title: 3,5-Di-t-butyl catechol is a potent human ryanodine receptor 1 activator, not suitable for the diagnosis of malignant hyperthermia susceptibility.
abstract: 3,5-Di-t-butyl catechol (DTCAT) releases Ca(2+) from rat skeletal muscle sarcoplasmic reticulum (SR) vesicles. Hence, it is a candidate for use as a substitute for halothane or caffeine in the in vitro contracture test for the diagnosis of susceptibility to malignant hyperthermia (MH). To characterize the effect of DTCAT at cell level, Ca(2+) release experiments were performed on cultured, human skeletal muscle myotubes using the fluorescent Ca(2+) indicator fura2-AM. DTCAT was also assayed in the in vitro contracture test on human skeletal muscle bundles obtained from individuals diagnosed susceptible (MHS), normal (MHN) or equivocal for halothane (MHEH) and compared to the standard test substances caffeine and halothane. DTCAT increased, in a concentration-dependent manner and with a higher efficacy as compared to caffeine, the free, intracellular Ca(2+) levels of cultured MHN and MHS skeletal muscle myotubes. This effect was similar in both types of myotubes and involved the release of Ca(2+) from SR stores as well as Ca(2+)-influx from the extracellular space. Inhibition of ryanodine receptors either with ryanodine or with ruthenium red markedly reduced DTCAT-induced increase in intracellular Ca(2+) concentration while abolishing that induced by caffeine. In MHN skeletal muscle bundles, DTCAT induced contractures with an EC(50) value of 160 ± 91 μM. However, the sensitivity of MHS or MHEH muscles to DTCAT was similar to that of MHN muscles. In conclusion, DTCAT is not suitable for the diagnosis of MH susceptibility due to its failure to discriminate between MHN and MHS muscles.
authors.affiliation: Department of Special Anaesthesia and Pain Therapy, Medical University of Vienna, Austria.
authors.forename: Caterina
authors.initials: C
authors.lastname: Lacava
authors.forename: Andrea
authors.initials: A
authors.lastname: Michalek-Sauberer
authors.forename: Birgit
authors.initials: B
authors.lastname: Kraft
authors.forename: Giampietro
authors.initials: G
authors.lastname: Sgaragli
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Sipos
authors.forename: Carmen
authors.initials: C
authors.lastname: Höller
authors.forename: Hans Georg
authors.initials: HG
authors.lastname: Kress
authors.forename: Fabio
authors.initials: F
authors.lastname: Fusi
authors.forename: Lukas G
authors.initials: LG
authors.lastname: Weigl
mesh_terms: D002110:Caffeine; D002118:Calcium / Q000378:metabolism*; D002120:Calcium Channel Agonists; D002396:Catechols; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D006221:Halothane; D006801:Humans; D008305:Malignant Hyperthermia / Q000175:diagnosis* / Q000209:etiology / Q000503:physiopathology; D009119:Muscle Contraction / Q000187:drug effects*; D018485:Muscle Fibers, Skeletal / Q000187:drug effects* / Q000378:metabolism; D011237:Predictive Value of Tests; D018570:Risk Assessment; D012307:Risk Factors; D019837:Ryanodine Receptor Calcium Release Channel / Q000187:drug effects* / Q000378:metabolism; D012519:Sarcoplasmic Reticulum / Q000187:drug effects / Q000378:metabolism; D013997:Time Factors
chemical_list: D002120:Calcium Channel Agonists; D002396:Catechols; D019837:Ryanodine Receptor Calcium Release Channel; C054068:3,5-di-tert-butylcatechol; D002110:Caffeine; D002118:Calcium; D006221:Halothane