Neural effects of parathyroid hormone: modulation of the calcium channel current and metabolism of monoamines in identified Helisoma snail neurons

1993 ◽  
Vol 71 (8) ◽  
pp. 582-591 ◽  
Author(s):  
R. Wang ◽  
P. K. T. Pang ◽  
L. Wu ◽  
A. Shipley ◽  
E. Karpinski ◽  
...  
Keyword(s):  
Parathyroid Hormone ◽  
Patch Clamp ◽  
Calcium Channel ◽  
Dependent Manner ◽  
Vibrating Probe ◽  
Buccal Ganglion ◽  
Patch Clamp Technique ◽  
Concentration Dependent Manner ◽  
Buccal Ganglia ◽  
Channel Currents

Neuronal effects of parathyroid hormone (PTH) have been reported in vertebrates. The effect of PTH on invertebrate central neurons within the buccal ganglion of Helisoma trivolvis snails was examined in the present study. By using a vibrating probe, PTH was found to induce a transient calcium-dependent inward current in intact buccal ganglia. Intracellular micro-electrode recording revealed that PTH broadened the spontaneous action potential in buccal B5 neurons in situ. By using the whole-cell configuration of the patch-clamp technique, PTH was demonstrated to increase the N-like calcium channel currents in isolated B5 neurons in a concentration-dependent manner. This effect of PTH on the N-like calcium channel currents depended on the activation of a G protein insensitive to pertussis toxin, but was unlikely to be mediated by the cyclic AMP dependent protein kinase. Furthermore, the release of γ-glutamyl conjugate of dopamine from buccal ganglia was selectively increased in the presence of PTH. These results represent the first demonstration that a vertebrate peptide hormone, PTH, selectively modulates the N-like voltage-dependent calcium channel currents in identified invertebrate neurons. Therefore, a novel role of PTH in the regulation of invertebrate central neural functions is indicated.Key words: parathyroid hormone, patch clamp, vibrating probe, dopamine, invertebrate neuron.

Gramicidin perforated patch-clamp technique reveals glycine-gated outward chloride current in dissociated nucleus solitarii neurons of the rat

1994 ◽  
Vol 72 (3) ◽  
pp. 1103-1108 ◽  
Author(s):  
J. S. Rhee ◽  
S. Ebihara ◽  
N. Akaike
Keyword(s):  
Patch Clamp ◽  
Hill Coefficient ◽  
Dependent Manner ◽  
Patch Clamp Technique ◽  
Concentration Dependent Manner ◽  
Perforated Patch ◽  
Clamp Technique ◽  
Outward Currents ◽  
Patch Technique ◽  
Perforated Patch Clamp

1. The inhibitory response of exogenously applied glycine was investigated in freshly dissociated rat nucleus tractus solitarii neurons under whole cell configuration using new perforated patch-clamp technique termed "gramicidin perforated patch technique," which maintains intact intracellular Cl- concentrations. 2. Using the gramicidin perforated patch technique, at a holding potential (VH) of -45 mV, glycine induced outward currents in a concentration-dependent manner with a EC50 of 4.0 x 10(-5) M and at a Hill coefficient of 1.5. In contrast, using the nystatin perforated patch technique, glycine induced inward currents at the same VH in a concentration-dependent manner with an EC50 of 4.9 x 10(-5) M and at a Hill coefficient of 1.2. 3. The glycine-induced outward currents were blocked by strychnine in a concentration dependent manner with an IC50 of 2.2 x 10(-8) M. The blockade was competitive. 4. The current-voltage relationship for the 10(-5) M glycine response showed a clear outward rectification. 5. Ten-fold change of extracellular Cl- with a large impermeable anion resulted in a 65 mV shift of the reversal potential of glycine-induced currents (EGly), indicating that the membrane behaves like a Cl- electrode in the presence of glycine. 6. The intracellular Cl- activity calculated from the EGly ranged from 7.3 to 18.2 mM, with a mean value of 13.3 mM. 7. The values of EGly in the individual neurons were significantly negative to the resting membrane potentials, suggesting the existence of active transport of Cl-.

