Plasma membrane IP3 receptors

2006 ◽  
Vol 34 (5) ◽  
pp. 910-912 ◽  
Author(s):  
C.W. Taylor ◽  
O. Dellis
Keyword(s):  
Plasma Membrane ◽  
Cell Receptor ◽  
Ip3 Receptors ◽  
Animal Cells ◽  
Patch Clamp Recording ◽  
Comparable Amount ◽  
Whole Cell Patch Clamp ◽  
Functional Consequences ◽  
Dt40 Cells ◽  
Stimulation Of

IP3Rs (inositol 1,4,5-trisphosphate receptors) are expressed in the membranes of non-mitochondrial organelles in most animal cells, but their presence and role within the plasma membrane are unclear. Whole-cell patch–clamp recording from DT40 cells expressing native or mutated IP3Rs has established that each cell expresses just two or three functional IP3Rs in its plasma membrane. Only approx. 50% of the Ca2+ entry evoked by stimulation of the B-cell receptor is mediated by store-operated Ca2+ entry, the remainder appears to be carried by the IP3Rs expressed in the plasma membrane. Ca2+ entering the cell via just two large-conductance IP3Rs is likely to have very different functional consequences from the comparable amount of Ca2+ that enters through the several thousand low-conductance store-operated channels.

scholarly journals Local circuit input to the medullary reticular formation from the rostral nucleus of the solitary tract

2008 ◽  
Vol 295 (5) ◽  
pp. R1391-R1408 ◽  
Author(s):  
J. Nasse ◽  
D. Terman ◽  
S. Venugopal ◽  
G. Hermann ◽  
R. Rogers ◽  
...  
Keyword(s):  
Patch Clamp ◽  
Reticular Formation ◽  
Calcium Imaging ◽  
Neonatal Rat ◽  
Solitary Tract ◽  
Patch Clamp Recording ◽  
Whole Cell ◽  
Cell Patch Clamp ◽  
Whole Cell Patch Clamp ◽  
Stimulation Of

The intermediate reticular formation (IRt) subjacent to the rostral (gustatory) nucleus of the solitary tract (rNST) receives projections from the rNST and appears essential to the expression of taste-elicited ingestion and rejection responses. We used whole cell patch-clamp recording and calcium imaging to characterize responses from an identified population of prehypoglossal neurons in the IRt to electrical stimulation of the rNST in a neonatal rat pup slice preparation. The calcium imaging studies indicated that IRt neurons could be activated by rNST stimulation and that many neurons were under tonic inhibition. Whole cell patch-clamp recording revealed mono- and polysynaptic projections from the rNST to identified prehypoglossal neurons. The projection was primarily excitatory and glutamatergic; however, there were some inhibitory GABAergic projections, and many neurons received excitatory and inhibitory inputs. There was also evidence of disinhibition. Overall, bath application of GABAA antagonists increased the amplitude of excitatory currents, and, in several neurons, stimulation of the rNST systematically decreased inhibitory currents. We have hypothesized that the transition from licks to gapes by natural stimuli, such as quinine monohydrochloride, could occur via such disinhibition. We present an updated dynamic model that summarizes the complex synaptic interface between the rNST and the IRt and demonstrates how inhibition could contribute to the transition from ingestion to rejection.

A P2X7 receptor stimulates plasma membrane trafficking in the FRTL rat thyrocyte cell line

2004 ◽  
Vol 287 (4) ◽  
pp. C992-C1002 ◽  
Author(s):  
M. Y. Kochukov ◽  
A. K. Ritchie
Keyword(s):  
Plasma Membrane ◽  
Cell Line ◽  
Fluorescence Imaging ◽  
Receptor Activation ◽  
Disulfonic Acid ◽  
Receptor Subtypes ◽  
Patch Clamp Recording ◽  
Thyroid Cells ◽  
Rat Thyroid ◽  
Stimulation Of

