Voltage dependence of Ca2+sparks in intact cerebral arteries

1998 ◽  
Vol 274 (6) ◽  
pp. C1755-C1761 ◽  
Author(s):  
Jonathan H. Jaggar ◽  
Andrá S. Stevenson ◽  
Mark T. Nelson
Keyword(s):  
Smooth Muscle ◽  
Membrane Potential ◽  
Smooth Muscle Cells ◽  
Laser Scanning ◽  
Cerebral Arteries ◽  
Muscle Cells ◽  
Dependent Manner ◽  
Isolated Cells ◽  
Concentration Dependent Manner ◽  
Smooth Muscle Preparation

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 μm 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 (∼2-fold) as well as global arterial wall [Ca2+]i(∼1.7-fold). The half time of decay (∼50 ms) was not affected by membrane potential depolarization. Ryanodine (10 μM), 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+]iand 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.

Beta-adrenergic actions on membrane electrical properties of dissociated smooth muscle cells

1988 ◽  
Vol 254 (3) ◽  
pp. C423-C431 ◽  
Author(s):  
H. Yamaguchi ◽  
T. W. Honeyman ◽  
F. S. Fay
Keyword(s):  
Smooth Muscle ◽  
Membrane Potential ◽  
Electrical Properties ◽  
Smooth Muscle Cells ◽  
Input Resistance ◽  
Muscle Cells ◽  
Resting Potential ◽  
Equilibrium Potential ◽  
Dependent Manner ◽  
Beta Adrenergic

Studies were carried out to determine the effects of the beta-adrenergic agent, isoproterenol (ISO), on membrane electrical properties in single smooth muscle cells enzymatically dispersed from toad stomach. In cells bathed in buffer of physiological composition, the average resting potential was -56.4 +/- 1.4 mV (mean +/- SE, n = 35). The dominant effect of exposure to ISO was hyperpolarization. The hyperpolarization was apparent in all cells studied and averaged 11.6 +/- 1.2 mV (n = 27). In the majority of the cells, hyperpolarization was accompanied by a decreased input resistance (Rin). Often the change in resistance appeared to lag behind the change in membrane potential. The lack of coincident changes in membrane potential and resistance may reflect a superposition of the outward rectification properties of the membrane on beta-adrenergic-induced increases in ionic conductance. In about half of the cells, an initial small depolarization (3.1 +/- 0.3 mV, n = 14) was accompanied by a small but distinct increase in Rin (12 +/- 2.5%). When membrane potential was made more negative than the estimated equilibrium potential for K+ (EK) by injection of current, ISO also produced biphasic effects, an initial hyperpolarization which reversed to a sustained depolarization to a value (-90 mV) near the estimated EK. The hyperpolarization by ISO could be diminished in a time-dependent manner by previous exposure to ouabain. The inhibition by ouabain, however, appeared to be a fortuitous result of glycoside-induced positive shifts in EK. These observations indicate that the dominant electrophysiological effect of beta-adrenergic stimuli is to hyperpolarize the cell membrane.(ABSTRACT TRUNCATED AT 250 WORDS)

Differential blockade of agonist- and depolarization-induced 45Ca2+ influx in smooth muscle cells

1989 ◽  
Vol 257 (4) ◽  
pp. C607-C611 ◽  
Author(s):  
A. Wallnofer ◽  
C. Cauvin ◽  
T. W. Lategan ◽  
U. T. Ruegg
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Aortic Smooth Muscle Cells ◽  
Aortic Smooth Muscle ◽  
Gamma S ◽  
Ca2 Channels ◽  
Stimulation Of

ATP stimulated 45Ca2+ influx in rat aortic smooth muscle cells in a concentration-dependent manner (EC50 = 3.6 +/- 0.5 X 10(-7) M). ADP and GTP were less effective than ATP in stimulating 45Ca2+ influx; AMP was weakly active and the adenosine agonist 5'-(N-ethyl-carboxamido)-adenosine (NECA) had no effect. ATP gamma S was about equieffective with ATP, whereas alpha,beta-methylene-ATP (APCPP) did not induce 45Ca2+ influx. Stimulation of 45Ca2+ influx by ATP was not abolished by the dihydropyridine Ca2+ channel antagonist darodipine (PY 108-068), which completely blocked depolarization-induced 45Ca2+ influx. Inorganic cations (La3+, Cd2+, Co2+, Ni2+, Mn2+, and Mg2+) were able to inhibit both agonist- and depolarization-induced 45Ca2+ influx. Cd2+, however, was approximately 20 times more selective in blocking K+-stimulated than agonist-stimulated 45Ca2+ influx. These data indicate that ATP-stimulated Ca2+ influx in rat aortic smooth muscle cells is resistant to darodipine but is reduced by La3+, Cd2+, and other inorganic blockers of Ca2+ channels.

