Inositol trisphosphate activates a voltage-dependent calcium influx in Xenopus oocytes

1987 ◽  
Vol 231 (1262) ◽  
pp. 27-36 ◽  
Keyword(s):  
Chloride Channels ◽  
Calcium Influx ◽  
Inositol Trisphosphate ◽  
Ringer Solution ◽  
Chloride Ions ◽  
Bathing Solution ◽  
Calcium Dependent ◽  
Large Numbers ◽  
Voltage Dependent ◽  
Oocyte Membrane

Injection of inositol trisphosphate (IP 3 ) into oocytes of Xenopus laevis induces the appearance of a transient inward ( T in ) current on hyper­polarization of the membrane. This current is carried largely by chloride ions, but is shown to depend on extracellular calcium, because it is abolished by removal of calcium in the bathing fluid or by addition of manganese. Recordings with aequorin as an intracellular calcium indi­cator show that a calcium influx is activated by hyperpolarization after intracellular injection of IP 3 as well as after activation of neurotrans­mitter receptors thought to mediate a rise in IP 3 . Furthermore, by substituting barium for calcium in the bathing solution, inward barium currents can be recorded during hyperpolarization. We conclude that intracellular IP 3 modulates the activity of a class of calcium channels, so as to allow an influx of calcium on hyperpolarization. In normal Ringer solution this then leads to the generation of a chloride current, because of the large numbers of calcium-dependent chloride channels in the oocyte membrane.

Tonic regulation of vascular tone by nitric oxide and chloride ions in rat isolated small coronary arteries

2000 ◽  
Vol 279 (6) ◽  
pp. H2604-H2611 ◽  
Author(s):  
Jonathan E. Graves ◽  
Iain A. Greenwood ◽  
William A. Large
Keyword(s):  
Nitric Oxide ◽  
Coronary Arteries ◽  
Vascular Tone ◽  
Physiological Saline ◽  
Chloride Ions ◽  
Bathing Solution ◽  
Contractile Mechanism ◽  
Mechanical Removal ◽  
Voltage Dependent ◽  
Physiological Saline Solution

We have investigated the involvement of Cl− in regulating vascular tone in rat isolated coronary arteries mounted on a small vessel myograph. Mechanical removal of the endothelium or inhibition of nitric oxide (NO) synthase with N ω-nitro-l-arginine methyl ester (l-NAME, 10−4 M) led to contraction of rat coronary arteries, and these contractions were sensitive to nicardipine (10−6 M). This suggests that release of NO tonically inhibits a contractile mechanism that involves voltage-dependent Ca2+ channels. In arteries contracted withl-NAME, switching the bathing solution to physiological saline solution with a reduced Cl− concentration potentiated the contraction. DIDS (5 × 10−6–3 × 10−4 M) caused relaxation of l-NAME-induced tension (IC50 = 55 ± 10 μM), providing evidence for a role of Cl−. SITS (10−5–5 × 10−4 M) did not affectl-NAME-induced tension, suggesting that DIDS is not acting by inhibition of anion exchange. Mechanical removal of the endothelium led to contraction of arteries, which was sensitive to DIDS (IC50 = 50 ± 8 μM) and was not affected by SITS. This study suggests that, in rat coronary arteries, NO tonically suppresses a contractile mechanism that involves a Cl−conductance.

scholarly journals Mechanism of the Inhibition of Ca2+-Activated Cl− Currents by Phosphorylation in Pulmonary Arterial Smooth Muscle Cells

2006 ◽  
Vol 128 (1) ◽  
pp. 73-87 ◽  
Author(s):  
Jeff E. Angermann ◽  
Amy R. Sanguinetti ◽  
James L. Kenyon ◽  
Normand Leblanc ◽  
Iain A. Greenwood
Keyword(s):  
Chloride Channels ◽  
Voltage Dependence ◽  
Critical Voltage ◽  
Kinetic Properties ◽  
Calcium Dependent ◽  
Membrane Rupture ◽  
Channel Opening ◽  
Voltage Dependent ◽  
Pulmonary Arterial ◽  
The Impact

