Role of Ca2+-activated Cl−channels and MLCK in slow IJP in opossum esophageal smooth muscle

2002 ◽  
Vol 283 (1) ◽  
pp. G104-G114 ◽  
Author(s):  
Yong Zhang ◽  
William G. Paterson
Keyword(s):  
Smooth Muscle ◽  
Guinea Pig ◽  
Nerve Stimulation ◽  
Resting Membrane Potential ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Circular Smooth Muscle ◽  
Cl Channels ◽  
Muscle Nerve

The possible contribution of Ca2+-activated Cl− channel [ICl(Ca)] and myosin light-chain kinase (MLCK) to nonadrenergic, noncholinergic slow inhibitory junction potentials (sIJP) was studied using conventional intracellular microelectrode recordings in circular smooth muscle of opossum esophageal body and guinea pig ileum perfused with Krebs solution containing atropine (3 μM), guanethidine (3 μM), and substance P (1 μM). In opossum esophageal circular smooth muscle, resting membrane potential (MP) was −51.9 ± 0.7 mV ( n = 89) with MP fluctuations of 1–3 mV. A single square-wave nerve stimulation of 0.5 ms duration and 80 V induced a sIJP with amplitude of 6.3 ± 0.2 mV, half-amplitude duration of 635 ± 19 ms, and rebound depolarization amplitude of 2.4 ± 0.1 mV ( n = 89). 9-Anthroic acid (A-9-C), niflumic acid (NFA), wortmannin, and 1-(5-chloronaphthalene-1-sulfonyl)-1H-hexahydro-1,4-diazepine (ML-9) abolished MP fluctuations, sIJP, and rebound depolarization in a concentration-dependent manner. A-9-C and NFA but not wortmannin and ML-9 hyperpolarized MP. In guinea pig ileal circular smooth muscle, nerve stimulation elicited an IJP composed of both fast (fIJP) and slow (sIJP) components, followed by rebound depolarization. NFA (200 μM) abolished sIJP and rebound depolarization but left the fIJP intact. These data suggest that in the tissues studied, activation of ICl(Ca), which requires MLCK, contributes to resting MP, and that closing of ICl(Ca) is responsible for sIJP.

Neural and myogenic effects of cyclooxygenase products on canine bronchial smooth muscle

1995 ◽  
Vol 268 (1) ◽  
pp. L47-L55 ◽  
Author(s):  
A. P. Abela ◽  
E. E. Daniel
Keyword(s):  
Smooth Muscle ◽  
Membrane Potential ◽  
Electrical Field Stimulation ◽  
Resting Membrane Potential ◽  
Dependent Manner ◽  
Ach Release ◽  
Concentration Dependent Manner ◽  
Excitatory Junction Potentials ◽  
Pg E2 ◽  
Large Contraction

In canine bronchi bathed in 10(-6) M indomethacin (IDM), prostaglandin (PG) E2 inhibited electrical field stimulation (EFS)- and acetylcholine (ACh)-mediated contractions and excitatory junction potentials (EJP) in a concentration-dependent manner without altering the resting membrane potential. EFS-induced EJPs were abolished at 10(-7) M PGE2, which shifted responses to ACh 10-fold rightward. Thus PGE2 predominantly inhibited the release of ACh and secondarily decreased smooth muscle response to ACh. U-46619, an analogue of thromboxane A2 (TxA2), initiated tetrodotoxin- and atropine-insensitive contractions in a concentration-dependent manner. U-46619 (10(-9) M) did not alter significantly EFS- or ACh-stimulated contractions and potentiated EFS amplitude of EJPs without depolarizing muscle cells. Either prejunctional activation of ACh release by TxA2 or postjunctional potentiation of the response to ACh can explain these findings. U-46619 (<or = 10(-8) M) depolarized the membrane potential, initiating oscillations accompanied by a large contraction. Addition of 10(-8) M nitrendipine, but not tetraethylammonium (25 mM), blocked the oscillations selectively. Other prostanoids (PGD2, PGI2, and PGF2 alpha) had no significant effects on canine bronchi. In the absence of IDM, PGE2 accumulated, EFS contractions decreased with time, and EJPs disappeared. We conclude that in canine bronchi PGE2 predominantly inhibits ACh release and endogenous PGE2 acts similarly, whereas TxA2 excites, probably at postjunctional sites.

