Abnormal Action Potential Responses to Halothane in Heart Muscle Isolated from Malignant Hyperthermia-susceptible Pigs

1995 ◽  
Vol 82 (4) ◽  
pp. 947-953. ◽  
Author(s):  
Norbert Roewer ◽  
Clemens Greim ◽  
Eckhart Rumberger ◽  
Jochen Schulte am Esch
Keyword(s):  
Malignant Hyperthermia ◽  
Action Potentials ◽  
Myocardial Function ◽  
In Vitro Study ◽  
Resting Potential ◽  
Cardiac Symptoms ◽  
Cardiac Dysrhythmias ◽  
Malignant Hyperthermia Susceptible ◽  
The Right

Background During human and porcine malignant hyperthermia (MH), cardiac dysrhythmias and altered myocardial function can be observed. It is unknown whether a primary abnormality in cardiac muscle contributes to the cardiac symptoms during MH. An abnormal response to halothane has recently been demonstrated in action potentials (APs) from MH-susceptible (MHS) human skeletal muscles. We investigated the electrophysiologic properties in trabeculae isolated from the right ventricles of normal (MHN) and MHS pigs. Methods The experiments were performed on electrically stimulated (1 Hz) trabeculae isolated from the right ventricles of MHS and MHN pigs. Resting membrane potentials, APs, and tension were measured with and without the presence of 1% halothane. In addition, the halothane-equilibrated muscles were exposed to caffeine in increasing doses (1, 2, and 4 mM). Results In the absence of halothane, resting potential and AP characteristics in MHS and MHN muscles did not differ significantly. Halothane did not alter resting potentials but produced different alterations in the APs in MHS and MHN muscles, whereas the decrease in twitch tension was identical. In contrast to reductions in the AP amplitude and duration in MHN muscle, halothane produced an enlargement of the APs in MHS muscle. The addition of caffeine caused nearly identical prolongations of AP duration in MHS and MHN muscles. Conclusions This in vitro study demonstrates that halothane produces abnormal alterations in the dynamic electric properties of the ventricular excitable membrane from MHS pigs. These results suggest a latent defect in the myocardium of MHS pigs that becomes apparent in the presence of MH-triggering agents.

scholarly journals P1591Assessment of flow disturbances in the right ventricle: an in vitro study using a novel heart model

EP Europace ◽  
2017 ◽  
Vol 19 (suppl_3) ◽  
pp. iii339-iii339
Author(s):  
U. Gulan ◽  
AM. Saguner ◽  
D. Akdis ◽  
C. Brunckhorst ◽  
M. Holzner ◽  
...  
Keyword(s):  
Right Ventricle ◽  
In Vitro Study ◽  
Vitro Study ◽  
Heart Model ◽  
Flow Disturbances ◽  
The Right

Characterization of an early afterhyperpolarization after a brief train of action potentials in rat hippocampal neurons in vitro

1990 ◽  
Vol 63 (1) ◽  
pp. 72-81 ◽  
Author(s):  
A. Williamson ◽  
B. E. Alger
Keyword(s):  
Action Potentials ◽  
Hippocampal Neurons ◽  
Pyramidal Cells ◽  
Chloride Ions ◽  
Membrane Potentials ◽  
Resting Potential ◽  
K Channel ◽  
Delayed Rectifier ◽  
Extracellular Potassium