Thyroid cells express a variety of P2Y and P2X purinergic receptor subtypes. G protein-coupled P2Y receptors influence a wide variety of thyrocyte-specific functions; however, functional P2X receptor-gated channels have not been observed. In this study, we used whole cell patch-clamp recording and fluorescence imaging of the plasma membrane marker FM1-43 to examine the effects of extracellular ATP on membrane permeability and trafficking in the Fisher rat thyroid cell line FRTL. We found a cation-selective current that was gated by ATP and 2′,3′- O-(4-benzoylbenzoyl)-ATP but not by UTP. The ATP-evoked currents were inhibited by pyridoxal phosphate 6-azophenyl-2′,4′-disulfonic acid, adenosine 5′-triphosphate-2′,3′-dialdehyde, 100 μM Zn2+, and 50 μM Cu2+. Fluorescence imaging revealed pronounced, temperature-sensitive stimulation of exocytosis and membrane internalization by ATP with the same pharmacological profile as observed for activation of current. The EC50 for ATP stimulation of internalization was 440 μM in saline containing 2 mM Ca2+ and 2 mM Mg2+, and 33 μM in low-Mg2+, nominally Ca2+-free saline. Overall, the results are most consistent with activation of a P2X7 receptor by ATP4−. However, low permeability to N-methyl-d-glucamine+ and the propidium cation YO-PRO-1 indicates absence of the cytolytic pore that often accompanies P2X7 receptor activation. ATP stimulation of internalization occurs in Na+-free, Ca2+-free, or low-Mg2+ saline and therefore does not depend on cation influx through the ATP-gated channel. We conclude that ATP activation of a P2X7 receptor stimulates membrane internalization in FRTL cells via a transduction pathway that does not depend on cation influx.

Potassium and chloride currents in rat gastric enterochromaffin-like cells

1996 ◽  
Vol 270 (5) ◽  
pp. G739-G745 ◽  
Author(s):  
Donald D. F. Loo ◽  
George Sachs ◽  
Christian Prinz
Keyword(s):  
Plasma Membrane ◽  
Time Course ◽  
Gradient Centrifugation ◽  
Reversal Potential ◽  
Resting Potential ◽  
Chloride Currents ◽  
Whole Cell Patch Clamp ◽  
Ecl Cell ◽  
Steady State Current ◽  
Stimulation Of

The gastric enterochromaffin-like (ECL) cell se cretes histamine in response to secretagogues (gastrin, acetylcholine) by calcium signaling-dependent exocytosis of intracellular vacuoles containing the hormone. ECL cells were isolated from rat fundic gastric mucosa by elutriation and density-gradient centrifugation. Currents across the plasma membrane were measured using whole cell patch-clamp methods. These cells had a low conductance of 0.5 nS and resting potential of -50 mV Depolarization activated a K+ current that was blocked by Ba2+. Steady-state current in absence of K+ was due to Cl- because of the magnitude of the reversal potential and the effects of Cl- removal. Stimulation of secretion by gastrin, cholecystokinin octapeptide (CCK-8), and the phorbol ester 12-O-tetradecanoylphorbol 13-acetate activated the Cl- conductance with a time course similar to that of histamine release. Therefore the ECL cell maintains a high resting potential, largely due to K+ currents, and stimulation of secretion activates a Cl- current, perhaps deriving from the membrane of the secretory granule that fuses with the plasma membrane. The depolarization that ensues may activate the K+ current to maintain the membrane potential during exocytosis. exocytosis; acid secretion Submitted on July 31, 1995 Accepted on October 2, 1995

scholarly journals Intracellular Ca2+Release Triggers Translocation of Membrane Marker FM1–43 from the Extracellular Leaflet of Plasma Membrane into Endoplasmic Reticulum in T Lymphocytes

2005 ◽  
Vol 280 (16) ◽  
pp. 16377-16382 ◽  
Author(s):  
Sepehr Dadsetan ◽  
Vyacheslav Shishkin ◽  
Alla F. Fomina
Keyword(s):  
Endoplasmic Reticulum ◽  
Plasma Membrane ◽  
T Cell ◽  
T Cell Receptor ◽  
Membrane Trafficking ◽  
Cell Receptor ◽  
Multivesicular Bodies ◽  
Close Proximity ◽  
Intracellular Ca ◽  
Stimulation Of

Stimulation of T cell receptor in lymphocytes enhances Ca2+signaling and accelerates membrane trafficking. The relationships between these processes are not well understood. We employed membrane-impermeable lipid marker FM1–43 to explore membrane trafficking upon mobilization of intracellular Ca2+in Jurkat T cells. We established that liberation of intracellular Ca2+with T cell receptor agonist phytohemagglutinin P or with Ca2+-mobilizing agents ionomycin or thapsigargin induced accumulation of FM1–43 within the lumen of the endoplasmic reticulum (ER), nuclear envelope (NE), and Golgi. FM1–43 loading into ER-NE and Golgi was not mediated via the cytosol because other organelles such as mitochondria and multivesicular bodies located in close proximity to the FM1–43-containing ER were free of dye. Intralumenal FM1–43 accumulation was observed even when Ca2+signaling in the cytosol was abolished by the removal of extracellular Ca2+. Our findings strongly suggest that release of intracellular Ca2+may create continuity between the extracellular leaflet of the plasma membrane and the lumenal membrane leaflet of the ER by a mechanism that does not require global cytosolic Ca2+elevation.

