scholarly journals Peptide fragments of the dihydropyridine receptor can modulate cardiac ryanodine receptor channel activity and sarcoplasmic reticulum Ca2+ release

2004 ◽  
Vol 379 (1) ◽  
pp. 161-172 ◽  
Author(s):  
Angela F. DULHUNTY ◽  
Suzanne M. CURTIS ◽  
Louise CENGIA ◽  
Magdalena SAKOWSKA ◽  
Marco G. CASAROTTO
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Lipid Bilayers ◽  
Ryanodine Receptor ◽  
Helical Structure ◽  
Dihydropyridine Receptor ◽  
Dependent Manner ◽  
Channel Activity ◽  
Peptide Fragments ◽  
Cardiac Sarcoplasmic Reticulum ◽  
Receptor Channel

We show that peptide fragments of the dihydropyridine receptor II–III loop alter cardiac RyR (ryanodine receptor) channel activity in a cytoplasmic Ca2+-dependent manner. The peptides were AC (Thr-793–Ala-812 of the cardiac dihydropyridine receptor), AS (Thr-671–Leu-690 of the skeletal dihydropyridine receptor), and a modified AS peptide [AS(D-R18)], with an extended helical structure. The peptides added to the cytoplasmic side of channels in lipid bilayers at ≥10 nM activated channels when the cytoplasmic [Ca2+] was 100 nM, but either inhibited or did not affect channel activity when the cytoplasmic [Ca2+] was 10 or 100 µM. Both activation and inhibition were independent of bilayer potential. Activation by AS, but not by AC or AS(D-R18), was reduced at peptide concentrations >1 µM in a voltage-dependent manner (at +40 mV). In control experiments, channels were not activated by the scrambled AS sequence (ASS) or skeletal II–III loop peptide (NB). Resting Ca2+ release from cardiac sarcoplasmic reticulum was not altered by peptide AC, but Ca2+-induced Ca2+ release was depressed. Resting and Ca2+-induced Ca2+ release were enhanced by both the native and modified AS peptides. NMR revealed (i) that the structure of peptide AS(D-R18) is not influenced by [Ca2+] and (ii) that peptide AC adopts a helical structure, particularly in the region containing positively charged residues. This is the first report of specific functional interactions between dihydropyridine receptor A region peptides and cardiac RyR ion channels in lipid bilayers.

cADP-ribose releases Ca2+ from cardiac sarcoplasmic reticulum independently of ryanodine receptor

1997 ◽  
Vol 273 (3) ◽  
pp. H1082-H1089 ◽  
Author(s):  
P. Lahouratate ◽  
J. Guibert ◽  
J. F. Faivre
Keyword(s):  
Endoplasmic Reticulum ◽  
Sarcoplasmic Reticulum ◽  
Ryanodine Receptor ◽  
Sea Urchin ◽  
Calcium Release ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Cardiac Sarcoplasmic Reticulum ◽  
Consistent Effect ◽  
Cyclic Adp Ribose

Cyclic ADP-ribose (cADPR), an endogenous metabolite of beta-NAD+, activates Ca2+ release from endoplasmic reticulum in sea urchin eggs via the ryanodine receptor (RyR) pathway. A similar role has been proposed in cardiac sarcoplasmic reticulum (SR), although this remains controversial. We therefore investigated the ability of cADPR to induce Ca2+ release from canine cardiac SR microsomes using fluo 3 to monitor extravesicular Ca2+ concentration. We found that cADPR induced Ca2+ release in a concentration-dependent manner, whereas neither its precursor, NAD+, nor its metabolite, ADP-ribose, elicited a consistent effect. In addition, an additive effect on calcium release between cADPR and 9-Me-7-Br-eudistomin-D (MBED), an activator of RyR, was found as well as no cross-desensitization between cADPR and MBED. Specific blockers of the RyR did not abolish the cADPR-induced Ca2+ release. These results provide evidence for cADPR-induced Ca2+ release from dog cardiac SR via a novel mechanism which is independent of RyR activation.

scholarly journals A model for ionic conduction in the ryanodine receptor channel of sheep cardiac muscle sarcoplasmic reticulum.

1992 ◽  
Vol 100 (3) ◽  
pp. 495-517 ◽  
Author(s):  
A Tinker ◽  
A R Lindsay ◽  
A J Williams
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Binding Site ◽  
Ryanodine Receptor ◽  
Binding Sites ◽  
Ionic Conduction ◽  
Divalent Cations ◽  
Rate Theory ◽  
Cardiac Sarcoplasmic Reticulum ◽  
Alkaline Earths ◽  
Receptor Channel

A model is developed for ionic conduction in the sheep cardiac sarcoplasmic reticulum ryanodine receptor channel based on Eyring rate theory. A simple scheme is proposed founded on single-ion occupancy and an energy profile with four barriers and three binding sites. The model is able to quantitatively predict a large number of conduction properties of the purified and native receptor with monovalent and divalent cations as permeant species. It suggests that discrimination between divalent and monovalent cations is due to a high affinity central binding site and a process that favors the passage of divalent cations between binding sites. Furthermore, differences in conductance among the group Ia cations and among the alkaline earths are largely explained by differing affinity at this putative central binding site.

