Measurement of Free Ca2+ in Sarcoplasmic Reticulum in Perfused Rabbit Heart Loaded with 1,2-Bis(2-amino-5,6-difluorophenoxy)ethane-N,N,N′,N′-tetraacetic Acid by 19F NMR

Chen, Weina; Steenbergen, Charles; Levy, Louis; Vance, Joseph E.; London, Robert E.; Murphy, Elizabeth

doi:10.1074/jbc.271.13.7398

Cited by 87 publications

(51 citation statements)

References 35 publications

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“…Elevation of extracellular [Ca 2ϩ ] created the conditions for an increased SR Ca 2ϩ loading, as previously reported in cardiac myocytes (35,36), except that a pretreatment of 1 h in 10 mM [Ca 2ϩ ] o was needed for vascular myocytes to reach a steady state. We found that inhibition of Ca 2ϩ accumulation into the SR by cyclopiazonic acid completely suppressed the caffeineinduced Ca 2ϩ responses, whereas removal of external Ca 2ϩ for 10 s had no effect on the increased caffeine-induced Ca 2ϩ responses in 10 mM [Ca 2ϩ ] o , indicating that they were strictly dependent on Ca 2ϩ release from the SR.…”

Section: Discussionmentioning

confidence: 78%

Contribution of Ryanodine Receptor Subtype 3 to Ca2+Responses in Ca2+-overloaded Cultured Rat Portal Vein Myocytes

Mironneau

Coussin

Jeyakumar

et al. 2001

Journal of Biological Chemistry

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Since the description of a Ca 2ϩ -induced Ca 2ϩ release mechanism in skeletal muscle (1), the function of ryanodine receptor channels (RYRs) 1 have been widely studied in both skeletal and cardiac muscles (2-7) and more recently in smooth muscle (8,9). After the cloning and sequencing of three genes encoding different RYR subtypes, the localization and role of each RYR subtype in Ca 2ϩ signaling have begun to be studied. Of the three RYRs, RYR subtype 3 (RYR3) is the most widely expressed (10), whereas RYR1 and RYR2 are mainly found in skeletal and cardiac muscles, respectively (11, 12). However, in arterial and venous smooth muscles, the three RYR subtypes have been identified (13,14), but their role in Ca 2ϩ release is still unclear.The regulation of the different RYR subtypes has been extensively studied using single channel recordings in lipid bilayers. The single channel properties of RYR subtypes are rather similar, i.e. they form a large conductance channel permeable to monovalent and divalent cations, which can be activated by ATP, caffeine, and submicromolar concentrations of Ca 2ϩ ; inhibited by Mg 2ϩ , ruthenium red, and millimolar concentrations of Ca 2ϩ ; and modulated by ryanodine (15-17). However, differences in responses to cyclic ADP-ribose and caffeine as well as in sensitivities to Ca 2ϩ activation and Ca 2ϩ inactivation have been reported between RYR1 and RYR3 and between RYR3s cloned from skeletal and smooth muscles (17)(18)(19)(20). It has been proposed that these differences may result from the expression of different splice variants of RYR3 (21). The physiological contribution of the different RYR subtypes to Ca 2ϩ signaling has been addressed first by using either RYR1 and RYR2 knockout mice (12, 22) or RYR3 knockout mice (23-25). In RYR1-null myotubes in culture, the Ca 2ϩ release from the sarcoplasmic reticulum (SR) in response to increases in cytosolic Ca 2ϩ concentration ([Ca 2ϩ ] i ) or caffeine is strongly reduced, but a similar decrease in caffeine sensitivity is also observed in RYR3-null neonatal myocytes, suggesting a possible co-contribution of each RYR subtype to Ca 2ϩ signaling, at least at some stages of myogenesis. Accordingly, it has been recently proposed that, in embryonic skeletal muscle, both RYR1 and RYR3 may co-contribute to Ca 2ϩ release during Ca 2ϩ sparks (25). In addition, Ca 2ϩ sparks produced independently in RYR1-or RYR3-null cells reveal similar spatio-temporal parameters (26). Another approach using antisense oligonucleotides, that specifically targeted each one of the RYR subtypes, has been used to determine which RYR subtypes are responsible for channels (8, 9, 27, 28), and their localization corresponds to coupling areas between the plasma membrane and the SR (28,29). In rat portal vein myocytes, spatial and temporal recruitment of Ca 2ϩ sparks results in propagating Ca 2ϩ waves, which trigger cell contraction (30).

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Section: Discussionmentioning

confidence: 78%

Contribution of Ryanodine Receptor Subtype 3 to Ca2+Responses in Ca2+-overloaded Cultured Rat Portal Vein Myocytes

Mironneau

Coussin

Jeyakumar

et al. 2001

Journal of Biological Chemistry

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“…Regarding the data obtained at 22 [19] to near 1 mM [20], with most of the obtained figures around 400-800 M [21][22][23][24][25][26][27]. On the other hand, NMR measurements [21], skeletal muscle cells [25,27] and rabbit heart cells [28] The new probe has also a very important technical and experimental advantage over the previous aequorin probes. All the [Ca 2+ ] ER measurements carried out before with these probes were performed in cells previously depleted of Ca 2+ , because the high Ca 2+ content of the ER precluded reconstitution with the coelenterazine cofactor.…”

Section: Discussionmentioning

confidence: 89%

Ca2+ homeostasis in the endoplasmic reticulum measured with a new low-Ca2+-affinity targeted aequorin

et al. 2013

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a b s t r a c tWe use here a new very low-Ca 2+ -affinity targeted aequorin to measure the [Ca 2+ ] between 0.1 and 3 mM, and was only partially affected by mitochondrial membrane depolarization. Instead, it was significantly reduced by loading cells with chelators, and the fast chelator BAPTA was much more effective than the slow chelator EGTA. This suggests that local [Ca 2+ ] microdomains connecting the store operated Ca 2+ channels with the ER Ca 2+ pumps may be important during refilling.

