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G Haudecoeur

Publications and source records attributed to G Haudecoeur.

At least 19 recordsLinked to original sources
PubMed2000

Shortening velocity of skeletal muscle from humans with malignant hyperthermia susceptibility: effects of halothane.

The aim of this investigation was to assess the effect of halothane on the velocity of shortening and lengthening of muscle from normal subjects and from patients with malignant hyperthermia susceptibility. Strips were mounted horizontally at optimal length in normal Krebs-Ringer's solution and mechanical parameters were obtained before and after exposure to 3 vol.% halothane. The maximun shortening velocity at zero load (V(max)) was determined by using Hill's characteristic equation. The contraction and relaxation indices were measured under isotonic and isometric conditions: maximum shortening and lengthening velocities (maxV(c) and maxV(r), respectively); isometric peak twitch tension; peak of the positive (+dP/dt(max)) and negative (-dP/dt(max)) twitch tension derivative; ratio R1=maxV(c)/maxV(r) and ratio R2=(+dP/dt(max))/(-dP/dt(max)). In normal muscle, halothane markedly increased V(max), maxV(c) and peak twitch tension by 30+/-10%, 30+/-5% and 40+/-15%, respectively. The maxV(r) values increased concomitantly with the maxV(c) values, such that no change in the ratio R1 was observed. Both +dP/dt(max) and -dP/dt(max) increased such that the ratio R2 did not vary. In malignant hyperthermia susceptibility muscle, halothane induced a significant decrease in V(max) (-30+/-10%) and maxV(r) (-45+/-15%) without changing maxV(c). The decrease in maxV(r) was greater than that of maxV(c), such that the ratio R1 increased significantly. Peak twitch tension and +dP/dt(max) remained unchanged whereas -dP/dt(max) decreased significantly; the ratio R2 increased by 40+/-10%. These results suggest that halothane alters the contractile properties of malignant hyperthermia susceptibility muscle.

Anesthetics, Inhalation↗
PubMed1999

[Caffeine skinned fiber tension test: application to the diagnosis of susceptibility to malignant hyperthermia].

OBJECTIVE: To assess the reactivity of sarcoplasmic reticulum to caffeine, using the skinned muscle fibre tension test and to compare it with the reference in vitro contracture test in the diagnosis of malignant hyperthermia (HM) susceptibility. STUDY DESIGN: Laboratory investigation. MATERIAL: Muscle biopsies from 63 patients, including 29 classified as susceptible to MH (MHS) and 34 classified as non-susceptible (MHN) according to criteria of the European and the North American MH groups. METHOD: The reactivity to caffeine and halothane of skinned muscle fibres was compared, according to the type of fibres, with the data of the in vitro contracture test. The type of fibres (type I: oxidative, slow; type II: glycolytic, fast) were determined with strontium dose-response curves. RESULTS: The reactivity to caffeine was significantly lower in the MHS group, for both type I and type II skinned fibres. However, in comparison with the data of the in vitro contracture tests, using the ROC curve analysis, the best sensitivity-specificity compromise was 90%-71% and 74%-84% for type I and type II skinned fibres respectively. CONCLUSION: The skinned muscle fibre tension test cannot be used instead of the in vitro contracture test for the diagnostic of MHS. However, it may strengthen the data of the latter.

Caffeine↗
PubMed1999

Halothane induces calcium release from human skinned masseter muscle fibers.