The aim of the present study was to provide a mechanistic insight into how phosphatase activity influences calcium-activated chloride channels in rabbit pulmonary artery myocytes. Calcium-dependent Cl− currents (IClCa) were evoked by pipette solutions containing concentrations between 20 and 1000 nM Ca2+ and the calcium and voltage dependence was determined. Under control conditions with pipette solutions containing ATP and 500 nM Ca2+, IClCa was evoked immediately upon membrane rupture but then exhibited marked rundown to ∼20% of initial values. In contrast, when phosphorylation was prohibited by using pipette solutions containing adenosine 5′-(β,γ-imido)-triphosphate (AMP-PNP) or with ATP omitted, the rundown was severely impaired, and after 20 min dialysis, IClCa was ∼100% of initial levels. IClCa recorded with AMP-PNP–containing pipette solutions were significantly larger than control currents and had faster kinetics at positive potentials and slower deactivation kinetics at negative potentials. The marked increase in IClCa was due to a negative shift in the voltage dependence of activation and not due to an increase in the apparent binding affinity for Ca2+. Mathematical simulations were carried out based on gating schemes involving voltage-independent binding of three Ca2+, each binding step resulting in channel opening at fixed calcium but progressively greater “on” rates, and voltage-dependent closing steps (“off” rates). Our model reproduced well the Ca2+ and voltage dependence of IClCa as well as its kinetic properties. The impact of global phosphorylation could be well mimicked by alterations in the magnitude, voltage dependence, and state of the gating variable of the channel closure rates. These data reveal that the phosphorylation status of the Ca2+-activated Cl− channel complex influences current generation dramatically through one or more critical voltage-dependent steps.

Effect of intracellular pH on depolarization-evoked calcium influx in human sperm

2004 ◽  
Vol 287 (6) ◽  
pp. C1688-C1696 ◽  
Author(s):  
Juan J. Fraire-Zamora ◽  
Marco T. González-Martínez
Keyword(s):  
Intracellular Ph ◽  
Calcium Release ◽  
Calcium Influx ◽  
Human Sperm ◽  
Calcium Dependent ◽  
Voltage Dependent ◽  
Sigmoid Curve ◽  
Voltage Dependent Calcium Channels ◽  
Calcium Permeability

Human sperm are endowed with putative voltage-dependent calcium channels (VDCC) that produce measurable increases in intracellular calcium concentration ([Ca2+]i) in response to membrane depolarization with potassium. These channels are blocked by nickel, inactivate in 1–2 min in calcium-deprived medium, and are remarkably stimulated by NH4Cl, suggesting a role for intracellular pH (pHi). In a previous work, we showed that calcium permeability through these channels increases approximately onefold during in vitro “capacitation,” a calcium-dependent process that sperm require to fertilize eggs. In this work, we have determined the pHi dependence of sperm VDCC. Simultaneous depolarization and pHi alkalinization with NH4Cl induced an [Ca2+]i increase that depended on the amount of NH4Cl added. VDCC stimulation as a function of pHi showed a sigmoid curve in the 6.6–7.2 pHi range, with a half-maximum stimulation at pH ∼7.00. At higher pHi (≥7.3), a further stimulation occurred. Calcium release from internal stores did not contribute to the stimulating effect of pHi because the [Ca2+]i increase induced by progesterone, which opens a calcium permeability pathway that does not involve gating of VDCC, was unaffected by ammonium. The ratio of pHi-stimulated-to-nonstimulated calcium influx was nearly constant at different test depolarization values. Likewise, depolarization-induced calcium influx in pHi-stimulated and nonstimulated cells was equally blocked by nickel. In our capacitating conditions pHi increased 0.11 pH units, suggesting that the calcium influx stimulation observed during sperm capacitation might be partially caused by pHi alkalinization. Additionally, a calcium permeability pathway triggered exclusively by pHi alkalinization was detected.

Flickery block of single CFTR chloride channels by intracellular anions and osmolytes

1996 ◽  
Vol 271 (2) ◽  
pp. C628-C634 ◽  
Author(s):  
P. Linsdell ◽  
J. W. Hanrahan
Keyword(s):  
Chloride Channels ◽  
Single Channel ◽  
Chinese Hamster Ovary Cells ◽  
Specific Interaction ◽  
Chinese Hamster ◽  
Chloride Concentration ◽  
Chloride Ion ◽  
Chloride Ions ◽  
Outward Rectification ◽  
Voltage Dependent

