Association of increased pHi with calcium ion release in skeletal muscle

1978 ◽  
Vol 234 (3) ◽  
pp. C110-C114 ◽  
Author(s):  
R. J. Connett
Keyword(s):  
Skeletal Muscle ◽  
Calcium Ion ◽  
Calcium Release ◽  
Muscle Membrane ◽  
Sartorius Muscle ◽  
Ion Release ◽  
Extracellular Medium ◽  
Dantrolene Sodium ◽  
External Potassium ◽  
Frog Sartorius

The pH difference across the cell membrane of frog sartorius muscle cells was measured with the distribution of 5,5-dimethyl-2,4-oxazolidine-dione (DMO) as the marker. Depolarization of the muscles to values at or below the contraction threshold caused by elevating external potassium up to approximately 20 mM resulted in an internal alkalinization. The change was smaller with superthreshold depolarization (20--30 mM [K+]). The alkalinization was blocked by agents that block calcium release from the sarcoplasmic reticulum (procaine and dantrolene sodium). Other agents that cause calcium release (caffeine, theophylline, and quinine) were found to give alkalinization when tested at concentrations just below the contracture threshold. Increased acidification of the extracellular medium was associated with the internal alkalinization. The data were interpreted as indicating the presence of a calcium-stimulated H+ and/or OH- ion transport system in the muscle membrane.

scholarly journals The Potassium Flux Ratio in Skeletal Muscle As a Test for Independent Ion Movement

1965 ◽  
Vol 48 (5) ◽  
pp. 777-795 ◽  
Author(s):  
R. A. Sjodin
Keyword(s):  
Skeletal Muscle ◽  
Flux Ratio ◽  
Muscle Membrane ◽  
Sartorius Muscle ◽  
Potassium Ions ◽  
Theoretical Relation ◽  
Independence Principle ◽  
Potassium Flux ◽  
Frog Sartorius ◽  
Muscle Fiber Membrane

The flux ratio of potassium ions was measured on frog sartorius muscle under conditions in which a substantial net potassium loss occurs. Muscle fiber membrane potentials were measured under identical conditions. The observed flux ratios were compared with values calculated from a theoretical relation derived on the assumptions that the unidirectional fluxes are both passive and occur independently. The results favor the conclusion that the potassium fluxes across skeletal muscle membrane occur along passive electrochemical gradients and obey the independence principle.

Evidence for an inotropic positive action of cGMP during excitation–contraction coupling in frog sartorius muscle

1983 ◽  
Vol 61 (6) ◽  
pp. 590-594 ◽  
Author(s):  
L. Mancinelli ◽  
G. Fanò ◽  
L. Ferroni ◽  
T. Secca ◽  
B. M. Dolcini
Keyword(s):  
Calcium Release ◽  
Sartorius Muscle ◽  
Maximum Increase ◽  
General Hypothesis ◽  
Tension Development ◽  
Dantrolene Sodium ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling ◽  
Frog Sartorius Muscle ◽  
Frog Sartorius

Within the realm of the general hypothesis concerning the role of cGMP on intracellular calcium regulation in biological systems, we have investigated the action of cyclic nucleotides during excitation–contraction coupling in frog sartorius muscle. Our data show that several guanosine nucleotides (GTP, GDP, dibutyryl-cGMP) can increase the isometric twitch tension with a maximum increase of 40% in the muscles treated with cGMP. This increase is completely independent of external Ca2+ concentration. The use of dantrolene sodium (known to inhibit calcium release from sarcoplasmic reticulum) results in a decrease in the twitch tension with a contemporary decrease in the intracellular levels of cGMP; whereas, the addition of cGMP to the muscles treated with dantrolene antagonizes, at least partially, the effect of the drug on tension development. Finally, in chemically skinned muscles, cGMP induces a reversible contracture equal to approximately one-half of that evoked by 10−4 M Ca2+.

Dantrolene Sodium: Effects on Crustacean Muscle

1974 ◽  
Vol 52 (4) ◽  
pp. 887-890 ◽  
Author(s):  
L. L. Odette ◽  
H. L. Atwood
Keyword(s):  
Skeletal Muscle ◽  
Electrical Properties ◽  
Neuromuscular Transmission ◽  
Contractile Response ◽  
Callinectes Sapidus ◽  
Muscle Membrane ◽  
Dantrolene Sodium ◽  
Muscle Contractile ◽  
Indirect Stimulation ◽  
Vertebrate Skeletal Muscle

The effect of dantrolene sodium, a muscle relaxant effective on vertebrate skeletal muscle, has been studied on the stretcher muscle of a crab (Callinectes sapidus). The drug rapidly and reversibly attenuates the muscle contractile response to direct and indirect stimulation. Neuromuscular transmission is unaffected, as are the electrical properties of the muscle membrane. It is concluded that dantrolene sodium uncouples excitation–contraction mechanisms in crustacean tonic muscle.

