Ca2+ release dynamics in parotid and pancreatic exocrine acinar cells evoked by spatially limited flash photolysis

2007 ◽  
Vol 293 (6) ◽  
pp. G1166-G1177 ◽  
Author(s):  
Jong Hak Won ◽  
William J. Cottrell ◽  
Thomas H. Foster ◽  
David I. Yule
Keyword(s):  
Latent Period ◽  
Wave Speed ◽  
Calcium Release ◽  
Flash Photolysis ◽  
Physiological Role ◽  
Acinar Cells ◽  
Apical Region ◽  
Cell Type ◽  
Fast Kinetics ◽  
Kinetics Of

Intracellular calcium concentration ([Ca2+]i) signals are central to the mechanisms underlying fluid and protein secretion in pancreatic and parotid acinar cells. Calcium release was studied in natively buffered cells following focal laser photolysis of caged molecules. Focal photolysis of caged-inositol 1,4,5 trisphosphate (InsP3) in the apical region resulted in Ca2+ release from the apical trigger zone and, after a latent period, the initiation of an apical-to-basal Ca2+ wave. The latency was longer and the wave speed significantly slower in pancreatic compared with parotid cells. Focal photolysis in basal regions evoked only limited Ca2+ release at the photolysis site and never resulted in a propagating wave. Instead, an apical-to-basal wave was initiated following a latent period. Again, the latent period was significantly longer under all conditions in pancreas than parotid. Although slower in pancreas than parotid, once initiated, the apical-to-basal wave speed was constant in a particular cell type. Photo release of caged-Ca2+ failed to evoke a propagating Ca2+ wave in either cell type. However, the kinetics of the Ca2+ signal evoked following photolysis of caged-InsP3 were significantly dampened by ryanodine in parotid but not pancreas, indicating a more prominent functional role for ryanodine receptor (RyR) following InsP3 receptor (InsP3R) activation. These data suggest that differing expression levels of InsP3R, RyR, and possibly cellular buffering capacity may contribute to the fast kinetics of Ca2+ signals in parotid compared with pancreas. These properties may represent a specialization of the cell type to effectively stimulate Ca2+-dependent effectors important for the differing primary physiological role of each gland.

scholarly journals Spatial characterisation of ryanodine-induced calcium release in mouse pancreatic acinar cells

2003 ◽  
Vol 369 (3) ◽  
pp. 441-445 ◽  
Author(s):  
Michael C. ASHBY ◽  
Ole H. PETERSEN ◽  
Alexei V. TEPIKIN
Keyword(s):  
Experimental Data ◽  
Calcium Release ◽  
Ryanodine Receptors ◽  
Acinar Cells ◽  
Pancreatic Acinar Cells ◽  
Apical Region ◽  
Low Doses ◽  
Polarized Cells ◽  
Inositol 1,4,5 Trisphosphate ◽  
Increased Sensitivity

In pancreatic acinar cells, agonists evoke intracellular Ca2+ transients which are initiated in the apical region of these polarized cells. There are contradictory experimental data concerning Ca2+ release from ryanodine receptors (RyRs) in the apical region. In the present study, we have used low doses of ryanodine to open RyRs leading to the release of Ca2+ from intracellular stores. Ryanodine causes Ca2+ release that is initiated in the apical region of the cell but is dependent upon functional inositol 1,4,5-trisphosphate receptors (IP3Rs). These results suggests that co-ordinated release from co-localized RyRs and IP3Rs underlies the increased sensitivity of the apical region to initiation of intracellular Ca2+ transients.

scholarly journals Calcium-activated chloride channels in the apical region of mouse vomeronasal sensory neurons

2012 ◽  
Vol 140 (1) ◽  
pp. 3-15 ◽  
Author(s):  
Michele Dibattista ◽  
Asma Amjad ◽  
Devendra Kumar Maurya ◽  
Claudia Sagheddu ◽  
Giorgia Montani ◽  
...  
Keyword(s):  
Sensory Neurons ◽  
Chloride Channels ◽  
Calcium Concentration ◽  
Transient Receptor Potential ◽  
Flash Photolysis ◽  
Physiological Role ◽  
Disulfonic Acid ◽  
Apical Region ◽  
Caged Calcium ◽  
Vomeronasal Sensory Neurons

