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Article ; Online: ANO1, CaV1.2, and IP3R form a localized unit of EC-coupling in mouse pulmonary arterial smooth muscle.

Akin, Elizabeth J / Aoun, Joydeep / Jimenez, Connor / Mayne, Katie / Baeck, Julius / Young, Michael D / Sullivan, Brennan / Sanders, Kenton M / Ward, Sean M / Bulley, Simon / Jaggar, Jonathan H / Earley, Scott / Greenwood, Iain A / Leblanc, Normand

The Journal of general physiology

2023 Volume 155, Issue 11

Abstract: Pulmonary arterial (PA) smooth muscle cells (PASMC) generate vascular tone in response to agonists coupled to Gq-protein receptor signaling. Such agonists stimulate oscillating calcium waves, the frequency of which drives the strength of contraction. ... ...

Abstract	Pulmonary arterial (PA) smooth muscle cells (PASMC) generate vascular tone in response to agonists coupled to Gq-protein receptor signaling. Such agonists stimulate oscillating calcium waves, the frequency of which drives the strength of contraction. These Ca2+ events are modulated by a variety of ion channels including voltage-gated calcium channels (CaV1.2), the Tmem16a or Anoctamin-1 (ANO1)-encoded calcium-activated chloride (CaCC) channel, and Ca2+ release from the sarcoplasmic reticulum through inositol-trisphosphate receptors (IP3R). Although these calcium events have been characterized, it is unclear how these calcium oscillations underly a sustained contraction in these muscle cells. We used smooth muscle-specific ablation of ANO1 and pharmacological tools to establish the role of ANO1, CaV1.2, and IP3R in the contractile and intracellular Ca2+ signaling properties of mouse PA smooth muscle expressing the Ca2+ biosensor GCaMP3 or GCaMP6. Pharmacological block or genetic ablation of ANO1 or inhibition of CaV1.2 or IP3R, or Ca2+ store depletion equally inhibited 5-HT-induced tone and intracellular Ca2+ waves. Coimmunoprecipitation experiments showed that an anti-ANO1 antibody was able to pull down both CaV1.2 and IP3R. Confocal and superresolution nanomicroscopy showed that ANO1 coassembles with both CaV1.2 and IP3R at or near the plasma membrane of PASMC from wild-type mice. We conclude that the stable 5-HT-induced PA contraction results from the integration of stochastic and localized Ca2+ events supported by a microenvironment comprising ANO1, CaV1.2, and IP3R. In this model, ANO1 and CaV1.2 would indirectly support cyclical Ca2+ release events from IP3R and propagation of intracellular Ca2+ waves.
MeSH term(s)	Animals ; Mice ; Anoctamin-1 ; Calcium ; Hypertension, Pulmonary ; Serotonin ; Muscle, Smooth
Chemical Substances	Anoctamin-1 ; Calcium (SY7Q814VUP) ; Serotonin (333DO1RDJY)
Language	English
Publishing date	2023-09-13
Publishing country	United States
Document type	Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
ZDB-ID	3118-5
ISSN	1540-7748 ; 0022-1295
ISSN (online)	1540-7748
ISSN	0022-1295
DOI	10.1085/jgp.202213217
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Article ; Online: Ano1 mediates pressure-sensitive contraction frequency changes in mouse lymphatic collecting vessels.

Zawieja, Scott D / Castorena, Jorge A / Gui, Peichun / Li, Min / Bulley, Simon A / Jaggar, Jonathan H / Rock, Jason R / Davis, Michael J

The Journal of general physiology

2019 Volume 151, Issue 4, Page(s) 532–554

Abstract: Lymphatic collecting vessels exhibit spontaneous contractions with a pressure-dependent contraction frequency. The initiation of contraction has been proposed to be mediated by the activity of a ... ...