Role of IL-4, IL-13, and STAT6 in inflammation-induced hypercontractility of murine smooth muscle cells

2002 ◽  
Vol 282 (2) ◽  
pp. G226-G232 ◽  
Author(s):  
Hirotada Akiho ◽  
Patricia Blennerhassett ◽  
Yikang Deng ◽  
Stephen M. Collins
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Trichinella Spiralis ◽  
Muscle Cells ◽  
Dependent Manner ◽  
T Helper ◽  
Concentration Dependent Manner ◽  
T Helper 2 ◽  
Muscularis Externa

T helper 2 (Th2) cytokines interleukin (IL)-4 and IL-13, which activate signal transducer and activator of transcription 6 (STAT6) are expressed in the muscularis externa during nematode infection and are candidate mediators of the associated hypercontractility. To determine the locus of action of these cytokines, we examined the IL-4- and IL-13-induced hypercontractility of the isolated muscle cells from STAT6 +/+ and STAT6 −/− mice. We compared the results with cells isolated from Trichinella spiralis-infected STAT6 +/+ and STAT6 −/− mice. Carbamylcholine chloride (Carbachol) induced the contraction of jejunal muscle cells in a concentration-dependent manner maximal contraction (Rmax26.7 ± 1.9%). Cells from T. spiralis-infected STAT6 −/− mice showed the hypertrophy (cell lengths 41.4 ± 0.8 to 89.0 ± 8.7 μm) and hypercontractility (Rmax37.5 ± 1.3%) induced by infection. IL-4Rα mRNA was detected in dispersed smooth muscle cells. Incubation of longitudinal muscle-myenteric plexus (LMMP) with IL-4 and IL-13 enhanced Carbachol-induced muscle contraction (Rmax35.5 ± 1.9 and 32.4 ± 2.9%, respectively). Incubation of LMMP from STAT6 −/− mice with IL-4 did not enhance the contraction. The hypercontractility in T. spiralis-infected mice was attenuated in STAT6 −/− mice ( P < 0.02). These results indicate both IL-4 and IL-13 induce hypercontractility of muscle cells via the STAT6 pathway, and this is the basis for hypercontractility observed in T. spiralis-infected mice.

scholarly journals The contribution of inositol 1,4,5-trisphosphate and ryanodine receptors to agonist-induced Ca2+ signaling of airway smooth muscle cells

2009 ◽  
Vol 297 (2) ◽  
pp. L347-L361 ◽  
Author(s):  
Yan Bai ◽  
Martin Edelmann ◽  
Michael J. Sanderson
Keyword(s):  
Wave Propagation ◽  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Airway Smooth Muscle ◽  
Ryanodine Receptors ◽  
Muscle Cells ◽  
Airway Smooth Muscle Cells ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Inositol 1,4,5 Trisphosphate

The relative contribution of inositol 1,4,5-trisphosphate (IP3) receptors (IP3Rs) and ryanodine receptors (RyRs) to agonist-induced Ca2+ signaling in mouse airway smooth muscle cells (SMCs) was investigated in lung slices with phase-contrast or laser scanning microscopy. At room temperature (RT), methacholine (MCh) or 5-hydroxytryptamine (5-HT) induced Ca2+ oscillations and an associated contraction in small airway SMCs. The subsequent exposure to an IP3R antagonist, 2-aminoethoxydiphenyl borate (2-APB), inhibited the Ca2+ oscillations and induced airway relaxation in a concentration-dependent manner. 2-APB also inhibited Ca2+ waves generated by the photolytic release of IP3. However, the RyR antagonist ryanodine had no significant effect, at any concentration, on airway contraction or agonist- or IP3-induced Ca2+ oscillations or Ca2+ wave propagation. By contrast, a second RyR antagonist, tetracaine, relaxed agonist-contracted airways and inhibited agonist-induced Ca2+ oscillations in a concentration-dependent manner. However, tetracaine did not affect IP3-induced Ca2+ release or wave propagation nor the Ca2+ content of SMC Ca2+ stores as evaluated by Ca2+-release induced by caffeine. Conversely, both ryanodine and tetracaine completely blocked agonist-independent slow Ca2+ oscillations induced by KCl. The inhibitory effects of 2-APB and absence of an effect of ryanodine on MCh-induced airway contraction or Ca2+ oscillations of SMCs were also observed at 37°C. In Ca2+-permeable SMCs, tetracaine inhibited agonist-induced contraction without affecting intracellular Ca2+ levels indicating that relaxation also resulted from a reduction in Ca2+ sensitivity. These results indicate that agonist-induced Ca2+ oscillations in mouse small airway SMCs are primary mediated via IP3Rs and that tetracaine induces relaxation by both decreasing Ca2+ sensitivity and inhibiting agonist-induced Ca2+ oscillations via an IP3-dependent mechanism.