BACKGROUND: An increase in masseter muscle tone in response to halothane or succinylcholine anesthesia (or both) can be observed in healthy persons. Thus the authors compared the fiber-type halothane and succinylcholine sensitivities in human masseter and vastus lateralis muscles. METHODS: Masseter and vastus lateralis muscle segments were obtained from 13 and 9 healthy persons, respectively. After chemical skinning of a single fiber and loading the sarcoplasmic reticulum with Ca++ 0.16 microM solution, halothane (0.5-4 vol% bubbled in the incubating solution), succinylcholine (0.1 microM to 10 mM), or both sensitivities were defined as the concentration inducing more than 10% of the maximum tension obtained by application of 16 microM Ca++ solution. The myofilament response to Ca++ was studied with and without halothane by observing the isometric tension of skinned masseter fibers challenged with increasing concentrations of Ca++. Muscle fiber type was determined by the difference in strontium-induced tension measurements. RESULTS: A significant difference in halothane sensitivity was found between type 1 masseter fibers (0.6+/-0.2 vol%; mean +/- SD) versus type 1 (2.7+/-0.6 vol%) and type 2 vastus lateralis muscle (2.5+/-0.4 vol%). Succinylcholine did not induce Ca++ release by the sarcoplasmic reticulum. In the masseter muscle, 0.75 vol% halothane decreased the maximal activated tension by 40% but did not change the Ca++ concentration that yields 50% of the maximal tension. CONCLUSIONS: The very low halothane threshold for Ca++ release from the masseter muscle usually could be counteracted by a direct negative inotropic effect on contractile proteins. However, halothane may increase the sensitivity of the sarcoplasmic reticulum Ca++ release to succinylcholine-induced depolarization, leading to an increase in masseter muscle tone.

Adult↗
PubMed1998

Effects of halothane on mechanical response of skeletal muscle from malignant hyperthermia susceptible patients.

The purpose of this investigation was to compare the effects of halothane on malignant hyperthermia (MH) and normal isolated muscle bundle performance during isometric contraction and relaxation phases. Mechanical parameters were measured: peak tension (PT), time to peak tension (TPT) and positive peak of isometric tension derivative (+dP/dtmax) characterized the contraction phase. Half-relaxation time (RT1/2) and negative peak of isometric tension derivative (-dP/dtmax) characterized the relaxation phase. The ratio R = (+dP/dtmax)/(-dP/dtmax) was used to study the coupling between contraction and relaxation under isometric condition. In normal muscle, halothane increased PT by nearly 40% without altering TPT. The +dP/dtmax value increased concomitantly with the -dP/dtmax values, thus no changes in R was observed. In MH muscle, PT was first potentiated (0.5-1.0 vol% halothane) and then depressed (2.0-3.0 vol% halothane). TPT and +dP/dtmax were not altered whereas RT1/2 increased progressively with concomitant decrease in -dP/dtmax, thus R increased by nearly 40%. The amplitude of MH muscle contracture with stepwise concentrations of halothane was correlated with the increase of RT1/2 and R, and the decrease of -dP/dtmax. These results suggest that halothane alters the relaxation phase more than the contraction phase in MH human skeletal muscle compared to normal muscle.

Anesthetics, Inhalation↗
PubMed1998

Effects of veratridine on mechanical responses of human malignant hyperthermic muscle fibers.

BACKGROUND: To determine if alteration in the function of the sodium channel may in turn modify halothane-induced changes in mechanical responses of muscle bundles from patients susceptible to malignant hyperthermia (MH). METHODS: Mechanical responses of muscle bundles from 12 MH-susceptible and 20 MH non-susceptible patients were measured prior to and during administration of halothane alone and in the presence of 10 microM veratridine, an inhibitor of sodium channel inactivation. Peak tension (PT), time to peak tension (TPT), positive peak of isometric tension derivative (+dP/dtmax) were used to characterize the inotropic state. Analysis of relaxation process was performed using half relaxation time (RT 1/2) and the negative peak of isometric tension derivative (-dP/dtmax). The ratio (R) = (+dP/dtmax)/(-dP/dtmax) was used to measure the coupling between contraction and relaxation under isometric condition. RESULTS: Veratridine significantly enhanced the 0.5, 1, 2 and 3 vol% halothane-induced contracture and induced a negative inotropic effect in MH-susceptible muscle bundles. R increased by nearly 90% indicating that the combined effects were more pronounced in the relaxation phase. In MH non-susceptible muscle, veratridine did not significantly enhance the effects of halothane. CONCLUSIONS: These results on cut MH-susceptible human muscle bundles support the hypothesis that halothane-induced contracture in MH can be modified by the binding of an inhibitor of sodium channel inactivation.