Abstract	Lymphatic collecting vessels exhibit spontaneous contractions with a pressure-dependent contraction frequency. The initiation of contraction has been proposed to be mediated by the activity of a Ca
MeSH term(s)	Animals ; Anoctamin-1/genetics ; Anoctamin-1/metabolism ; Benzbromarone/pharmacology ; Calcium/metabolism ; Gene Expression Regulation ; Lymphatic Vessels/drug effects ; Lymphatic Vessels/physiology ; Male ; Membrane Potentials ; Mice ; Mice, Transgenic ; Pressure ; Protein Conformation ; Uricosuric Agents/pharmacology
Chemical Substances	ANO1 protein, mouse ; Anoctamin-1 ; Uricosuric Agents ; Benzbromarone (4POG0RL69O) ; Calcium (SY7Q814VUP)
Language	English
Publishing date	2019-03-12
Publishing country	United States
Document type	Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
ZDB-ID	3118-5
ISSN	1540-7748 ; 0022-1295
ISSN (online)	1540-7748
ISSN	0022-1295
DOI	10.1085/jgp.201812294
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Article: Intravascular pressure regulates local and global Ca(2+) signaling in cerebral artery smooth muscle cells.

Jaggar, J H

American journal of physiology. Cell physiology

2001 Volume 281, Issue 2, Page(s) C439–48

Abstract: The regulation of intracellular Ca(2+) signals in smooth muscle cells and arterial diameter by intravascular pressure was investigated in rat cerebral arteries (approximately 150 microm) using a laser scanning confocal microscope and the fluorescent Ca(2+ ...

Abstract	The regulation of intracellular Ca(2+) signals in smooth muscle cells and arterial diameter by intravascular pressure was investigated in rat cerebral arteries (approximately 150 microm) using a laser scanning confocal microscope and the fluorescent Ca(2+) indicator fluo 3. Elevation of pressure from 10 to 60 mmHg increased Ca(2+) spark frequency 2.6-fold, Ca(2+) wave frequency 1.9-fold, and global intracellular Ca(2+) concentration ([Ca(2+)](i)) 1.4-fold in smooth muscle cells, and constricted arteries. Ryanodine (10 microM), an inhibitor of ryanodine-sensitive Ca(2+) release channels, or thapsigargin (100 nM), an inhibitor of the sarcoplasmic reticulum Ca(2+)-ATPase, abolished sparks and waves, elevated global [Ca(2+)](i), and constricted pressurized (60 mmHg) arteries. Diltiazem (25 microM), a voltage-dependent Ca(2+) channel (VDCC) blocker, significantly reduced sparks, waves, and global [Ca(2+)](i), and dilated pressurized (60 mmHg) arteries. Steady membrane depolarization elevated Ca(2+) signaling similar to pressure and increased transient Ca(2+)-sensitive K(+) channel current frequency e-fold for approximately 7 mV, and these effects were prevented by VDCC blockers. Data are consistent with the hypothesis that pressure induces a steady membrane depolarization that activates VDCCs, leading to an elevation of spark frequency, wave frequency, and global [Ca(2+)](i). In addition, pressure induces contraction via an elevation of global [Ca(2+)](i), whereas the net effect of sparks and waves, which do not significantly contribute to global [Ca(2+)](i) in arteries pressurized to between 10 and 60 mmHg, is to oppose contraction.
MeSH term(s)	Animals ; Blood Pressure/drug effects ; Blood Pressure/physiology ; Calcium/metabolism ; Calcium Channel Blockers/pharmacology ; Calcium Signaling/physiology ; Cerebral Arteries/cytology ; Cerebral Arteries/drug effects ; Cerebral Arteries/physiology ; Diltiazem/pharmacology ; Electric Conductivity ; Electrophysiology ; Enzyme Inhibitors/pharmacology ; Female ; Homeostasis ; Male ; Muscle, Smooth, Vascular/cytology ; Muscle, Smooth, Vascular/drug effects ; Muscle, Smooth, Vascular/physiology ; Rats ; Rats, Sprague-Dawley ; Ryanodine/pharmacology ; Thapsigargin/pharmacology ; Vasoconstrictor Agents/pharmacology
Chemical Substances	Calcium Channel Blockers ; Enzyme Inhibitors ; Vasoconstrictor Agents ; Ryanodine (15662-33-6) ; Thapsigargin (67526-95-8) ; Diltiazem (EE92BBP03H) ; Calcium (SY7Q814VUP)
Language	English
Publishing date	2001-08
Publishing country	United States
Document type	Journal Article ; Research Support, Non-U.S. Gov't
ZDB-ID	392098-7
ISSN	1522-1563 ; 0363-6143
ISSN (online)	1522-1563
ISSN	0363-6143
DOI	10.1152/ajpcell.2001.281.2.C439
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Article ; Online: Intravascular flow stimulates PKD2 (polycystin-2) channels in endothelial cells to reduce blood pressure.