Intracellular pH recovery from lactic acidosis of single skeletal muscle fibres

1988 ◽  
Vol 66 (12) ◽  
pp. 1560-1564 ◽  
Author(s):  
Y. E. Allard
Keyword(s):  
Skeletal Muscle ◽  
Lactic Acid ◽  
Intracellular Ph ◽  
Buffer Capacity ◽  
Ringer Solution ◽  
Sartorius Muscle ◽  
Muscle Fibres ◽  
Diffusion Limited ◽  
Skeletal Muscle Fibres ◽  
Frog Sartorius

Intracellular pH (pHi, measured with H+-selective microelectrodes, in quiescent frog sartorius muscle fibres was 7.29 ± 0.09 (n = 13). Frog muscle fibres were superfused with a modified Ringer solution containing 30 mM HEPES buffer, at extracellular pH (pHo) 7.35. Intracellular pH decreased to 6.45 ± 0.14 (n = 13) following replacement of 30 mM NaCl with sodium lactate (30 mM MES, pHo 6.20). Intracellular pH recovery, upon removal of external lactic acid, depended on the buffer concentration of the modified Ringer solution. The measured values of the pHi recovery rates was 0.06 ± 0.01 ΔpHi/min (n = 5) in 3 mM HEPES and was 0.18 ± 0.06 ΔpHi/min (n = 13) in 30 mM HEPES, pHo 7.35. The Na+–H+ exchange inhibitor amiloride (2 mM) slightly reduced pHi recovery rate. The results indicate that the net proton efflux from lactic acidotic frog skeletal muscle is mainly by lactic acid efflux and is limited by the transmembrane pH gradient which, in turn, depends on the extracellular buffer capacity in the diffusion limited space around the muscle fibres.

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.

TETRAETHYLAMMONIUM-INDUCED CONTRACTIONS OF FROG'S SKELETAL MUSCLE: III. MECHANISM OF ACTION BY CALCIUM RELEASE

1967 ◽  
Vol 45 (5) ◽  
pp. 845-855 ◽  
Author(s):  
G. Beaulieu ◽  
G. B. Frank
Keyword(s):  
Skeletal Muscle ◽  
Mechanism Of Action ◽  
Binding Sites ◽  
Neuromuscular Transmission ◽  
Calcium Concentration ◽  
Calcium Release ◽  
Sartorius Muscle ◽  
Free Solution ◽  
Muscle Twitching ◽  
Solution Bathing

The effects of changes in the extracellular calcium concentration on the muscle 'twitching' response induced by tetraethylammonium of the frog's sartorius muscle were investigated. Decreasing the calcium concentration of a solution bathing the muscle increased the sensitivity of the muscle to TEA stimulation. However, with a sufficient calcium reduction (to 0.108 mM in most preparations) the muscles became completely insensitive to TEA stimulation. In contrast, calcium reduction resulted only in an increased muscle sensitivity to carbachol stimulation. Increasing the calcium concentration greatly decreased TEA sensitivity, and at 2.16 mM calcium a TEA-induced muscle 'twitching' response no longer could be produced. At this calcium concentration carbachol sensitivity was reduced but not eliminated and neuromuscular transmission was essentially unmodified. In studies with the toe muscle, it was found that TEA could restore the potassium-induced contracture that had been eliminated by soaking the muscle in a calcium-free solution. This effect of TEA was dependent upon the presence of a store of bound calcium in the muscle. These results are consistent with the hypothesis that TEA acts by releasing calcium from binding sites on the nerve endings, leading to an increased excitability and instability of these structures and resulting in the muscle twitching response. Other effects of TEA similar to those of increases in calcium are due to an increased level of ionized calcium at nerve and muscle membranes which also results from the release by TEA of calcium from membrane sites.

scholarly journals Evaluation of Physicochemical Properties of New Calcium Silicate-Based Sealer

2018 ◽  
Vol 29 (6) ◽  
pp. 536-540 ◽  
Author(s):  
Aline Teixeira Mendes ◽  
Paula Barcellos da Silva ◽  
Bruna Barcelos Só ◽  
Lina Naomi Hashizume ◽  
Rodrigo Ricci Vivan ◽  
...  
Keyword(s):  
Physicochemical Properties ◽  
Calcium Ion ◽  
Calcium Silicate ◽  
Calcium Release ◽  
Setting Time ◽  
Porto Alegre ◽  
Ion Release ◽  
Ph Values ◽  
Time Flow ◽  
Ah Plus