Calcium Channel Currents in Acutely Dissociated Intracardiac Neurons From Adult Rats

1997 ◽  
Vol 77 (4) ◽  
pp. 1769-1778 ◽  
Author(s):  
Seong-Woo Jeong ◽  
Robert D. Wurster
Keyword(s):  
Calcium Channel ◽  
Fold Change ◽  
Dependent Manner ◽  
High Concentration ◽  
Patch Clamp Technique ◽  
Adult Rats ◽  
Voltage Dependent ◽  
Steady State Inactivation ◽  
Channel Currents ◽  
Intracardiac Neurons

Jeong, Seong-Woo and Robert D. Wurster. Calcium channel currents in acutely dissociated intracardiac neurons from adult rats. J. Neurophysiol. 77: 1769–1778, 1997. With the use of the whole cell patch-clamp technique, multiple subtypes of voltage-activated calcium channels, as indicated by measuring Ba2+ currents, were pharmacologically identified in acutely dissociated intracardiac neurons from adult rats. All tested neurons that were held at −80 mV displayed only high-voltage-activated (HVA) Ca2+ channel currents that were completely blocked by 100 μM CdCl2. The current density of HVA Ca2+ currents was dependent on the external Ca2+ concentration. The Ba2+ (5 mM) currents were half-activated at −16.3 mV with a slope of 5.6 mV per e-fold change. The steady-state inactivation was also voltage dependent with half-inactivation at −33.7 mV and a slope of −12.1 mV per e-fold change. The most effective L-type channel activator, FPL 64176 (2 μM), enhanced the Ba2+ current in a voltage-dependent manner. When cells were held at −80 mV, the saturating concentration (10 μM) of nifedipine blocked ∼11% of the control Ba2+ current. The major component of the Ca2+ channels was N type (63%), which was blocked by a saturating concentration (1 μM) of ω-conotoxin GVIA. Approximately 19% of the control Ba2+ current was sensitive to ω-conotoxin MVIIC (5 μM) but insensitive to low concentrations (30 and 100 nM) of ω-agatoxin IVA (ω-Aga IVA). In addition, a high concentration (1 μM) of ω-Aga IVA occluded the effect of ω-conotoxin MVIIC. Taken together, these results indicate that the ω-conotoxin MVIIC-sensitive current represents only the Q type of Ca2+ channels. The current that was insensitive to nifedipine and various toxins represents the R-type current (7%), which was sensitive to 100 μM NiCl2. In conclusion, the intracardiac neurons from adult rats express at least four different subtypes (L, N, Q, and R) of HVA Ca2+ channels. This information is essential for understanding the regulation of synaptic transmission and excitability of intracardiac neurons by different neurotransmitters and neural regulation of cardiac functions.

Effect of magnetic field exposure on calcium channel currents using patch clamp technique

2002 ◽  
Vol 23 (4) ◽  
pp. 306-314 ◽  
Author(s):  
Mayumi Obo ◽  
Shiro Konishi ◽  
Yoshihisa Otaka ◽  
Satoshi Kitamura
Keyword(s):  
Magnetic Field ◽  
Patch Clamp ◽  
Calcium Channel ◽  
Patch Clamp Technique ◽  
Field Exposure ◽  
Magnetic Field Exposure ◽  
Clamp Technique ◽  
Channel Currents

Vasorelaxing Activity of R-(−)-3′-Hydroxy-2,4,5-trimethoxydalbergiquinol from Dalbergia tonkinensis: Involvement of Smooth Muscle CaV1.2 Channels

Planta Medica ◽  
2020 ◽  
Vol 86 (04) ◽  
pp. 284-293 ◽  
Author(s):  
Nguyen Manh Cuong ◽  
Ninh The Son ◽  
Ngu Truong Nhan ◽  
Pham Ngoc Khanh ◽  
Tran Thu Huong ◽  
...  
Keyword(s):  
Patch Clamp ◽  
Antihypertensive Drugs ◽  
Docking Simulation ◽  
Mechanical Activity ◽  
Dependent Manner ◽  
Vascular Effects ◽  
Patch Clamp Technique ◽  
Spasmolytic Activity ◽  
Cav1.2 Channels ◽  
Dalbergia Tonkinensis