Unitary excitatory synaptic currents in preganglionic neurons mediated by two distinct groups of interneurons in neonatal rat sacral parasympathetic nucleus

1996 ◽  
Vol 76 (1) ◽  
pp. 215-226 ◽  
Author(s):  
I. Araki ◽  
W. C. De Groat
Keyword(s):  
Nmda Receptor Antagonist ◽  
Neonatal Rat ◽  
Patch Clamp Recording ◽  
Lumbosacral Spinal Cord ◽  
Postsynaptic Currents ◽  
Preganglionic Neurons ◽  
Sacral Parasympathetic Nucleus ◽  
Whole Cell Patch Clamp ◽  
Two Populations ◽  
Stimulation Of

1. Excitatory postsynaptic currents (EPSCs) in parasympathetic preganglionic neurons (PGNs) were examined by the use of the whole cell patch-clamp recording technique in slice preparations of the neonatal rat lumbosacral spinal cord. Synaptic responses were evoked in PGNs by extracellular stimulation of a neighboring interneuron. 2. Stimulation of interneurons medial to the sacral parasympathetic nucleus (SPN) elicited EPSCs or inhibitory postsynaptic currents in 58 and 11%, respectively, of PGNs. Stimulation of interneurons dorsal to the SPN evoked EPSCs in 70% of PGNs. 3. EPSCs occurred at short latency (2.1 ms) and were usually elicited in an all-or-none manner, indicating that they were monosynaptic and mediated by a single interneuron (i.e., unitary). 4. EPSCs were mediated by both non-N-methyl-D-aspartate (non-NMDA) and NMDA receptors. 5. Unitary excitatory postsynaptic potentials evoked by single stimuli did not induce action potentials in PGNs, but repetitive stimulation (> 20 Hz) of the single interneurons could evoke firing of PGNs. 2-Amino-5-phosphonovalerate, an NMDA receptor antagonist, reduced the synaptic depolarization induced in PGNs by high-frequency interneuronal impulses. 6. EPSCs mediated by dorsal interneurons were smaller in amplitude (36.3 +/- 15.7 pA, mean +/- SD) than EPSCs mediated by medial interneurons (88.4 +/- 45.7 pA). 7. Paired-pulse facilitation of EPSCs was observed in PGNs (147.2 +/- 26.2%). The degree of facilitation was higher in dorsal (174.6 +/- 10.3%) than in medial interneuronal pathways (120.9 +/- 3.6%). Within each of interneuronal pathways the degree of facilitation was independent of the magnitude of the unitary EPSC. 8. The results show that PGNs receive monosynaptic glutamatergic excitatory inputs from two distinct populations of interneurons in the dorsal and medial regions of the SPN. These two populations of interneurons are likely to have different functions in the regulation of the preganglionic outflow to the pelvic organs.

Dynamic clustering of IP3 receptors by IP3

2012 ◽  
Vol 40 (2) ◽  
pp. 325-330 ◽  
Author(s):  
Taufiq Rahman
Keyword(s):  
Inhibitory Influence ◽  
Dynamic Clustering ◽  
Ip3 Receptors ◽  
Patch Clamp Recording ◽  
Open Probability ◽  
Low Concentrations ◽  
Inositol 1,4,5 Trisphosphate ◽  
Small Clusters ◽  
Dt40 Cells ◽  
Intracellular Messenger

The versatility of Ca2+ as an intracellular messenger stems largely from the impressive, but complex, spatiotemporal organization of the Ca2+ signals. For example, the latter when initiated by IP3 (inositol 1,4,5-trisphosphate) in many cells manifest hierarchical recruitment of elementary Ca2+ release events (‘blips’ and then ‘puffs’) en route to global regenerative Ca2+ waves as the cellular IP3 concentration rises. The spacing of IP3Rs (IP3 receptors) and their regulation by Ca2+ are key determinants of these spatially organized Ca2+ signals, but neither is adequately understood. IP3Rs have been proposed to be pre-assembled into clusters, but their composition, geometry and whether clustering affects IP3R behaviour are unknown. Using patch-clamp recording from the outer nuclear envelope of DT40 cells expressing rat IP3R1 or IP3R3, we have recently shown that low concentrations of IP3 cause IP3Rs to aggregate rapidly and reversibly into small clusters of approximately four IP3Rs. At resting cytosolic Ca2+ concentrations, clustered IP3Rs open independently, but with lower open probability, shorter open duration and lesser IP3-sensitivity than lone IP3Rs. This inhibitory influence of clustering on IP3R is reversed when the [Ca2+]i (cytosolic free Ca2+ concentration) increases. The gating of clustered IP3Rs exposed to increased [Ca2+]i is coupled: they are more likely to open and close together, and their simultaneous openings are prolonged. Dynamic clustering of IP3Rs by IP3 thus exposes them to local Ca2+ rises and increases their propensity for a CICR (Ca2+-induced Ca2+ rise), thereby facilitating hierarchical recruitment of the elementary events that underlie all IP3-evoked Ca2+ signals.

