Nuclear membrane R-type calcium channels mediate cytosolic ET-1-induced increase of nuclear calcium in human vascular smooth muscle cells

2015 ◽  
Vol 93 (4) ◽  
pp. 291-297 ◽  
Author(s):  
Ghassan Bkaily ◽  
Levon Avedanian ◽  
Johny Al-Khoury ◽  
Marc Chamoun ◽  
Rana Semaan ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Plasma Membrane ◽  
Steady State ◽  
Calcium Channels ◽  
Calcium Channel ◽  
Vascular Smooth Muscle Cells ◽  
Nuclear Membrane ◽  
Channel Blocker ◽  
Calcium Influx ◽  
Nuclear Calcium

The objective of this work was to verify whether, as in the case of the plasma membrane of human vascular smooth muscle cells (hVSMCs), cytosolic ET-1-induced increase of nuclear calcium is mediated via the activation of calcium influx through the steady-state R-type calcium channel. Pharmacological tools to identify the R-type calcium channels, as well as real 3-D confocal microscopy imaging techniques coupled to calcium fluorescent probes, were used to study the effect of cytosolic ET-1 on nuclear calcium in isolated nuclei of human hepatocytes and plasma membrane perforated hVSMCs. Our results showed that pre-treatment with pertussis toxin (PTX) or cholera toxin (CTX) prevented cytosolic ET-1 (10−9 mol/L) from inducing a sustained increase in nuclear calcium. Furthermore, the L-type calcium channel blocker nifedipine did not prevent cytosolic ET-1 from inducing an increase in nuclear calcium, as opposed to the dual L- and R-type calcium channel blocker isradipine (PN200-110) (in the presence of nifedipine). In conclusion, the preventative effect with PTX and CTX, and the absence of an effect with nifedipine, as well as the blockade by isradipine on cytosolic ET-1-induced increase in nuclear calcium, suggest that this nuclear calcium influx in hVSMCs is due to activation of the steady-state R-type calcium channel. The sarcolemmal and nuclear membrane R-type calcium channels in hVSMCs are involved in ET-1 modulation of vascular tone in physiology and pathology.

Resolution of the basal plasma membrane calcium flux in vascular smooth muscle cells

1996 ◽  
Vol 270 (6) ◽  
pp. H1972-H1978 ◽  
Author(s):  
A. H. Fayazi ◽  
S. A. Lapidot ◽  
B. K. Huang ◽  
R. W. Tucker ◽  
R. D. Phair
Keyword(s):  
Smooth Muscle ◽  
Plasma Membrane ◽  
Steady State ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Vascular Smooth Muscle Cells ◽  
Muscle Cells ◽  
Basal Plasma Membrane ◽  
Basal Plasma ◽  
The Absolute

Steady-state cytosolic calcium (Ca2+i) concentration in a vascular smooth muscle cell is determined by Ca2+ influx and Ca2+ extrusion across the plasma membrane, yet no means for determining the absolute magnitude of these transmembrane Ca2+ fluxes in the basal state of the resting cell has been devised. We now report a method that combines fluorescence measurement of Ca2+i, 45Ca kinetics, and computer modeling to yield the basal plasma membrane Ca2+ flux in A7r5 vascular smooth muscle cells. Kinetic analysis of basal Ca2+i and Ca2+i transients following chelation of extracellular Ca2+ yields a unique value for the ratio of the rate constant governing Ca2+ pumping into the sarcoplasmic reticulum (SR) to that for plasma membrane Ca2+ extrusion (1.12 +/- 0.06). When this ratio was used to constrain the least-squares fitting of 45Ca efflux data from A7r5 cells, it was possible to determine unique values for the unidirectional, steady-state Ca2+ fluxes across both SR and plasma membranes. The basal unidirectional plasma membrane Ca2+ flux was 0.062 +/- 0.018 fmol . min-1 . cell, and the basal SR Ca2+ flux was 0.069 +/- 0.019 fmol . min-1 . cell-1. These results demonstrate, within the limitations of measuring the absolute value of Ca2+i, the feasibility of measuring previously unresolvable subpicoamp basal Ca2+ fluxes in intact cells under normal physiological conditions.

Calcium Channels Involved in Synaptic Transmission From Reticulospinal Axons in Lamprey

1999 ◽  
Vol 81 (4) ◽  
pp. 1699-1705 ◽  
Author(s):  
P. Krieger ◽  
A. Büschges ◽  
A. el Manira
Keyword(s):  
Calcium Channels ◽  
Synaptic Transmission ◽  
Calcium Channel ◽  
Calcium Channel Blocker ◽  
Presynaptic Inhibition ◽  
Channel Blocker ◽  
Metabotropic Glutamate Receptor ◽  
Calcium Influx ◽  
Combined Application ◽  
Presynaptic Calcium

Calcium channels involved in synaptic transmission from reticulospinal axons in lamprey. The pharmacology of calcium channels involved in glutamatergic synaptic transmission from reticulospinal axons in the lamprey spinal cord was analyzed with specific agonists and antagonists of different high-voltage activated calcium channels. The N-type calcium channel blocker ω-conotoxin GVIA (ω-CgTx) induced a large decrease of the amplitude of reticulospinal-evoked excitatory postsynaptic potentials (EPSPs). The P/Q-type calcium channel blocker ω-agatoxin IVA (ω-Aga) also reduced the amplitude of the reticulospinal EPSPs, but to a lesser extent than ω-CgTx. The dihydropyridine agonist Bay K and antagonist nimodipine had no effect on the amplitude of the reticulospinal EPSP. Combined application of ω-CgTx and ω-Aga strongly decreased the amplitude the EPSPs but was never able to completely block them, indicating that calcium channels insensitive to these toxins (R-type) are also involved in synaptic transmission from reticulospinal axons. We have previously shown that the group III metabotropic glutamate receptor agonistl(+)-2-amino-4-phosphonobutyric acid (l-AP4) mediates presynaptic inhibition at the reticulospinal synapse. To test if this presynaptic effect is mediated through inhibition of calcium influx, the effect of l-AP4 on reticulospinal transmission was tested before and after blockade of N-type channels, which contribute predominantly to transmitter release at this synapse. Blocking the N-type channels with ω-CgTx did not prevent inhibition of reticulospinal synaptic transmission by l-AP4. In addition, l-AP4 had no affect on the calcium current recorded in the somata of reticulospinal neurons or on the calcium component of action potentials in reticulospinal axons. These results show that synaptic transmission from reticulospinal axons in the lamprey is mediated by calcium influx through N-, P/Q- and R-type channels, with N-type channels playing the major role. Furthermore, presynaptic inhibition of reticulospinal transmission byl-AP4 appears not to be mediated through inhibition of presynaptic calcium channels.

scholarly journals TRPC6 regulates phenotypic switching of vascular smooth muscle cells through plasma membrane potential‐dependent coupling with PTEN

2019 ◽  
Vol 33 (9) ◽  
pp. 9785-9796 ◽  
Author(s):  
Takuro Numaga‐Tomita ◽  
Tsukasa Shimauchi ◽  
Sayaka Oda ◽  
Tomohiro Tanaka ◽  
Kazuhiro Nishiyama ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Plasma Membrane ◽  
Membrane Potential ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Vascular Smooth Muscle Cells ◽  
Muscle Cells ◽  
Phenotypic Switching ◽  
Plasma Membrane Potential
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