MacKay, Charles E / Leo, M Dennis / Fernández-Peña, Carlos / Hasan, Raquibul / Yin, Wen / Mata-Daboin, Alejandro / Bulley, Simon / Gammons, Jesse / Mancarella, Salvatore / Jaggar, Jonathan H

eLife

2020 Volume 9

Abstract: PKD2 (polycystin-2, TRPP1), a TRP polycystin channel, is expressed in endothelial cells (ECs), but its physiological functions in this cell type are unclear. Here, we generated inducible, EC- ... ...

Abstract	PKD2 (polycystin-2, TRPP1), a TRP polycystin channel, is expressed in endothelial cells (ECs), but its physiological functions in this cell type are unclear. Here, we generated inducible, EC-specific
MeSH term(s)	Animals ; Arterial Pressure ; Calcium Signaling ; Endothelial Cells/metabolism ; Hypertension/genetics ; Hypertension/metabolism ; Hypertension/physiopathology ; Intermediate-Conductance Calcium-Activated Potassium Channels/metabolism ; Male ; Mechanotransduction, Cellular ; Membrane Potentials ; Mesenteric Arteries/metabolism ; Mesenteric Arteries/physiopathology ; Mice, Knockout ; Nitric Oxide/metabolism ; Nitric Oxide Synthase Type III/metabolism ; Phosphorylation ; Regional Blood Flow ; Small-Conductance Calcium-Activated Potassium Channels/metabolism ; TRPP Cation Channels/deficiency ; TRPP Cation Channels/genetics ; TRPP Cation Channels/metabolism ; Vasodilation
Chemical Substances	Intermediate-Conductance Calcium-Activated Potassium Channels ; Small-Conductance Calcium-Activated Potassium Channels ; TRPP Cation Channels ; polycystic kidney disease 2 protein ; Nitric Oxide (31C4KY9ESH) ; Nitric Oxide Synthase Type III (EC 1.14.13.39) ; Nos3 protein, mouse (EC 1.14.13.39)
Language	English
Publishing date	2020-05-04
Publishing country	England
Document type	Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't
ZDB-ID	2687154-3
ISSN	2050-084X ; 2050-084X
ISSN (online)	2050-084X
ISSN	2050-084X
DOI	10.7554/eLife.56655
Database	MEDical Literature Analysis and Retrieval System OnLINE

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Article ; Online: Correction: Intravascular flow stimulates PKD2 (polycystin-2) channels in endothelial cells to reduce blood pressure.

MacKay, Charles E / Leo, M Dennis / Fernández-Peña, Carlos / Hasan, Raquibul / Yin, Wen / Mata-Daboin, Alejandro / Bulley, Simon / Gammons, Jesse / Mancarella, Salvatore / Jaggar, Jonathan H

eLife

2020 Volume 9

Language	English
Publishing date	2020-06-30
Publishing country	England
Document type	Journal Article ; Published Erratum
ZDB-ID	2687154-3
ISSN	2050-084X ; 2050-084X
ISSN (online)	2050-084X
ISSN	2050-084X
DOI	10.7554/eLife.60401
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Article: Differential regulation of Ca(2+) sparks and Ca(2+) waves by UTP in rat cerebral artery smooth muscle cells.