Cystic fibrosis transmembrane conductance regulator (CFTR) is a phosphorylation- and nucleotide-dependent chloride channel. Single CFTR currents recorded on cell show slight outward rectification, which has previously been suggested to be due to an asymmetrical chloride ion gradient or to a specific interaction between permeant intracellular anions and the channel. Using a single-channel recording from Chinese hamster ovary cells stably expressing CFTR, we have found that both the sparingly permeant anion glutamate and the impermeant anion gluconate cause a rapid, voltage-dependent block of CFTR channels when applied to the intracellular, but not the extracellular, face of excised patches. Both the affinity and the voltage dependence of block were affected by the extracellular chloride concentration in a manner consistent with chloride ions being able to repel these blocking ions from the pore. These results are discussed in terms of previous models of CFTR current outward rectification, and it is suggested that this rectification may result from a combination of asymmetrical chloride concentrations and voltage-dependent block of the channel by large cytoplasmic anions. In addition, we find that CFTR conductance is decreased by high concentrations of intracellular sucrose, sorbitol, and urea in a manner consistent with a rapid block of the channel by these molecules.

scholarly journals Effect of Propolis Preparations on Transepithelial Electrical Potential, Resistance, and Ion Transport in In Vitro Study

2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
Paulina Smyk ◽  
Iga Hołyńska-Iwan ◽  
Dorota Olszewska-Słonina
Keyword(s):  
Electrical Resistance ◽  
Ussing Chamber ◽  
Electrical Potential ◽  
In Vitro Study ◽  
Ethanol Extract ◽  
Ringer Solution ◽  
Chloride Ions ◽  
Propolis Extract ◽  
Ions Transport

Background. Propolis and its ethanol extract show positive germicidal, bacteriostatic, and anti-inflammatory antioxidants and regenerative properties after use on the surface of the skin. Propolis is in common use in production of cosmetics and in folk medicine. The influence of this resinous mixture on ion channels, channels located in skin cells membranes and skin electrical resistance, was not explained. Objective. The main aim of the study was the evaluation of electrophysiological skin parameters during mechanical and chemical-mechanical stimulation after use of ethanol extract of propolis and propolis ointment in comparison with iso-osmotic Ringer solution. Methods. Skin fragments were taken from white New Zealand rabbits and distributed into three experimental groups which were incubated in ethanol extract of propolis (EEP), propolis ointment, and Ringer solution. Then they were placed in a Ussing chamber to measure electrophysiological parameters values. Results. In this study the influence of EEP on changes in value of electrical potential during block of chloride ions transport at the same time was observed. Ethanol propolis extract dissolved in water increases the transepidermal sodium ions transport in contrast to propolis ointment. Conclusion. The way of preparation cosmetics, which contain propolis, has effects on transepidermal ions transport in the rabbit’s skin. The value of skin electrical resistance is changing with penetration depth of active propolis substances contained in cosmetics.

Reciprocal inhibition of voltage-gated potassium currents (IK(V)) by activation of cannabinoid CB1and dopamine D1receptors in ON bipolar cells of goldfish retina

2005 ◽  
Vol 22 (1) ◽  
pp. 55-63 ◽  
Author(s):  
SHIH-FANG FAN ◽  
STEPHEN YAZULLA
Keyword(s):  
G Protein ◽  
Receptor Agonist ◽  
Lucifer Yellow ◽  
Reciprocal Inhibition ◽  
Receptor Activation ◽  
Light Signal ◽  
Bipolar Cells ◽  
Protein G ◽  
Calcium Dependent ◽  
Voltage Dependent

Cannabinoid CB1receptor (viaGs) and dopamine D2receptor (viaGi/o) antagonistically modulate goldfish cone membrane currents. As ON bipolar cells have CB1and D1receptors, but not D2receptors, we focused on whether CB1receptor agonist and dopamine interact to modulate voltage-dependent outward membrane K+currentsIK(V)of the ON mixed rod/cone (Mb) bipolar cells. Whole-cell currents were recorded from Mb bipolar cells in goldfish retinal slices. Mb bipolar cells were identified by intracellular filling with Lucifer yellow. The bath solution was calcium-free and contained 1 mM cobalt to block indirect calcium-dependent effects. Dopamine (10 μM) consistently increasedIK(V)by a factor of 1.57 ± 0.12 (S.E.M.,n= 15). A CB receptor agonist, WIN 55212-2 (0.25–1 μM), had no effect, but 4 μM WIN 55212-2 suppressedIK(V)by 60%. IfIK(V)was first increased by 10 μM dopamine, application of WIN 55212-2 (0.25–1 μM) reversibly blocked the effect of dopamine even though these concentrations of WIN 55212-2 had no effect of their own. If WIN 55212-2 was applied first and dopamine (10 μM) was added to the WIN-containing solution, 0.1 μM WIN 55212-2 blocked the effect of dopamine. All effects of WIN 55212-2 were blocked by coapplication of SR 141716A (CB1antagonist) and pretreatment with pertussis toxin (blocker of Gi/o) indicating actionviaCB1receptor activation of G protein Gi/o. Coactivation of CB1and D1receptors on Mb bipolar cells produces reciprocal effects onIK(V). The CB1-evoked suppression ofIK(V)is mediated by G protein Gi/o, whereas the D1-evoked enhancement is mediated by G protein Gs. As dopamine is a retinal “light” signal, these data support our notion that endocannabinoids function as a “dark” signal, interacting with dopamine to set retinal sensitivity.