1. In rat hippocampal pyramidal cells in vitro, a brief train of action potentials elicited by direct depolarizing current pulses injected through an intracellular recording electrode is followed by a medium-duration afterhyperpolarization (mAHP) and a longer, slow AHP. We studied the mAHP with the use of current-clamp techniques in the presence of dibutyryl cyclic adenosine 3',5'-monophosphate (cAMP) to block the slow AHP and isolate the mAHP. 2. The mAHP evoked at hyperpolarized membrane potentials was complicated by a potential generated by the anomalous rectifier current, IQ. The mAHP is insensitive to chloride ions (Cl-), whereas it is sensitive to the extracellular potassium concentration ([K+]o). 3. At slightly depolarized levels, the mAHP is partially Ca2+ dependent, being enhanced by increased [Ca2+]o and BAY K 8644 and depressed by decreased [Ca2+]o, nifedipine, and Cd2+. The Ca2(+)-dependent component of the mAHP was also reduced by 100 microM tetraethylammonium (TEA) and charybdotoxin (CTX), suggesting it is mediated by the voltage- and Ca2(+)-dependent K+ current, IC. 4. Most of the Ca2(+)-independent mAHP was blocked by carbachol, implying that IM plays a major role. In a few cells, a small Ca2(+)- and carbachol-insensitive mAHP component was detectable, and this component was blocked by 10 mM TEA, suggesting it was mediated by the delayed rectifier current, IK. The K+ channel antagonist 4-aminopyridine (4-AP, 500 microM) did not reduce the mAHP. 5. We infer that the mAHP is a complex potential due either to IQ or to the combined effects of IM and IC. The contributions of each current depend on the recording conditions, with IC playing a role when the cells are activated from depolarized potentials and IM dominating at the usual resting potential. IQ is principally responsible for the mAHP recorded at hyperpolarized membrane potentials.

scholarly journals P2834An in vitro study on the influence of increased heart rate on the right ventricular kinetic energy and shear stresses

2018 ◽  
Vol 39 (suppl_1) ◽  
Author(s):  
U Gulan ◽  
A M Saguner ◽  
D Akdis ◽  
A Denegri ◽  
M X Miranda ◽  
...  
Keyword(s):  
Heart Rate ◽  
Kinetic Energy ◽  
Right Ventricular ◽  
In Vitro Study ◽  
Vitro Study ◽  
Shear Stresses ◽  
The Right

scholarly journals DILTIAZEM INHIBITS HALOTHANE-INDUCED CONTRACTIONS IN MALIGNANT HYPERTHERMIA-SUSCEPTIBLE MUSCLES IN VITRO

1985 ◽  
Vol 57 (10) ◽  
pp. 994-996 ◽  
Author(s):  
W.K. ILIAS ◽  
C.H. WILLIAMS ◽  
R.T. FULFER ◽  
S.E. DOZIER
Keyword(s):  
Malignant Hyperthermia ◽  
Malignant Hyperthermia Susceptible

Dependence of delayed afterdepolarizations on diastolic potentials in ischemic Purkinje fibers

1989 ◽  
Vol 257 (3) ◽  
pp. H770-H777 ◽  
Author(s):  
W. B. Gough ◽  
N. el-Sherif
Keyword(s):  
Myocardial Infarction ◽  
Action Potentials ◽  
Resting Potential ◽  
Triggered Activity ◽  
Activity Maximum ◽  
Purkinje Fibers ◽  
Sustained Activity ◽  
Delayed Afterdepolarizations ◽  
Diastolic Potential

The mechanism of focal rhythms 1 day after myocardial infarction has been ascribed to both abnormal automaticity and triggered activity arising from delayed after-depolarizations (DADs). During the course of superfusion in vitro, diastolic potentials repolarize to more negative resting potentials. The dependence of DADs and triggered activity on diastolic potentials was studied using extrinsic currents. During sustained activity (maximum diastolic potential = -61 +/- 7 mV), hyperpolarizing current decreased the DADs, rendered them subthreshold, and terminated triggered activity. During the quiescence caused by constant hyperpolarizing current, a stimulated train of action potentials produced DADs. Decreasing the current permitted augmented DADs. In quiescent preparations (resting potential = -68 +/- 7 mV), a train of stimulated action potentials was followed by subthreshold DADs. Depolarizing current increased the DAD amplitude. To exclude depolarization-induced automaticity, constant currents were applied without a previous train of stimuli. Neither DADs nor triggered activity were evoked. Therefore, DADs and triggered activity, postinfarction, depend on the diastolic potential. There is a continuity between subthreshold DADs and sustained activity. DADs may reach a magnitude in which extrinsic interventions may not adequately terminate sustained triggered activity.

