scholarly journals T-type Ca2+channel modulation by otilonium bromide

2010 ◽  
Vol 298 (5) ◽  
pp. G706-G713 ◽  
Author(s):  
Peter R. Strege ◽  
Lei Sha ◽  
Arthur Beyder ◽  
Cheryl E. Bernard ◽  
Edward Perez-Reyes ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Contractile Activity ◽  
Clinical Effectiveness ◽  
Smooth Muscle Contraction ◽  
Hek293 Cells ◽  
Channel Blockers ◽  
Patch Clamp Technique ◽  
Extracellular Solution ◽  
Channel Modulation ◽  
Main Pathway

Antispasmodics are used clinically to treat a variety of gastrointestinal disorders by inhibition of smooth muscle contraction. The main pathway for smooth muscle Ca2+entry is through L-type channels; however, there is increasing evidence that T-type Ca2+channels also play a role in regulating contractility. Otilonium bromide, an antispasmodic, has previously been shown to inhibit L-type Ca2+channels and colonic contractile activity. The objective of this study was to determine whether otilonium bromide also inhibits T-type Ca2+channels. Whole cell currents were recorded by patch-clamp technique from HEK293 cells transfected with cDNAs encoding the T-type Ca2+channels, CaV3.1 (α1G), CaV3.2 (α1H), or CaV3.3 (α1I) alpha subunits. Extracellular solution was exchanged with otilonium bromide (10−8to 10−5M). Otilonium bromide reversibly blocked all T-type Ca2+channels with a significantly greater affinity for CaV3.3 than CaV3.1 or CaV3.2. Additionally, the drug slowed inactivation in CaV3.1 and CaV3.3. Inhibition of T-type Ca2+channels may contribute to inhibition of contractility by otilonium bromide. This may represent a new mechanism of action for antispasmodics and may contribute to the observed increased clinical effectiveness of antispasmodics compared with selective L-type Ca2+channel blockers.

The endothelium modulates the contribution of chloride currents to norepinephrine-induced vascular contraction

1998 ◽  
Vol 275 (1) ◽  
pp. H161-H168 ◽  
Author(s):  
Fred S. Lamb ◽  
Thomas J. Barna
Keyword(s):  
Smooth Muscle ◽  
Smooth Muscle Contraction ◽  
Maximum Response ◽  
Channel Blockers ◽  
Chloride Currents ◽  
Aortic Smooth Muscle ◽  
Independent Components ◽  
Voltage Change ◽  
Voltage Dependent ◽  
Transport Inhibitors

Activation of a Cl− current is critical to agonist-induced activation of rat aortic smooth muscle contraction. Substituting extracellular Cl− with 130 mM methanesulfonate (8 mM Cl−) increases the contractile response to norepinephrine (NE) but not to KCl. We hypothesized that endothelial factors modulate this effect. Removing the endothelium (rubbing) or treatment with N-nitrol-arginine (l-NNA) markedly increased the potentiation of NE-induced contraction by low-Cl− buffer. Indomethacin had no effect. The previously demonstrated ability of Cl−-channel blockers (DIDS, anthracene-9-carboxylic acid, niflumic acid) or Cl− transport inhibitors (bumetanide, bicarbonate-free buffer) to inhibit responses to NE was not altered by l-NNA. Low-Cl− buffer alone did not contract intact rings but produced nifedipine-sensitive contractile responses after rubbing or l-NNA treatment. These data suggest that the Cl− conductance of smooth muscle in intact blood vessels is low but increases with withdrawal of reduced nitric oxide (NO′) or agonist stimulation. Rubbing orl-NNA increased the sensitivity of rings to KCl but not to NE. Nifedipine reduced both sensitivity and maximum response to NE in intact vessels.l-NNA increased the maximum response to NE in nifedipine-treated rings without changing sensitivity. We conclude that although NO′ affects both the voltage-dependent and voltage-independent components of contraction, sensitivity to NE is determined by the voltage-dependent portion. The voltage change required for a full response to NE is dependent on activation of a Cl− current that may be under the tonic regulatory influence of NO′.

