Use of La3+ to distinguish activity of the plasmalemmal Ca2+ pump from Na+/Ca2+ exchange in arterial myocytes

Shimizu, Hiroshi; Borin, M. L.; Blaustein, Mordecai P.

doi:10.1016/s0143-4160(97)90094-4

Cited by 51 publications

(39 citation statements)

References 35 publications

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“…Fura-2 was alternately excited at 340 and 380 nm, and the emitted fluorescence filtered at 510 nm was collected and recorded using a CCD-based imaging system running Ultraview software (Perkin-Elmer, Norwalk, CT). Thapsigargin (Sigma) was applied in Ca 2+ -free Hanks' solution containing 0.5 mM LaCl 3 to block Ca 2+ extrusion across the plasma membrane 31 . Dye calibration was achieved by applying experimentally determined constants to the standard equation: [Ca 2+ ] = K d β(R−R min )/(R max −R).…”

Section: Calcium Measurement and Apoptosis Assaymentioning

confidence: 99%

The endoplasmic reticulum gateway to apoptosis by Bcl-XL modulation of the InsP3R

et al. 2005

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Members of the Bcl-2 protein family modulate outer mitochondrial membrane permeability to control apoptosis1 ,2 . However, these proteins also localize to the endoplasmic reticulum (ER), the functional significance of which is controversial 3, 4. Here we provide evidence that anti-apoptotic Bcl-2 proteins regulate the inositol 1,4,5-trisphosphate receptor (InsP 3 R) ER Ca 2+ release channel resulting in increased cellular apoptotic resistance and enhanced mitochondrial bioenergetics. Anti-apoptotic Bcl-X L interacts with the carboxyl terminus of the InsP 3 R and sensitizes single InsP 3 R channels in ER membranes to low [InsP 3 ], enhancing Ca 2+ and InsP 3 -dependent regulation of channel activity in vitro and in vivo, reducing ER Ca 2+ content and stimulating mitochondrial energetics. The proapoptotic proteins Bax and tBid antagonize this effect by blocking the biochemical interaction of Bcl-X L with the InsP 3 R. These data support a novel model in which Bcl-X L is a direct effector of the InsP 3 R, increasing its sensitivity to InsP 3 and enabling ER Ca 2+ release to be more sensitively coupled to extracellular signals. As a consequence, cells are protected against apoptosis by a more sensitive and dynamic coupling of ER to mitochondria through Ca 2+ -dependent signal transduction that enhances cellular bioenergetics and preserves survival.A central feature of molecular models of apoptosis is the control of outer mitochondrial membrane permeability by Bcl-2-related proteins. The pro-apoptotic Bcl-2-related proteins Bax and Bak are required to initiate cytochrome c release from mitochondria in response to diverse apoptotic stimuli 1,5 . Anti-apoptotic properties of Bcl-2 and Bcl-X L have been attributed to their ability to antagonize Bax/Bak by forming heterodimers that prevent their oligomerization and apoptosis initiation 6 . Pro-and anti-apoptotic Bcl-2 proteins also localize to the ER 3,7 , and it is now recognized that the ER has an important role in regulating apoptosis 8,9 . The ER is thought to contribute to apoptosis through its role as the principle Ca 2+ storage organelle in cells [8][9][10][11] . At physiological levels, Ca 2+ released from the ER during

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Section: Calcium Measurement and Apoptosis Assaymentioning

confidence: 99%

The endoplasmic reticulum gateway to apoptosis by Bcl-XL modulation of the InsP3R

et al. 2005

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“…They were imaged on a TILL Photonics system with a monochromator (TILL Photonics, Planegg, Germany) and a progressive line-scan digital camera (Imago, Scientific Instruments, Madison, WI). The cells were stimulated with 0.5 M carbamylcholine (CCh) to induce Ca 2ϩ oscillations, then 1 mM La 3ϩ was added to block both Ca 2ϩ entry and the plasma membrane Ca 2ϩ pump (29)(30)(31)(32)(33). Fig.…”

Section: Experimental Verificationmentioning

confidence: 99%

Control of calcium oscillations by membrane fluxes

Sneyd

Tsaneva-Atanasova

et al. 2004

Proc. Natl. Acad. Sci. U.S.A.

