Modulation of ICa-L by α1-adrenergic stimulation in rat ventricular myocytes

2005 ◽  
Vol 83 (11) ◽  
pp. 1015-1024 ◽  
Author(s):  
Shetuan Zhang ◽  
Jijin Lin ◽  
Yuji Hirano ◽  
Masayasu Hiraoka
Keyword(s):  
Protein Kinase ◽  
Patch Clamp ◽  
Kinase Inhibitor ◽  
Ventricular Myocytes ◽  
Adrenergic Stimulation ◽  
Pipette Solution ◽  
Rat Ventricular Myocytes ◽  
Perforated Patch ◽  
Intracellular Ca ◽  
Perforated Patch Clamp

We found when L-type calcium current (ICa-L) was recorded with the perforated patch-clamp method in rat ventricular myocytes that bath application of phenylephrine (with propranolol) evoked a biphasic response characterized by an initial transient suppression followed by a sustained potentiation. The transient suppression occurred 30–60 s after phenylephrine perfusion and reached peak inhibition at approximately 2 min. The biphasic modulation of ICa-L was also elicited by methoxamine, and the effects of phenylephrine were blocked by prazosin, indicating that the responses were mediated through α1-adrenoceptors. Pretreatment of cells with H7 (100 µmol/L), a broad-spectrum protein kinase inhibitor that inhibits both protein kinase C and A, eliminated potentiation but did not affect transient suppression. The transient suppression occurred concurrently with the acceleration of the fast component of ICa-L inactivation. Depletion of intracellular Ca2+ stores by ryanodine plus caffeine or thapsigargin eliminated the transient suppression. When ICa-L was recorded with whole-cell patch-clamp and with 0.05 mmol/L EGTA in the pipette solution to allow intracellular Ca2+ to fluctuate, phenylephrine evoked a transient suppression as in the perforated patch recordings. Heparin, a specific blocker of IP3 (inositol 1,4,5-trisphosphate) receptors, eliminated the phenylephrine-induced transient suppression of ICa-L when added to the pipette solution. Intensive chelation of intracellular Ca2+ by 5 mmol/L BAPTA (1,2-bis(2-aminophenoxy)ethane-N,N,N′,N′-tetraacetic acid) in the pipette solution also eliminated the phenylephrine-induced transient suppression of ICa-L. We conclude that transient increase in the concentration of intracellular calcium ([Ca2+]i) caused by Ca2+ release from intracellular stores underlies the transient suppression of ICa-L, whereas the potentiation of ICa-L is a result of activation of protein kinases.Key words: Ca2+ mobilization, IP3, Ca2+-induced inactivation of Ca2+ current, perforated patch-clamp.

Protein kinase inhibitor H-89 reverses forskolin stimulation of cardiac L-type calcium current

1995 ◽  
Vol 268 (3) ◽  
pp. C651-C659 ◽  
Author(s):  
W. Yuan ◽  
D. M. Bers
Keyword(s):  
Protein Kinase ◽  
Patch Clamp ◽  
Kinase Inhibitor ◽  
Ventricular Myocytes ◽  
Calcium Currents ◽  
Maximal Conductance ◽  
Perforated Patch ◽  
Dependent Inactivation ◽  
Protein Kinase N ◽  
Steady State Inactivation

Calcium currents (ICa) and barium currents (IBa) were measured in freshly isolated single ferret ventricular myocytes, using the whole cell patch-clamp and perforated patch-clamp techniques with Na and K currents blocked by tetraethylammonium and Cs. The membrane potential (Em) dependence of activation and steady-state inactivation curves were determined using a Boltzmann relation, where E0.5 is the Em at half-maximal conductance. Forskolin (1 microM) increased the rate of ICa inactivation, especially in perforated patch, but slowed IBa inactivation. The acceleration is likely to be due to greater Ca-dependent inactivation of ICa, where the slowing of IBa inactivation may be due to protein kinase A-dependent slowing of Em-dependent inactivation. Forskolin (1-10 microM) also increased ICa amplitude by two- to threefold and shifted the E0.5 for both activation and inactivation to more negative potentials by 7-8 mV. The effect of forskolin on the amplitude of ICa could be reversed by an inhibitor of adenosine 3',5'-cyclic monophosphate-dependent protein kinase, N-[2-(p-bromocinnamylamino)ethyl]-5-isoquinolinesulfonamide (H-89; 1-10 microM). However, H-89 did not reverse the shift of E0.5 induced by forskolin. H-89 application by itself does not decrease basal ICa but does shift the E0.5 of both activation and inactivation to more negative values of Em. It is possible that H-89 reverses the shift induced by regulatory phosphorylation (due to forskolin) but induces a coincidental negative shift itself.