The rodent vomeronasal organ plays a crucial role in several social behaviors. Detection of pheromones or other emitted signaling molecules occurs in the dendritic microvilli of vomeronasal sensory neurons, where the binding of molecules to vomeronasal receptors leads to the influx of sodium and calcium ions mainly through the transient receptor potential canonical 2 (TRPC2) channel. To investigate the physiological role played by the increase in intracellular calcium concentration in the apical region of these neurons, we produced localized, rapid, and reproducible increases in calcium concentration with flash photolysis of caged calcium and measured calcium-activated currents with the whole cell voltage-clamp technique. On average, a large inward calcium-activated current of −261 pA was measured at −50 mV, rising with a time constant of 13 ms. Ion substitution experiments showed that this current is anion selective. Moreover, the chloride channel blockers niflumic acid and 4,4′-diisothiocyanatostilbene-2,2′-disulfonic acid partially inhibited the calcium-activated current. These results directly demonstrate that a large chloride current can be activated by calcium in the apical region of mouse vomeronasal sensory neurons. Furthermore, we showed by immunohistochemistry that the calcium-activated chloride channels TMEM16A/anoctamin1 and TMEM16B/anoctamin2 are present in the apical layer of the vomeronasal epithelium, where they largely colocalize with the TRPC2 transduction channel. Immunocytochemistry on isolated vomeronasal sensory neurons showed that TMEM16A and TMEM16B coexpress in the neuronal microvilli. Therefore, we conclude that microvilli of mouse vomeronasal sensory neurons have a high density of calcium-activated chloride channels that may play an important role in vomeronasal transduction.

Mechanisms of intracellular calcium release during hormone and neurotransmitter action investigated with flash photolysis

1993 ◽  
Vol 184 (1) ◽  
pp. 105-127
Author(s):  
D. C. Ogden ◽  
K. Khodakhah ◽  
T. D. Carter ◽  
P. T. Gray ◽  
T. Capiod
Keyword(s):  
Time Course ◽  
Calcium Release ◽  
Flash Photolysis ◽  
Single Cells ◽  
Cell Types ◽  
Peripheral Tissues ◽  
Perfusion Studies ◽  
Kinetics Of ◽  
Purkinje Neurones ◽  
Fast Perfusion

To understand the complex time course of cytosolic Ca2+ signalling evoked by hormones and neurotransmitters, it is necessary to know the kinetics of steps in the second-messenger cascade, particularly cooperative and inhibitory interactions between components that might give rise to periodic fluctuations. In the case of inositol trisphosphate (InsP3)-evoked Ca2+ release, fast perfusion studies with subcellular fractions or permeabilised cells can be made if sufficient homogeneous tissue is available. Single-cell studies can be made by combining whole-cell patch-clamp techniques and microspectrofluorimetry with flash photolytic release of InsP3 to give quantitative, time-resolved data of Ca2+ release from stores. A technical description is given here of flash photolysis of caged InsP3, and the results of fast perfusion and flash photolytic experiments are reviewed. Studies of kinetics of Ca2+ release have shown that the InsP3 receptor/channel is regulated first by positive and then by negative feedback by free cytosolic Ca2+ concentration, producing a pulse of Ca2+ release having properties that may be important in the spatial propagation of Ca2+ signals within and between cells. The properties of InsP3-evoked Ca2+ release in single cells differ between peripheral tissues, such as the liver, and Purkinje neurones of the cerebellum. Purkinje neurones need 20–50 times higher InsP3 concentrations and release Ca2+ to change the free cytosolic concentration 30 times faster and to higher peak concentrations than in liver. The InsP3 receptors in the two cell types appear to differ in apparent affinity, and the greater Ca2+ efflux from stores in Purkinje cells is probably due to a high receptor density.

scholarly journals Expression and subcellular localization of the ryanodine receptor in rat pancreatic acinar cells

1999 ◽  
Vol 337 (2) ◽  
pp. 305-309 ◽  
Author(s):  
M. Fatima LEITE ◽  
Jonathan A. DRANOFF ◽  
Ling GAO ◽  
Michael H. NATHANSON
Keyword(s):  
Ryanodine Receptor ◽  
Acinar Cell ◽  
Acinar Cells ◽  
Pancreatic Acinar Cells ◽  
Apical Region ◽  
Cell Type ◽  
Excitable Cells ◽  
Release Channel ◽  
Trigger Zone

The ryanodine receptor (RyR) is the principal Ca2+-release channel in excitable cells, whereas the inositol 1,4,5-trisphosphate (InsP3) receptor (InsP3R) is primarily responsible for Ca2+ release in non-excitable cells, including epithelia. RyR also is expressed in a number of non-excitable cell types, but is thought to serve as an auxiliary or alternative Ca2+-release pathway in those cells. Here we use reverse transcription PCR to show that a polarized epithelium, the pancreatic acinar cell, expresses the type 2, but not the type 1 or 3, isoform of RyR. We furthermore use immunochemistry to demonstrate that the type 2 RyR is distributed throughout the basolateral and, to a lesser extent, the apical region of the acinar cell, but is excluded from the trigger zone, where cytosolic Ca2+ signals originate in this cell type. Since propagation of Ca2+ waves in acinar cells is sensitive to ryanodine, caffeine and Ca2+, these findings suggest that Ca2+ waves in this cell type result from the co-ordinated release of Ca2+, first from InsP3Rs in the trigger zone, then from RyRs elsewhere in the cell. RyR may play a fundamental role in Ca2+ signalling in polarized epithelia, including for Ca2+ signals initiated by InsP3.

