Intracellular regulation of sustained contraction stimulated by L-type Ca2+ channel activation in swine carotid smooth muscle

Airway smooth muscle (ASM) contracts partly due to an increase in cytosolic Ca2+. In this work, we found that the contraction caused by histamine depends on external Na+, possibly involving nonselective cationic channels (NSCC) and the Na+/Ca2+ exchanger (NCX). We performed various protocols using isometric force measurement of guinea pig tracheal rings stimulated by histamine. We observed that force reached 53 ± 1% of control during external Na+ substitution by N-methyl-d-glucamine+, whereas substitution by Li+ led to no significant change (91 ± 1%). Preincubation with KB-R7943 decreased the maximal force developed (52.3 ± 5.6%), whereas preincubation with nifedipine did not (89.7 ± 1.8%). Also, application of the nonspecific NCX blocker KB-R7943 and nifedipine on histamine-precontracted tracheal rings reduced force to 1 ± 3%, significantly different from nifedipine alone (49 ± 6%). Moreover, nonspecific NSCC inhibitors SKF-96365 and 2-aminoethyldiphenyl borate reduced force to 1 ± 1% and 19 ± 7%, respectively. Intracellular Ca2+ measurements in isolated ASM cells showed that KB-R7943 and SKF-96365 reduced the peak and sustained response to histamine (0.20 ± 0.1 and 0.19 ± 0.09 for KB-R, 0.43 ± 0.16 and 0.47 ± 0.18 for SKF, expressed as mean of differences). Moreover, Na+-free solution only inhibited the sustained response (0.54 ± 0.25). These data support an important role for NSCC and NCX during histamine stimulation. We speculate that histamine induces Na+ influx through NSCC that promotes the Ca2+ entry mode of NCX and CaV1.2 channel activation, thereby causing contraction.

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Abstract 507: G Proteins are Required for Lipoxygenase EDHF Activity of Rabbit Arterial Smooth Muscle Cells

Hypertension ◽

10.1161/hyp.60.suppl_1.a507 ◽

2012 ◽

Vol 60 (suppl_1) ◽

Author(s):

Kathryn M Gauthier ◽

J. R Falck ◽

William B Campbell

Keyword(s):

Smooth Muscle ◽

Smooth Muscle Cells ◽

G Proteins ◽

Muscle Cells ◽

Specific Structure ◽

Inhibitory Peptide ◽

Receptor Binding Site ◽

Channel Activation ◽

Sk Channel ◽

Vascular Activity

Arachidonic acid 15-lipoxygenase (15-LO) metabolites function as endothelium-derived hyperpolarizing factors in rabbit and human arteries. In rabbit arteries, LO metabolites mediate nitric-oxide and prostaglandin-independent relaxations to acetylcholine and AA. Previously, we characterized 11,12,15-trihydroxyeicosatrienoic acid (11,12,15-THETA) as a major vasoactive 15-LO metabolite in rabbit arteries. 11,12,15-THETA requires a specific structure for vascular activity. 11(R),12(S),15(S)-THETA causes concentration-related relaxation whereas 11(R),12(R),15(S)-THETA is without activity. The specific structure requirement suggests a role for a receptor. Therefore, we examined the role of G proteins in 11(R),12(S),15(S)-THETA vascular activity. Western immunoblot verified protein expression of Gαs, Gαi and a Gαo in rabbit endothelial and smooth muscle cells. 11(R),12(S),15(S)-THETA increased GTPγ35S binding to rabbit arterial membranes 280±25% while 11(R),12(S),15(S)-THETA was without effect. In cell-attached patches of rabbit smooth muscle, 11(R),12(S),15(S)-THETA (100 nM) increased mean open time of apamin-sensitive, calcium-activated, small conductance potassium (SK) channels from 0.0001±0.0001 to 0.0015±0.0006. In inside-out patches, 11(R),12(S),15(S)-THETA did not increase channel opening (0.0001±0.0001) unless GTP was present (0.0051±0.0023). In the presence of GTP, an antibody against Gαs and a Gαs inhibitory peptide inhibited 11(R),12(S),15(S)-THETA SK channel activation (0.0007±0.0005, 0.0013±0.0012, respectively) whereas an antibody against Gαi was without effect (0.0042±0.0018). A cell-permeant, penetratin-linked Gαs inhibitory peptide also inhibited 11(R),12(S),15(S)-THETA SK channel activation in cell-attached patches (0.0005±0.0002) and blocked 11(R),12(S),15(S)-THETA relaxations in rabbit aorta (max relaxations = 74±6%, 23±7% for control and permeant peptide, respectively). These studies indicate that 11,12,15-THETA-induced SK channel activation and vascular relaxation are mediated by a Gs-coupled mechanism and that 11,12,15-THETA acts via a stereo-specific G protein coupled receptor/binding site.