Abstract Dalbergia species heartwood, widely used in traditional medicine to treat various cardiovascular diseases, might represent a rich source of vasoactive agents. In Vietnam, Dalbergia tonkinensis is an endemic tree. Therefore, the aim of the present work was to investigate the vascular activity of R-(−)-3′-hydroxy-2,4,5-trimethoxydalbergiquinol isolated from the heartwood of D. tonkinensis and to provide circular dichroism features of its R absolute configuration. The vascular effects of R-(−)-3′-hydroxy-2,4,5-trimethoxydalbergiquinol were assessed on the in vitro mechanical activity of rat aorta rings, under isometric conditions, and on whole-cell Ba2+ currents through CaV1.2 channels (IBa1.2) recorded in single, rat tail main artery myocytes by means of the patch-clamp technique. R-(−)-3′-Hydroxy-2,4,5-trimethoxydalbergiquinol showed concentration-dependent, vasorelaxant activity on both endothelium-deprived and endothelium intact rings precontracted with the α 1 receptor agonist phenylephrine. Neither the NO (nitric oxide) synthase inhibitor Nω-nitro-L-arginine methyl ester nor the cyclooxygenase inhibitor indomethacin affected its spasmolytic activity. R-(−)-3′-Hydroxy-2,4,5-trimethoxydalbergiquinol-induced vasorelaxation was antagonized by (S)-(−)-Bay K 8644 and unaffected by tetraethylammonium plus glibenclamide. In patch-clamp experiments, R-(−)-3′-hydroxy-2,4,5-trimethoxydalbergiquinol inhibited IBa1.2 in a concentration-dependent manner and significantly decreased the time constant of current inactivation. R-(−)-3′-Hydroxy-2,4,5-trimethoxydalbergiquinol likely stabilized the channel in its closed state, as suggested by molecular modelling and docking simulation to the CaV1.2 channel α 1c subunit. In conclusion, D. tonkinensis species may represent a source of agents potentially useful for the development of novel antihypertensive drugs.

scholarly journals Oxytocin Inhibits T-Type Calcium Current of Human Decidual Stromal Cells

2005 ◽  
Vol 90 (7) ◽  
pp. 4191-4197 ◽  
Author(s):  
Bo Liu ◽  
Stephen J. Hill ◽  
Raheela N. Khan
Keyword(s):  
Stromal Cells ◽  
Calcium Current ◽  
Elective Cesarean Section ◽  
Dependent Manner ◽  
Uterine Contractility ◽  
Patch Clamp Technique ◽  
Concentration Dependent Manner ◽  
Inactivation Curve ◽  
Decidual Cells ◽  
Elective Cesarean

Abstract Context: Little is known about the crosstalk between the decidua and myometrium in relation to human labor. The hormone oxytocin (OT) is considered to be a key mediator of uterine contractility during parturition, exerting some of its effects through calcium channels. Objective: The objective was to characterize the effect of OT on the T-type calcium channel in human decidual stromal cells before and after the onset of labor. Design: The nystatin-perforated patch-clamp technique was used to record inward T-type calcium current (ICa(T)) from acutely dispersed decidual stromal cells obtained from women at either elective cesarean section [CS (nonlabor)] or after normal spontaneous vaginal delivery [SVD (labor)]. Setting: These studies took place at the University of Nottingham Medical School. Results: I Ca(T) of both SVD and CS cells were blocked by nickel (IC50 of 5.6 μm) and cobalt chloride (1 mm) but unaffected by nifedipine (10 μm). OT (1 nm to 3.5 μm) inhibited ICa(T) of SVD cells in a concentration-dependent manner, with a maximal inhibition of 79.0% compared with 26.2% in decidual cells of the CS group. OT-evoked reduction of ICa(T) was prevented by preincubation with the OT antagonist L371,257 in the SVD but not CS group. OT, in a concentration-dependent manner, displaced the steady-state inactivation curve for ICa(T) to the left in the SVD group with no significant effect on curves of the CS group. Conclusion: Inhibition of ICa(T) by OT in decidual cells obtained during labor may signify important functional remodeling of uterine signaling during this period.

