Search results for "Smooth"
showing 10 items of 710 documents
Antispasmodic effect of 4'-methylepigallocatechin on guinea pig ileum.
2012
AbstractThe antispasmodic effect of 4′-methylepigallocatechin (MEC), which was isolated from Maytenus rigida Mart (Celestraceae), was investigated in vitro in guinea pig intestinal segments. In the isolated ileum, MEC (1 nM–100μM) did not modify the ileal spontaneous tonus or the electrically elicited contractions. MEC (8μM) significantly (p<0.01) reduced the submaximal contractions induced by histamine (2μM), carbachol (100μM) and BaCl2 (0.03M). An additive relaxing action (p<0.001) was observed by co-incubation of verapamil (10 nM) and MEC (8μM). Although MEC (1nM–100μM) did not modify the contractions elicited by 60mM KCl, it significantly reduced the CaCl2 contractile response without c…
Mechanism of vascular relaxation by thaligrisine
2000
Abstract In the present study we examine the mechanism by which thaligrisine, a bisbenzyltetrahydroisoquinoline alkaloid, inhibits the contractile response of vascular smooth muscle. The work includes functional studies on rat isolated aorta and tail artery precontracted with noradrenaline or KCl. In other experiments rat aorta was precontracted by caffeine in the presence or absence of extracellular Ca 2 +. In order to assess whether thaligrisine interacts directly with calcium channel binding sites or with α-adrenoceptors we examined the effect of the alkaloid on [ 3 H]-(+)- cis diltiazem, [ 3 H]-nitrendipine and [ 3 H]-prazosin binding to cerebral cortical membranes. The functional studi…
Vascular Activity of (-)-Anonaine, (-)-Roemerine and (-)-Pukateine, Three Natural 6a(R)-1,2-Methylenedioxyaporphines with Different Affinities for α1…
2004
We have studied the mechanism of action of three 6a( R)-1,2-methylenedioxyaporphines as vasorelaxant compounds. The alkaloids assayed showed different affinities for the three human cloned alpha (1)-adrenoceptor (AR) subtypes stably expressed in rat-1 fibroblasts, showing lower affinity for alpha(1B)-AR with regard to the alpha(1A)- or alpha(1D)-subtypes. These three natural compounds are more potent inhibitors of [ (3)H]-prazosin binding than of [ (3)H]-diltiazem binding to rat cerebral cortical membranes. As all these alkaloids inhibited noradrenaline (NA)-induced [ (3)H]-inositol phosphate formation in cerebral cortex and rat tail artery, they may be safely viewed as alpha (1)-AR antagon…
Isolation and characterization of a complement-activating lipid extracted from human atherosclerotic lesions.
1990
The major characteristics of human atherosclerotic lesions are similar to those of a chronic inflammatory reaction, namely fibrosis, mesenchymal cell proliferation, the presence of resident macrophages, and cell necrosis. Atherosclerosis exhibits in addition the feature of lipid (mainly cholesterol) accumulation. The results of the present report demonstrate that a specific cholesterol-containing lipid particle present in human atherosclerotic lesions activates the complement system to completion. Thus, lipid could represent a stimulatory factor for the inflammatory reaction, whose underlying mechanistic basis may be, at least in part, complement activation. The complement-activating lipid …
Histopathology of the gut in rheumatic diseases
2018
The gastrointestinal tract regulates the trafficking of macromolecules between the environment and the host through an epithelial barrier mechanism and is an important part of the immune system controlling the equilibrium between tolerance and immunity to non-self-antigens. Various evidence indicates that intestinal inflammation occurs in patients with rheumatic diseases. In many rheumatic diseases intestinal inflammation appears to be linked to dysbiosis and possibly represents the common denominator in the pathogenesis of different rheumatic diseases. The continuative interaction between dysbiosis and the intestinal immune system may lead to the aberrant activation of immune cells that ca…
A filtering algorithm for maneuvering target tracking based on smoothing spline fitting
2014
Published version of an article in the journal: Abstract and Applied Analysis. Also available from the publisher at: http://dx.doi.org/10.1155/2014/127643 Open Access Maneuvering target tracking is a challenge. Target's sudden speed or direction changing would make the common filtering tracker divergence. To improve the accuracy of maneuvering target tracking, we propose a tracking algorithm based on spline fitting. Curve fitting, based on historical point trace, reflects the mobility information. The innovation of this paper is assuming that there is no dynamic motion model, and prediction is only based on the curve fitting over the measured data. Monte Carlo simulation results show that, …
EMG activity of pigeon oesophagus in vivo.
1982
At rest, the pigeon cervical oesophagus, which is entirely smooth muscle, shows electric activity. This activity consists of bursts of spikes with frequency increasing in the oral-aboral direction. The bursts are un-phase locked, and there are no slow waves (E.C.A.). The surgical transection of the oesophageal muscular wall does not affect the electric activity even in a disconnected segment. After asphyxia electric activity persists, whereas the aboral gradient of frequency disappears. Therefore, the electric activity is thought to be myogenic in origin, and the frequency gradient nervous in origin. Atropine and neostigmine administration suggests that the cholinergic system modulates the …
Involvement of purinergic nerves in the NANC inhibitory junction potentials in pigeon oesophageal smooth muscle.
2004
1. Electrical field stimulation (EFS) (0.5 ms in train of 2-32 Hz for 300 ms) in smooth muscle of pigeon oesophagus, in the presence of atropine (1 microm) and guanethidine (1 microm), elicited an inhibitory response consisting of a transient hyperpolarization (inhibitory junction potential, IJP) associated with muscle relaxation. 2. Sodium nitroprusside (SNP, 100 microm) induced hyperpolarization correlated to mechanical relaxation. 3. The nitric oxide (NO) synthase inhibitor N(omega)-nitro-l-arginine (from 0.1 to 100 microm) caused a concentration-dependent reduction of electromechanical response to EFS indicating a role for NO in this response. 4. Apamin (1 microm) reduced both IJP and r…
Evidence that adenosine is not involved in the non-adrenergic non-cholinergic relaxation in the rat duodenum.
1990
In rat isolated duodenal segments, adenosine induced, in the presence of atropine and guanethidine, a dose-dependent, long-lasting (about 20 s), tetrodotoxin (TTX)-resistant relaxation both in endoluminal pressure and in isometric tension. Electrical field stimulation (EFS) induced, in the presence of atropine and guanethidine, a TTX-sensitive short-lasting (about 6 s) relaxation followed by a sustained rebound contraction. Theophylline, a P1 receptor antagonist, at the concentration of 100 microM caused a marked inhibition of the adenosine-induced relaxation, while the EFS-induced relaxation was not modified. Our results suggest that adenosine induces relaxation of the rat duodenal smooth …
Non-adrenergic non-cholinergic nerve-mediated inhibitory control of pigeon oesophageal muscle.
1996
Pigeon oesophageal smooth muscle in vitro has spontaneous electromechanical activity. In the presence of atropine and guanethidine, electrical field stimulation evokes a transient TTX-sensitive response comprising inhibition of electric bursting activity and muscular relaxation. This NANC inhibitory response was analysed using the K+ channel blockers TEA and apamin, TEA perfusion (0.1-5 mM) induced a concentration-dependent reduction in amplitude of EFS-evoked relaxation. Responses to higher stimulation frequencies were more sensitive to TEA than those to lower ones. The maximum reduction in amplitude (29% of control) was obtained on 30 Hz EFS evoked responses during 5 mM TEA perfusion. In …