HEPARIN FORMULAS CONTAINING CHLOROCRESOL INDUCE CONTRACTURES IN MALIGNANT HYPERTHERMIA SUSCEPTIBLE SKELETAL MUSCLE IN VITRO

1999 ◽  
Vol 88 (Supplement) ◽  
pp. 313S
Author(s):  
M. Anetseder ◽  
L. Ritter ◽  
H. Horbaschek ◽  
E. Hartung ◽  
N. Roewer
Keyword(s):  
Skeletal Muscle ◽  
Malignant Hyperthermia ◽  
Malignant Hyperthermia Susceptible

Comparison of the In-Vitro Effects of Dibucaine on Skeletal Muscle Specimens from Malignant Hyperthermia Susceptible and Normal Patients

2002 ◽  
Vol 96 (Sup 2) ◽  
pp. A76
Author(s):  
Mark U. Gerbershagen ◽  
Frank Wappler ◽  
Marko Fiege ◽  
Ralf Weisshorn ◽  
Jochen Schulte am Esch
Keyword(s):  
Skeletal Muscle ◽  
Malignant Hyperthermia ◽  
Malignant Hyperthermia Susceptible ◽  
In Vitro Effects

scholarly journals Muscle Biopsy and In Vitro  Contracture Test in Subjects with Idiopathic HyperCKemia

2008 ◽  
Vol 109 (4) ◽  
pp. 625-628 ◽  
Author(s):  
Alessandro Malandrini ◽  
Alfredo Orrico ◽  
Carmen Gaudiano ◽  
Simona Gambelli ◽  
Lucia Galli ◽  
...  
Keyword(s):  
Malignant Hyperthermia ◽  
Muscle Biopsy ◽  
Malignant Hyperthermia Susceptibility ◽  
Manual Muscle Testing ◽  
In Vitro Contracture Test ◽  
Muscle Testing ◽  
Malignant Hyperthermia Susceptible ◽  
Fiber Size ◽  
Precise Diagnosis

Background Persistent high creatine kinase (CK) levels may reflect underlying subclinical myopathies. In most cases, pathogenesis is unknown and clinical management is unclear. Though clinically asymptomatic, these subjects are potentially susceptible to malignant hyperthermia. Methods The authors analyzed 37 subjects with persistent elevation of CK without significant weakness or other neurologic symptoms. Neurologic examination was performed according to manual muscle testing. Muscle biopsy and the in vitro contracture test were performed in all subjects. Results Twenty-three subjects (51.1%) were completely asymptomatic. The others had minor symptoms such as occasional cramps (11 subjects, 24.4%), fatigue (5 subjects, 11.1%), a combination of cramps and fatigue (5 subjects, 11.1%), and muscle pain (1 case, 2.2%). Muscle biopsy enabled precise diagnosis in 3 cases and was normal in 3 cases. The more frequent changes were variation in fiber size (31.1%), a combination of nuclear internalization and variation in fiber size (26.6%), nuclear internalization (6.6%), minor mitochondrial changes (4.4%), and neurogenic atrophy (4.4%). Immunocytochemical analysis was normal in all patients. In vitro contracture testing detected one malignant hyperthermia-susceptible and one malignant hyperthermia-equivocal subject. Conclusions The evidence of malignant hyperthermia susceptibility by in vitro contracture test seems to be relatively infrequent among subjects with idiopathic hyperCKemia, but the incidence of true malignant hyperthermia in idiopathic hyperCKemia is unknown. Muscle biopsy should be considered a useful, though not very sensitive, diagnostic tool in idiopathic hyperCKemia, because it enables potentially treatable disorders, such as inflammatory myopathies, to be discovered. No uniform morphologic finding typical of idiopathic hyperCKemia or malignant hyperthermia susceptibility was identified by muscle biopsy.

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