Voltage sensitivity of slow wave frequency in isolated circular muscle strips from guinea pig gastric antrum

1999 ◽  
Vol 276 (2) ◽  
pp. G518-G528 ◽  
Author(s):  
S.-M. Huang ◽  
S. Nakayama ◽  
S. Iino ◽  
T. Tomita
Keyword(s):  
Smooth Muscle ◽  
Guinea Pig ◽  
Slow Wave ◽  
Circular Muscle ◽  
Gastric Antrum ◽  
Slow Waves ◽  
Wave Frequency ◽  
Voltage Sensitivity ◽  
Dependent Manner ◽  
Circular Smooth Muscle

In circular muscle preparations isolated from the guinea pig gastric antrum, regular spontaneous electrical activity (slow waves) was recorded. Under normal conditions (6 mM K+), the frequency and shape of the slow waves were similar to those observed in ordinary stomach smooth muscle preparations. When the resting membrane potential was hyperpolarized and depolarized by changing the extracellular K+ concentration (2–18 mM), the frequency of slow waves decreased and increased, respectively. Application of cromakalim hyperpolarized the cell membrane and reduced the frequency of slow waves in a dose-dependent manner. Cromakalim (3 μM) hyperpolarized the membrane, and slow waves ceased in most preparations. In the presence of cromakalim, subsequent increases in the extracellular K+ concentration restored the frequency of slow waves accompanied by depolarization. Also, glibenclamide completely antagonized this effect of cromakalim. In smooth muscle strips containing both circular and longitudinal muscle layers, such changes in the slow wave frequency were not observed. It was concluded that the maneuver of isolating circular smooth muscle altered the voltage dependence of the slow wave frequency.

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 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.

scholarly journals Phytochemical Evaluation of Lythrum Salicaria Extracts and Their Effects on Guinea-Pig Ileum

2013 ◽  
Vol 8 (9) ◽  
pp. 1934578X1300800 ◽  
Author(s):  
Tímea Bencsik ◽  
Loránd Barthó ◽  
Viktor Sándor ◽  
Nóra Papp ◽  
Rita Benkó ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Guinea Pig ◽  
Ethyl Acetate ◽  
Water Extract ◽  
Lythrum Salicaria ◽  
Dependent Manner ◽  
Guinea Pig Ileum ◽  
Concentration Dependent Manner ◽  
Ethanol In Water

n-Hexane, chloroform, ethyl acetate and 50% ethanol in water extracts prepared from the air-dried flowering parts of Lythrum salicaria L. were tested for in vitro pharmacological properties on Guinea-pig ileum, which is suitable for detecting a whole range of neuronal and smooth muscle effects. UHPLC-MS was used to evaluate polyphenol components of the extracts. In the ileum, the most prominent response (46.4% related to 0.5 μM histamine) of the extracts causing smooth muscle contractions were triggered by the 50% ethanol in water extract in a concentration-dependent manner. Atropine, indomethacin and PPADS plus suramin significantly reduced the contractile response caused by this extract. The strongest inhibition was due to atropine. The results suggest that L. salicaria extracts have a moderate muscarinic receptor agonist effect in Guinea-pig ileum and that prostanoids and purinoceptor mechanisms are involved to some extent. Therefore diluted extracts of L. salicaria p.o. could be used as a mild stimulant of gastrointestinal motility. The 50% ethanol in water extract was rich in polyphenols. n-Hexane, chloroform and ethyl acetate extracts failed to contain catechin, caffeic acid, quercetin-3-D-galactoside and rutin, but they all showed spasmogenic effects, and, therefore we do not think that these compounds could be involved in the spasmogenic activity.

scholarly journals Stimulation of mucosal secretion by lubiprostone (SPI-0211) in guinea pig small intestine and colon