Ca2+ antagonist-insensitive coronary smooth muscle contraction involves activation of ϵ-protein kinase C-dependent pathway

2003 ◽  
Vol 285 (6) ◽  
pp. C1454-C1463 ◽  
Author(s):  
Andrea Dallas ◽  
Raouf A. Khalil
Keyword(s):  
Smooth Muscle ◽  
Coronary Artery ◽  
Muscle Contraction ◽  
Smooth Muscle Contraction ◽  
Channel Blockers ◽  
Cell Contraction ◽  
Coronary Smooth Muscle ◽  
Calphostin C ◽  
Gf 109203X ◽  
Dependent Pathway

Certain angina and coronary artery disease forms do not respond to Ca2+ channel blockers, and a role for vasoactive eicosanoids such as PGF2α in Ca2+ antagonist-insensitive coronary vasospasm is suggested; however, the signaling mechanisms are unclear. We investigated whether PGF2α-induced coronary smooth muscle contraction is Ca2+ antagonist insensitive and involves activation of a PKC-dependent pathway. We measured contraction in single porcine coronary artery smooth muscle cells and intracellular free Ca2+ concentration ([Ca2+]i) in fura 2-loaded cells and examined cytosolic and particulate fractions for PKC activity and reactivity with isoform-specific PKC antibodies. In Hanks' solution (1 mM Ca2+), PGF2α (10-5 M) caused transient [Ca2+]i increase followed by maintained [Ca2+]i increase and 34% cell contraction. Ca2+ channel blockers verapamil and diltiazem (10-6 M) abolished maintained PGF2α-induced [Ca2+]i increase but only partially inhibited PGF2α-induced cell contraction to 17%. Verapamil-insensitive PGF2α contraction was inhibited by PKC inhibitors GF-109203X, calphostin C, and ϵ-PKC V1-2. PGF2α caused Ca2+-dependent α-PKC and Ca2+-independent ϵ-PKC translocation from cytosolic to particulate fractions that was inhibited by calphostin C. Verapamil abolished PGF2α-induced α-but not ϵ-PKC translocation. PMA (10-6 M), a direct activator of PKC, caused 21% contraction with no significant [Ca2+]i increase and ϵ-PKC translocation that were inhibited by calphostin C but not verapamil. Membrane depolarization by 51 mM KCl, which stimulates Ca2+ influx, caused 36% cell contraction and [Ca2+]i increase that were inhibited by verapamil but not GF-109203X or calphostin C and did not cause α- or ϵ-PKC translocation. Thus a significant component of PGF2α-induced contraction of coronary smooth muscle is Ca2+ antagonist insensitive, involves Ca2+-independent ϵ-PKC activation and translocation, and may represent a signaling mechanism of Ca2+ antagonist-resistant coronary vasospasm.

Ionic mechanisms and Ca2+ regulation in airway smooth muscle contraction: do the data contradict dogma?

2002 ◽  
Vol 282 (6) ◽  
pp. L1161-L1178 ◽  
Author(s):  
Luke J. Janssen
Keyword(s):  
Smooth Muscle ◽  
Airway Smooth Muscle ◽  
Smooth Muscle Contraction ◽  
Channel Blockers ◽  
Excitation Contraction Coupling ◽  
Contraction Coupling ◽  
Spatial And Temporal Heterogeneity ◽  
Voltage Dependent ◽  
Intracellular Ca ◽  
Ionic Mechanisms

In general, excitation-contraction coupling in muscle is dependent on membrane depolarization and hyperpolarization to regulate the opening of voltage-dependent Ca2+ channels and, thereby, influence intracellular Ca2+ concentration ([Ca2+]i). Thus Ca2+ channel blockers and K+ channel openers are important tools in the arsenals against hypertension, stroke, and myocardial infarction, etc. Airway smooth muscle (ASM) also exhibits robust Ca2+, K+, and Cl− currents, and there are elaborate signaling pathways that regulate them. It is easy, then, to presume that these also play a central role in contraction/relaxation of ASM. However, several lines of evidence speak to the contrary. Also, too many researchers in the ASM field view the sarcoplasmic reticulum as being centrally located and displacing its contents uniformly throughout the cell, and they have focused almost exclusively on the initial single [Ca2+] spike evoked by excitatory agonists. Several recent studies have revealed complex spatial and temporal heterogeneity in [Ca2+]i, the significance of which is only just beginning to be appreciated. In this review, we will compare what is known about ion channels in ASM with what is believed to be their roles in ASM physiology. Also, we will examine some novel ionic mechanisms in the context of Ca2+ handling and excitation-contraction coupling in ASM.

scholarly journals Features of the bradykinin-induced contraction of the gastric smooth muscle depending on the concentration of compounds based on 3-substituted-1,4-benzodiazepin-2-ones