gamma-Aminobutyric acid-induced response in rat dissociated paratracheal ganglion cells

1992 ◽  
Vol 67 (5) ◽  
pp. 1367-1374 ◽  
Author(s):  
S. Itabashi ◽  
K. Aibara ◽  
H. Sasaki ◽  
N. Akaike
Keyword(s):  
Response Curve ◽  
Ganglion Cells ◽  
Aminobutyric Acid ◽  
Equilibrium Potential ◽  
Induced Response ◽  
Dependent Manner ◽  
Gamma Aminobutyric Acid ◽  
Patch Clamp Technique ◽  
Concentration Dependent Manner ◽  
Concentration Response Curve

1. The pharmacologic properties of gamma-aminobutyric acid (GABA)-induced Cl- current (ICl) were studied in the paratracheal ganglion cells freshly dissociated from 7- to 10-day-old rat trachea in a whole-cell recording mode by the use of a conventional patch-clamp technique. 2. GABA- and muscimol-induced currents increased sigmoidally in a concentration-dependent manner, and both currents reversed at approximately -3 mV, which was close to the Cl- equilibrium potential (ECl). 3. Strychnine (STR) at low concentration and bicuculline (BIC) inhibited GABA response competitively, whereas STR at the higher concentrations, benzylpenicillin (PCG), or picrotoxin (PTX) inhibited noncompetitively. Inhibition of GABA response by PCG but not other antagonists was voltage dependent, indicating that PCG acts as a Cl- channel blocker. 4. The concentration-response curve of pentobarbital sodium (PB)-induced ICl was bell shaped. At concentrations higher than 10(-3) M, both the peak and plateau currents decreased, and a transient "hump" current appeared immediately after washing out PB. In the presence of PB, the concentration-response curve of GABA shifted toward left without changing the maximum response. 5. Although diazepam (DZP) at concentration used did not induce a response, it potentiated the GABA response in a concentration-dependent manner between 10(-8) and 10(-6) M. DZP also caused a parallel shift toward left in the concentration-response curve of GABA. 6. PB or DZP further enhanced the GABA response in the presence of the other agent. 7. It is concluded that the properties of GABAA receptors in the paratracheal ganglion cells are essentially similar to those reported in other preparations.

CALCIUM CHANNEL CURRENTS IN NEURONES FROM LOCUST (SCHISTOCERCA GREGARIA) THORACIC GANGLIA

1993 ◽  
Vol 177 (1) ◽  
pp. 201-221 ◽  
Author(s):  
H. A. Pearson ◽  
G. Lees ◽  
D. Wray
Keyword(s):  
Calcium Channel ◽  
Single Channel ◽  
Schistocerca Gregaria ◽  
Patch Clamp Technique ◽  
Whole Cell ◽  
Transient Component ◽  
Thoracic Ganglia ◽  
Steady State Inactivation ◽  
Inward Currents ◽  
Channel Currents

1. Using the patch-clamp technique, Ca2+ channel currents were recorded from neurones freshly isolated from the thoracic ganglia of the desert locust Schistocerca gregaria. 2. In solutions containing 10 mmol l-1 Ba2+ we observed high-voltage-activated whole-cell inward currents with sustained and transient components, both of which had similar steady-state inactivation properties. 3. Substitution of Ca2+ for Ba2+ was found to reduce whole-cell currents, whereas removal of monovalent cations had no effect. 4. Cd2+ (1 mmol l-1) completely blocked the whole-cell current, but at 10 micromolar preferentially inhibited the sustained component without affecting the transient component. 5. Verapamil (1 micromolar) inhibited both current components but appeared to be more selective for the sustained component, whereas nitrendipine (1 micromolar) had no effect on either component. 6. A single-channel recording suggested that the transient component was carried by a low- conductance channel. 7. Certain compounds with insecticidal action (ryanodine, S-bioallethrin, deltamethrin and avermectin) did not affect calcium channel currents in these cells. 8. These data suggest that there are two types of Ca2+ channels present in locust neurones. These channel types have properties differing from the T-, L- and N-type channels found in vertebrates and, furthermore, were not targets for the insecticides we tested.