Abstract This study aimed to evaluate the physicochemical properties of a calcium silicate-based sealer (Sealer Plus BC; MK Life, Porto Alegre, Brazil) compared with an epoxy-resin sealer (AH Plus; Dentsply DeTrey GmbH, Konstanz, Germany). Initial and final setting time was assessed based on ISO 6876:2012 and ASTM C266:03. Calcium ion release and pH were evaluated by filling polyethylene tubes with sealers and then immersing them in 10 mL of deionized water. Following experimental periods of 1, 24, 72 and 168 hours, the samples were measured regarding pH and calcium ion release with a pH meter and a colorimetric spectrophotometer, respectively. The flow was examined based on ISO 6876:2012. Rings of 10 mm in diameter with 1 mm thickness were prepared to analyze the radiopacity (ISO 6876:2012 and ADA n.57) and solubility (ISO 6876:2012). The data were analyzed by variance analysis, Student-T and Tukey tests (p<0.05). The calcium ion release and pH values were significantly higher for the Sealer Plus BC compared with the AH Plus (p<0.05). Lower setting time, flow and radiopacity were observed for the bioceramic sealer than for AH Plus (p<0.05). Sealer Plus BC exhibited higher solubility compared with AH Plus (p<0.05). Sealer Plus BC showed physicochemical properties as setting time, pH, calcium release, flow, and radiopacity following the required standards, but higher solubility than the minimum values required by ISO 6876:2012.

scholarly journals Molecular architecture of membranes involved in excitation-contraction coupling of cardiac muscle.

1995 ◽  
Vol 129 (3) ◽  
pp. 659-671 ◽  
Author(s):  
X H Sun ◽  
F Protasi ◽  
M Takahashi ◽  
H Takeshima ◽  
D G Ferguson ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Cardiac Muscle ◽  
Calcium Release ◽  
Surface Membrane ◽  
Freeze Fracture ◽  
Muscle Membrane ◽  
Charge Movement ◽  
Molecular Architecture ◽  
Direct Role ◽  
Large Particles

Peripheral couplings are junctions between the sarcoplasmic reticulum (SR) and the surface membrane (SM). Feet occupy the SR/SM junctional gap and are identified as the SR calcium release channels, or ryanodine receptors (RyRs). In cardiac muscle, the activation of RyRs during excitation-contraction (e-c) coupling is initiated by surface membrane depolarization, followed by the opening of surface membrane calcium channels, the dihydropyridine receptors (DHPRs). We have studied the disposition of DHPRs and RyRs, and the structure of peripheral couplings in chick myocardium, a muscle that has no transverse tubules. Immunolabeling shows colocalization of RyRs and DHPRs in clusters at the fiber's periphery. The positions of DHPR and RyR clusters change coincidentally during development. Freeze-fracture of the surface membrane reveals the presence of domains (junctional domains) occupied by clusters of large particles. Junctional domains in the surface membrane and arrays of feet in the junctional gap have similar sizes and corresponding positions during development, suggesting that both are components of peripheral couplings. As opposed to skeletal muscle, membrane particles in junctional domains of cardiac muscle do not form tetrads. Thus, despite their proximity to the feet, they do not appear to be specifically associated with them. Two observations establish the identify of the structurally identified feet arrays/junctional domain complexes with the immunocytochemically defined RyRs/DHPRs coclusters: the concomitant changes during development and the identification of feet as the cytoplasmic domains of RyRs. We suggest that the large particles in junctional domains of the surface membrane represent DHPRs. These observations have two important functional consequences. First, the apposition of DHPRs and RyRs indicates that most of the inward calcium current flows into the restricted space where feet are located. Secondly, contrary to skeletal muscle, presumptive DHPRs do not show a specific association with the feet, which is consistent with a less direct role of charge movement in cardiac than in skeletal e-c coupling.

Qualitative measurements of the entry of L-lactate into single surface fibres of frog skeletal muscle using a lactate-sensitive microelectrode

1987 ◽  
Vol 65 (12) ◽  
pp. 2488-2491 ◽  
Author(s):  
M. J. Mason
Keyword(s):  
Skeletal Muscle ◽  
Lactate Concentration ◽  
Ion Exchanger ◽  
Sartorius Muscle ◽  
Muscle Fibres ◽  
Frog Skeletal Muscle ◽  
Frog Sartorius Muscle ◽  
Frog Sartorius ◽  
Qualitative Measurements ◽  
Liquid Ion Exchanger

The present results demonstrate the sensitivity of the Corning chloride liquid ion exchanger 477913 to L-lactate. Microelectrodes filled with this exchanger showed responses to changes in L-lactate concentration in chloride-free solutions. In these experiments L-lactate replaced gluconate in equimolar amounts. Microelectrodes filled with this exchanger were used to qualitatively detect changes in intracellular anion in chloride-depleted frog sartorius muscle fibres during exposure to extracellular concentrations of L-lactate. The increase in intracellular anion concentration is consistent with the movement of L-lactate into the cell. This microelectrode enables one to qualitatively monitor changes in intracellular L-lactate in chloride-free experiments without incorporating selectivity coefficients.

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