scholarly journals Reversible Block of the Calcium Release Channel/Ryanodine Receptor by Protamine, a Heparin Antidote

2000 ◽  
Vol 11 (7) ◽  
pp. 2213-2219 ◽  
Author(s):  
Peter Koulen ◽  
Barbara E. Ehrlich
Keyword(s):  
Lipid Bilayers ◽  
Ryanodine Receptor ◽  
Calcium Release ◽  
Single Channel ◽  
Reversible Inhibitor ◽  
Channel Activity ◽  
Calcium Release Channel ◽  
Release Channel ◽  
Mouse Muscle ◽  
Cytoplasmic Side

Channel activity of the calcium release channel from skeletal muscle, ryanodine receptor type 1, was measured in the presence and absence of protamine sulfate on the cytoplasmic side of the channel. Single-channel activity was measured after incorporating channels into planar lipid bilayers. Optimally and suboptimally calcium-activated calcium release channels were inactivated by the application of protamine to the cytoplasmic side of the channel. Recovery of channel activity was not observed while protamine was present. The addition of protamine bound to agarose beads did not change channel activity, implying that the mechanism of action involves an interaction with the ryanodine receptor rather than changes in the bulk calcium concentration of the medium. The block of channel activity by protamine could be reversed either by removal by perfusion with buffer or by the addition of heparin to the cytoplasmic side of the channel. Microinjection of protamine into differentiated C2C12 mouse muscle cells prevented caffeine-induced intracellular calcium release. The results suggest that protamine acts on the ryanodine receptor in a similar but opposite manner from heparin and that protamine can be used as a potent, reversible inhibitor of ryanodine receptor activity.

H2O2 and ethanol act synergistically to gate ryanodine receptor/calcium-release channel

2000 ◽  
Vol 279 (5) ◽  
pp. C1366-C1374 ◽  
Author(s):  
Toshiharu Oba ◽  
Tatsuya Ishikawa ◽  
Takashi Murayama ◽  
Yasuo Ogawa ◽  
Mamoru Yamaguchi
Keyword(s):  
Skeletal Muscle ◽  
Lipid Bilayers ◽  
Ryanodine Receptor ◽  
Calcium Release ◽  
Physiological Role ◽  
Channel Activity ◽  
Calcium Release Channel ◽  
Open Probability ◽  
Skeletal Muscle Function ◽  
Release Channel

We examined the effect of low concentrations of H2O2 on the Ca2+-release channel/ryanodine receptor (RyR) to determine if H2O2 plays a physiological role in skeletal muscle function. Sarcoplasmic reticulum vesicles from frog skeletal muscle and type 1 RyRs (RyR1) purified from rabbit skeletal muscle were incorporated into lipid bilayers. Channel activity of the frog RyR was not affected by application of 4.4 mM (0.02%) ethanol. Open probability ( P o) of such ethanol-treated RyR channels was markedly increased on subsequent addition of 10 μM H2O2. Increase of H2O2to 100 μM caused a further increase in channel activity. Application of 4.4 mM ethanol to 10 μM H2O2-treated RyRs activated channel activity. Exposure to 10 or 100 μM H2O2 alone, however, failed to increase P o. Synergistic action of ethanol and H2O2 was also observed on the purified RyR1 channel, which was free from FK506 binding protein (FKBP12). H2O2 at 100–500 μM had no effect on purified channel activity. Application of FKBP12 to the purified RyR1 drastically decreased channel activity but did not alter the effects of ethanol and H2O2. These results suggest that H2O2 may play a pathophysiological, but probably not a physiological, role by directly acting on skeletal muscle RyRs in the presence of ethanol.

