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Query: UMLS:C0026850 (muscular dystrophy)
 5,870 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

A comparative study was carried out in the properties of ATPase system of the skeletal muscle nuclei in the rabbits in norm and with experimental muscular dystrophy conditioned by E-avitaminosis. It is shown that in the system, containing 1.5 mM of MgCl2, ATPase system of the nuclei is activated by sodium and potassium ions. In norm maximum activation is observed with their presence in the medium, the concentration being 80 and 70 mM, respectively. With experimental muscular dystrophy maximum activating concentrations decrease and are equal for both cations - 30 mM. Activation of the enzymatic system by these ions is specific because the introduction of equimolar quantities of cholin-chloride or lithium, cesium ions instead of sodium ions into the incubation medium evokes no activation of the ATPase system of the rabbit skeletal muscles both in norm and with experimental muscular dystrophy. A simultaneous presence of sodium and potassium ions in optimum concentrations in the incubation medium makes for an increase of ATPase activity to the same extent as the presence of one of these cations. Oubain, a specific inhibitor of Mg2+, Na+, K+- ATPase, taken in the concentrations of 10(-4) and 10(-3) M did not decrease the intensity of ATP hydrolysis and its activation conditioned by the presence of sodium or potassium. A conclusion is made that Mg2+, Na+, K+-ATPase taking part in the work of "sodium pump" is absent in the nuclei of skeletal muscles.
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PMID:[Availability of Mg2+, Na+, and K+-ATPase in the nuclei of the skeletal muscles of rabbits normally and during experimental muscular dystrophy]. 12 69

The total ATPase activity of the rabbit skeletal muscle nuclei was established to be a sum of activities of two ATPases--Mg2+ and Mg2+, Ca2+-ATPases. The latter composes 50% of total ATPase activity for skeletal muscles nuclei of the normal rabbits and 30% for skeletal muscles nuclei of the rabbits with muscular dystrophy. Mg+, Ca2+-ATPase of the skeletal muscle nuclei is activated by calcium ions within a range of 10(-6)--10(-4) M and is inhibited with its concentration of 0.5-10(-3) M and higher. Sodium and potassium ions activate Mg2+, Ca2+-ATPase. Inhibition of Mg2+-ATPase is observed for the skeletal muscle nuclei of the rabbits in norm with the presence of 80 mM of Na+ and 70 mM of K+ in the incubation medium. Under experimental muscular dystrophy such an effect is not observed in connection with the fact that the concentration of monovalent cations in the incubation medium does not exceed 60 mM. The ATPase activity in nuclei of the rabbit skeletal muscles may be also manifested in the presence of Mn2+ greater than Ca2+ greater than Ba2+. A problem is under discussion as to substitution of ions Mg2+ by ions Mn2+, Ca2+, Ba2+ in manifestation of the Mg2+ATPase activity for the skeletal muscle nuclei of the normal rabbits and of those with experimental dystrophy.
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PMID:[Mg 2+, Ca 2+-ATPase of skeletal muscle nuclei in normal rabbits and in rabbits with experimental muscular dystrophy]. 12 61

A patient with advanced muscular dystrophy of the Duchenne type developed severe hypokalemia thought to be secondary to moderate gastro-intestinal losses in association with reduced intracellular potassium stores. With correction of the hypokalemia, the cardiac rhythm became more normal. In patients with advanced dystrophy, hypokalemia may be functionally significant.
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PMID:Acute hypokalemia as a possible cause of death in a patient with advanced muscular dystrophy. 44 73

Four adolescent boys with Duchenne (progressive) muscular dystrophy (DMD) of 10-11 years duration and six normal boys of similar age were studied on a metabolism ward for 22 days. Sodium and potassium intake was as follows: Period I, Na 60 mEq, K 60 mEq; Period II, Na 10, K 60; Period III, Na 10, K 95-150; Period IV, Na 60, K 60. The differences between the DMD group and the group of normal boys for sodium and potassium in serum and urine and for urinary aldosterone were not significant. These findings show that the pathologically elevated sodium-potassium ratio in skeletal muscle of patients with DMD is not due to increased aldosterone or other causes of renal wastage of potassium.
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PMID:Urinary sodium, potassium and aldosterone in Duchenne muscular dystrophy. 83 56

Skeletal muscles from normal dogs and labrador retrievers with a hereditary muscular dystrophy were examined morphologically and histochemically and were analysed for sodium (Na+), potassium (K+) and chloride (Cl-) ions and total muscle water. The partition of total muscle water and electrolytes between intracellular and extracellular phases was calculated on the basis of the chloride space method as the estimate of extracellular fluid volume. Muscle samples from dystrophic dogs contained significantly increased concentrations of Na+, Cl-, total muscle water, and a significant reduction in the level of K+ compared with normal values. There was a significant increase in the intracellular water and Na+ levels with a concomitant reduction of intracellular K+ content. Most dystrophic muscle samples had a pronounced type 2 fibre deficiency and a marked increase in numbers of fibres with internalised nuclei.
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PMID:Intracellular electrolytes and water analysis in dystrophic canine muscles. 277 3