Muscarinic stimulation increases basal Ca2+ and inhibits spontaneous Ca2+ transients in murine colonic myocytes

2001 ◽  
Vol 280 (3) ◽  
pp. C689-C700 ◽  
Author(s):  
Orline Bayguinov ◽  
Brian Hagen ◽  
Kenton M. Sanders
Keyword(s):  
Nonselective Cation Channel ◽  
Inhibitory Effects ◽  
Patch Clamp Recording ◽  
Fk 506 ◽  
Whole Cell Patch Clamp ◽  
Outward Currents ◽  
Receptor Interactions ◽  
Muscarinic Stimulation ◽  
Spontaneous Transient Outward Currents ◽  
Stimulation Of

Localized Ca2+ transients in isolated murine colonic myocytes depend on Ca2+ release from inositol 1,4,5-trisphosphate (IP3) receptors. Localized Ca2+ transients couple to spontaneous transient outward currents (STOCs) and mediate hyperpolarization responses in these cells. We used confocal microscopy and whole cell patch-clamp recording to investigate how muscarinic stimulation, which causes formation of IP3, can suppress Ca2+ transients and STOCs that might override the excitatory nature of cholinergic responses. ACh (10 μM) reduced localized Ca2+ transients and STOCs, and these effects were associated with a rise in basal cytosolic Ca2+. These effects of ACh were mimicked by generalized rises in basal Ca2+ caused by ionomycin (250–500 nM) or elevated external Ca2+ (6 mM). Atropine (10 μM) abolished the effects of ACh. Pretreatment of cells with nicardipine (1 μM), or Cd2+ (200 μM) had no effect on responses to ACh. An inhibitor of phospholipase C, U-73122, blocked Ca2+ transients and STOCs but did not affect the increase in basal Ca2+ after ACh stimulation. Xestospongin C (Xe-C; 5 μM), a membrane-permeable antagonist of IP3 receptors, blocked spontaneous Ca2+ transients but did not prevent the increase of basal Ca2+ in response to ACh. Gd3+(10 μM), a nonselective cation channel inhibitor, prevented the increase in basal Ca2+ after ACh and increased the frequency and amplitude of Ca2+ transients and waves. Another inhibitor of receptor-mediated Ca2+ influx channels, SKF-96365, also prevented the rise in basal Ca2+after ACh and increased Ca2+ transients and development of Ca2+ waves. FK-506, an inhibitor of FKBP12/IP3 receptor interactions, had no effect on the rise in basal Ca2+ but blocked the inhibitory effects of increased basal Ca2+ and ACh on Ca2+transients. These results suggest that the rise in basal Ca2+ that accompanies muscarinic stimulation of colonic muscles inhibits localized Ca2+ transients that could couple to activation of Ca2+-activated K+channels and reduce the excitatory effects of ACh.

Localization of Adenosine Triphosphatase Activity in the Phleom of Nicotiana Tabacum

1972 ◽  
Vol 30 ◽  
pp. 230-231
Author(s):  
James Cronshaw ◽  
Jamison E. Gilder
Keyword(s):  
Plasma Membrane ◽  
Atpase Activity ◽  
Adenosine Triphosphatase ◽  
Higher Plants ◽  
High Surface ◽  
Root Tip ◽  
Animal Cells ◽  
Physiological Processes ◽  
Tip Cells ◽  
Atpase Localization

Adenosine triphosphatase (ATPase) activity has been shown to be associated with numerous physiological processes in both plants and animal cells. Biochemical studies have shown that in higher plants ATPase activity is high in cell wall preparations and is associated with the plasma membrane, nuclei, mitochondria, chloroplasts and lysosomes. However, there have been only a few ATPase localization studies of higher plants at the electron microscope level. Poux (1967) demonstrated ATPase activity associated with most cellular organelles in the protoderm cells of Cucumis roots. Hall (1971) has demonstrated ATPase activity in root tip cells of Zea mays. There was high surface activity largely associated with the plasma membrane and plasmodesmata. ATPase activity was also demonstrated in mitochondria, dictyosomes, endoplasmic reticulum and plastids.

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