Biomaterial Database

Phosphorylase ratio and susceptibility to malignant hyperthermia. 1983

C A Traynor, and R A Van Dyke, and G A Gronert

The ratio of muscle phosphorylase a to total phosphorylase, expressed as a percent, was determined in vastus lateralis muscle of 26 patients to examine the efficacy of this parameter as a method for screening for susceptibility to malignant hyperthermia (MH). As standard screening, all patients also had muscle contracture responses determined to 2% halothane and 0.25-32 mM caffeine at 37 degrees C. Each drug was given separately and not combined. Nine patients were susceptible to MH, based upon caffeine threshold of 2 mM or less (seven patients) or a rapidly developing contracture tension to halothane of more than 400 mg (seven patients, including five with positive caffeine responses). Mean phosphorylase ratio in these nine patients was 14.5 +/- 2.0% (mean, SEM). In the 17 nonsusceptible patients mean phosphorylase ratio (12.4 +/- 1.9%) was not significantly different. The range of phosphorylase ratios in susceptible patients was 6.5-26% while 13 nonsusceptible patients had ratios greater than 6% and up to 29%. The unacceptably high number of false-positive responses in nonsusceptible patients precludes the use of phosphorylase ratio as a definitive diagnostic test.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D008305	Malignant Hyperthermia	Rapid and excessive rise of temperature accompanied by muscular rigidity following general anesthesia.	Hyperpyrexia, Malignant,Hyperthermia, Malignant,Malignant Hyperpyrexia,Anesthesia Related Hyperthermia,Hyperthermia of Anesthesia,Anesthesia Hyperthermia,Hyperthermia, Anesthesia Related,Malignant Hyperpyrexias
D009119	Muscle Contraction	A process leading to shortening and/or development of tension in muscle tissue. Muscle contraction occurs by a sliding filament mechanism whereby actin filaments slide inward among the myosin filaments.	Inotropism,Muscular Contraction,Contraction, Muscle,Contraction, Muscular,Contractions, Muscle,Contractions, Muscular,Inotropisms,Muscle Contractions,Muscular Contractions
D009132	Muscles	Contractile tissue that produces movement in animals.	Muscle Tissue,Muscle,Muscle Tissues,Tissue, Muscle,Tissues, Muscle
D010762	Phosphorylase a	The active form of GLYCOGEN PHOSPHORYLASE that is derived from the phosphorylation of PHOSPHORYLASE B. Phosphorylase a is deactivated via hydrolysis of phosphoserine by PHOSPHORYLASE PHOSPHATASE to form PHOSPHORYLASE B.
D010766	Phosphorylation	The introduction of a phosphoryl group into a compound through the formation of an ester bond between the compound and a phosphorus moiety.	Phosphorylations
D010770	Phosphotransferases	A rather large group of enzymes comprising not only those transferring phosphate but also diphosphate, nucleotidyl residues, and others. These have also been subdivided according to the acceptor group. (From Enzyme Nomenclature, 1992) EC 2.7.	Kinases,Phosphotransferase,Phosphotransferases, ATP,Transphosphorylase,Transphosphorylases,Kinase,ATP Phosphotransferases
D002110	Caffeine	A methylxanthine naturally occurring in some beverages and also used as a pharmacological agent. Caffeine's most notable pharmacological effect is as a central nervous system stimulant, increasing alertness and producing agitation. It also relaxes SMOOTH MUSCLE, stimulates CARDIAC MUSCLE, stimulates DIURESIS, and appears to be useful in the treatment of some types of headache. Several cellular actions of caffeine have been observed, but it is not entirely clear how each contributes to its pharmacological profile. Among the most important are inhibition of cyclic nucleotide PHOSPHODIESTERASES, antagonism of ADENOSINE RECEPTORS, and modulation of intracellular calcium handling.	1,3,7-Trimethylxanthine,Caffedrine,Coffeinum N,Coffeinum Purrum,Dexitac,Durvitan,No Doz,Percoffedrinol N,Percutaféine,Quick-Pep,Vivarin,Quick Pep,QuickPep
D004796	Clinical Enzyme Tests	Analyses for a specific enzyme activity, or of the level of a specific enzyme that is used to assess health and disease risk, for early detection of disease or disease prediction, diagnosis, and change in disease status.	Enzyme Tests, Clinical,Clinical Enzyme Test,Enzyme Test, Clinical,Test, Clinical Enzyme,Tests, Clinical Enzyme
D005260	Female		Females