Effects of Caffeine, Halothane, and 4-Chloro-m -cresol on Skeletal Muscle Lactate and Pyruvate in Malignant Hyperthermia–susceptible and Normal Swine as Assessed by Microdialysis (original) (raw)
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Malignant Hyperthermia (MH) is a potentially fatal pharmacogenetic syndrome caused by exposure to halogenated volatile anesthetics and/or depolarizing muscle relaxants. We have measured intracellular calcium concentration ([Ca 2+ ] i ), using doublebarreled Ca 2+ -selective microelectrodes in myoballs prepared from skeletal muscle from malignant hyperthermia susceptible (MHS) and non-susceptible (MHN) swine. Resting [Ca 2+ ] i was ~2-fold higher in MHS than in MHN quiescent myoballs (232±35 vs. 112±11 nM). Treatment of myoballs with caffeine or 4-chloro-m-cresol (4-CmC) produced an elevation of [Ca 2+ ] i in both groups, however the concentration required to cause a rise in intracellular Ca 2+ elevation was 4-fold lower in MHS than in MHN. Incubation of MHS cells with the fast complexing Ca 2+ buffer BAPTA, reduced [Ca 2+ ] i , raised the concentration of caffeine and 4-CmC required to cause an elevation of intracellular Ca 2+
Pharmacological Research, 2012
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 M. 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.
BJA: British Journal of Anaesthesia, 1992
We have examined the influence of electrical stimulation on caffeine-induced tension generation during contracture testing used to diagnose malignant hyperthermia. The cumulative contracture response to caffeine was compared in pairs of morphologically comparable muscle bundles obtained from the same patient. Only one of the two bundles was stimulated electrically during'the test. Statistically significant differences in tension were found at caffeine concentrations ^ 4 mmol litre''', the tension developed being invariably larger in the unstimulated fascicles. These results suggest that electrical stimulation results in suppression of the dose-dependent, caffeine-induced contracture. This effect could be a result of the potentiation of twitch tension by caffeine, muscle fatigue, or both. Overall, the observed differences did not alter the in vitro diagnosis of malignant hyperthermia.
Anesthesia & Analgesia, 2008
In vitro contracture testing to diagnose malignant hyperthermia (MH) susceptibility requires a muscle biopsy, which may be associated with severe side effects for the patient. After investigation of several different protocols, we present a less invasive metabolic test that involves IM injection of caffeine and halothane, and subsequent measurement of interstitial lactate to differentiate between MH susceptible (MHS) and MH non-susceptible (MHN) individuals. METHODS: Two microdialysis probes with attached microtubing for trigger injection were inserted into the lateral vastus muscle of eight previously diagnosed MHS patients (representing three genetic variants Gly2434Arg, Thr2206Met, and Arg614Cys), seven MHN patients, and seven control individuals. After equilibration and lactate baseline recording, a single bolus of 200 L caffeine 80 mM and a suspension of 200 L halothane 4%V/V in soy bean oil (triggers) were injected locally. Lactate was measured spectrophotometrically. Data are presented as medians and interquartile ranges. RESULTS: Although baseline lactate values were similar in the investigated groups before trigger injection, caffeine increased local lactate in MHS patients significantly more (2.0 [1.8 -2.6] mM) than in MHN (0.8 [0.6 -1.1] mM) or in control individuals (0.8 [0.6 -0.8 mM]). Similarly, halothane lead to a significant lactate increase in MHS compared to ] mM vs 0.9 [0.5-1.1] mM and 1.7 [0.9 -2.3] mM, respectively). However, a relevant increase of lactate was observed in one MHN and in two control individuals. Systemic hemodynamic and metabolic variables did not differ between the investigated groups. DISCUSSION: Metabolic monitoring of IM lactate after local caffeine and halothane injection may allow less invasive testing to detect MH susceptibility, without systemic side effects.
BJA: British Journal of Anaesthesia, 1985
Malignant hyperthermia (MH) is a rare, but serious, complication of anaesthesia with a high mortality rate. During the syndrome, transmembranous and intracellular movements of Ca 2+-caused by genetically transmitted defects in calcium ion regulation-lead to pathological musclecontracture,increasedenergy consumption, and muscle cell death (Williams, 1976; Gronert, 1980). Dantrolene, which may block the intracellular movement of Ca 1+ (Britt, 1984), is currently the drug of choice in the treatment of the syndrome (Nelson and Flewellen, 1983; Britt, 1984). Since muscle contracture in MH is dependent on an increase in the intracellular concentrations of unbound Ca !+ (Britt et al., 1982), blockade of transmembranous Ca !+ influx by calcium entry blockers was suggested as a possible mode of treatment (Bikhazi, Thomas and Foldes, 1979). A single observation in isolated human MH susceptible muscle showed that diltiazem was able to suppress halothane and halothane-caffeine induced muscle contracture (Iwatsuki, Koga and Amaha, 1983). The purpose of this investigation was to assess, in a controlled study, the suppressive effect of diltiazem on halothane-and halothane-caffeineinduced contracture of MH susceptible pig muscle.
Anesthesia & Analgesia, 2004
Malignant hyperthermia (MH) is an inherited skeletal muscle disorder triggered by commonly used anesthetics. Mutated ryanodine receptors have been identified as molecular targets. The sensitivity of myotubes from individuals classified by the in vitro contracture test as MH susceptible (MHS), normal (MHN), and equivocal (MHEH) was assessed for the Ca 2ϩ -releasing activity of 4-chloro-m-cresol (4-CmC) and caffeine. In this study, we sought to determine whether 4-CmC can differentiate the MH status of an individual on the basis of the release of intracellular Ca 2ϩ , particularly in regard to MHEH diagnosis. Intracellular Ca 2ϩ concentration was determined photometrically with Fura2. Regions of the ryanodine receptor 1 harboring most of the described MH mutations were sequenced from MHS and MHEH cells. One MH mutation (Gly2434Arg) was found in one MHS individual. Results of the caffeine-induced Ca 2ϩ release in MHS and MHN cells correlated well with the in vitro contracture test results. MHS cells showed a higher sensitivity against caffeine and, to a lesser extent, against 4-CmC. Cells of MHEH individuals showed low sensitivities against both caffeine and 4-CmC, comparable to those of the MHN group. Therefore, with myotubes, caffeine was able to discriminate between MHS and MHN cells, but both caffeine and 4-CmC failed to detect MHEH cells.
Acta Anaesthesiologica Scandinavica, 1989
The effects of two structurally similar butyrophenones (droperidol and haloperidol) and ketamine were evaluated in an in vitro system to determine their potential for eliciting or exacerbating an episode of malignant hyperthermia. Muscle strips from patients referred for diagnostic testing for malignant hyperthermia and muscle strips from the rat diaphragm were exposed to droperidol, haloperidol, or ketamine prior to challenge with halothane, succinylcholine or caffeine. If any agent augmented the contracture response to the malignant hyperthermia triggering or diagnostic agents, then the agent was considered unsafe for use in malignant hyperthermia susceptible patients. Droperidol 10 pmol/l and ketamine 100 pmol/l did not induce contractures in human or rat skeletal muscle when added alone, nor did they augment halothane, succinylcholine or caffeine contractures. These agents appear to be safe for use in patients susceptible to malignant hyperthermia. In contrast, haloperidol 10 pmol/l augmented the response to succinylcholine about 1.5-fold and may be contraindicated in M H susceptibles.