2009 ◽  
Vol 296 (4) ◽  
pp. G823-G832 ◽  
Author(s):  
Guijun Fei ◽  
Yu-Zhong Wang ◽  
Sumei Liu ◽  
Hong-Zhen Hu ◽  
Guo-Du Wang ◽  
...  
Keyword(s):  
Small Intestine ◽  
Guinea Pig ◽  
Short Circuit ◽  
Enteric Neurons ◽  
Resting Membrane Potential ◽  
Small Intestinal Mucosa ◽  
Dependent Manner ◽  
Concentration Dependent Manner ◽  
Mucosal Secretion ◽  
Stimulation Of

Actions of lubiprostone, a selective type-2 chloride channel activator, on mucosal secretion were investigated in guinea pig small intestine and colon. Flat-sheet preparations were mounted in Ussing flux chambers for recording short-circuit current ( Isc) as a marker for electrogenic chloride secretion. Lubiprostone, applied to the small intestinal mucosa in eight concentrations ranging from 1–3000 nM, evoked increases in Isc in a concentration-dependent manner with an EC50 of 42.5 nM. Lubiprostone applied to the mucosa of the colon in eight concentrations ranging from 1–3000 nM evoked increases in Isc in a concentration-dependent manner with an EC50 of 31.7 nM. Blockade of enteric nerves by tetrodotoxin did not influence stimulation of Isc by lubiprostone. Antagonists acting at prostaglandin (PG)E2, EP1–3, or EP4 receptors did not suppress stimulation of Isc by lubiprostone but suppressed or abolished PGE2-evoked responses. Substitution of gluconate for chloride abolished all responses to lubiprostone. The selective CFTR channel blocker, CFTR(inh)-172, did not suppress lubiprostone-evoked Isc. The broadly acting blocker, glibenclamide, suppressed ( P < 0.001) lubiprostone-evoked Isc. Lubiprostone, in the presence of tetrodotoxin, enhanced carbachol-evoked Isc. The cholinergic component, but not the putative vasoactive intestinal peptide component, of neural responses to electrical field stimulation was enhanced by lubiprostone. Application of any of the prostaglandins, E2, F2, or I2, evoked depolarization of the resting membrane potential in enteric neurons. Unlike the prostaglandins, lubiprostone did not alter the electrical behavior of enteric neurons. Exposure to the histamine H2 receptor agonists increased basal Isc followed by persistent cyclical increases in Isc. Lubiprostone increased the peak amplitude of the dimaprit-evoked cycles.

Effect of disulfonic stilbene anion-channel blockers on the guinea-pig myocardium

1985 ◽  
Vol 63 (8) ◽  
pp. 912-917 ◽  
Author(s):  
Arda-E-Viraf M. Minocherhomjee ◽  
Basil D. Roufogalis ◽  
John H. McNeill
Keyword(s):  
Guinea Pig ◽  
Anion Channel ◽  
Channel Blockers ◽  
Dependent Manner ◽  
Maximal Inhibition ◽  
Concentration Dependent Manner ◽  
Covalent Interaction ◽  
Disulfonic Stilbene ◽  
Frequency Of Stimulation

The role of anions in the maintenance of tension in electrically driven left atria isolated from guinea pigs has been examined. The disulfonic stilbene anion-channel blockers SITS (4-acetamido-4′-isothiocyanostilbene 2′-disulfonate) and DIDS (4,4′-diisothiocyano-2,2′-stilbene disulfonate) decreased the contractile force developed in a time- and concentration-dependent manner. As in the red cell anion channel, DIDS was more potent than SITS, but the maximal inhibition of tension produced by N-(4-azido-2-nitrophenyl)-2-aminoethyl sulfonate (NAP-taurine) was considerably lower than the near maximal inhibition produced by SITS and DIDS. The inhibition by SITS and DIDS was irreversible, suggesting a covalent interaction, and could not be overcome by increasing the calcium concentration or the frequency of stimulation. Consistent with a requirement for chloride anion, substitution of chloride and bicarbonate by the impermeant anion gluconate did not support contraction, while only partial tension was maintained with the lipophilic anions acetate and thiocyanate. Incubation of atria with 400 μM SITS blocked both 36Cl and 45Ca uptake to a similar extent, whereas the efflux of both these ions was not affected by incubation of the atria with SITS. The blockade by disulfonic stilbene anion-channel blockers of the contraction of the guinea pig myocardium may result from impairment of excitation–contraction coupling.

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