45 results match your criteria: "Center for Swallowing and Motility Disorders[Affiliation]"

Role of HERG-like K(+) currents in opossum esophageal circular smooth muscle.

Am J Physiol

December 1999

Center for Swallowing and Motility Disorders, Harvard Medical School, West Roxbury Veterans Affairs Medical Center, West Roxbury, Massachusetts 02132, USA.

An inwardly rectifying K(+) conductance closely resembling the human ether-a-go-go-related gene (HERG) current was identified in single smooth muscle cells of opossum esophageal circular muscle. When cells were voltage clamped at 0 mV, in isotonic K(+) solution (140 mM), step hyperpolarizations to -120 mV in 10-mV increments resulted in large inward currents that activated rapidly and then declined slowly (inactivated) during the test pulse in a time- and voltage- dependent fashion. The HERG K(+) channel blockers E-4031 (1 microM), cisapride (1 microM), and La(3+) (100 microM) strongly inhibited these currents as did millimolar concentrations of Ba(2+).

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To identify the enzymatic source of nitric oxide (NO) in the lower esophageal sphincter (LES), studies were performed in wild-type and genetically engineered endothelial nitric oxide synthase [eNOS(-)] and neuronal NOS [nNOS(-)] mice. Under nonadrenergic noncholinergic (NANC) conditions, LES ring preparations developed spontaneous tone in all animals. In the wild-type mice, electrical field stimulation produced frequency-dependent intrastimulus relaxation and a poststimulus rebound contraction.

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Calponin binds to the 20-kilodalton regulatory light chain of myosin.

Biochemistry

March 1999

Center for Swallowing and Motility Disorders, VA Medical Center, West Roxbury, Massachusetts 02132, USA.

Calponin (CaP) is a 34 kDa smooth muscle-specific protein that has been implicated in regulation of smooth muscle contractility. Two CaP binding sites on smooth muscle myosin rod have been recently described [Szymanski and Tao (1997) J.Biol.

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Evidence for NO. redox form of nitric oxide as nitrergic inhibitory neurotransmitter in gut.

Am J Physiol

November 1998

Center for Swallowing and Motility Disorders, Brockton/West Roxbury Department of Veterans Affairs Medical Center, West Roxbury 02132; and Harvard Medical School, Boston, Massachusetts 02215, USA.

A nitric oxide (NO)-like product of the L-arginine NO synthase pathway has been shown to be a major inhibitory neurotransmitter that is involved in the slow component of the inhibitory junction potential (IJP) elicited by stimulation of nonadrenergic, noncholinergic nerves. However, the exact nature of the nitrergic transmitter, the role of cGMP, and the involvement of a potassium or a chloride conductance in the slow IJP remain unresolved. We examined the effects of soluble guanylate cyclase inhibitors LY-83583 and 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ), potassium-channel blockers and putative chloride-channel blockers diphenylamine-2-carboxylate (DPC) and niflumic acid (NFA) on the hyperpolarization elicited by an NO.

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Differences in contractile protein content and isoforms in phasic and tonic smooth muscles.

Am J Physiol

September 1998

Center for Swallowing and Motility Disorders, Harvard Medical School, West Roxbury Veterans Affairs Medical Center, West Roxbury, Massachusetts 02132, USA.

The basis of tonic vs. phasic contractile phenotypes of visceral smooth muscles is poorly understood. We used gel electrophoresis and quantitative scanning densitometry to measure the content and isoform composition of contractile proteins in opossum lower esophageal sphincter (LES), to represent tonic muscle, and circular muscle of the esophageal body (EB), to represent phasic smooth muscle.

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Nitric oxide (NO) hyperpolarizes visceral smooth muscles. Using the patch-clamp technique, we investigated the possibility that NO-mediated hyperpolarization in the circular muscle of opossum esophagus results from the suppression of a Ca(2+)-stimulated Cl- current. Smooth muscle cells were dissociated from the circular layer and bathed in high-K+ Ca(2+)-EGTA-buffered solution.

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Sodium nitroprusside (SNP) has been shown to elicit a guanosine 3',5'-cyclic monophosphate (cGMP)-mediated, indomethacin-sensitive contraction of the opossum esophageal longitudinal muscle. We examined the role of tyrosine phosphorylation in the signal transduction pathway of contractions induced by SNP and cGMP in longitudinal muscle strips in vitro. Force of isometric contractions was expressed as the percentage of responses to KCl (73 mM).

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Caffeine- and carbachol-induced Cl- and cation currents in single opossum esophageal circular muscle cells.

Am J Physiol

November 1996

Center for Swallowing and Motility Disorders, Beth Israel Hospital, Harvard Medical School, Boston 02215, USA.

Cl- and cation currents may play important roles in esophageal smooth muscle membrane potential changes and contraction. We studied Ca2+ release-activated cell-shortening and membrane currents in single cells freshly dispersed from the circular muscle of the opossum esophagus using the standard patch-clamp whole cell recording method. Caffeine (10-20 microM) and carbachol (10-100 microM) shortened the single smooth muscle cells by releasing intracellular Ca2+.

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Transient outward current in opossum esophageal circular muscle.

Am J Physiol

June 1995

Center for Swallowing and Motility Disorders, Beth Israel Hospital, Boston, Massachusetts 02215, USA.

The whole cell patch-clamp technique was used to record a transient outward K+ current (ITO) from single smooth muscle cells isolated from opossum esophageal circular muscle. The threshold for its activation was -50 mV from holding potentials negative to -70 mV. The current peaked within 10 ms and decayed completely in 200 ms between test depolarization of -40 and -10 mV.