Enhanced dihydropyridine receptor channel activity in the presence of ryanodine receptor

Nature ◽  
1996 ◽  
Vol 380 (6569) ◽  
pp. 72-75 ◽  
Author(s):  
Junichi Nakai ◽  
Robert T. Dirksen ◽  
Hanh T. Nguyen ◽  
Isaac N. Pessah ◽  
Kurt G. Beam ◽  
...  
Keyword(s):  
Ryanodine Receptor ◽  
Dihydropyridine Receptor ◽  
Channel Activity ◽  
Receptor Channel

scholarly journals Divalent cation conduction in the ryanodine receptor channel of sheep cardiac muscle sarcoplasmic reticulum.

1992 ◽  
Vol 100 (3) ◽  
pp. 479-493 ◽  
Author(s):  
A Tinker ◽  
A J Williams
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Ryanodine Receptor ◽  
Single Channel ◽  
Divalent Cations ◽  
Channel Conductance ◽  
Single Channel Conductance ◽  
Cardiac Sarcoplasmic Reticulum ◽  
Conduction Pathway ◽  
Significant Difference ◽  
Receptor Channel

The conduction properties of the alkaline earth divalent cations were determined in the purified sheep cardiac sarcoplasmic reticulum ryanodine receptor channel after reconstitution into planar phospholipid bilayers. Under bi-ionic conditions there was little difference in permeability among Ba2+, Ca2+, Sr2+, and Mg2+. However, there was a significant difference between the divalent cations and K+, with the divalent cations between 5.8- and 6.7-fold more permeant. Single-channel conductances were determined under symmetrical ionic conditions with 210 mM Ba2+ and Sr2+ and from the single-channel current-voltage relationship under bi-ionic conditions with 210 mM divalent cations and 210 mM K+. Single-channel conductance ranged from 202 pS for Ba2+ to 89 pS for Mg2+ and fell in the sequence Ba2+ greater than Sr2+ greater than Ca2+ greater than Mg2+. Near-maximal single-channel conductance is observed at concentrations as low as 2 mM Ba2+. Single-channel conductance and current measurements in mixtures of Ba(2+)-Mg2+ and Ba(2+)-Ca2+ reveal no anomalous behavior as the mole fraction of the ions is varied. The Ca(2+)-K+ reversal potential determined under bi-ionic conditions was independent of the absolute value of the ion concentrations. The data are compatible with the ryanodine receptor channel acting as a high conductance channel displaying moderate discrimination between divalent and monovalent cations. The channel behaves as though ion translocation occurs in single file with at most one ion able to occupy the conduction pathway at a time.

scholarly journals Direct binding of verapamil to the ryanodine receptor channel of sarcoplasmic reticulum

1990 ◽  
Vol 58 (2) ◽  
pp. 471-481 ◽  
Author(s):  
H.H. Valdivia ◽  
C. Valdivia ◽  
J. Ma ◽  
R. Coronado
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Ryanodine Receptor ◽  
Direct Binding ◽  
Receptor Channel

Low concentrations of A23187 increase calcium uptake by cardiac sarcoplasmic reticulum

1985 ◽  
Vol 249 (6) ◽  
pp. H1211-H1215
Author(s):  
J. J. Murray ◽  
A. V. Kuzmin ◽  
P. W. Reed ◽  
D. O. Levitsky
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Calcium Uptake ◽  
Atp Hydrolysis ◽  
Ionophore A23187 ◽  
Uptake System ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Cardiac Sarcoplasmic Reticulum ◽  
Calcium Dependent ◽  
Uptake Measurement