Jaggar, J H / Nelson, M T

American journal of physiology. Cell physiology

2000 Volume 279, Issue 5, Page(s) C1528–39

Abstract: Uridine 5'-triphosphate (UTP), a potent vasoconstrictor that activates phospholipase C, shifted Ca(2+) signaling from sparks to waves in the smooth muscle cells of rat cerebral arteries. UTP decreased the frequency of Ca(2+) sparks and transient Ca(2+)- ... ...

Abstract	Uridine 5'-triphosphate (UTP), a potent vasoconstrictor that activates phospholipase C, shifted Ca(2+) signaling from sparks to waves in the smooth muscle cells of rat cerebral arteries. UTP decreased the frequency of Ca(2+) sparks and transient Ca(2+)-activated K(+) (K(Ca)) currents and increased the frequency of Ca(2+) waves. The UTP-induced reduction in Ca(2+) spark frequency did not reflect a decrease in global cytoplasmic Ca(2+), Ca(2+) influx through voltage-dependent Ca(2+) channels (VDCC), or Ca(2+) load of the sarcoplasmic reticulum (SR), since global Ca(2+) was elevated, blocking VDCC did not prevent the effect, and SR Ca(2+) load did not decrease. However, blocking protein kinase C (PKC) with bisindolylmaleimide I did prevent UTP reduction of Ca(2+) sparks and transient K(Ca) currents. UTP decreased the effectiveness of caffeine, which increases the Ca(2+) sensitivity of ryanodine-sensitive Ca(2+) release (RyR) channels, to activate transient K(Ca) currents. This work supports the concept that vasoconstrictors shift Ca(2+) signaling modalities from Ca(2+) sparks to Ca(2+) waves through the concerted actions of PKC on the Ca(2+) sensitivity of RyR channels, which cause Ca(2+) sparks, and of inositol trisphosphate (IP(3)) on IP(3) receptors to generate Ca(2+) waves.
MeSH term(s)	Animals ; Cadmium/pharmacology ; Caffeine/pharmacology ; Calcium/metabolism ; Calcium/physiology ; Calcium Channel Blockers/pharmacology ; Calcium Signaling/drug effects ; Cerebral Arteries/cytology ; Cerebral Arteries/metabolism ; Drug Synergism ; Electric Conductivity ; Enzyme Activation ; Female ; In Vitro Techniques ; Male ; Muscle, Smooth, Vascular/cytology ; Muscle, Smooth, Vascular/metabolism ; Patch-Clamp Techniques ; Potassium/physiology ; Rats ; Rats, Sprague-Dawley ; Type C Phospholipases/metabolism ; Uridine Triphosphate/physiology
Chemical Substances	Calcium Channel Blockers ; Cadmium (00BH33GNGH) ; Caffeine (3G6A5W338E) ; Type C Phospholipases (EC 3.1.4.-) ; Potassium (RWP5GA015D) ; Calcium (SY7Q814VUP) ; Uridine Triphosphate (UT0S826Z60)
Language	English
Publishing date	2000-11
Publishing country	United States
Document type	Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S. ; Research Support, U.S. Gov't, P.H.S.
ZDB-ID	392098-7
ISSN	1522-1563 ; 0363-6143
ISSN (online)	1522-1563
ISSN	0363-6143
DOI	10.1152/ajpcell.2000.279.5.C1528
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Article: Physical simulation and application of a new TEM configuration

Xue, G. Q / Li, X / Quan, H. J / Jaggar, S / Zhou, N. N

Environmental earth sciences. 2012 Nov., v. 67, no. 5

2012

Abstract: In some applications, especially for tunnel surveys and ancient tomb investigations, the scale of survey location is so small that it is impossible to lay a large enough transmitter loop for detection. A small-scale and high-power Transient ... ...