Calcium↗
PubMed1997

Identification of heterozygous and homozygous individuals with the novel RYR1 mutation Cys35Arg in a large kindred.

BACKGROUND: Malignant hyperthermia (MH) is a potentially fatal, often autosomal dominant, disorder of skeletal muscle and is triggered in susceptible people by all commonly used inhalational anesthetics. In this article, the authors describe a malignant hyperthermia susceptible (MHS) kindred in which both parents of the proband are MHS and are first-degree cousins. Haplotype analysis in this kindred with chromosome 19 linked markers revealed that the proband and another sibling were homozygous for the affected RYR1 allele. METHODS: Eighteen members of this large pedigree were investigated, with a clinical examination for signs of a myopathy, a caffeine halothane contracture test, a histo-enzymologic study on the muscle biopsies, and linkage analysis on genomic DNA isolated from family blood samples. RYR1 cDNA was amplified by polymerase chain reaction and was cloned and sequenced, facilitating mutation detection. RESULTS: Linkage analysis demonstrated linkage between RYR1-linked markers and MH susceptibility in this family. DNA sequencing identified a T to C transition at nucleotide position 103, resulting in the substitution of an arginine for cysteine 35, representing the most N-terminal mutation reported to date in the RYR1 gene. This mutation segregates fully with the MHS trait, generating a lod score of 4.65 in favor of linkage to MHS at a recombination frequency of 0.0. CONCLUSIONS: The proband in this kindred is the first reported homozygote to have presented with an MH episode. The homozygotes in this pedigree do not have an overt myopathy. The sensitivity of muscle samples to caffeine clearly distinguished the two homozygotes from other heterozygous-susceptible individuals. No clear differentiation was observed with the halothane contracture results.

Adolescent↗
PubMed1996

In vitro human masseter muscle hypersensitivity: a possible explanation for increase in masseter tone.

To determine whether a difference in fiber-type caffeine and Ca2+ sensitivities exists between human masseter and vastus lateralis skeletal muscle, we compared the fiber-type caffeine sensitivities in chemically skinned muscle fibers from 13 masseter and 18 vastus lateralis muscles. Caffeine sensitivity was defined as the threshold concentration inducing > 10% of the maximal tension obtained after the fiber was loaded with a 1.6 x 10(-2) mM Ca2+ solution for 30 s. Significant difference in the mean caffeine sensitivity was found between type I masseter fibers [2.57 +/- 1.32 (SD) mM] vs. type I (6.02 +/- 1.74 mM) and type II vastus lateralis fibers (11.25 +/- 3.13 mM). Maximal Ca(2+)-activated force per cross-sectional area was significantly different between masseter and vastus lateralis fibers. However, the Ca2+ concentration corresponding to half-maximal tension (pCa50) was not significantly different between type I masseter (pCa50 5.9 +/- 0.02) and type I vastus lateralis muscle (pCa50 6.01 +/- 0.08). These results suggest that the increase in caffeine sensitivity of masseter muscle reflects the presence of a low reactivity threshold of the sarcoplasmic reticulum.

Caffeine↗
PubMed1994

Viability criterion of muscle bundles used in the in vitro contracture test in patients with neuromuscular diseases.

We have compared the viability criteria of muscle bundles used in the in vitro contracture test for susceptibility to malignant hyperthermia (MH) in a group of 28 patients with various neuromuscular diseases (NMD) and 93 MH-related family patients. In the patients with NMD, this standard test gave one positive, six equivocal and 21 negative results. Compared with MH-related family patients, muscle bundles used had significantly smaller resting membrane potentials and smaller predrug twitch tension amplitudes. Some results from the group with NMD were obtained with muscles which were damaged, more rapidly deteriorating, non-standard or both, and should not be taken to indicate that the patients have the genetic trait for MH. The in vitro contracture test is not always relevant for myopathic muscle (especially dystrophic muscle) and this could explain the lack of specificity for MH.