The divalent cation ionophore A23187 at a concentration of 1 nM produced an increased rate of oxalate-supported calcium uptake by isolated cardiac sarcoplasmic reticulum as determined by absorbance changes of the calcium-sensitive dye murexide. Addition of a higher concentration of A23187 (0.1 microM) produced a decreased rate of calcium uptake. Measurement of the time during which ATPase was activated by calcium addition also suggested an increased rate of calcium uptake in the presence of 1 nM A23187 and an inhibition of calcium uptake at a higher concentration of the ionophore (0.1 microM). Ca2+-stimulated ATPase activity and incorporation of 32Pi from [gamma-32P]ATP into sarcoplasmic reticular proteins were increased by A23187 at concentrations of 1 nM or greater. An increased coupling of calcium uptake to ATP hydrolysis was observed at 1 nM A23187, while concentrations of the ionophore greater than or equal to 10 nM produced a decreased coupling. Addition of an inhibitor of cyclic AMP-dependent protein kinase decreased the rate of calcium uptake, and this inhibition was reversed in a concentration-dependent manner by 0.01–1 nM A23187. These data suggest that A23187 can activate a mechanism involving the calcium-dependent phosphorylation of protein that may regulate the activity of the calcium uptake system of the sarcoplasmic reticulum. These observations appear to provide an explanation for some of the contractile effects of A23187 in intact cardiac muscle that suggest that treatment with the ionophore results in an increased sequestration of calcium from the cytoplasm.

Caffeine sensitivity of native RyR channels from normal and malignant hyperthermic pigs: effects of a DHPR II–III loop peptide

2004 ◽  
Vol 286 (4) ◽  
pp. C821-C830 ◽  
Author(s):  
Esther M. Gallant ◽  
James Hart ◽  
Kevin Eager ◽  
Suzanne Curtis ◽  
Angela F. Dulhunty
Keyword(s):  
Skeletal Muscle ◽  
Sarcoplasmic Reticulum ◽  
Malignant Hyperthermia ◽  
Lipid Bilayers ◽  
Ryanodine Receptor ◽  
High Affinity ◽  
Enhanced Sensitivity ◽  
Skeletal Muscle Contraction ◽  
Activation Mechanisms ◽  
Standard Tests

Enhanced sensitivity to caffeine is part of the standard tests for susceptibility to malignant hyperthermia (MH) in humans and pigs. The caffeine sensitivity of skeletal muscle contraction and Ca2+ release from the sarcoplasmic reticulum is enhanced, but surprisingly, the caffeine sensitivity of purified porcine ryanodine receptor Ca2+-release channels (RyRs) is not affected by the MH mutation (Arg615Cys). In contrast, we show here that native malignant hyperthermic pig RyRs (incorporated into lipid bilayers with RyR-associated lipids and proteins) were activated by caffeine at 100- to 1,000-fold lower concentrations than native normal pig RyRs. In addition, the results show that the mutant ryanodine receptor channels were less sensitive to high-affinity activation by a peptide (CS) that corresponds to a part of the II–III loop of the skeletal dihydropyridine receptor (DHPR). Furthermore, subactivating concentrations of peptide CS enhanced the response of normal pig and rabbit RyRs to caffeine. In contrast, the caffeine sensitivity of MH RyRs was not enhanced by the peptide. These novel results showed that in MH-susceptible pig muscles 1) the caffeine sensitivity of native RyRs was enhanced, 2) the sensitivity of RyRs to a skeletal II–III loop peptide was depressed, and 3) an interaction between the caffeine and peptide CS activation mechanisms seen in normal RyRs was lost.

scholarly journals Sphingosylphosphocholine modulates the ryanodine receptor/calcium-release channel of cardiac sarcoplasmic reticulum membranes

1997 ◽  
Vol 322 (1) ◽  
pp. 327-333 ◽  
Author(s):  
Romeo BETTO ◽  
Alessandra TERESI ◽  
Federica TURCATO ◽  
Giovanni SALVIATI ◽  
Roger A. SABBADINI ◽  
...  
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Ryanodine Receptor ◽  
Calcium Release ◽  
Cardiac Tissue ◽  
Ruthenium Red ◽  
Release Mechanism ◽  
Calcium Release Channel ◽  
Release Channel ◽  
Cardiac Sarcoplasmic Reticulum ◽  
High Calcium

Sphingosylphosphocholine (SPC) modulates Ca2+ release from isolated cardiac sarcoplasmic reticulum membranes; 50 ƁM SPC induces the release of 70Ő80% of the accumulated calcium. SPC releases calcium from cardiac sarcoplasmic reticulum through the ryanodine receptor, since the release is inhibited by the ryanodine receptor channel antagonists ryanodine, Ruthenium Red and sphingosine. In intact cardiac myocytes, even in the absence of extracellular calcium, SPC causes a rise in diastolic Ca2+, which is greatly reduced when the sarcoplasmic reticulum is depleted of Ca2+ by prior thapsigargin treatment. SPC action on the ryanodine receptor is Ca2+-dependent. SPC shifts to the left the Ca2+-dependence of [3H]ryanodine binding, but only at high pCa values, suggesting that SPC might increase the sensitivity to calcium of the Ca2+-induced Ca2+-release mechanism. At high calcium concentrations (pCa 4.0 or lower), where [3H]ryanodine binding is maximally stimulated, no effect of SPC is observed. We conclude that SPC releases calcium from cardiac sarcoplasmic reticulum membranes by activating the ryanodine receptor and possibly another intracellular Ca2+-release channel, the sphingolipid Ca2+-release-mediating protein of endoplasmic reticulum (SCaMPER) [Mao, Kim, Almenoff, Rudner, Kearney and Kindman (1996) Proc. Natl. Acad. Sci. U.S.A 93, 1993Ő1996], which we have identified for the first time in cardiac tissue.

scholarly journals Divalent cation activation and inhibition of single calcium release channels from sheep cardiac sarcoplasmic reticulum.