Ba2+, TEA+, and quinine effects on apical membrane K+ conductance and maxi K+ channels in gallbladder epithelium

1990 ◽  
Vol 259 (1) ◽  
pp. C56-C68 ◽  
Author(s):  
Y. Segal ◽  
L. Reuss
Keyword(s):  
Apical Membrane ◽  
Membrane Conductance ◽  
Membrane Resistance ◽  
K Channel ◽  
Dependent Manner ◽  
Gallbladder Epithelium ◽  
Concentration Dependent Manner ◽  
K Channels ◽  
Voltage Dependent ◽  
Channel Currents

The apical membrane of Necturus gallbladder epithelium contains a voltage-activated K+ conductance [Ga(V)]. Large-conductance (maxi) K+ channels underlie Ga(V) and account for 17% of the membrane conductance (Ga) under control conditions. We examined the Ba2+, tetraethylammonium (TEA+), and quinine sensitivities of Ga and single maxi K+ channels. Mucosal Ba2+ addition decreased resting Ga in a concentration-dependent manner (65% block at 5 mM) and decreased Ga(V) in a concentration- and voltage-dependent manner. Mucosal TEA+ addition also decreased control Ga (60% reduction at 5 mM). TEA+ block of Ga(V) was more potent and less voltage dependent that Ba2+ block. Maxi K+ channels were blocked by external Ba2+ at millimolar levels and by external TEA+ at submillimolar levels. At 0.3 mM, quinine (mucosal addition) hyperpolarized the cell membranes by 6 mV and reduced the fractional apical membrane resistance by 50%, suggesting activation of an apical membrane K+ conductance. At 1 mM, quinine both activated and blocked K(+)-conductive pathways. Quinine blocked maxi K+ channel currents at submillimolar concentrations. We conclude that 1) Ba2+ and TEA+ block maxi K+ channels and other K+ channels underlying resting Ga; 2) parallels between the Ba2+ and TEA+ sensitivities of Ga(V) and maxi K+ channels support a role for these channels in Ga(V); and 3) quinine has multiple effects on K(+)-conductive pathways in gallbladder epithelium, which are only partially explained by block of apical membrane maxi K+ channels.

Reserpine is a calcium channel antagonist in normal and GH3 rat pituitary cells

1985 ◽  
Vol 248 (1) ◽  
pp. E15-E19
Author(s):  
I. S. Login ◽  
A. M. Judd ◽  
M. J. Cronin ◽  
T. Yasumoto ◽  
R. M. MacLeod
Keyword(s):  
Calcium Channel ◽  
Calcium Channel Antagonist ◽  
Anterior Pituitary ◽  
Calcium Uptake ◽  
Calcium Ionophore ◽  
Gh3 Cells ◽  
Pituitary Cells ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Anterior Pituitary Cells

Reserpine exerts direct effects on several tissues, including inhibition of hormone release from rat anterior pituitary cells. To test the hypothesis that reserpine may be acting as a calcium channel antagonist, normal or GH3 rat anterior pituitary cells were preincubated in reserpine or the conventional calcium channel blocker, D-600, followed by exposure to 45Ca2+ together with stimulants of calcium uptake: maitotoxin, a potent calcium channel activator; A23187, a calcium ionophore; or 50 mMK+. After incubation, the cells were harvested by vacuum filtration and cell-associated radioactivity determined. In normal cells, reserpine blocked both basal and K+-stimulated calcium uptake. Reserpine selectively blocked maitotoxin but not A23187-induced calcium uptake. In GH3 cells 9 microM reserpine and 30 microM D-600 were equally effective in blocking maitotoxin-stimulated calcium uptake. Reserpine appears to block voltage-dependent calcium channels in pituitary cells in a concentration-dependent manner but not calcium uptake caused nonspecifically by A23187.

Sign in / Sign up

Export Citation Format

Share Document