PKC regulation of cardiac CFTR Cl− channel function in guinea pig ventricular myocytes

1998 ◽  
Vol 275 (1) ◽  
pp. C293-C302 ◽  
Author(s):  
Lisa M. Middleton ◽  
Robert D. Harvey
Keyword(s):  
Protein Kinase ◽  
Patch Clamp ◽  
Guinea Pig ◽  
Ventricular Myocytes ◽  
Transmembrane Conductance Regulator ◽  
Transmembrane Conductance ◽  
Patch Clamp Technique ◽  
Clamp Technique ◽  
Whole Cell Patch Clamp ◽  
Perforated Patch Clamp

The role of protein kinase C (PKC) in regulating the protein kinase A (PKA)-activated Cl− current conducted by the cardiac isoform of the cystic fibrosis transmembrane conductance regulator (cCFTR) was studied in guinea pig ventricular myocytes using the whole cell patch-clamp technique. Although stimulation of endogenous PKC with phorbol 12,13-dibutyrate (PDBu) alone did not activate this Cl− current, even when intracellular dialysis was limited with the perforated patch-clamp technique, activation of PKC did elicit a significant response in the presence of PKA-dependent activation of the current by the β-adrenergic receptor agonist isoproterenol. PDBu increased the magnitude of the Cl− conductance activated by a supramaximally stimulating concentration of isoproterenol by 21 ± 3.3% ( n = 9) when added after isoproterenol and by 36 ± 16% ( n= 14) when introduced before isoproterenol. 4α-Phorbol 12,13-didecanoate, a phorbol ester that does not activate PKC, did not mimic these effects. Preexposure to chelerythrine or bisindolylmaleimide, two highly selective inhibitors of PKC, significantly reduced the magnitude of the isoproterenol-activated Cl− current by 79 ± 7.7% ( n = 11) and 52 ± 10% ( n = 8), respectively. Our results suggest that although acute activation of endogenous PKC alone does not significantly regulate cCFTR Cl− channel activity in native myocytes, it does potentiate PKA-dependent responses, perhaps most dramatically demonstrated by basal PKC activity, which may play a pivotal role in modulating the function of these channels.

Altered beta-adrenergic and muscarinic response of CFTR Cl- current in dialyzed cardiac myocytes

1995 ◽  
Vol 268 (5) ◽  
pp. H1795-H1802
Author(s):  
S. I. Zakharov ◽  
R. D. Harvey
Keyword(s):  
Patch Clamp ◽  
Muscarinic Receptor ◽  
Ventricular Myocytes ◽  
Receptor Activation ◽  
Current Response ◽  
Patch Clamp Technique ◽  
Beta Adrenergic ◽  
Perforated Patch ◽  
Clamp Technique ◽  
Perforated Patch Clamp

Autonomic regulation of the cardiac cystic fibrosis transmembrane conductance regulator (CFTR) Cl- current was studied in isolated guinea pig ventricular myocytes using various configurations of the whole cell patch-clamp technique. When currents were recorded using the conventional patch-clamp technique, it was possible to continue to activate the Cl- current on repeated exposure to isoproterenol (Iso) for up to 60 min after initiating dialysis. However, there was significant rundown of the magnitude of the Cl- current response to the maximally stimulating concentrations of Iso. In addition, the concentration of Iso that produced half-maximal activation of the Cl- current (K1/2) increased with time. Conversely, the K1/2 for acetylcholine inhibition of the Iso-activated current decreased with time. When currents were recorded using the perforated patch-clamp technique, the sensitivity to both beta-adrenergic- and muscarinic-receptor stimulation was stable. Immediately after initiation of dialysis with the conventional patch-clamp technique, the sensitivity to Iso was nearly identical to that determined using the perforated patch-clamp technique. However, the initial sensitivity to muscarinic-receptor activation was significantly greater. These results indicate that cell dialysis associated with conventional patch-clamp techniques not only results in a time-dependent rundown of current amplitude, but it also significantly alters the concentration dependence of beta-adrenergic and muscarinic-receptor regulation of ion channel function.