1990 ◽  
Vol 95 (5) ◽  
pp. 981-1005 ◽  
Author(s):  
R H Ashley ◽  
A J Williams
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Lipid Bilayers ◽  
Calcium Release ◽  
Single Channel ◽  
Fluctuation Analysis ◽  
Open Probability ◽  
Cardiac Sarcoplasmic Reticulum ◽  
Channel Opening ◽  
Lifetime Analysis ◽  
Single Channel Currents

Single Ca2+ release channels from vesicles of sheep cardiac junctional sarcoplasmic reticulum have been incorporated into uncharged planar lipid bilayers. Single-channel currents were recorded from Ca2(+)-activated channels that had a Ca2+ conductance of approximately 90 pS. Channel open probability increased sublinearly as the concentration of free Ca2+ was raised at the myoplasmic face, and without additional agonists the channels could not be fully activated even by 100 microM free Ca2+. Lifetime analysis revealed a minimum of two open and three closed states, and indicates that Ca2+ activated the channels by interacting with at least one of the closed states to increase the rate of channel opening. Correlations between adjacent lifetimes suggested there were at least two pathways between the open- and closed-state aggregates. An analysis of bursting behavior also revealed correlations between successive burst lengths and the number of openings per burst. The latter had two geometric components, providing additional evidence for at least two open states. One component appeared to comprise unit bursts, and the lifetime of most of these fell within the dominant shorter open-time distribution associated with over 90% of all openings. A cyclic gating scheme is proposed, with channel activation regulated by the binding of Ca2+ to a closed conformation of the channel protein. Mg2+ may inhibit activation by competing for this binding site, but lifetime and fluctuation analysis suggested that once activated the channels continue to gate normally.

scholarly journals The recombinant dihydropyridine receptor II–III loop and partly structured ‘C’ region peptides modify cardiac ryanodine receptor activity

2005 ◽  
Vol 385 (3) ◽  
pp. 803-813 ◽  
Author(s):  
Angela F. DULHUNTY ◽  
Yamuna KARUNASEKARA ◽  
Suzanne M. CURTIS ◽  
Peta J. HARVEY ◽  
Philip G. BOARD ◽  
...  
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Secondary Structure ◽  
Cardiac Muscle ◽  
Ryanodine Receptor ◽  
Structure Analysis ◽  
Room Temperature ◽  
Random Coil ◽  
Cardiac Sarcoplasmic Reticulum ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling

A physical association between the II–III loop of the DHPR (dihydropryidine receptor) and the RyR (ryanodine receptor) is essential for excitation–contraction coupling in skeletal, but not cardiac, muscle. However, peptides corresponding to a part of the II–III loop interact with the cardiac RyR2 suggesting the possibility of a physical coupling between the proteins. Whether the full II–III loop and its functionally important ‘C’ region (cardiac DHPR residues 855–891 or skeletal 724–760) interact with cardiac RyR2 is not known and is examined in the present study. Both the cardiac DHPR II–III loop (CDCL) and cardiac peptide (Cc) activated RyR2 channels at concentrations >10 nM. The skeletal DHPR II–III loop (SDCL) activated channels at ≤100 nM and weakly inhibited at ≥1 μM. In contrast, skeletal peptide (Cs) inhibited channels at all concentrations when added alone, or was ineffective if added in the presence of Cc. Ca2+-induced Ca2+ release from cardiac sarcoplasmic reticulum was enhanced by CDCL, SDCL and the C peptides. The results indicate that the interaction between the II–III loop and RyR2 depends critically on the ‘A’ region (skeletal DHPR residues 671–690 or cardiac 793–812) and also involves the C region. Structure analysis indicated that (i) both Cs and Cc are random coil at room temperature, but, at 5 °C, have partial helical regions in their N-terminal and central parts, and (ii) secondary-structure profiles for CDCL and SDCL are similar. The data provide novel evidence that the DHPR II–III loop and its C region interact with cardiac RyR2, and that the ability to interact is not isoform-specific.

Sign in / Sign up

Export Citation Format

Share Document