Carnosine is a novel peptide modulator of intracellular calcium and contractility in cardiac cells

1997 ◽  
Vol 272 (1) ◽  
pp. H462-H468 ◽  
Author(s):  
G. P. Zaloga ◽  
P. R. Roberts ◽  
K. W. Black ◽  
M. Lin ◽  
G. Zapata-Sudo ◽  
...  
Keyword(s):  
Intracellular Calcium ◽  
Lipid Bilayers ◽  
Ryanodine Receptor ◽  
Calcium Release ◽  
Cardiac Contractility ◽  
Cardiac Cells ◽  
Dependent Manner ◽  
Calcium Release Channel ◽  
Release Channel ◽  
Contractile Failure

Myocardial contractile failure is a common cause of morbidity and mortality in patients with ischemic heart disease and systemic inflammatory states such as sepsis. Accumulating evidence indicates that contractile failure is associated with dysregulation of myoplasmic calcium levels. In a search for biochemical causes for contractile dysfunction, we found that the dipeptide carnosine improves cardiac contractility and tested the possibility that carnosine plays a role in the regulation of intracellular calcium. Carnosine increased contractility in a dose-dependent manner (1-10 mM) in isolated perfused rat hearts. and it also increased free intracellular calcium levels in isolated myocytes. Carnosine increased myocyte tension via calcium release from the ryanodine receptor calcium release channel in skinned myocardial fibers and increased open-state probability and dwell time of the isolated ryanodine receptor calcium release channel in lipid bilayers. In addition. we report that carnosine sensitizes the contractile proteins so calcium. These results suggest a novel role for carnosine as a modulator of intracellular calcium and contractility in cardiac tissue.

scholarly journals Chloroform extract of hog barn dust modulates skeletal muscle ryanodine receptor calcium-release channel (RyR1)

2010 ◽  
Vol 109 (3) ◽  
pp. 830-839 ◽  
Author(s):  
Chengju Tian ◽  
Chun Hong Shao ◽  
Danielle S. Fenster ◽  
Mark Mixan ◽  
Debra J. Romberger ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Ryanodine Receptor ◽  
Muscle Weakness ◽  
Calcium Release ◽  
Single Channel ◽  
Calcium Release Channel ◽  
Open Probability ◽  
Skeletal Muscle Function ◽  
Release Channel ◽  
Skeletal Muscle Weakness

Skeletal muscle weakness is a reported ailment in individuals working in commercial hog confinement facilities. To date, specific mechanisms responsible for this symptom remain undefined. The purpose of this study was to assess whether hog barn dust (HBD) contains components that are capable of binding to and modulating the activity of type 1 ryanodine receptor Ca2+-release channel (RyR1), a key regulator of skeletal muscle function. HBD collected from confinement facilities in Nebraska were extracted with chloroform, filtered, and rotary evaporated to dryness. Residues were resuspended in hexane-chloroform (20:1) and precipitates, referred to as HBDorg, were air-dried and studied further. In competition assays, HBDorg dose-dependently displaced [3H]ryanodine from binding sites on RyR1 with an IC50 of 1.5 ± 0.1 μg/ml ( Ki = 0.4 ± 0.0 μg/ml). In single-channel assays using RyR1 reconstituted into a lipid bilayer, HBDorg exhibited three distinct dose-dependent effects: first it increased the open probability of RyR1 by increasing its gating frequency and dwell time in the open state, then it induced a state of reduced conductance (55% of maximum) that was more likely to occur and persist at positive holding potentials, and finally it irreversibly closed RyR1. In differentiated C2C12 myotubes, addition of HBD triggered a rise in intracellular Ca2+ that was blocked by pretreatment with ryanodine. Since persistent activation and/or closure of RyR1 results in skeletal muscle weakness, these new data suggest that HBD is responsible, at least in part, for the muscle ailment reported by hog confinement workers.

scholarly journals Single channel measurements of the calcium release channel from skeletal muscle sarcoplasmic reticulum. Activation by Ca2+ and ATP and modulation by Mg2+.

