scholarly journals Pharmacological distinction between dantrolene and ryanodine binding sites: evidence from normal and malignant hyperthermia-susceptible porcine skeletal muscle

1997 ◽  
Vol 326 (3) ◽  
pp. 847-852 ◽  
Author(s):  
Sanjay S. PALNITKAR ◽  
James R. MICKELSON ◽  
Charles F. LOUIS ◽  
Jerome PARNESS
Keyword(s):  
Skeletal Muscle ◽  
Malignant Hyperthermia ◽  
Binding Sites ◽  
Calcium Release ◽  
Drug Binding ◽  
Protein Patterns ◽  
Open Probability ◽  
Malignant Hyperthermia Susceptible ◽  
Discontinuous Sucrose Gradient ◽  
Muscle Types

Dantrolene inhibits and ryanodine stimulates calcium release from skeletal-muscle sarcoplasmic reticulum (SR), the former by an unknown mechanism, and the latter by activating the ryanodine receptor (RyR), the primary Ca2+-release channel of SR. Dantrolene is used to treat malignant hyperthermia (MH), a genetic predisposition to excessive intracellular Ca2+ release upon exposure to volatile anaesthetics. Porcine MH results from a point mutation in the SR RyR that alters the open probability of the channel, and is reflected in altered [3H]ryanodine binding parameters. Specific binding sites for [3H]dantrolene and [3H]ryanodine co-distribute on SR that has been isolated by discontinuous sucrose gradient centrifugation. If the two drug-binding sites are functionally linked, [3H]dantrolene binding might be affected both by pharmacological and by genetic modulators of the functional state of the RyR. Accordingly, we compared the characteristics of [3H]dantrolene binding to porcine malignant-hyperthermia-susceptible and normal-skeletal-muscle SR, and examined the effects of RyR modulators on [3H]dantrolene binding to these membranes. Additionally, the feasibility of separating the SR binding sites for [3H]dantrolene and [3H]ryanodine was investigated. No significant differences in [3H]dantrolene binding characteristics to SR membranes from the two muscle types were detected, and the Bmax ratio for [3H]dantrolene/[3H]ryanodine was 1.4(±0.1):1 in both muscle types. [3H]Dantrolene binding is unaffected by the RyR modulators caffeine, ryanodine, Ruthenium Red and calmodulin, and neither dantrolene nor azumolene have any effect on [3H]ryanodine binding. Additionally, distinct peaks of [3H]dantrolene and [3H]ryanodine binding are detected in SR membranes fractionated by linear sucrose centrifugation, although no differences in protein patterns are detected by SDS/PAGE or Western-blot analysis. We suggest that the binding sites for these two drugs are pharmacologically distinct, and may exist on separate molecules.

Dantrolene Sodium Can Increase or Attenuate Activity of Skeletal Muscle Ryanodine Receptor Calcium Release Channel

1996 ◽  
Vol 84 (6) ◽  
pp. 1368-1379 ◽  
Author(s):  
Thomas E. Nelson ◽  
Marina Lin ◽  
Gisele Zapata-Sudo ◽  
Roberto Takashi Sudo
Keyword(s):  
Skeletal Muscle ◽  
Muscle Relaxant ◽  
Binding Sites ◽  
Calcium Release ◽  
Vastus Lateralis Muscle ◽  
Calcium Release Channel ◽  
Dantrolene Sodium ◽  
Study Results ◽  
20 Nm ◽  
Reduced Activity

Background Dantrolene sodium (DS) is a direct-acting skeletal muscle relaxant whose only known action is to block calcium release from intracellular storage sites. The exact site of action for DS is unknown, but its efficacy in treating and preventing anesthetic-induced malignant hyperthermia (MH) is well established. Methods Single ryanodine (Ry1) receptor calcium release channels were incorporated into a planar lipid bilayer for electrophysiologic recording and for subsequent analysis of the channel's gating and conductance properties. The cellular effects of low DS concentrations were investigated by isometric contracture tension responses in biopsied MH human and dog muscle fascicles and in normal, single fibers from human vastus lateralis muscle. Results Two concentration-dependent DS effects on the isolated Ry1 receptor were discovered, suggesting at least two different binding sites. At nanomolar concentrations, DS activated the channel by causing three-to fivefold increases in open-state probability and dwell times. At micromolar concentrations, DS first increased then reduced activity in the channels; with the dominant effect being reduced activity. A 20 nm concentration of DS produced significant contracture tension in human muscle from one MH subject and caused potentiation of twitch in muscle from another MH patient. Halothane contracture in MH dog muscle was followed by an additional increase in tension when treated with 20 nm DS. Other investigations on chemically skinned, human fibers showed that calcium loaded in the sarcoplasmic reticulum was partially released by nM DS. Conclusions The study results suggest that at least two binding sites for DS exist on the Ry1 receptor calcium channel. A low-affinity (microM) site is associated with reduced channel gating and open-state dwell time and may relate to the established pharmacologic muscle relaxant effect of DS. The proposed high-affinity (nM) DS binding site activates the channel, producing Ca2+ release to the myoplasm, which, under environmentally adverse conditions, could damage genetically predisposed MH muscle. Such a phenomenon, if it occurs in DS treated MH patients, could generate a recrudescence of the syndrome.