Altered frequency-dependent inactivation and steady-state inactivation of polyglutamine-expanded α1A in SCA6

2007 ◽  
Vol 292 (3) ◽  
pp. C1078-C1086 ◽  
Author(s):  
Haiyan Chen ◽  
Erika S. Piedras-Rentería
Keyword(s):  
Steady State ◽  
Late Onset ◽  
Spinocerebellar Ataxia Type ◽  
Gain Of Function ◽  
Calcium Dependent ◽  
Spinocerebellar Ataxia Type 6 ◽  
Dependent Inactivation ◽  
Voltage Dependent ◽  
Steady State Inactivation ◽  
Activity Dependent

Spinocerebellar ataxia type 6 (SCA6) is a neurodegenerative disease of the cerebellum and inferior olives characterized by a late-onset cerebellar ataxia and selective loss of Purkinje neurons ( 15 , 16 ). SCA6 arises from an expansion of the polyglutamine tract located in exon 47 of the α1A (P/Q-type calcium channel) gene from a nonpathogenic size of 4 to 18 glutamines (CAG4–18) to CAG19–33 in SCA6. The molecular basis of SCA6 is poorly understood. To date, the biophysical properties studied in heterologous systems support both a gain and a loss of channel function in SCA6. We studied the behavior of the human α1A isoform, previously found to elicit a gain of function in disease ( 41 ), focusing on properties in which the COOH terminus of the channel is critical for function: we analyzed the current properties in the presence of β4- and β2a-subunits (both known to interact with the α1A COOH terminus), current kinetics of activation and inactivation, calcium-dependent inactivation and facilitation, voltage-dependent inactivation, frequency dependence, and steady-state activation and inactivation properties. We found that SCA6 channels have decreased activity-dependent inactivation and a depolarizing shift (+6 mV) in steady-state inactivation properties consistent with a gain of function.

Levobupivacaine-induced contraction of isolated rat aorta is calcium dependent

2011 ◽  
Vol 89 (7) ◽  
pp. 467-476 ◽  
Author(s):  
Ji Seok Baik ◽  
Ju-Tae Sohn ◽  
Seong-Ho Ok ◽  
Jae-Gak Kim ◽  
Hui-Jin Sung ◽  
...  
Keyword(s):  
Methylene Blue ◽  
Smooth Muscle ◽  
Calcium Influx ◽  
Rat Aorta ◽  
Isometric Tension ◽  
Guanosine Monophosphate ◽  
Response Curves ◽  
Calcium Dependent ◽  
Isolated Rat

Levobupivacaine is a long-acting local anesthetic that intrinsically produces vasoconstriction in isolated vessels. The goals of this study were to investigate the calcium-dependent mechanism underlying levobupivacaine-induced contraction of isolated rat aorta in vitro and to elucidate the pathway responsible for the endothelium-dependent attenuation of levobupivacaine-induced contraction. Isolated rat aortic rings were suspended to record isometric tension. Cumulative levobupivacaine concentration–response curves were generated in either the presence or absence of the antagonists verapamil, nifedipine, SKF-96365, 2-aminoethoxydiphenylborate, Gd3+, NW-nitro-l-arginine methyl ester (L-NAME), 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), and methylene blue, either alone or in combination. Verapamil, nifedipine, SKF-96365, 2-aminoethoxydiphenylborate, low calcium concentrations, and calcium-free Krebs solution attenuated levobupivacaine-induced contraction. Gd3+ had no effect on levobupivacaine-induced contraction. Levobupivacaine increased intracellular calcium levels in vascular smooth muscle cells. L-NAME, ODQ, and methylene blue increased levobupivacaine-induced contraction in endothelium-intact aorta. SKF-96365 attenuated calcium-induced contraction in a previously calcium-free isotonic depolarizing solution containing 100 mmol/L KCl. Levobupivacaine-induced contraction of rat aortic smooth muscle is mediated primarily by calcium influx from the extracellular space mainly via voltage-operated calcium channels and, in part, by inositol 1,4,5-trisphosphate receptor-mediated release of calcium from the sarcoplasmic reticulum. The nitric oxide – cyclic guanosine monophosphate pathway is involved in the endothelium-dependent attenuation of levobupivacaine-induced contraction.