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The effects of sodium nitroprusside (SNP) on ionic currents in single opossum esophageal circular muscle cells were examined. In voltage clamp, Ca2+ currents were studied after K+ currents were blocked with Cs+ in the patch pipette. The threshold for inward Ca2+ currents was -30 mV with peak current between 0 and +10 mV from holding potentials of -90 mV.

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Effects of nitric oxide (NO)-containing compounds on opossum esophageal longitudinal smooth muscle in vitro were examined. Sodium nitroprusside (SNP) and authentic NO produced a biphasic concentration-dependent relaxation-contraction sequence in the esophageal longitudinal muscle (ELM) but only a concentration-dependent relaxation of the lower esophageal sphincter (LES) and no effect in the esophageal circular muscle. A cell membrane-permeable analogue of guanosine 3',5'-cyclic monophosphate (cGMP), 8-bromoguanosine 3',5'-cyclic monophosphate (8-BrcGMP) also produced relaxation-contraction sequence in the ELM and relaxation of the LES.

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Nitric oxide involvement in the peptide VIP-associated inhibitory junction potential in the guinea-pig ileum.

J Physiol

February 1993

Center for Swallowing and Motility Disorders, Harvard-Thorndike Laboratory, Charles A. Dana Research Institute, Department of Medicine, Boston, MA 02215.

1. Intracellular membrane potential recordings were made from circular smooth muscle cells of the guinea-pig ileum in the presence of atropine (1 microM) and nifedipine (0.1 microM) at 30 degrees C.

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The cricopharyngeus muscle is generally thought to be responsible for the high pressure zone of the pharyngoesophageal (upper esophageal) sphincter. In this review we critically examined the evidence for the role of the cricopharyngeus muscle in the manometric pharyngoesophageal sphincter. The available studies show disparities between the anatomic location of the cricopharyngeus muscle and the manometric high pressure zone of the pharyngoesophageal sphincter.

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Role of chloride ions in lower esophageal sphincter tone and relaxation.

Am J Physiol

July 1992

Center for Swallowing and Motility Disorders, Charles A. Dana Research Institute, Boston, Massachusetts.

Studies were performed in strips of opossum lower esophageal sphincter (LES) muscle in vitro. External Cl(-)-free Krebs solution (0[Cl-]o) inhibited resting tone. Treatment with the Cl- channel blocker diphenylamine-2-carboxylate (DPC, 0.

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Role of nitric oxide in esophageal peristalsis in the opossum.

Gastroenterology

July 1992

Center for Swallowing and Motility Disorders, Charles A. Dana Research Institute, Boston, Massachusetts.

To explore the involvement of NO in normal peristalsis, the effects of inhibitors of NO synthase, including N omega-nitro-L-arginine (L-NNA) and N omega-nitro-L-arginine methyl ester (L-NAME), on esophageal peristaltic contractions induced by diverse stimuli that may involve different neuronal circuits were studied. Studies were performed in opossums. Experimental conditions in vivo included primary peristalsis (P) induced by pharyngeal stroking, short-train (1 second) electrical stimulation of the vagus nerve which caused peristaltic (S) contractions, and long-train (10 second) electrical stimulation of the vagus nerves which caused contractions at the onset of (A contractions) and after (B contractions) the stimulation period.

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Background: Conventional medical treatment for gastroesophageal reflux disease involves life-style modifications and combination drug therapy, but few studies have included these features in their protocols. Antireflux surgery has seldom been studied prospectively, and there have been no trials comparing modern medical and surgical treatments for reflux disease.

Methods: We conducted a long-term, randomized trial of medical therapy (lifestyle modifications and up to four medications) and surgical therapy (Nissen fundoplication) in 247 patients (243 men and 4 women) with peptic esophageal ulcer, stricture, erosive esophagitis, or Barrett's esophagus.

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Studies were performed in the opossum to define the role of the L-arginine-nitric oxide (NO) pathway in lower esophageal sphincter (LES) relaxation to swallowing and vagal stimulation in viv and intramural nerve stimulation in vitro. In vivo, L-NAME, a water soluble NO synthase (NOS) inhibitor, caused antagonism of LES relaxation due to reflex-induced swallowing. L-NAME (20 mg/kg i.

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Chloride-mediated junction potentials in circular muscle of the guinea pig ileum.

Am J Physiol

November 1991

Center for Swallowing and Motility Disorders, Charles A. Dana Research Institute, Beth Israel Hospital, Boston, Massachusetts.

Junction potentials were recorded from circular muscle cells of the guinea pig ileum at various sites oral and anal to a transmural stimulus in the presence of atropine, apamin, and substance P antagonism (desensitization) at 30 degrees C. A short train of pulses produced an inhibitory junction potential (slow IJP), which preceded an excitatory junction potential (slow EJP). The slow IJP was observed up to 56.

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Chloride-mediated inhibitory junction potentials in opossum esophageal circular smooth muscle.

Am J Physiol

November 1991

Center for Swallowing and Motility Disorders, Charles A. Dana Research Institute, Beth Israel Hospital, Boston, Massachusetts.

Intracellular recordings were made from circular smooth muscle cells of the opossum esophagus. Inhibitory junction potentials (IJPs) 8.3 +/- 0.

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Bradykinin (BK) caused the circular muscle of opossum lower esophageal sphincter to relax and then contract in vitro. The effects of BK were not modified by indomethacin, tetrodotoxin, omega-conotoxin, atropine, propranolol, phentolamine, haloperidol, methysergide, pyrilamine or cimetidine. Apamin but not tetraethylammonium antagonized the inhibitory effect of BK and nifedipine antagonized its excitatory effect.

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