Abstract	In some applications, especially for tunnel surveys and ancient tomb investigations, the scale of survey location is so small that it is impossible to lay a large enough transmitter loop for detection. A small-scale and high-power Transient Electromagnetic (TEM) transmitter configuration must be adapted to detect longer distance or greater depth. Redesigning the TEM surveying configuration may facilitate improving signal penetration and precision of TEM soundings. Based on physical simulation, a newly designed special-loop-source TEM survey configuration has been introduced, which employs four square apertures within a single large transmitter loop to excite stronger fields. The primary and secondary fields have been measured using both the new special-loop system and standard normal single loop TEM configuration for different receiver-transmitter separations and for different target depths. The response curves were compared, revealing that the primary field intensity and the secondary field response were improved by the special-loop transmitter system as compared to the standard system. The new special-loop configuration can be used for tunnel TEM prediction and other TEM investigations. A case study was conducted on tunnel forecasting in Hubei Province, China. This terra TEM survey showed that it is an effective and successful method for exploring and predicting challenging geological structures ahead of a tunnel wall during excavation.
Keywords	case studies ; prediction ; surveys ; China
Language	English
Dates of publication	2012-11
Size	p. 1291-1298.
Publishing place	Springer-Verlag
Document type	Article
ZDB-ID	2493699-6
ISSN	1866-6299 ; 1866-6280
ISSN (online)	1866-6299
ISSN	1866-6280
DOI	10.1007/s12665-012-1572-8
Database	NAL-Catalogue (AGRICOLA)

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Article ; Online: Transcriptional upregulation of α2δ-1 elevates arterial smooth muscle cell voltage-dependent Ca2+ channel surface expression and cerebrovascular constriction in genetic hypertension.

Bannister, John P / Bulley, Simon / Narayanan, Damodaran / Thomas-Gatewood, Candice / Luzny, Patrik / Pachuau, Judith / Jaggar, Jonathan H

Hypertension (Dallas, Tex. : 1979)

2012 Volume 60, Issue 4, Page(s) 1006–1015

Abstract: A hallmark of hypertension is an increase in arterial myocyte voltage-dependent Ca2+ (CaV1.2) currents that induces pathological vasoconstriction. CaV1.2 channels are heteromeric complexes composed of a pore-forming CaV1.2α1 with auxiliary α2δ and β ... ...

Abstract	A hallmark of hypertension is an increase in arterial myocyte voltage-dependent Ca2+ (CaV1.2) currents that induces pathological vasoconstriction. CaV1.2 channels are heteromeric complexes composed of a pore-forming CaV1.2α1 with auxiliary α2δ and β subunits. Molecular mechanisms that elevate CaV1.2 currents during hypertension and the potential contribution of CaV1.2 auxiliary subunits are unclear. Here, we investigated the pathological significance of α2δ subunits in vasoconstriction associated with hypertension. Age-dependent development of hypertension in spontaneously hypertensive rats was associated with an unequal elevation in α2δ-1 and CaV1.2α1 mRNA and protein in cerebral artery myocytes, with α2δ-1 increasing more than CaV1.2α1. Other α2δ isoforms did not emerge in hypertension. Myocytes and arteries of hypertensive spontaneously hypertensive rats displayed higher surface-localized α2δ-1 and CaV1.2α1 proteins, surface α2δ-1:CaV1.2α1 ratio, CaV1.2 current density and noninactivating current, and pressure- and depolarization-induced vasoconstriction than those of Wistar-Kyoto controls. Pregabalin, an α2δ-1 ligand, did not alter α2δ-1 or CaV1.2α1 total protein but normalized α2δ-1 and CaV1.2α1 surface expression, surface α2δ-1:CaV1.2α1, CaV1.2 current density and inactivation, and vasoconstriction in myocytes and arteries of hypertensive rats to control levels. Genetic hypertension is associated with an elevation in α2δ-1 expression that promotes surface trafficking of CaV1.2 channels in cerebral artery myocytes. This leads to an increase in CaV1.2 current-density and a reduction in current inactivation that induces vasoconstriction. Data also suggest that α2δ-1 targeting is a novel strategy that may be used to reverse pathological CaV1.2 channel trafficking to induce cerebrovascular dilation in hypertension.
MeSH term(s)	Animals ; Calcium Channels/genetics ; Calcium Channels/metabolism ; Calcium Channels, L-Type/genetics ; Calcium Channels, L-Type/metabolism ; Cerebral Arteries/drug effects ; Cerebral Arteries/metabolism ; Hypertension/genetics ; Hypertension/metabolism ; Hypertension/physiopathology ; Muscle, Smooth, Vascular/drug effects ; Muscle, Smooth, Vascular/metabolism ; Myocytes, Smooth Muscle/drug effects ; Myocytes, Smooth Muscle/metabolism ; Pregabalin ; Rats ; Rats, Inbred SHR ; Rats, Inbred WKY ; Transcriptional Activation/drug effects ; Transcriptional Activation/genetics ; Up-Regulation/drug effects ; Up-Regulation/genetics ; Vasoconstriction/drug effects ; Vasoconstriction/genetics ; gamma-Aminobutyric Acid/analogs & derivatives ; gamma-Aminobutyric Acid/pharmacology
Chemical Substances	Cacna2d1 protein, rat ; Calcium Channels ; Calcium Channels, L-Type ; Pregabalin (55JG375S6M) ; gamma-Aminobutyric Acid (56-12-2)
Language	English
Publishing date	2012-09-04
Publishing country	United States
Document type	Journal Article ; Research Support, N.I.H., Extramural
ZDB-ID	423736-5
ISSN	1524-4563 ; 0194-911X ; 0362-4323
ISSN (online)	1524-4563
ISSN	0194-911X ; 0362-4323
DOI	10.1161/HYPERTENSIONAHA.112.199661
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Article: Voltage-dependent K+ currents in smooth muscle cells from mouse gallbladder.