Role of Ca2+/calmodulin-dependent protein kinase II in the regulation of the cardiac L-type Ca2+ current during endothelin-1 stimulation

2010 ◽  
Vol 298 (6) ◽  
pp. H1902-H1907 ◽  
Author(s):  
Kimiaki Komukai ◽  
Jin O-Uchi ◽  
Satoshi Morimoto ◽  
Makoto Kawai ◽  
Kenichi Hongo ◽  
...  
Keyword(s):  
Protein Kinase ◽  
Patch Clamp ◽  
Receptor Antagonist ◽  
Ventricular Myocytes ◽  
Receptor Protein ◽  
Dependent Protein Kinase ◽  
Rat Ventricular Myocytes ◽  
Endothelin 1 ◽  
Protein Kinase Ii ◽  
Dependent Protein

Endothelin-1 (ET-1) shows a positive inotropic effect on cardiac muscle. Although the L-type Ca2+ current ( ICa) is one of the important determinants of cardiac excitation-contraction coupling, the effect of ET-1 on the ICa is not always clear. The controversial results appear to be due to different patch-clamp methods. The present study measured the effect of ET-1 on the ICa of rat ventricular myocytes using the perforated patch-clamp technique. The holding potential was set to −40 mV, and depolarization was applied every 10 s. ET-1 (10 nM) increased the ICa in a monophasic manner. The current reached a steady state 15 min after the application of ET-1, when the measurement was done. Endothelin receptor subtype expression was also investigated using Western immunoblotting. ETA-receptor protein was expressed, but ETB-receptor protein was not expressed, in the cell membranes of rat ventricular myocytes. The effect of ET-1 on the ICa was inhibited by a selective ETA-receptor antagonist, BQ-123, but not by a selective ETB-receptor antagonist, BQ-788. The effect was inhibited by protein kinase C (PKC) inhibitor chelerythrine and Ca2+/calmodulin-dependent protein kinase II (CaMKII) inhibitor KN-93, but not by its inactive analog KN-92. The effect of ET-1 was also blocked by another CaMKII inhibitor, autocamtide-2-related inhibitory peptide. These results suggest that ET-1 increases the ICa via the ETA-receptor-PKC-CaMKII pathway.

Intracellular Cs+ activates the PKA pathway, revealing a fast, reversible, Ca2+-dependent inactivation of L-type Ca2+ current

2003 ◽  
Vol 285 (2) ◽  
pp. C310-C318 ◽  
Author(s):  
Fabien Brette ◽  
Alain Lacampagne ◽  
Laurent Sallé ◽  
Ian Findlay ◽  
Jean-Yves Le Guennec
Keyword(s):  
Protein Kinase ◽  
Kinase Inhibitor ◽  
Ventricular Myocytes ◽  
Cyclopiazonic Acid ◽  
Dependent Protein Kinase ◽  
Pipette Solution ◽  
Camp Dependent Protein Kinase ◽  
Dependent Inactivation ◽  
Dependent Protein ◽  
Pka Pathway