Stimulation of 5-HT2 Receptors in Prefrontal Pyramidal Neurons Inhibits Cav1.2 L-Type Ca2+Currents Via a PLCβ/IP3/Calcineurin Signaling Cascade

2002 ◽  
Vol 87 (5) ◽  
pp. 2490-2504 ◽  
Author(s):  
Michelle Day ◽  
Patricia A. Olson ◽  
Josef Platzer ◽  
Joerg Striessnig ◽  
D. James Surmeier
Keyword(s):  
Pyramidal Neurons ◽  
Inositol Trisphosphate ◽  
Cell Voltage ◽  
Signaling Cascade ◽  
Channel Modulation ◽  
Receptor Modulation ◽  
Bath Application ◽  
Voltage Dependent ◽  
Intracellular Ca ◽  
Layer V

There is growing evidence linking alterations in serotonergic signaling in the prefrontal cortex to the etiology of schizophrenia. Prefrontal pyramidal neurons are richly innervated by serotonergic fibers and express high levels of serotonergic 5-HT2-class receptors. It is unclear, however, how activation of these receptors modulates cellular activity. To help fill this gap, whole cell voltage-clamp and single-cell RT-PCR studies of acutely isolated layer V–VI prefrontal pyramidal neurons were undertaken. The vast majority (>80%) of these neurons had detectable levels of 5-HT2A or 5-HT2C receptor mRNA. Bath application of 5-HT2 agonists inhibited voltage-dependent Ca2+ channel currents. L-type Ca2+ channels were a particularly prominent target of this signaling pathway. The L-type channel modulation was blocked by disruption of Gαq signaling or by inhibition of phospholipase Cβ. Antagonism of intracellular inositol trisphosphate signaling, chelation of intracellular Ca2+, or depletion of intracellular Ca2+ stores also blocked this modulation. Inhibition of the Ca2+-dependent phosphatase calcineurin prevented receptor-mediated modulation of L-type currents. Last, the 5-HT2 receptor modulation was robustly expressed in neurons from Cav1.3 knockout mice. These findings argue that 5-HT2receptors couple through Gαq proteins to trigger a phospholipase Cβ/inositol trisphosphate signaling cascade resulting in the mobilization of intracellular Ca2+, activation of calcineurin, and inhibition of Cav1.2 L-type Ca2+currents. This modulation and its blockade by atypical neuroleptics could have wide-ranging effects on synaptic integration and long-term gene expression in deep-layer prefrontal pyramidal neurons.

Expression of myogenic constrictor tone in the aorta of hypertensive rats

2001 ◽  
Vol 280 (4) ◽  
pp. R968-R975 ◽  
Author(s):  
Michelle Rapacon-Baker ◽  
Fan Zhang ◽  
Michael L. Pucci ◽  
Hui Guan ◽  
Alberto Nasjletti
Keyword(s):  
Protein Kinase C ◽  
Protein Kinase ◽  
Calcium Channels ◽  
Thoracic Aorta ◽  
Calcium Influx ◽  
Intraluminal Pressure ◽  
Hypertensive Rats ◽  
Calcium Dependent ◽  
Kinase C ◽  
Basal Tone

We investigated the effect of intraluminal pressure or stretch on the development of tone in the descending thoracic aorta from rats with aortic coarctation-induced hypertension of 7–14 days duration. Increments of pressure >100 mmHg decreased the diameter of thoracic aortas from hypertensive but not from normotensive rats. The pressure-induced constriction was not demonstrable in vessels superfused with calcium-free buffer. Stretched rings of aorta from hypertensive rats exhibited a calcium-dependent constrictor tone accompanied by elevated calcium influx that varied in relation to the degree of stretch. Blockers of l-type calcium channels and inhibitors of protein kinase C reduced both basal tone and calcium influx in aortic rings of hypertensive rats. Hence, the thoracic aorta of hypertensive rats expresses a pressure- and stretch-activated constrictor mechanism that relies on increased calcium influx throughl-type calcium channels via a protein kinase C-regulated pathway. The expression of such a constrictor mechanism is suggestive of acquired myogenic behavior.

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