Duchenne muscular dystrophy, the most common childhood-onset muscular dystrophy, is X-linked and is associated with cardiac and mental abnormalities. Becker's muscular dystrophy is similar to but milder than Duchenne muscular dystrophy. The rare facioscapulohumeral muscular dystrophy has an autosomal dominant mode of transmission. Myotonic muscular dystrophy is the most common of the adult-onset muscular dystrophies. Treatable diseases that must be excluded include polymyositis, potassium disorders and endocrine abnormalities.
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PMID:The muscular dystrophies. 372 55

In the avian model of muscular dystrophy, electrophysiologic studies have shown alterations in the action potential characteristics of dystrophic muscle in vitro, supporting the notion that a membrane defect exists in avian dystrophy. As neurogenic and vascular etiologies have also been proposed, we examined the characteristics of action potentials recorded in a novel in vivo preparation of the extensor digitorum communis muscle in 8-week-old normal and dystrophic chickens. To facilitate intracellular recording, dantrolene sodium was used to attenuate the muscle twitch. Results showed that although the resting membrane potential, action potential amplitude and the action potential maximum rate of rise were similar in normal and dystrophic cells, the action potential duration at half the maximum amplitude was increased in dystrophic cells. This observation has not been previously reported for dystrophic avian muscle and suggests that a defect in the sarcolemmal potassium conductance is an early change in dystrophic avian muscle.
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PMID:Electrophysiologic differences between normal and dystrophic avian muscle. 377 Jan 30

Zinc has been reported to be important in protein synthesis, collagen crosslinking, membrane structure and function, cellular necrosis, muscle glycolysis, and cardiac dysfunction. As all these processes are affected by muscular dystrophy, we studied the Zn concentrations in the cardiac and skeletal muscles of 7-month-old male dystrophic hamsters with advanced hypertrophic cardiomyopathy. Age- and sex-matched normal hamsters served as controls. Calcium, magnesium, and copper concentrations were also measured in the dystrophic and normal tissues. Flame atomic absorption spectrophotometry was used for mineral quantitation of the nitric acid tissue extracts. Zn concentrations in the myocardium (P less than 0.002), diaphragm (P less than 0.005), and rectus femoris muscles (P less than 0.001) were significantly elevated with concomitant elevations of Ca in dystrophic compared with normal hamsters. Although no appreciable changes in Cu or Mg concentrations were noted in the myocardium, slight depletions of Cu in the dystrophic diaphragm (P less than 0.025) and Mg in the dystrophic rectus femoris (P less than 0.05) were present. The intracellular Zn and Ca accumulations in the cardiac and skeletal muscles of dystrophic hamsters correlated with other dystrophic features such as increased rates of protein synthesis, significant myocardial enlargement, characteristic electrocardiographic and mechanophysiologic abnormalities, and classical histopathologic changes. We hypothesize that Zn2+ may be cotransported with Ca2+ across the cellular membrane or substituted for Ca2+ in certain pathways. These mechanisms may be affected by the high-energy ATP-pump and/or the sodium-potassium exchange system at the cellular level. Our observations suggest a possible pathogenetic involvement of Zn in muscular dystrophy which may be associated with an accelerated effort by the cellular system to repair the damaged cardiac and skeletal muscles.
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PMID:Excessive intracellular zinc accumulation in cardiac and skeletal muscles of dystrophic hamsters. 380 14

A patient thought to be normal was admitted with premature labor at 29+ weeks' gestation. Treatment with the beta-mimetic ritodrine hydrochloride appeared to provoke symptoms of myotonic muscular dystrophy. Neurological history and examination confirmed the presence of previously unsuspected myotonic dystrophy in the patient, her father, and paternal grandfather. Discontinuation of the drug led to improvement in myotonia symptoms but worsening premature labor. Magnesium sulfate did not provoke the same symptoms but was unsuccessful in controlling premature contractions. Long-term management with bed rest, phenytoin, and isoxsuprine hydrochloride resulted in term delivery. Subsequently, maternal symptoms of myotonia disappeared. Congenital myotonia was suspected in the fetus because of the ultrasonic demonstration of polyhydramnios and reduced fetal movements. This was confirmed at delivery. The mechanism by which ritodrine unmasked the myotonia is unclear but may be related to changes in the cell membrane (chloride conductance, the sodium-potassium pump, or membrane polarization).
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PMID:Myotonic muscular dystrophy associated with ritodrine tocolysis. 396 11

Total body potassium (40K method) and total body water and exchangeable sodium (both by isotope dilution) were determined in 26 boys, aged 5-17 years, with muscular dystrophy. Total body potassium values were compared with measurements in a large series of normal boys on the basis of height. Total body potassium was reduced even in the youngest patients and was only slightly higher in the older boys, despite their considerably greater height. Exchangeable sodium increased with increasing height in a way similar to that of normal boys. Total body water was also reduced but increased with growth, although to a lesser extent than expected for normal boys. The total body water measurements indicated that many of the affected boys were very obese, despite an apparently normal body weight. An intravenous bolus of 22Na distributed at a similar rate in boys with muscular dystrophy to that in normal males. In relation to the predicted values, total body potassium and 24 h urinary creatinine excretion of the affected boys both declined at a rate of 4% per year.
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PMID:Total body potassium and water, and exchangeable sodium, in muscular dystrophy. 397 66


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