle age, suggestive of progressive supranuclear palsy. Although the concurrence of these findings may be coincidental, these features may evade recognition in other patients by being misattributed to chronic myopathy or depression.

Bulbar Palsy, Progressive↗
PubMed1993

Possible normokalemic variant of hyperkalemic periodic paralysis in two horses.

Hyperkalemic periodic paralysis (HPP), characterized by intermittent episodes of muscle fasciculations, profound muscle weakness, and hyperkalemia, has been described in Quarter Horses, Appaloosas, and Paints. In previous reports, the hallmark of this syndrome has been the development of hyperkalemia during each episode. Two affected horses had episodes of paralysis without associated hyperkalemia, demonstrating that normokalemia during an episode otherwise consistent with HPP does not eliminate HPP as a diagnosis. This clinical presentation appeared to be a variant of HPP.

Animals↗
PubMed1985

beta-Adrenergic treatment of hyperkalemic periodic paralysis.

In a patient with hyperkalemic periodic paralysis, metaproterenol prevented muscular weakness and hyperkalemia in periods of rest after exercise. During a severe attack, the drug rapidly corrected hyperkalemia and seemed to enhance the return of strength. The action of metaproterenol may involve a beta-adrenergic-mediated increase of potassium transport via the sodium-potassium pump.

Adolescent↗
PubMed1986

Lack of cold sensitivity in hyperkalemic periodic paralysis.

The nosologic distinction between paramyotonia congenita and hyperkalemic periodic paralysis is somewhat blurred. Muscle membrane inexcitability induced by cooling seems to be characteristic of paramyotonia congenita. The effect of cooling on the maximal compound muscle action potential (CMAP) in patients with paramyotonia congenita was compared to that in patients with hyperkalemic periodic paralysis. Diminution in CMAP amplitude and area, which was observed in paramyotonia congenita, did not occur in hyperkalemic periodic paralysis. We suggest that this effect of cooling on the CMAP can be utilized in the differentiation of these two syndromes.

Action Potentials↗
PubMed1990

Psychosis in a patient with hyperkalemic periodic paralysis.

Presentation of an unusual case of a hyperkalemic periodic paralysis patient who developed a psychotic illness during the course of treatment is made in a conference format. The differential diagnosis of this psychotic episode together with some information regarding hyperkalemic periodic paralysis are discussed. The case illustrates the benefits of close cooperation between medical and psychiatric teams in the management of the psychotic patient with medical illness.

Adult↗