2016 ◽  
Vol 21 (2) ◽  
pp. 19-23
Author(s):  
P. Virych ◽  
O. Shelyuk ◽  
V. Martynyuk ◽  
V. Pavlovsky
Keyword(s):  
Smooth Muscle ◽  
Muscle Contraction ◽  
Contractile Activity ◽  
Smooth Muscles ◽  
Competitive Inhibitor ◽  
Smooth Muscle Contraction ◽  
Gastric Smooth Muscle ◽  
Low Concentrations

The effect of compounds based on 3-substituted-1,4-benzodiazepine-2-ones on contractile activity of smooth muscles of the rat's stomach was analyzed. Action substances MX-1626, MX-1775 for the smooth muscle contraction of like competitive inhibitor of bradykinin – des-Arg9- [Leu8]-Bradykinin acetate, which is observed as increase normalized rate of contraction with increasing of bradykinin concentration and characterized by a slowdown in the first phase of contraction. The most effective 3-subtituted 1,4-benzodiazepin-2-ones was at low concentrations of bradykinin, increasing it concentration their effect is reduced.

Increased intracellular Cl- Concentrations in Pulmonary Arterial Myocytes Associated with Chronic Hypoxic Pulmonary Hypertension

2021 ◽  
Author(s):  
Hui Sun ◽  
Omkar Paudel ◽  
James S.K. Sham
Keyword(s):  
Pulmonary Hypertension ◽  
Smooth Muscle ◽  
Gene Family ◽  
Chloride Channels ◽  
Pulmonary Arteries ◽  
Smooth Muscle Contraction ◽  
Patch Clamp Technique ◽  
Pulmonary Arterial ◽  
Perforated Patch Clamp ◽  
First Time

Chloride channels play an important role in regulating smooth muscle contraction and proliferation, and contribute to the enhanced constriction of pulmonary arteries (PAs) in pulmonary hypertension (PH). The intracellular Cl- concentration ([Cl-]i), tightly regulated by various Cl- transporters, determines the driving force for Cl- conductance, thereby the functional outcome of Cl- channel activation. This study characterizes for the first time the expression profile of Cl- transporters/exchangers in PA smooth muscle and provides the first evidence that the intracellular Cl- homeostasis is altered in PA smooth muscle cells (PASMCs) associated with chronic hypoxic PH (CHPH). Quantitative RT-PCR revealed that the endothelium-denuded intralobar PA of rats expressed Slc12a gene family-encoded Na-K-2Cl cotransporter 1 (NKCC1), K-Cl cotransporters (KCC) 1, 3 and 4, and Slc4a gene family-encoded Na+-independent and Na +-dependent Cl-/HCO3- exchangers. Exposure of rats to chronic hypoxia (10% O2, 3 weeks) caused CHPH and selectively increased the expression of Cl--accumulating NKCC1 and reduced the Cl--extruding KCC4. The intracellular Cl- concentration ([Cl-]i) averaged at 45 mM and 47 mM in normoxic PASMCs as determined by fluorescent indicator MEQ and by gramicidin perforated patch clamp technique, respectively, The ([Cl-]i was increased by ~ 10 mM in PASMCs of rats with CHPH. Future studies are warranted to further establish the hypothesis that the altered intracellular Cl- homeostasis contributes to the pathogenesis of CHPH.

Temporal and spatial dynamics underlying capacitative calcium entry in human colonic smooth muscle

2008 ◽  
Vol 294 (1) ◽  
pp. G88-G98 ◽  
Author(s):  
Jason R. Kovac ◽  
Tom Chrones ◽  
Stephen M. Sims
Keyword(s):  
Smooth Muscle ◽  
High Speed ◽  
Imaging Techniques ◽  
Spatial Dynamics ◽  
Cyclopiazonic Acid ◽  
Smooth Muscle Contraction ◽  
Bathing Solution ◽  
Channel Blockers ◽  
Intracellular Ca ◽  
Inward Currents