scholarly journals Fast kinetics of calcium release induced by myo-inositol trisphosphate in permeabilized rat hepatocytes

1989 ◽  
Vol 264 (30) ◽  
pp. 17665-17673
Author(s):  
P Champeil ◽  
L Combettes ◽  
B Berthon ◽  
E Doucet ◽  
S Orlowski ◽  
...  
Keyword(s):  
Calcium Release ◽  
Inositol Trisphosphate ◽  
Rat Hepatocytes ◽  
Fast Kinetics ◽  
Kinetics Of

scholarly journals Polarized Ca2+ release in saponin-permeabilized parotid acinar cells evoked by flash photolysis of ‘caged’ inositol 1,4,5-trisphosphate

1998 ◽  
Vol 332 (3) ◽  
pp. 769-772 ◽  
Author(s):  
Akihiko TANIMURA ◽  
Yoshito MATSUMOTO ◽  
Yosuke TOJYO
Keyword(s):  
Flash Photolysis ◽  
Imaging System ◽  
Acinar Cells ◽  
Apical Region ◽  
Fluorescence Ratio ◽  
High Concentration ◽  
Parotid Acinar Cells ◽  
Inositol 1,4,5 Trisphosphate ◽  
Intracellular Organelles ◽  
Rat Parotid

In exocrine acinar cells, agonist stimulation results in a polarized Ca2+ signal, termed the ‘Ca2+ wave’, that propagates from the apical pole towards the basolateral region. We attempted to detect the inositol 1,4,5-trisphosphate (InsP3)-induced Ca2+ wave in saponin-permeabilized rat parotid acinar cells using a digital imaging system. The permeabilized acinar cells were labelled with the membrane-bound Ca2+ indicator Calcium Green C18 to detect changes in Ca2+ concentration adjacent to the membrane of intracellular organelles. Application of InsP3 was made by the photolysis of InsP3 P4(5)-1-(2-nitrophenyl)ethyl ester (caged InsP3) to expose simultaneously all regions of the permeabilized acinar cells to InsP3. The increase in fluorescence ratio following the photolysis of 0.5 µM caged InsP3 started at the apical region of the acinar cells within 0.1 s and spread towards the basolateral region, indicating that Ca2+ release from intracellular Ca2+ stores was initially evoked at the apical region. Pretreatment with thapsigargin, an inhibitor of endoplasmic reticulum Ca2+ pumps, failed to prevent the InsP3-induced Ca2+ wave, suggesting that the generation of the Ca2+ wave is not attributed to the polarized distribution of the Ca2+ pumps. The photolysis of a high concentration (10 µM) of caged InsP3 caused a homogeneous increase in the fluorescence ratio throughout the cells, indicating that all regions of intracellular Ca2+ stores similarly responded to the high concentration of InsP3. The present study is the first demonstration of the InsP3-induced Ca2+ wave in permeabilized exocrine acinar cells. The result provides fresh evidence that the apical region contains elements of intracellular Ca2+ stores particularly sensitive to InsP3 and that the Ca2+ wave results from a polarized distribution of InsP3-sensitive Ca2+ stores.

Kinetics of calcium uptake by isolated sarcoplasmic reticulum vesicles using flash photolysis of caged ATP

Biochemistry ◽  
1983 ◽  
Vol 22 (23) ◽  
pp. 5254-5261 ◽  
Author(s):  
Dorothy H. Pierce ◽  
Antonio Scarpa ◽  
Michael R. Topp ◽  
J. Kent Blasie
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Calcium Uptake ◽  
Flash Photolysis ◽  
Caged Atp ◽  
Kinetics Of

Single atom catalysts supported on N-doped graphene toward fast kinetic Li−S batteries: a theoretical study

2021 ◽  
Author(s):  
Xu Han ◽  
Zeyun Zhang ◽  
Xuefei Xu
Keyword(s):  
Theoretical Study ◽  
Single Atom ◽  
Discharge Process ◽  
Fast Kinetics ◽  
Shuttle Effect ◽  
Sufficient Stability ◽  
Doped Graphene ◽  
Fast Kinetic ◽  
Kinetics Of ◽  
Charge Discharge

To suppress the shuttle effect of lithium polysulfides and promote fast kinetics of charge−discharge process in Li−S batteries, it is essential to search promising catalysts with sufficient stability and high...

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