Cocaine Induces Apoptosis in Primary Cultured Rat Aortic Vascular Smooth Muscle Cells: Possible Relationship to Aortic Dissection, Atherosclerosis, and Hypertension

2004 ◽  
Vol 23 (4) ◽  
pp. 233-237 ◽  
Author(s):  
Jialin Su ◽  
Jianfeng Li ◽  
Wenyan Li ◽  
Bella T. Altura ◽  
Burton M. Altura
Keyword(s):  
Smooth Muscle ◽  
Aortic Dissection ◽  
Vascular Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Vascular Smooth Muscle Cells ◽  
Cocaine Abuse ◽  
Cardiovascular Effects ◽  
Muscle Cells ◽  
Dependent Manner ◽  
Concentration Dependent Manner

Cocaine abuse is known to induce many adverse cardiovascular effects, including hypertension, atherosclerosis, and aortic dissection. A major physiological event leading to these pathophysiological actions of cocaine could be apoptosis. This study was designed to investigate if primary cultured rat aortic vascular smooth muscle cells (VSMCs) can undergo apoptosis when treated with cocaine. After treatment with cocaine (10−6 to 10−4 M), morphological analysis of aortic VSMCs using confocal fluoresence microscopy showed that the percentage of apoptotic aortic VSMCs increased after cocaine (10−6 to 10−4 M) treatment for 12, 24, and 48 h. These results demonstrate that aortic VSMCs can undergo rapid apoptosis in response to cocaine in a concentration-dependent manner. Cocaine-induced apoptosis may thus play a major role in cocaine abuse-induced aortic dissection, atherosclerosis, and hypertension.

Regulation of glucose transport in aortic smooth muscle cells by cAMP and cGMP

2001 ◽  
Vol 353 (3) ◽  
pp. 513-519 ◽  
Author(s):  
Christopher J. MacKENZIE ◽  
Jill M. WAKEFIELD ◽  
Fiona CAIRNS ◽  
Anna F. DOMINICZAK ◽  
Gwyn W. GOULD
Keyword(s):  
Smooth Muscle ◽  
Protein Kinase ◽  
Smooth Muscle Cells ◽  
Primary Cultures ◽  
Muscle Cells ◽  
Mek Inhibitor ◽  
Mitogen Activated Protein Kinase ◽  
Common Element ◽  
Dependent Manner ◽  
Concentration Dependent Manner

We have studied the ability of cGMP and cAMP to modulate platelet-derived growth factor (PDGF)-stimulated 2-deoxy-d-glucose (deGlc) transport in primary cultures of vascular smooth muscle cells (VMSC) from rat aorta. PDGF stimulated deGlc transport in a time- and concentration-dependent manner. 8-Bromo-cGMP and atrial natriuretic peptide(1–28) [ANP(1–28)] were found to reduce PDGF-stimulated deGlc transport without affecting basal (unstimulated) transport activity. In contrast, 8-bromo-cAMP and dibutyryl-cAMP stimulated basal deGlc transport 2-fold and were without effect on PDGF-stimulated deGlc transport. 8-Bromo-cGMP also inhibited 8-bromo-cAMP-stimulated deGlc transport. The stimulation of deGlc transport by PDGF was sensitive to the mitogen-activated protein kinase (MAPK)/extracellular-signal-regulated kinase (ERK) kinase (MEK) inhibitor PD98059, and we show that ERK1/2 was activated by PDGF. Neither 8-bromo-cGMP nor ANP(1–28) inhibited PDGF-stimulated ERK activation, suggesting that the effects of cGMP and ANP(1–28) were not mediated by inhibition of this kinase. Our data also argue against a role for cGMP-dependent protein kinase in mediating the effects of cGMP or ANP(1–28). Collectively, our data suggest that in VSMC: (i) cGMP and cAMP have opposing effects on deGlc transport; (ii) PDGF and cAMP have common elements in the pathways by which they activate deGlc transport; and (iii) a common element may be the target of the cGMP-mediated inhibition of deGlc transport.

scholarly journals Endothelium-independent, ouabain-sensitive relaxation of bovine coronary arteries by EETs