1986 ◽  
Vol 88 (5) ◽  
pp. 573-588 ◽  
Author(s):  
J S Smith ◽  
R Coronado ◽  
G Meissner
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Lipid Bilayers ◽  
Calcium Release ◽  
Single Channel ◽  
Ca Channel ◽  
Channel Measurements ◽  
Calcium Release Channel ◽  
Open Probability ◽  
Release Channel

A high-conductance (100 pS in 53 mM trans Ca2+) Ca2+ channel was incorporated from heavy-density skeletal muscle sarcoplasmic reticulum (SR) fractions into planar lipid bilayers of the Mueller-Rudin type. cis Ca2+ in the range of 2-950 microM increased open probability (Po) in single channel records without affecting open event lifetimes. Millimolar ATP was found to be as good as or better than Ca2+ in activation; however, both Ca2+ and ATP were required to fully activate the channel, i.e., to bring Po = 1. Exponential fits to open and closed single channel lifetimes suggested that the channel may exist in many distinct states. Two open and two closed states were identified when the channel was activated by either Ca2+ or ATP alone or by Ca2+ plus nucleotide. Mg2+ was found to permeate the SR Ca channel in a trans-to-cis direction such that iMg2+/iCa2+ = 0.40. cis Mg2+ was inhibitory and in single channel recordings produced an unresolvable flickering of Ca- and nucleotide-activated channels. At nanomolar cis Ca2+, 4 microM Mg2+ completely inhibited nucleotide-activated channels. In the presence of 2 microM cis Ca2+, the nucleotide-activated macroscopic Ba conductance was inhibited by cis Mg2+ with an IC50 equal to 1.5 mM.

scholarly journals Selenoprotein N is required for ryanodine receptor calcium release channel activity in human and zebrafish muscle

2008 ◽  
Vol 105 (34) ◽  
pp. 12485-12490 ◽  
Author(s):  
M. J. Jurynec ◽  
R. Xia ◽  
J. J. Mackrill ◽  
D. Gunther ◽  
T. Crawford ◽  
...  
Keyword(s):  
Ryanodine Receptor ◽  
Calcium Release ◽  
Channel Activity ◽  
Calcium Release Channel ◽  
Release Channel

scholarly journals Ryanodine receptor/calcium release channel conformations as reflected in the different effects of propranolol on its ryanodine binding and channel activity

1996 ◽  
Vol 315 (2) ◽  
pp. 377-383 ◽  
Author(s):  
Sigalit ZCHUT ◽  
Wei FENG ◽  
Varda SHOSHAN-BARMATZ
Keyword(s):  
Ryanodine Receptor ◽  
Calcium Release ◽  
Single Channel ◽  
Adenine Nucleotides ◽  
Local Anaesthetics ◽  
Inhibitory Effect ◽  
Calcium Release Channel ◽  
Release Channel ◽  
Interaction Sites ◽  
Nacl Concentration

1. Propranolol, a β-blocker, inhibited or stimulated ryanodine binding to both the membrane-bound and purified ryanodine receptor (RyR) depending on the assay conditions. At high NaCl concentrations, propranolol increased the number of ryanodine-binding sites (Bmax) with no effect on the binding affinity. In the presence of 0.2 M NaCl, ryanodine binding was inhibited by propranolol. Half-maximal inhibition was obtained at 1.2 mM and complete inhibition at 2 mM propranolol. The inhibitory effect of propranolol obtained at low NaCl concentration was not restored by increasing the NaCl concentration to 1 M. 2. Modulators of the RyR that are known to alter its conformational states, such as adenine nucleotides, Ca2+ concentration and pH, modified the effect of propranolol on ryanodine binding. In the presence of propranolol and at low NaCl concentrations, ryanodine binding was inhibited and showed no Ca2+-, pH- or time-dependence. 3. Propranolol immediately and completely blocked the channel opening of RyR reconstituted into a planar lipid bilayer. Propranolol-modified non-active channel was reactivated to a subconductive state (about 40% of the control conductance) by ATP. 4. Competition experiments between lidocaine (a stimulatory drug) or tetracaine (an inhibitory drug) and propranolol at 0.2 or 1.0 M NaCl, respectively, suggest the existence of different interaction sites for local anaesthetics and propranolol. 5. These results suggest that propranolol interacts directly with the RyR and modifies its ryanodine binding and single-channel activities. Propranolol effects are altered by the RyR conformational state, suggesting its possible use as a conformational probe for RyR.

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