Caffeine↗
PubMed1994

Halothane and isoflurane decrease calcium sensitivity and maximal force in human skinned cardiac fibers.

BACKGROUND: Reports of the direct effects of volatile anesthetics on cardiac myofibrils, studied in various mammalian species but not in humans, have conflicted. To determine whether volatile anesthetics directly affect cardiac contractile proteins in humans, we examined the effects of various equianesthetic doses of halothane (0.46, 0.83, and 1.23 mM, equivalent to 0.75, 1.50, and 2.25%, respectively) and isoflurane (0.63, 1.22, and 1.93 mM, equivalent to 1.15, 2.30, and 3.50%, respectively) on the Ca2+ sensitivity and maximal force in human skinned cardiac fibers. METHODS: Left ventricular muscle strips were obtained from seven patients undergoing cardiac surgery. Sarcolemma was disrupted with EGTA (ethylene glycol bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid), and sarcoplasmic reticulum was destroyed with EGTA plus BRIJ 58 detergent. Ca2+ sensitivity was studied by observing the isometric tension developed by skinned fiber bundles challenged with solutions of increasing Ca2+ concentrations expressed in pCa (where pCa = -log10[Ca2+]). Maximal force was measured with a pCa 4.8 solution. RESULTS: Both anesthetics shifted the pCa-tension curves toward higher Ca2+ concentrations and decreased pCa for half-maximal activation in a dose-dependent and reversible fashion (from 5.71 for control to 5.56 and 5.55 for 1 MAC halothane and isoflurane, respectively) without changing the slope of this relationship (Hill coefficient). No differences between agents were observed at equianesthetic concentrations. The two agents also decreased the maximal activated tension in a dose-dependent fashion (-27 and -28% vs. control for 2 MAC halothane and isoflurane, respectively). CONCLUSIONS: The current study indicates that halothane and isoflurane decrease Ca2+ sensitivity and maximal force in human skinned cardiac fibers at 20 degrees C. If these effects extend to higher temperatures, they may contribute to the negative inotropic effect of these agents.

Aged↗
PubMed1993

Fiber-type caffeine sensitivities in skinned muscle fibers from humans susceptible to malignant hyperthermia.

BACKGROUND: The response to contracture tests may depend upon the relative proportion of muscle fiber types within the muscle specimen. To determine whether a difference in fiber-type caffeine sensitivities exists between malignant hyperthermia susceptible (MHS) and malignant hyperthermia-nonsusceptible (MHN) skeletal muscle, we compared the fiber-type caffeine sensitivities in chemically skinned muscle fibers dissected from vastus lateralis muscle from 15 MHS and 16 MHN patients. METHODS: Muscle fiber type was determined in each fiber by the difference in strontium-induced tension measurements and in 36 fibers, after contracture testing, by ATPase enzyme histochemistry. Caffeine sensitivity was defined as the threshold concentration inducing more than 10% of the maximal tension obtained with a calcium 1.6 x 10(-2) mM solution. RESULTS: Significant difference in the mean (+/- SD) caffeine sensitivity was found between type I MHS fibers (2.63 +/- 0.85 mM) versus type II MHS fibers (3.47 +/- 1.2 mM) and between type I MHN fibers (5.89 +/- 1.8 mM) versus type II MHN fibers (10.46 +/- 2.6 mM). The mean (+/- SD) caffeine sensitivities for a given muscle fiber type (I or II) were different between groups of MHS and MHN patients. Both type I and II MHS fibers had significantly lower caffeine sensitivities, and this increase in caffeine sensitivity was significantly smaller in type I than in type II fiber. CONCLUSIONS: The current study indicates that a truly MHS patient cannot have a false-negative result solely related to abnormal type II fibers contained in a given muscle strip. Although the occurrence of a very high proportion of type I fibers in MHN human muscle could result in a false-positive contracture outcome, such an occurrence is expected to be rare.