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Involvement of channel activation in procainamide-induced relaxation of bovine tracheal smooth muscle

The Japanese Journal of Pharmacology ◽

10.1016/s0021-5198(19)48449-7 ◽

2000 ◽

Vol 82 ◽

pp. 247

Author(s):

Hiroshi Moriuchi ◽

Tsutomu Nakahara ◽

Motonari Yunoki ◽

Yoshio Tanaka ◽

Kenji Sakamato ◽

...

Keyword(s):

Smooth Muscle ◽

Tracheal Smooth Muscle ◽

Channel Activation

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Mitochondrial uncoupler carbonyl cyanide m-chlorophenylhydrazone induces vasorelaxation without involving KATP channel activation in smooth muscle cells of arteries

British Journal of Pharmacology ◽

10.1111/bph.13578 ◽

2016 ◽

Vol 173 (21) ◽

pp. 3145-3158 ◽

Cited By ~ 16

Author(s):

Yan-Qiu Zhang ◽

Xin Shen ◽

Xiao-Lin Xiao ◽

Ming-Yu Liu ◽

Shan-Liang Li ◽

...

Keyword(s):

Smooth Muscle ◽

Smooth Muscle Cells ◽

Katp Channel ◽

Muscle Cells ◽

Channel Activation ◽

Carbonyl Cyanide ◽

Mitochondrial Uncoupler

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Sarcoplasmic reticulum and endothelium independently regulate venous smooth muscle [Ca2+]iand contraction

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1999.277.2.h749 ◽

1999 ◽

Vol 277 (2) ◽

pp. H749-H755

Author(s):

Régent Laporte ◽

Ismail Laher

Keyword(s):

Smooth Muscle ◽

Steady State ◽

Sarcoplasmic Reticulum ◽

Salt Solution ◽

Isometric Contraction ◽

Cyclopiazonic Acid ◽

Physiological Salt Solution ◽

Sustained Contraction ◽

Facial Vein ◽

State Increase

In rings of rabbit facial vein (RFV), depletion of sarcoplasmic reticulum (SR) Ca2+ by caffeine abolished the subsequent isometric contraction to 25 mM K+ physiological salt solution (25K-PSS). However, the associated steady-state increase of smooth muscle intracellular free Ca2+concentration ([Ca2+]i), measured using fura PE3 and cuvette photometry, was not altered. Treatment with the specific SR Ca2+ pump inhibitor cyclopiazonic acid (30 μM) after caffeine-induced SR Ca2+ depletion restored and greatly augmented the 25K-PSS-induced contraction. This suggests that SR Ca2+ depletion leads to a dissociation of K+-induced [Ca2+]iincrease from contraction that was dependent on Ca2+ pump-mediated SR Ca2+ uptake. Endothelium removal augmented the 25K-PSS-induced [Ca2+]iincrease after caffeine-induced SR Ca2+ depletion. However, this was associated with only a small and transient contraction. Exposure of endothelium-denuded RFV to cyclopiazonic acid after caffeine-induced SR Ca2+ depletion further amplified the 25K-PSS-induced [Ca2+]iincrease, which was associated with a large and sustained contraction. However, the latter [Ca2+]iincrease was still higher than in endothelium-intact RFV. This suggests that the endothelium dampens the [Ca2+]irise associated with K+-induced Ca2+ influx, but independently of Ca2+ pump-mediated SR Ca2+ uptake.