Following smooth muscle excitation and contraction, depletion of intracellular Ca2+ stores activates capacitative Ca2+ entry (CCE) to replenish stores and sustain cytoplasmic Ca2+ (Ca2+i) elevations. The objectives of the present study were to characterize CCE and the Ca2+i dynamics underlying human colonic smooth muscle contraction by using tension recordings, fluorescent Ca2+-indicator dyes, and patch-clamp electrophysiology. The neurotransmitter acetylcholine (ACh) contracted tissue strips and, in freshly isolated colonic smooth muscle cells (SMCs), caused elevation of Ca2+i as well as activation of nonselective cation currents. To deplete Ca2+i stores, the sarcoplasmic reticulum Ca2+-ATPase (SERCA) inhibitors thapsigargin and cyclopiazonic acid were added to a Ca2+-free bathing solution. Under these conditions, addition of extracellular Ca2+ (3 mM) elicited increased tension that was inhibited by the cation channel blockers SKF-96365 (10 μM) and lanthanum (100 μM), suggestive of CCE. In a separate series of experiments on isolated SMCs, SERCA inhibition generated a gradual and sustained inward current. When combined with high-speed Ca2+-imaging techniques, the CCE-evoked rise of Ca2+i was associated with inward currents carrying Ca2+ that were inhibited by SKF-96365. Regional specializations in Ca2+ influx and handling during CCE were observed. Distinct “hotspot” regions of Ca2+ rise and plateau were evident in 70% of cells, a feature not previously recognized in smooth muscle. We propose that store-operated Ca2+ entry occurs in hotspots contributing to localized Ca2+ elevations in human colonic smooth muscle.

scholarly journals Effect of 3-substituted 1,4-benzodiazepin-2-ones on maximal normalized rate of bradykinin-induced smooth muscle contraction in the presence of calcium channel blockers

2017 ◽  
Vol 8 (2) ◽  
pp. 224-230 ◽  
Author(s):  
P. A. Virych ◽  
O. V. Shelyuk ◽  
T. A. Kabanova ◽  
O. I. Khalimova ◽  
V. S. Martynyuk ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Calcium Channel ◽  
Muscle Contraction ◽  
Calcium Channel Blockers ◽  
Smooth Muscle Contraction ◽  
Channel Blockers ◽  
B2 Receptors ◽  
The One ◽  
Potential Inhibitors ◽  
Contraction And Relaxation

The development of modern organic chemistry and molecular modeling technologies simplify the search for potential inhibitors of various receptor systems and biological processes. The one of the directions is the development of analgesics of broad spectrum and low toxicity. It is important to search for inhibitors of the kinin-kallikrein system that regulates many functions: inflammation, pain, carcinogenesis, vascular tone, smooth muscle contraction and other. Derivatives of 3-substituted 1,4-benzodiazepine-2-ones have a unique spatial conformation that allows one to simulate β-structures of bioactive peptides. The functional activity of compounds is determined by properties of their peripheral chemical radicals. We analyzed the effect of 3-substituted 1,4-benzodiazepin-2-ones derivatives on the normalized maximal rate of bradykinin-induced smooth muscle contraction and relaxation of the stomach in the presence of calcium channel blockers: verapamil (1 μM), gadolinium (300 μM) and 2-aminoethyl diphenylborinate (0.1 μM). The levels of bradykinin and 3-arylamino-1,2-dihydro-3H-1,4-benzodiazepine-2-ones in incubation solution were 10–6 M. Data processing on dynamics of contraction was performed according to the method of Burdyha and Kosterin. Compounds MX-1775 and MX-1925 reduced maximal normalized rate (Vn) of bradykinin-induced smooth muscle contraction in the presence of Gd3+ by 21.2% and 31.0% respectively. Compound MX-1925 increased Vn of relaxation by 11.6%. A similar effect is typical for MX-2011, where there is an increase by 34.6%. In the presence of verapamil this compound additionally decreased Vn contraction by 20.5%. Substances MX-1775, MX-2004 and MX-1925 restored maximal normalized rate of relaxation to original values of bradykinin-induced contraction. In the presence of 2-aminoethyldiphenylborinate MX-1775 additionally reduced Vn of contractions by 7.5%. 3-substituted 1,4-benzo­diazepine-2-ones did not change the maximal normalized rate of contraction and relaxation of carbachol- and potential-induced smooth muscle contraction. Based on the results and previous investigations, the MX-1775 is a potential blocker of kinin B2-receptors. Effects obtained for other compounds require additional research. 

Mechanics of K(+)-induced isotonic and isometric contractions in isolated canine coronary microarteries

1990 ◽  
Vol 258 (3) ◽  
pp. C512-C523 ◽  
Author(s):  
P. J. Boels ◽  
V. A. Claes ◽  
D. L. Brutsaert
Keyword(s):  
Smooth Muscle ◽  
Contractile Activity ◽  
Smooth Muscle Contraction ◽  
Isometric Contractions ◽  
Maximal Velocity ◽  
Physiological Control ◽  
Force Relation ◽  
Force Velocity ◽  
Isotonic Contractions ◽  
Isotonic Shortening