2001 ◽  
Vol 280 (3) ◽  
pp. H1113-H1121 ◽  
Author(s):  
Phillip F. Pratt ◽  
Pinlan Li ◽  
Cecilia J. Hillard ◽  
Jason Kurian ◽  
William B. Campbell
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Potassium Chloride ◽  
Coronary Arteries ◽  
Muscle Tone ◽  
Muscle Cells ◽  
Resting Membrane Potential ◽  
Dependent Manner ◽  
Independent Manner ◽  
Concentration Dependent Manner

Endothelium-derived hyperpolarizing factor (EDHF) is released in response to agonists such as ACh and bradykinin and regulates vascular smooth muscle tone. Several studies have indicated that ouabain blocks agonist-induced, endothelium-dependent hyperpolarization of smooth muscle. We have demonstrated that epoxyeicosatrienoic acids (EETs), cytochrome P-450 metabolites of arachidonic acid, function as EDHFs. To further test the hypothesis that EETs represent EDHFs, we have examined the effects of ouabain on the electrical and mechanical effects of 14,15- and 11,12-EET in bovine coronary arteries. These arteries are relaxed in a concentration-dependent manner to 14,15- and 11,12-EET (EC50 = 6 × 10−7 M), bradykinin (EC50 = 1 × 10−9 M), sodium nitroprusside (SNP; EC50 = 2 × 10−7 M), and bimakalim (BMK; EC50 = 1 × 10−7 M). 11,12-EET-induced relaxations were identical in vessels with and without an endothelium. Potassium chloride (1–15 × 10−3 M) inhibited [3H]ouabain binding to smooth muscle cells but failed to relax the arteries. Ouabain (10−5 to 10−4 M) increased basal tone and inhibited the relaxations to bradykinin, 11,12-EET, and 14,15-EET, but not to SNP or BMK. Barium (3 × 10−5 M) did not alter EET-induced relaxations and ouabain plus barium was similar to ouabain alone. Resting membrane potential ( E m) of isolated smooth muscle cells was −50.2 ± 0.5 mV. Ouabain (3 × 10−5 and 1 × 10−4 M) decreased E m(−48.4 ± 0.2 mV), whereas 11,12-EET (10−7 M) increased E m (−59.2 ± 2.2 mV). Ouabain inhibited the 11,12-EET-induced increase in E m. In cell-attached patch clamp studies, 11,12-EET significantly increased the open-state probability ( NP o) of a calcium-activated potassium channel compared with control cells (0.26 ± 0.06 vs. 0.02 ± 0.01). Ouabain did not change NP o but blocked the 14,15-EET-induced increase in NP o. These results indicate that: 1) EETs relax coronary arteries in an endothelium-independent manner, 2) unlike EETs, potassium chloride does not relax the coronary artery, and 3) ouabain inhibits bradykinin- and EET-induced relaxations as has been reported for EDHF. These findings provide further evidence that EETs are EDHFs.

Regulation of membrane potential and diameter by voltage-dependent K+ channels in rabbit myogenic cerebral arteries

1995 ◽  
Vol 269 (1) ◽  
pp. H348-H355 ◽  
Author(s):  
H. J. Knot ◽  
M. T. Nelson
Keyword(s):  
Smooth Muscle ◽  
Membrane Potential ◽  
Smooth Muscle Cells ◽  
Cerebral Arteries ◽  
Muscle Cells ◽  
Transmural Pressure ◽  
Muscle Membrane ◽  
K Channels ◽  
Wide Range ◽  
Voltage Dependent

The hypothesis that voltage-dependent K+ channels are involved in the regulation of arterial smooth muscle membrane potential and blood vessel diameter was tested by examining the effects of inhibitors [4-aminopyridine (4-AP) and 3,4-diaminopyridine (3,4-DAP)] of voltage-dependent K+ channels on the membrane potential and diameter of pressurized small (100- to 300-microns diam) cerebral arteries from rabbit. In response to graded elevations in transmural pressure (20-100 mmHg), the membrane potential of smooth muscle cells in these arteries depolarized and the arteries constricted. 4-AP (1 mM) and 3,4-DAP (1 mM) depolarized cerebral arteries by 19 and 21 mV, respectively, when they were subjected to a transmural pressure of 80 mmHg. 3-Aminopyridine (3-AP, 1 mM), which is a relatively poor inhibitor of voltage-dependent K+ channels, depolarized smooth muscle cells in the arteries by 1 mV. 4-AP and 3,4-DAP constricted pressurized (to 80 mmHg) cerebral arteries. 3-AP had little effect on arterial diameter. 4-AP increased the arterial constriction to transmural pressure over a wide range of pressures (40-90 mmHg). The effects of 4-AP and 3,4-DAP on membrane potential and diameter were not prevented by inhibitors of calcium channels, calcium-activated K+ channels, ATP-sensitive K+ channels, inward rectifier K+ channels, blockers of adrenergic, serotonergic, muscarinic, and histaminergic receptors, or removal of the endothelium. These results suggest that voltage-dependent K+ channels are involved in the regulation of membrane potential and response of small cerebral arteries to changes in intravascular pressure.

scholarly journals Control of ion distribution in isolated smooth muscle cells. I. Potassium.