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Pulmonary vein contracts in response to hypoxia

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.1993.265.1.l87 ◽

1993 ◽

Vol 265 (1) ◽

pp. L87-L92 ◽

Cited By ~ 20

Author(s):

Y. Zhao ◽

C. S. Packer ◽

R. A. Rhoades

Keyword(s):

Smooth Muscle ◽

Regional Blood Flow ◽

Hypoxic Pulmonary Vasoconstriction ◽

Phase 1 ◽

Pulmonary Veins ◽

Arterial Phase ◽

Channel Blockers ◽

Phase 2 ◽

Hypoxic Response ◽

Sustained Contraction

Hypoxic pulmonary vasoconstriction (HPV) is an important regulatory mechanism in matching regional blood flow and ventilation. The HPV response has been well documented on the arterial side, but the response of pulmonary veins to hypoxia has received little attention. The purpose of the present study was to determine whether isolated rat pulmonary veins contract in response to decreased PO2 and, if so, to compare the venous response with that of the pulmonary artery. Rat pulmonary venous and arterial rings were attached to force transducers and precontracted with either a submaximal dose of KCl or norepinephrine under normoxic conditions and then made hypoxic. The pulmonary venous hypoxic response consisted of a single sustained contraction, whereas the arterial response to hypoxia was biphasic, consisting of an initial rapid contraction and then a slowly developed but sustained contraction. The venous hypoxic contraction was significantly greater in magnitude than either phase 1 or phase 2 of the arterial response. Endothelium denudation did not affect the venous hypoxic response. However, the venous hypoxic response was dependent on the level of precontractile tone and also appeared to be dependent on the specific contractile agonist. Unlike the isolated arterial phase 1 hypoxic response (but similar to the arterial phase 2 response) the pulmonary venous hypoxic contraction was inhibited in Ca(2+)-free media or by Ca2+ channel blockers. In summary, pulmonary venous smooth muscle contracts to a relatively greater degree in response to severe hypoxia than does pulmonary arterial smooth muscle. The venous hypoxic response is endothelium independent, as is phase 2 of the arterial response.(ABSTRACT TRUNCATED AT 250 WORDS)

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Calcium channel activation in vascular smooth muscle by BAY K 8644

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y84-233 ◽

1984 ◽

Vol 62 (11) ◽

pp. 1401-1410 ◽

Cited By ~ 85

Author(s):

C. M. Su ◽

V. C. Swamy ◽

D. J. Triggle

Keyword(s):

Smooth Muscle ◽

Dose Response ◽

Response Curve ◽

Bay K 8644 ◽

Rat Tail Artery ◽

Channel Activation ◽

Tail Artery ◽

Voltage Dependent ◽

Adrenoceptor Agonists ◽

Rat Tail

BAY K 8644 (methyl-1,4-dihydro-2,6-dimethyl-3-nitro-4-(2-trifluoromethylphenyl)pyridine-5-carboxylate) and CGP 28 392 (ethyl-4(2-difluoromethoxyphenyl)-1,4,5,7-tetrahydro-2-methyl-5-oxofuro-[3,4-b]pyridine-3-carboxylate) are closely related in structure to nifedipine and other 1,4-dihydropyridine Ca2+ channel antagonists. However, both BAY K 8644 and CGP 28 392 serve as activators of Ca2+ channels. In the rat tail artery, responses to BAY K 8644 are dependent upon [Formula: see text] and prior stimulation by K+ or by the α-adrenoceptor agonists, phenylephrine and BHT 920 (6-allyl-2-amino-5,6,7,8,-tetrahydro-4H-thiazolo[4,5-d]azepin dihydrochloride). Responses are blocked noncompetitively by the Ca2+ channel antagonists D-600 ((−)-D-600 > (+)-D-600) and diltiazem, but competitively by nifedipine (pA2 = 8.27). This suggests that activator and inhibitor 1,4-dihydropyridines interact at the same site. BAY K 8644 potentiates K+ responses and Ca2+ responses in K+-depolarizing media. The leftward shift of the K+ dose–response curve produced by BAY K 8644 suggests that this ligand facilitates the voltage-dependent activation of the Ca2+ channel. The pA2 value for nifedipine antagonism of BAY K 8644 responses is significantly lower than that for nifedipine antagonism of Ca2+ responses in K+ (25–80 mM) depolarizing media (9.4–9.6), suggesting that the state of the channel may differ according to the activating stimulus.

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