126

116

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It is known that Ca 2؉ influx plays an important role in the modulation of inositol trisphosphate-generated Ca 2؉ oscillations, but controversy over the mechanisms underlying these effects exists. In addition, the effects of blocking membrane transport or reducing Ca 2؉ entry vary from one cell type to another; in some cell types oscillations persist in the absence of Ca 2؉ entry (although their frequency is affected), whereas in other cell types oscillations depend on Ca 2؉ entry. We present theoretical and experimental evidence that membrane transport can control oscillations by controlling the total amount of Ca 2؉ in the cell (the Ca 2؉ load). Our model predicts that the cell can be balanced at a point where small changes in the Ca 2؉ load can move the cell into or out of oscillatory regions, resulting in the appearance or disappearance of oscillations. Our theoretical predictions are verified by experimental results from HEK293 cells. We predict that the role of Ca 2؉ influx during an oscillation is to replenish the Ca 2؉ load of the cell. Despite this prediction, even during the peak of an oscillation the cell or the endoplasmic reticulum may not be measurably depleted of Ca 2؉ .I n response to an increased concentration of inositol trisphosphate (IP 3 ), oscillations in the concentration of free intracellular calcium (Ca 2ϩ ) occur in many cell types and are important for the control of many cellular functions (1-4). In nonexcitable cells, such as epithelial cells, these oscillations occur as the result of Ca 2ϩ flux into and out of the endoplasmic reticulum (ER). However, although the oscillations result from the cycling of Ca 2ϩ between the ER and the cytoplasm, the transport of Ca 2ϩ across the cell membrane can have a dramatic effect on these oscillations.Although Ca 2ϩ influx is known to be important, disagreement exists, first, over the mechanisms by which Ca 2ϩ influx is modulated during a Ca 2ϩ oscillation, and, second, over the role played by Ca 2ϩ influx. The capacitative entry hypothesis proposes that depletion of ER Ca 2ϩ causes enhanced entry of Ca 2ϩ across the plasma membrane (5-9). Often, although not necessarily, in this scenario, Ca 2ϩ entry is necessary for the refilling of the ER, and thus oscillation frequency is controlled by the refilling time (10, 11). Although capacitative entry is certainly an important factor during the response to a maximal stimulus, other investigators have pointed to a lack of direct evidence that it plays an important role during smaller stimuli that generate oscillatory behavior (12). They maintain that Ca 2ϩ influx, under these conditions, is controlled by a noncapacitative pathway involving arachidonic acid and that the purpose of the influx is to increase the likelihood that low levels of IP 3 will induce Ca 2ϩ release from internal stores (13). This controversy is complicated by the fact that, in some cell types, Ca 2ϩ oscillations persist in the absence of Ca 2ϩ influx (14-16), whereas in other cell types, oscillations depend absolutely on influx (17, ...

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“…Like the oscillatory response, the single spike response only occurred at lower concentrations of BBS (Table I). (24) and inhibits the activity of the plasma membrane Ca 2ϩ -dependent ATPase (25). It is also the most potent metal ion to block the sodium-calcium exchanger in vesicle systems (26) and in the squid axon (27).…”

Section: Effects Of Bbs Stimulation On [Ca 2ϩ ] I -Bbs Stimulation Ofmentioning

confidence: 99%

Multiple Protein Kinase Pathways Are Involved in Gastrin-releasing Peptide Receptor-regulated Secretion

Hellmich¹,

Ives²,

Udupi³

et al. 1999

Journal of Biological Chemistry

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Use of La3+ to distinguish activity of the plasmalemmal Ca2+ pump from Na+/Ca2+ exchange in arterial myocytes

Cited by 51 publications

References 35 publications

The endoplasmic reticulum gateway to apoptosis by Bcl-XL modulation of the InsP3R

The endoplasmic reticulum gateway to apoptosis by Bcl-XL modulation of the InsP3R

Control of calcium oscillations by membrane fluxes

Multiple Protein Kinase Pathways Are Involved in Gastrin-releasing Peptide Receptor-regulated Secretion

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