Caffeine↗
PubMed1992

Effect of Bay K 8644 on the magnitude of isoflurane and halothane contracture of skeletal muscle from patients susceptible to malignant hyperthermia.

Isoflurane has a lesser ability than halothane to induce contracture in malignant hyperthermia (MH) muscle in vitro. This does not necessarily imply that isoflurane is not as potent an MH trigger as halothane in vivo. A hypothesis was tested that in vitro treatment with Bay K 8644, an activator of both the dihydropyridine receptors as well as the sodium channels of the T-tubules, potentiates isoflurane-induced MH-susceptible skeletal muscle contracture. In addition to the usual halothane-caffeine test, other muscle bundles were exposed to 10 microM Bay K 8644-halothane and equipotent anesthetic concentrations (expressed in multiple minimum alveolar concentration [MAC]) of isoflurane either alone or combined with Bay K 8644. In 14 MH-susceptible muscle bundles, the mean maximum contracture induced by 2 MAC isoflurane was 0.20 +/- 0.22 g (mean +/- SD), and this value was significantly less than that obtained with 2 MAC halothane (0.68 +/- 0.40 g). Bay K 8644 did not induce muscle contracture on its own but consistently enhanced both the 0.5 MAC isoflurane and halothane to the same maximal isometric tension (1.09 +/- 0.35 g and 1.11 +/- 0.37 g, respectively). Such an effect was not observed in the MH-nonsusceptible group. Under the conditions of this in vitro study, 0.5 MAC isoflurane appears to be as potent as halothane in inducing muscle contracture in skeletal muscle bundles from individuals susceptible to MH.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1992

Is resting membrane potential a possible indicator of viability of muscle bundles used in the in vitro caffeine contracture test?

In 22 patients susceptible to and 34 patients not susceptible to malignant hyperthermia, we examined which muscle conditions may influence the degree of sensitivity of skeletal muscle to the in vitro caffeine contracture test: predrug resting membrane potential, predrug twitch tension, and maximum contracture induced by 32 mM caffeine in two caffeine tests performed respectively at 30 and 75 min after biopsy. No differences in the measured variables were observed between the first and the second caffeine tests in the 34 patients susceptible to malignant hyperthermia. The first caffeine test was found to be positive in all of the 22 patients susceptible to malignant hyperthermia. However, in eight patients, the second caffeine test was negative and the muscle fibers were found to be significantly depolarized. Resting membrane potential was -73.4 +/- 7.9 mV before the first caffeine test and -65.8 +/- 8.8 mV before the second test. We suggest that when time-induced partial depolarization of malignant hyperthermia-susceptible fibers occurs, fibers may become less sensitive to caffeine.

Caffeine↗
PubMed1991

Effects of calcium-free solution, calcium antagonists, and the calcium agonist BAY K 8644 on mechanical responses of skeletal muscle from patients susceptible to malignant hyperthermia.

The purpose of this investigation was to determine if alteration in the function of the dihydropyridine receptor may in turn modify halothane-induced contractures in muscle bundles from patients susceptible to malignant hyperthermia (MH). The effects of Ca(2+)-free Krebs Ringer (KR) solution, 5 microM verapamil, 5 microM nifedipine, and 10 microM of the Ca2+ agonist BAY K 8644 on halothane-induced contracture were therefore investigated. The halothane-induced contracture was prevented in the absence of extracellular Ca2+ and significantly reduced in the presence of verapamil or nifedipine. BAY K 8644 significantly enhanced the 0.5-, 1.0-, and 1.5-vol % halothane-induced contracture in MH-susceptible muscle bundles. When BAY K 8644 was dissolved in Ca(2+)-free KR solution, no contracture was observed in MH-susceptible muscle bundles. These results on cut MH-susceptible human muscle bundles support the hypothesis that halothane-induced contracture in MH can be modified by the binding of Ca2+ agonists or antagonists to the dihydropyridine receptor. The role of Ca2+ entry phenomena remains unclear, but the results suggest that extracellular Ca2+ is required to reprime or to bind to some sites of the dihydropyridine receptors.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1990