Jaggar, J H / Mawe, G M / Nelson, M T

The American journal of physiology

1998 Volume 274, Issue 4, Page(s) G687–93

Abstract: The ionic mechanisms associated with the control of gallbladder contractility are incompletely understood. One type of K+ current, the voltage-dependent K+ (KV) current, is relatively uncharacterized in gallbladder cells and may contribute to muscular ... ...

Abstract	The ionic mechanisms associated with the control of gallbladder contractility are incompletely understood. One type of K+ current, the voltage-dependent K+ (KV) current, is relatively uncharacterized in gallbladder cells and may contribute to muscular excitability. The main focus of this study was therefore to determine the voltage dependence and pharmacological nature of this K+ current in isolated myocytes from mouse gallbladder, using the patch-clamp technique. Currents through Ca(2+)-activated K+ channels were minimized by buffering of intracellular Ca2+ (20 nM free Ca2+) and by inclusion of 1 mM tetraethylammonium (TEA+) in the bathing solution. With 140 mM symmetrical K+, membrane depolarization increased K+ currents, independent of driving force, as assessed by tail current analysis. Half-maximal activation of K+ currents occurred at approximately 1 mV and increased e-fold per 9 mV. Inactivation also increased on depolarization, with a midpoint of -24 mV. Single KV channels were recorded in the cell-attached configuration, exhibiting a single-channel conductance of 4.9 pS. TEA+ at 10 mM reduced KV currents by 36%. At +50 mV, 1 mM and 10 mM 4-aminopyridine inhibited currents by 18% and 35%, respectively, whereas 1 and 10 mM 3,4-diaminopyridine inhibited currents by 11% and 21%, respectively. Quinine inhibited KV currents (at +50 mV, 100 microM and 1 mM quinine inhibited current by 24% and 70%, respectively). In summary, we describe voltage-activated K+ currents from the mouse gallbladder that are likely to contribute to the control of muscular excitability.
MeSH term(s)	Aminopyridines/pharmacology ; Animals ; Electric Conductivity ; Electrophysiology ; Female ; Gallbladder/metabolism ; Male ; Mice ; Mice, Inbred Strains ; Muscle, Smooth/metabolism ; Potassium Channel Blockers ; Potassium Channels/physiology ; Quinine/pharmacology ; Tetraethylammonium/pharmacology
Chemical Substances	Aminopyridines ; Potassium Channel Blockers ; Potassium Channels ; Tetraethylammonium (66-40-0) ; Quinine (A7V27PHC7A)
Language	English
Publishing date	1998
Publishing country	United States
Document type	Journal Article ; Research Support, U.S. Gov't, P.H.S.
ZDB-ID	2948-8
ISSN	0002-9513
ISSN	0002-9513
DOI	10.1152/ajpgi.1998.274.4.G687
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Article: Voltage dependence of Ca2+ sparks in intact cerebral arteries.