The effects of shortening in isotonic contractions on the mechanics of microvascular smooth muscle were investigated. Intramyocardial canine coronary microarteries (in situ diameter 60 +/- 3 microns) were mounted as rings, connected to a newly developed photoelectromagnetic force-length transducer, and activated with 125 mM K+. Shortening during isotonic contractions depressed the length-force relation (shortening deactivation) compared with the length-force relation obtained from isometric contractions; the effect was present at the earliest moments after activation, suggesting that a fundamental mechanism associated with the actual sliding of contractile filaments delayed onset of contractile activity in isotonic contractions compared with isometric contractions. Force-velocity relations were obtained by isotonic quick releases from isotonic and isometric contractions at various times. Isotonic shortening before the quick releases reduced the constants of the apparent hyperbolic force-velocity relations and maximal velocity of shortening (Vmax) compared with isometric contractions released at the same time. Increasing contraction duration reduced Vmax but more so in isotonic than in isometric contractions. Vmax also decreased with decreasing instantaneous length. A possible effect of force development on Vmax before the isotonic quick release was also described. Quick increments of load during isotonic contractions were sustained during active shortening in the phasic part, but during the tonic part loading resulted in a pronounced transient relaxation. Thus, in microvascular preparations, active isotonic shortening altered the length-force, force-velocity, and velocity-time relations and uncovered a time-dependent sensitivity to loading conditions. These experiments suggested that the mechanics of smooth muscle contraction may contribute significantly to the mechanisms of the physiological control of coronary microvascular diameter.

scholarly journals The regulation mechanisms of contractile activity of smooth muscle cells: reactive oxygen species role

2011 ◽  
Vol 10 (3) ◽  
pp. 30-36
Author(s):  
S. V. Gusakova ◽  
M. B. Baskakov ◽  
I. V. Kovalev ◽  
A. S. Zheludeva ◽  
L. V. Smagly ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Smooth Muscle ◽  
Smooth Muscle Cells ◽  
Intracellular Signaling ◽  
Contractile Activity ◽  
Reactive Oxygen ◽  
Muscle Cells ◽  
Smooth Muscle Contraction ◽  
Oxygen Species ◽  
Signaling Systems

The effect of modulation of hydrogen peroxide, nitric oxide and hydrogen sulfide on contractile reactions of smooth muscle cells caused by depolarization, phenylephrine and solutions with altered osmolarity has been investigated by the mechanographical method. The new data of the fundamental nature of the role of reactive oxygen species in the operation of calcium and cGMP-mediated intracellular signaling systems, as well as in volume-dependent regulation of smooth muscle contraction.

scholarly journals GATA4 is a negative regulator of contractility in testicular peritubular myoid cells

Reproduction ◽  
2018 ◽  
Author(s):  
Yu-Qian Wang ◽  
Aalia Batool ◽  
Su-Ren Chen ◽  
Yi-Xun Liu
Keyword(s):  
Smooth Muscle ◽  
Contractile Activity ◽  
Primary Cultures ◽  
Collagen Gel ◽  
Smooth Muscle Contraction ◽  
Negative Regulator ◽  
Limited Attention ◽  
Cell Contraction ◽  
Promoting Effect ◽  
Cytokines And Chemokines

Reduced contractility of the testicular peritubular myoid (PTM) cells may contribute to human male sub- or infertility. Transcription factor GATA4 in Sertoli and Leydig cells is essential for murine spermatogenesis; but limited attention has been paid to the potential role of GATA4 in PTM cells. In primary cultures of mouse PTM cells, siRNA knockdown of GATA4 increased the contractile activity, while GATA4 overexpression significantly attenuated the contractility of PTM cells using a collagen gel contraction assay. Using RNA sequencing and qRT-PCR, we identified a set of genes that exhibited opposite expressional alternation between Gata4 siRNA vs nontargeting siRNA-treated PTM cells and Gata4 adenovirus vs control adenovirus-treated PTM cells. Notably, ion channels, smooth muscle function, cytokines and chemokines, cytoskeleton, adhesion and extracellular matrix were the top four enriched pathways, as revealed by cluster analysis. Natriuretic peptide type B (NPPB) content was significantly upregulated by GATA4 overexpression in both PTM cells and their culture supernatant. More importantly, the addition of 100 μM NPPB could abolish the promoting effect of Gata4 silencing on PTM cell contraction. Taken together, we suggest that the inhibitory action of GATA4 on PTM cell contraction is mediated at least partly by regulating genes belonging to smooth muscle contraction pathway (e.g. Nppb).

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