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“…We can thus confidently conclude that, given the same intrinsic leak and a similar uptake rate for the two cations, in steady state, the concentration of Ca2+ in the SR lumen should not significantly differ from that of Sr2+ and thus be around 1 mM. Using a completely different experimental approach, l9FNMR in cells loaded with 1,2-bis(2-amino-5,6-difluorophenoxy)ethone-N,N,N',N'-tetraacetic adic (TF-BAPTA), Chen et al (1996) data suggest that the influx of divalent cations generates local high concentrations sensed by the SERCAs, but with little affect on the increases occurring in the bulk cytosol. The importance for the physiology of skeletal muscles of these local high concentrations could be twofold: on the one hand, they may be critical to ensure a more rapid and efficient reloading of the SR, on the other they may participate in the activation of Ca2+-induced Ca + release, a known characteristic of the ryanodine receptors, whose relevance in skeletal muscle is presently still highly debated (Rios et al, 1992;Schneider, 1994).…”

Section: Discussionmentioning

confidence: 99%

Subcellular analysis of Ca2+ homeostasis in primary cultures of skeletal muscle myotubes.

Brini

Giorgi

Murgia

et al. 1997

MBoC

116

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Specifically targeted aequorin chimeras were used for studying the dynamic changes of Ca2+ concentration in different subcellular compartments of differentiated skeletal muscle myotubes. For the cytosol, mitochondria, and nucleus, the previously described chimeric aequorins were utilized; for the sarcoplasmic reticulum (SR), a new chimera (srAEQ) was developed by fusing an aequorin mutant with low Ca2+ affinity to the resident protein calsequestrin. By using an appropriate transfection procedure, the expression of the recombinant proteins was restricted, within the culture, to the differentiated myotubes, and the correct sorting of the various chimeras was verified with immunocytochemical techniques. Single-cell analysis of cytosolic Ca2+ concentration ([Ca2+]c) with fura-2 showed that the myotubes responded, as predicted, to stimuli known to be characteristic of skeletal muscle fibers, i.e., KCl-induced depolarization, caffeine, and carbamylcholine. Using these stimuli in cultures transfected with the various aequorin chimeras, we show that: 1) the nucleoplasmic Ca2+ concentration ([Ca2+]n) closely mimics the [Ca2+Ic, at rest and after stimulation, indicating a rapid equilibration of the two compartments also in this cell type; 2) on the contrary, mitochondria amplify 4-6-fold the [Ca2+]c increases; and 3) the lumenal concentration of Ca2+ within the SR ([Ca2+Isr) is much higher than in the other compartments (>100 JIM), too high to be accurately measured also with the aequorin mutant with low Ca2+ affinity. An indirect estimate of the resting value (-1-2 mM) was obtained using Sr2+, a surrogate of Ca2+ which, because of the lower affinity of the photoprotein for this cation, elicits a lower rate of aequorin consumption. With Sr2 , the kinetics and amplitudes of the changes in [cationii]sr evoked by the various stimuli could also be directly analyzed. INTRODUCTION Stimulus-contraction (MacLennan et al., 1985;Lytton and MacLennan, 1988;Burk et al., 1989) and the overall molecular architecture of the pump (Toyoshima et al., 1993) as well as the kinetic details of the transport mechanism (Inesi et al., 1992) have been clarified. Similarly, the Ca2+ release channels, also known as the ryanodine receptors (Takeshima et al., 1989;Otsu et al., 1990;Giannini et al., 1992;Sorrentino and Volpe, 1993) (Rizzuto et al., 1992). Through the addition to the cDNA coding for the native photoprotein of specific targeting sequences or through its fusion with suitable polypeptides, we have produced a series of new aequorin chimeras targeted to different intracellular locations, the mitochondrial matrix (Rizzuto et al., 1992, nucleoplasm (Brini et al., 1993nucleoplasm (Brini et al., , 1994 (Franzini-Armstrong et al., 1987) and is thought to play a major role in intralumenal Ca2' binding (Ikemoto et al., 1989;Lytton and Nigam, 1992;Damiani and Margreth, 1994 Primary cultures of skeletal muscle were prepared from newborn rats (2-3 days) as described previously (Cantini et al., 1994). In brief, posterior limb muscles were remove...

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Measurement of Free Ca2+ in Sarcoplasmic Reticulum in Perfused Rabbit Heart Loaded with 1,2-Bis(2-amino-5,6-difluorophenoxy)ethane-N,N,N′,N′-tetraacetic Acid by 19F NMR

Cited by 87 publications

References 35 publications

Contribution of Ryanodine Receptor Subtype 3 to Ca2+Responses in Ca2+-overloaded Cultured Rat Portal Vein Myocytes

Contribution of Ryanodine Receptor Subtype 3 to Ca2+Responses in Ca2+-overloaded Cultured Rat Portal Vein Myocytes

Ca2+ homeostasis in the endoplasmic reticulum measured with a new low-Ca2+-affinity targeted aequorin

Subcellular analysis of Ca2+ homeostasis in primary cultures of skeletal muscle myotubes.

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