Inactivation of the L-type Ca2+ current ( ICaL) was studied in isolated guinea pig ventricular myocytes with different ionic solutions. Under basal conditions, ICaL of 82% of cells infused with Cs+-based intracellular solutions showed enhanced amplitude with multiphasic decay and diastolic depolarization-induced facilitation. The characteristics of ICaL in this population of cells were not due to contamination by other currents or an artifact. These phenomena were reduced by ryanodine, caffeine, cyclopiazonic acid, the protein kinase A inhibitor H-89, and the cAMP-dependent protein kinase inhibitor. Forskolin and isoproterenol increased ICaL by only ∼60% in these cells. Cells infused with either N-methyl-d-glucamine or K+-based intracellular solutions did not show multiphasic decay or facilitation under basal conditions. Isoproterenol increased ICaL by ∼200% in these cells. In conclusion, we show that multiphasic inactivation of ICaL is due to Ca2+-dependent inactivation that is reversible on a time scale of tens of milliseconds. Cs+ seems to activate the cAMP-dependent protein kinase pathway when used as a substitute for K+ in the pipette solution.

scholarly journals Analysis of neuronal Ca2+ handling properties by combining perforated patch clamp recordings and the added buffer approach

2020 ◽  
Author(s):  
Simon Hess ◽  
Christophe Pouzat ◽  
Lars Paeger ◽  
Andreas Pippow ◽  
Peter Kloppenburg
Keyword(s):  
Patch Clamp ◽  
Intracellular Signaling ◽  
Whole Cell ◽  
Perforated Patch ◽  
Cellular Processes ◽  
Wide Range ◽  
Intracellular Ca ◽  
Precise Quantification ◽  
Perforated Patch Clamp ◽  
Whole Cell Recordings

AbstractCa2+ functions as an important intracellular signal for a wide range of cellular processes. These processes are selectively activated by controlled spatiotemporal dynamics of the free cytosolic Ca2+. Intracellular Ca2+ dynamics are regulated by numerous cellular parameters. Here, we established a new way to determine neuronal Ca2+ handling properties by combining the ‘added buffer’ approach (Neher and Augustine, 1992) with perforated patch-clamp recordings (Horn and Marty, 1988). Since the added buffer approach typically employs the standard whole-cell configuration for concentration-controlled Ca2+ indicator loading, it only allows for the reliable estimation of the immobile fraction of intracellular Ca2+ buffers. Furthermore, crucial components of intracellular signaling pathways are being washed out during prolonged whole-cell recordings, leading to cellular deterioration. By combining the added buffer approach with perforated patch-clamp recordings, these issues are circumvented, allowing the precise quantification of the cellular Ca2+ handling properties, including immobile as well as mobile Ca2+ buffers.

Effect of acidosis on Ca2+uptake and release by sarcoplasmic reticulum of intact rat ventricular myocytes

1998 ◽  
Vol 275 (3) ◽  
pp. H977-H987 ◽  
Author(s):  
J. T. Hulme ◽  
C. H. Orchard
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Acid Solution ◽  
Ventricular Myocytes ◽  
Intracellular Acidosis ◽  
Patch Clamp Technique ◽  
Rat Ventricular Myocytes ◽  
Extracellular Acidosis ◽  
Intracellular Ca ◽  
Perforated Patch Clamp ◽  
Uptake And Release

The effect of acidosis on Ca2+ uptake and release by the sarcoplasmic reticulum (SR) of rat ventricular myocytes has been investigated. Intracellular Ca2+concentration ([Ca2+]i) was monitored using fura 2; the L-type Ca2+ current ( I Ca) was monitored using the perforated patch-clamp technique. Acidosis was produced either by superfusing the cells with an acid solution (intracellular and extracellular acidosis) or by NH4Cl withdrawal (intracellular acidosis). Both types of acidosis increased the amplitude, and slowed the declining phase, of the Ca2+transient. Application of caffeine produced a rise of [Ca2+]i, which declined in the continued presence of caffeine; the declining phase was slowed by the acid solution but was unaffected by NH4Cl withdrawal. Acidosis decreased the fraction of the caffeine-induced release that was released by electrical stimulation but had no effect on I Ca. It is concluded that acidosis inhibits SR Ca2+ uptake and Ca2+-induced Ca2+ release in intact myocytes but that these effects are compensated by an increase in SR Ca2+ content secondary to a rise in cytoplasmic [Ca2+].