Diltiazem and nifedipine reduce the in vitro contracture response to halothane in malignant hyperthermia-susceptible muscle.

The effects of diltiazem (1 microM) and nifedipine (1 microM) were examined separately on the in vitro halothane tests for malignant hyperthermia (MH) susceptibility. Eighteen patients with MH susceptibility were diagnosed as MH-susceptible (MHS) according to the protocol of the European MH Group. In addition, halothane tests were carried out in the presence of either diltiazem (ten patients) or nifedipine (eight patients). These two calcium channel blockers significantly reduced the halothane contracture. Furthermore, in five of the ten MHS patients tested in the presence of diltiazem as well as in five of the eight MHS patients tested in the presence of nifedipine the halothane contracture test could be classified as negative. It is concluded that the presence of clinical concentrations of either diltiazem or nifedipine in the muscle bath affects the in vitro discrimination for MH susceptibility to halothane.

Depression, Chemical↗
PubMed1990

Clinical concentrations of verapamil affect the in vitro diagnosis of susceptibility to malignant hyperpyrexia.

We examined the effects of verapamil on the in vitro caffeine and halothane tests for malignant hyperpyrexia (MH) susceptibility. Ten consecutive MH-susceptible patients were investigated according to the protocol of the European MH group. Additional tests were carried out in the presence of verapamil 10(-6) mol litre-1. In four of the 10 patients, the halothane contracture response following pretreatment with verapamil was classified as positive to halothane. In contrast, in nine of the 10 patients, contracture tests of muscle in the presence of verapamil were classified as negative to caffeine. It is advised that verapamil should be discontinued before performing a contracture test.

Caffeine↗
PubMed1990

Use of the calcium agonist BAY K 8644 for in vitro diagnosis of susceptibility to malignant hyperthermia.

We have studied the effects of the calcium agonist BAY K 8644 on the in vitro halothane test in 10 malignant hyperthermia-susceptible (MHS), 12 MH "equivocal" to halothane (MHEh), 30 MH non-susceptible (MHN) and 10 control patients. BAY K 8644 potentiated the halothane-induced contracture in muscle strips from both MHS and MHEh patients. The drug produced a more obvious difference in contracture responses between the MHEh group compared with the MHN and control groups.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMed1989

The association between the neuroleptic malignant syndrome and malignant hyperthermia.

The neuroleptic malignant syndrome (NMS) is an uncommon but dangerous complication of treatment with neuroleptic drugs. A primary defect in skeletal muscle has been suggested in view of similarities in the clinical presentations of NMS and anaesthetic-induced malignant hyperthermia (MH). The in vitro halothane-caffeine contracture tests are the most reliable method of identifying individuals susceptible to MH. The aim of this study was to define if a relationship exists between NMS and MH susceptibility. Hence, the in vitro halothane and caffeine contracture tests were performed on muscle tissue obtained from eight NMS, ten MH-susceptible and ten control patients. The results, which are expressed in accordance with the criteria of the European MH Group, defined the eight NMS subjects as MH non-susceptible. The response to halothane and caffeine exposure of skeletal muscle from NMS and control subjects was the same and significantly different from that of muscle from patients susceptible to MH. Furthermore, muscle from subjects in NMS and control group responded similarly to increasing concentrations of chlorpromazine. These results do not point towards an association between NMS and MH.

Adult↗