1980 ◽  
Vol 75 (2) ◽  
pp. 163-182 ◽  
Author(s):  
C R Scheid ◽  
F S Fay
Keyword(s):  
Smooth Muscle ◽  
Membrane Potential ◽  
Smooth Muscle Cells ◽  
Muscle Cells ◽  
Resting Membrane Potential ◽  
Stomach Muscle ◽  
Isolated Cells ◽  
Intracellular Space ◽  
Ion Movements ◽  
Isolated Smooth Muscle Cells

We describe a technique for examining unidirectional ion movements in suspensions of enzymatically disaggregated smooth muscle cells derived from stomach muscle of the toad. This technique has been used to analyze the movement of 42K across these cells. This analysis was greatly simplified by the finding that the cells were in a steady state with respect to K+ distribution after isolation. The potassium contents of the isolated cells were identical to those of intact smooth muscle (131 mM/liter intracellular fluid) and stable for over 4 h; moreover, the unidirectional influx and efflux rates were equal. An additional simplification was provided by the finding that virtually all the K+ exchanges in a manner predicted for a simple two-compartment system consisting of an extracellular and an intracellular space. Transmembrane K+ flux in these cells averaged 1.2 pmol.cm-2.s-1 at room temperature. A large portion (approximately 80%) of 42K influx appeared to be mediated by a saturable transport system with an apparent Km of 0.6 mM and an apparent Vmax of 1.3 pmol.cm-2.s-1. The calculated resting membrane permeability to K+ in these isolated smooth muscle cells, assuming a membrane potential of -50 mV, was 2.9 X 10(-8) cm/s. The calculated gK+ was 2.7 mumho/cm2 constituting only a small fraction of the total membrane conductance as measured electrophysiologically. The latter finding suggests that the resting membrane potential in the isolated cells must be determined by ions in addition to K+. We propose that these methods for studying ion movements in smooth muscle should aid in unraveling the mechanisms responsible for controlling the distribution of ions both at rest, as in the present study, as well as in response to neurotransmitters.

Pioglitazone attenuates hypertension and inhibits growth of renal arteriolar smooth muscle in rats

1993 ◽  
Vol 265 (4) ◽  
pp. R726-R732 ◽  
Author(s):  
R. K. Dubey ◽  
H. Y. Zhang ◽  
S. R. Reddy ◽  
M. A. Boegehold ◽  
T. A. Kotchen
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Calf Serum ◽  
Muscle Cells ◽  
Dependent Manner ◽  
Sprague Dawley ◽  
In Vitro Proliferation ◽  
Concentration Dependent Manner ◽  
Blood Pressures ◽  
The One

Hypertension is frequently associated with insulin resistance. We evaluated the effects of pioglitazone, an agent that increases insulin sensitivity, on the development of hypertension in the Dahl salt-sensitive (Dahl-S) rat and in the one-kidney, one-clip Sprague-Dawley rat. We also evaluated the effects of pioglitazone on growth of cultured preglomerular renal arteriolar smooth muscle cells. In Dahl-S rats fed a 3% NaCl diet, tail systolic blood pressures and direct arterial pressures were lower (P < 0.05) in pioglitazone-treated (20 mg/kg daily by gavage for 3 wk) than in control rats (n = 10 rats/group). In one-kidney, one-clip Sprague-Dawley rats, systolic blood pressures were also lower in pioglitazone-treated animals (P < 0.0001). In vitro, proliferation of arteriolar smooth muscle cells was stimulated (P < 0.01) by insulin, epidermal growth factor (EGF), and fetal calf serum (FCS); pioglitazone (5 microM) reversibly inhibited (P < 0.01) insulin-, EGF-, and FCS-induced proliferation. Pioglitazone (0.01-100 microM) also inhibited insulin- (1 mU/ml), EGF- (100 ng/ml), and 5% FCS-induced [3H]thymidine incorporation in a concentration-dependent manner (P < 0.01). Thus pioglitazone attenuated the development of hypertension in the Dahl-S rat and the one-kidney, one-clip rat. The ability of pioglitazone to inhibit growth of vascular smooth muscle may contribute to its hypotensive effect.

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