α1-Adrenergic activation of L-type Ca current in rat ventricular myocytes: perforated patch-clamp recordings

1998 ◽  
Vol 274 (6) ◽  
pp. H2203-H2207 ◽  
Author(s):  
Shi J. Liu ◽  
Richard H. Kennedy
Keyword(s):  
Ventricular Myocytes ◽  
Cell Voltage ◽  
Adrenergic Stimulation ◽  
Whole Cell ◽  
Rat Ventricular Myocytes ◽  
Perforated Patch ◽  
Adult Rat ◽  
Transient Decrease ◽  
Adrenergic Antagonist ◽  
Patch Configuration

α1-Adrenergic stimulation has little effect on L-type Ca2+channel current ( I Ca,L) in adult cardiac myocytes measured using conventional whole cell voltage-clamp techniques. In this study using perforated-patch techniques, we reevaluated the effect of α1-adrenergic stimulation on I Ca,L in adult rat ventricular myocytes. Action potentials and I Ca,L were examined in the presence of 1 μM nadolol, a β-adrenergic antagonist, in myocytes internally dialyzed with Na+- and K+-free solutions (Cs+ and tetraethylammonium as substitutes). Phenylephrine (PE; 30 μM) increased the action potential duration measured at 25 and 70% of repolarization by 104 and 86%, respectively. In the perforated-patch configuration, PE elicited a transient decrease followed by a ∼60% increase in I Ca,L, whereas only the transient decrease in I Ca,L was observed in myocytes when the conventional whole cell configuration was used. The PE-induced increase in I Ca,L was reversibly blocked by 1 μM prazosin, an α1-adrenergic antagonist. These results suggest that α1-adrenergic stimulation enhances cardiac I Ca,L and that obligatory intracellular mediators for this action are lost during whole cell recordings.

scholarly journals Ca2+ release from the sarcoplasmic reticulum is required for sustained TRPM4 activity in cerebral artery smooth muscle cells

2010 ◽  
Vol 299 (2) ◽  
pp. C279-C288 ◽  
Author(s):  
Albert L. Gonzales ◽  
Gregory C. Amberg ◽  
Scott Earley
Keyword(s):  
Smooth Muscle ◽  
Sarcoplasmic Reticulum ◽  
Patch Clamp ◽  
Smooth Muscle Cells ◽  
Cerebral Artery ◽  
Perforated Patch ◽  
Inositol 1,4,5 Trisphosphate ◽  
Intracellular Ca ◽  
Trisphosphate Receptor ◽  
Perforated Patch Clamp

The melastatin transient receptor potential (TRP) channel TRPM4 is a critical regulator of vascular smooth muscle cell membrane potential and contractility. Activation of the channel is Ca2+-dependent, but prolonged exposure to high (>1 μM) levels of intracellular Ca2+ causes rapid (within ∼2 min) desensitization of TRPM4 currents under conventional whole cell and inside-out patch-clamp conditions. The goal of the present study was to establish a novel method to record sustained TRPM4 currents in smooth muscle cells under near-physiological conditions. Using the amphotericin B-perforated patch-clamp technique, we recorded and characterized sustained (up to 30 min) transient inward cation currents (TICCs) in freshly isolated cerebral artery myocytes. In symmetrical cation solutions, TICCs reversed at 0 mV and had an apparent unitary conductance of 25 pS. Replacement of extracellular Na+ with the nonpermeable cation N-methyl-d-glucamine abolished the current. TICC activity was attenuated by the TRPM4 blockers fluflenamic acid and 9-phenanthrol. Selective silencing of TRPM4 expression using small interfering RNA diminished TICC activity, suggesting that the molecular identity of the responsible ion channel is TRPM4. We used the perforated patch-clamp method to test the hypothesis that TRPM4 is activated by intracellular Ca2+ signaling events. We found that TICC activity is independent of Ca2+ influx and ryanodine receptor activity but is attenuated by sarco(endo)plasmic reticulum Ca2+-ATPase inhibition and blockade of inositol 1,4,5-trisphosphate receptor-mediated Ca2+ release from the sarcoplasmic reticulum. Our findings suggest that TRPM4 channels in cerebral artery myocytes are regulated by Ca2+ release from inositol 1,4,5-trisphosphate receptor on the sarcoplasmic reticulum.

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