Jaggar, J H / Stevenson, A S / Nelson, M T

The American journal of physiology

1998 Volume 274, Issue 6, Page(s) C1755–61

Abstract: Ca2+ sparks have been previously described in isolated smooth muscle cells. Here we present the first measurements of local Ca2+ transients ("Ca2+ sparks") in an intact smooth muscle preparation. Ca2+ sparks appear to result from the opening of ryanodine- ...

Abstract	Ca2+ sparks have been previously described in isolated smooth muscle cells. Here we present the first measurements of local Ca2+ transients ("Ca2+ sparks") in an intact smooth muscle preparation. Ca2+ sparks appear to result from the opening of ryanodine-sensitive Ca2+ release (RyR) channels in the sarcoplasmic reticulum (SR). Intracellular Ca2+ concentration ([Ca2+]i) was measured in intact cerebral arteries (40-150 micron in diameter) from rats, using the fluorescent Ca2+ indicator fluo 3 and a laser scanning confocal microscope. Membrane potential depolarization by elevation of external K+ from 6 to 30 mM increased Ca2+ spark frequency (4. 3-fold) and amplitude (approximately 2-fold) as well as global arterial wall [Ca2+]i (approximately 1.7-fold). The half time of decay ( approximately 50 ms) was not affected by membrane potential depolarization. Ryanodine (10 microM), which inhibits RyR channels and Ca2+ sparks in isolated cells, and thapsigargin (100 nM), which indirectly inhibits RyR channels by blocking the SR Ca2+-ATPase, completely inhibited Ca2+ sparks in intact cerebral arteries. Diltiazem, an inhibitor of voltage-dependent Ca2+ channels, lowered global [Ca2+]i and Ca2+ spark frequency and amplitude in intact cerebral arteries in a concentration-dependent manner. The frequency of Ca2+ sparks (<1 s-1 . cell-1), even under conditions of steady depolarization, was too low to contribute significant amounts of Ca2+ to global Ca2+ in intact arteries. These results provide direct evidence that Ca2+ sparks exist in quiescent smooth muscle cells in intact arteries and that changes of membrane potential that would simulate physiological changes modulate both Ca2+ spark frequency and amplitude in arterial smooth muscle.
MeSH term(s)	Animals ; Arterioles/metabolism ; Calcium/metabolism ; Calcium-Transporting ATPases/antagonists & inhibitors ; Cerebral Arteries/drug effects ; Cerebral Arteries/metabolism ; Enzyme Inhibitors/pharmacology ; Female ; Male ; Membrane Potentials/drug effects ; Potassium/pharmacology ; Rats ; Rats, Sprague-Dawley ; Ryanodine/pharmacology ; Ryanodine Receptor Calcium Release Channel/physiology ; Sarcoplasmic Reticulum/metabolism ; Thapsigargin/pharmacology
Chemical Substances	Enzyme Inhibitors ; Ryanodine Receptor Calcium Release Channel ; Ryanodine (15662-33-6) ; Thapsigargin (67526-95-8) ; Calcium-Transporting ATPases (EC 3.6.3.8) ; Potassium (RWP5GA015D) ; Calcium (SY7Q814VUP)
Language	English
Publishing date	1998
Publishing country	United States
Document type	Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S. ; Research Support, U.S. Gov't, P.H.S.
ZDB-ID	2948-8
ISSN	0002-9513
ISSN	0002-9513
DOI	10.1152/ajpcell.1998.274.6.C1755
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