Cholinergic inhibition of Ca2+ current in guinea‐pig gastric and tracheal smooth muscle cells.

Wade, Gregory R.; Barbera, Joseph; Sims, Stephen M.

doi:10.1113/jphysiol.1996.sp021217

Cited by 25 publications

(17 citation statements)

References 36 publications

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“…The values for the half‐maximal voltage activation ( V 1/2 ) and slope constant ( k ) that reflect voltage sensitivity were identical in cells from both regions, demonstrating functional similarity of the channel in both regions. These kinetic values of voltage‐dependent activation and inactivation are similar to those that have been reported in the rabbit 18 and opossum oesophagus, 19 as well as circular SM from other parts of the digestive tract including the stomach 31 and intestine 32 . Peak amplitude of window current was obtained at −20 mV and is similar to what has been reported in other SMs 32 .…”

Section: Discussionsupporting

confidence: 87%

L‐type Ca²⁺ channel expression along feline smooth muscle oesophagus

Muinuddin

Sheu

et al. 2004

Neurogastroenterology Motil

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Muscle from the proximal smooth muscle (SM) oesophagus of the cat demonstrates contractions of greater amplitude and greater sensitivity to cholinergic stimulation than muscle from the distal SM oesophagus. In the light of the central role of calcium influx in SM contractility, we hypothesized that regional differences in oesophageal contractility may be associated with differential expression of L-type calcium channels (L(Ca)) along the SM oesophagus. L(Ca) expression was compared between proximal and distal regions of the circular SM oesophagus by Western blots. Patch clamp technique was utilized to study L(Ca) currents. Muscle strip studies assessed L(Ca) contribution to contractile activity. The protein expression of L(Ca) and L(Ca) current density was greater in the proximal than distal region. L(Ca) voltage and time-dependent activation and inactivation curves were similar in cells from both regions. Stimulation of muscle strips with acetylcholine (ACh) in the presence of tetrodotoxin resulted in contractions of greater amplitude in the proximal region. The L(Ca) agonist Bay K 8644 caused a greater increase in ACh-induced contraction amplitude in muscle strips from the proximal region. Therefore, regional myogenic differences in L(Ca) expression along the circular SM oesophageal body exist and may contribute to the nature of oesophageal contractions.

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Section: Discussionsupporting

confidence: 87%

L‐type Ca²⁺ channel expression along feline smooth muscle oesophagus

Muinuddin

Sheu

et al. 2004

Neurogastroenterology Motil

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“…We also report that cholinergic stimulation causes a transient inhibition of Ca 2ϩ current in both EB and LES muscles, similar to that observed in guinea pig ileal, gastric, and tracheal muscles (36,37). PKC-mediated suppression of Ca 2ϩ current has been suggested (23); however, others have found that the initial suppression of Ca 2ϩ influx was due to the release of Ca 2ϩ from stores (36,37).…”

Section: Discussionsupporting

confidence: 62%

“…5D, peak inward current was reduced to Ϫ7 Ϯ 3 pA from a control level of Ϫ35 Ϯ 7 pA (n ϭ 9) in EB and to Ϫ7 Ϯ 1 pA from a control level of Ϫ39 Ϯ 8 pA in LES (n ϭ 8) SMCs. Inhibition of the Ca 2ϩ current was rapidly reversible and consistent with the time course for Ca 2ϩ inhibition of L-type Ca 2ϩ channels previously established in other smooth muscles (37). Evidence to support the agonistinduced rise of [Ca 2ϩ ] i in LES cells is shown below, which could account for the acute Ca 2ϩ current inhibition.…”

Section: L-type Ca 2ϩ Current In Eb and Les Smcssupporting

confidence: 51%

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Functional and molecular analysis of L-type calcium channels in human esophagus and lower esophageal sphincter smooth muscle

Kovac

Preiksaitis

Sims

2005

American Journal of Physiology-Gastrointestinal and Liver Physi

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Excitation of human esophageal smooth muscle involves the release of Ca(2+) from intracellular stores and influx. The lower esophageal sphincter (LES) shows the distinctive property of tonic contraction; however, the mechanisms by which this is maintained are incompletely understood. We examined Ca(2+) channels in human esophageal muscle and investigated their contribution to LES tone. Functional effects were examined with tension recordings, currents were recorded with patch-clamp electrophysiology, channel expression was explored by RT-PCR, and intracellular Ca(2+) concentration was monitored by fura-2 fluorescence. LES muscle strips developed tone that was abolished by the removal of extracellular Ca(2+) and reduced by the application of the L-type Ca(2+) channel blocker nifedipine (to 13 +/- 6% of control) but was unaffected by the inhibition of sarco(endo)plasmic reticulum Ca(2+)-ATPase by cyclopiazonic acid (CPA). Carbachol increased tension above basal tone, and this effect was attenuated by treatment with CPA and nifedipine. Voltage-dependent inward currents were studied using patch-clamp techniques and dissociated cells. Similar inward currents were observed in esophageal body (EB) and LES smooth muscle cells. The inward currents in both tissues were blocked by nifedipine, enhanced by Bay K8644, and transiently suppressed by acetylcholine. The molecular form of the Ca(2+) channel was explored using RT-PCR, and similar splice variant combinations of the pore-forming alpha(1C)-subunit were identified in EB and LES. This is the first characterization of Ca(2+) channels in human esophageal smooth muscle, and we establish that L-type Ca(2+) channels play a critical role in maintaining LES tone.

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“…Acetylcholine elicits release of Ca 2+ from intracellular stores and hence contraction, and there is considerable convergence with the histamine induced pathways [80]. However, acetylcholine actually suppresses L-type Ca 2+ current in airways smooth muscle [81], and this may impose a negative feedback control on the system. However, acetylcholine has no effect on T-type Ca 2+ current [75,79] and thus in airways resistance (bronchial) vessels the contractile response may proceed more completely.…”

Section: Airway Smooth Musclementioning

confidence: 99%

T-type Ca2+ channels in non-vascular smooth muscles

Fry

Sui

2006

Cell Calcium

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Cholinergic inhibition of Ca2+ current in guinea‐pig gastric and tracheal smooth muscle cells.

Abstract: 1. Cholinergic regulation of L-type Ca2P channels was investigated in freshly dissociated guinea-pig gastric and tracheal smooth muscle cells. Acetylcholine (ACh, 50 uM)

Cited by 25 publications

References 36 publications

L‐type Ca²⁺ channel expression along feline smooth muscle oesophagus

L‐type Ca²⁺ channel expression along feline smooth muscle oesophagus

Functional and molecular analysis of L-type calcium channels in human esophagus and lower esophageal sphincter smooth muscle

T-type Ca2+ channels in non-vascular smooth muscles

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Cholinergic inhibition of Ca2+ current in guinea‐pig gastric and tracheal smooth muscle cells.

Abstract: 1. Cholinergic regulation of L-type Ca2P channels was investigated in freshly dissociated guinea-pig gastric and tracheal smooth muscle cells. Acetylcholine (ACh, 50 uM)

Cited by 25 publications

References 36 publications

L‐type Ca2+ channel expression along feline smooth muscle oesophagus

L‐type Ca2+ channel expression along feline smooth muscle oesophagus

Functional and molecular analysis of L-type calcium channels in human esophagus and lower esophageal sphincter smooth muscle

T-type Ca2+ channels in non-vascular smooth muscles

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Product

Resources

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L‐type Ca²⁺ channel expression along feline smooth muscle oesophagus

L‐type Ca²⁺ channel expression along feline smooth muscle oesophagus