Altered E-C coupling in triads isolated from malignant hyperthermia-susceptible porcine muscle

1995 ◽  
Vol 268 (6) ◽  
pp. C1381-C1386 ◽  
Author(s):  
R. el-Hayek ◽  
M. Yano ◽  
B. Antoniu ◽  
J. R. Mickelson ◽  
C. F. Louis ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Malignant Hyperthermia ◽  
Dihydropyridine Receptor ◽  
Normal Muscle ◽  
Direct Stimulation ◽  
Release Channel ◽  
Malignant Hyperthermia Susceptible ◽  
T Tubules ◽  
Junctional Foot Protein ◽  
Stimulation Of

Triad vesicles were isolated from normal (N) and homozygous malignant hyperthermia-susceptible (MHS) porcine skeletal muscle, and two types of sarcoplasmic reticulum Ca2+ release were investigated: 1) polylysine-induced Ca2+ release (direct stimulation of the junctional foot protein), and 2) depolarization-induced Ca2+ release (stimulation of the junctional foot protein via the dihydropyridine receptor). At submaximal concentrations of polylysine, the rates of induced Ca2+ release from the MHS triads were greater than from normal triads. The T tubules of polarized triads were depolarized by the K(+)-to-Na+ ionic replacement protocol. Higher grades of T-tubule depolarization resulted in higher rates of Ca2+ release from both MHS and normal triads but, when compared at a given grade of T-tubule depolarization, the release rate was always greater from the MHS than from normal triads. Thus the activity of the SR Ca2+ release channel is always higher in MHS than in normal muscle at a given submaximal dose of release trigger. This difference is observed when the channel is stimulated directly by polylysine or indirectly via a depolarization-induced activation of the T-tubule dihydropyridine receptor.

Ca(2+)- and pH-dependent halothane stimulation of Ca2+ release in sarcoplasmic reticulum from frog muscle

1996 ◽  
Vol 271 (2) ◽  
pp. C540-C546 ◽  
Author(s):  
M. Beltran ◽  
R. Bull ◽  
P. Donoso ◽  
C. Hidalgo
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Calcium Release ◽  
Release Kinetics ◽  
Frog Muscle ◽  
Time Range ◽  
Frog Skeletal Muscle ◽  
Open Probability ◽  
Filtration System ◽  
Stimulation Of

The effect of halothane on calcium release kinetics was studied in triad-enriched sarcoplasmic reticulum vesicles from frog skeletal muscle. Release from vesicles passively equilibrated with 3 mM 45CaCl2 was measured in the millisecond time range by use of a fast-filtration system. Halothane (400 microM) increased release rate constants at pH 7.1 and 7.4 as a function of extravesicular pCa. In contrast, halothane at pH 6.8 produced the same stimulation of release from pCa 7.0 to 3.0; no release took place in these conditions in the absence of halothane. Halothane shifted the calcium activation curve at pH 7.1, but not at pH 7.4, to the left and increased channel open probability at pH 7.1 in the cis pCa range of 7.0 to 5.0. These results indicate that cytosolic pCa and pH modulate the stimulatory effects of halothane on calcium release. Furthermore, halothane stimulated release in frog skeletal muscle at low pH and resting calcium concentration, indicating that in frog muscle halothane can override the closing of the release channels produced by these conditions, as it does in malignant hyperthermia-susceptible porcine muscle.

Quantitative study of motor endplates in muscle fibres dissociated by a simple procedure

1980 ◽  
Vol 209 (1177) ◽  
pp. 555-562 ◽  
Keyword(s):  
Skeletal Muscle ◽  
Binding Sites ◽  
Simple Procedure ◽  
Muscle Fibres ◽  
Single Muscle ◽  
Muscle Sample ◽  
Motor Endplates ◽  
Large Numbers ◽  
Muscle Types ◽  
Receptor Number

Large numbers of single muscle fibres can be obtained reproducibly from glutaraldehyde-fixed skeletal muscle by the method described here. With suitable modifications, one can estimate acetylcholine receptor number (α-bungarotoxin binding sites) and endplate area in parallel portions produced from the same muscle sample, so that small differences (e. g. with growth or between muscle types) become detectable. Micro­-dissection further increases the precision of evaluation of junctional, perijunctional and extrajunctional binding sites. Other applications are illustrated.

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
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