Search results for " Smooth"
showing 10 items of 455 documents
COOLING-INDUCED CONTRACTION OF TRACHEA ISOLATED FROM NORMAL AND SENSITIZED GUINEA-PIGS
1991
Fast (−7°C/min) cooling of guinea-pig isolated trachea produced a rapidly developing, transient contraction followed by relaxation. Cooling-induced contraction was dependent on temperature (30, 20 or 10°C) and responses in trachea obtained from actively sensitized guinea pigs were significantly greater (20 and 10°-C) than those observed in normal trachea. Cooling to 20°C was selected for subsequent experiments. Pre-treatment with sufficient concentrations of atropine, clemastine, cromoglycate, indomethacin, or nordihydroguaiaretic acid did not depress contraction to cooling in either normal or sensitized trachea. This indicates a direct effect of cooling. The contraction. produced by coolin…
Effect of dantrolene sodium in isolated guinea-pig trachea.
1990
The effect of dantrolene sodium (3 microM-0.3 mM) on the spontaneous tone and responses to various contractile agonists was studied in isolated guinea-pig trachea. Dantrolene produced a concentration-related inhibition of the spontaneous tracheal tone, reaching a value of 94.8 +/- 4.8% of the relaxation induced by caffeine 10 mM. Removal of the epithelium did not affect the dantrolene-induced relaxation. Dantrolene did not alter the concentration-response curve for KCl and produced only small displacements of the concentration-response curves for CaCl2, acetylcholine and histamine, without affecting their maximal effects. Dantrolene dose relatedly inhibited the contraction induced by caffei…
Effects of K(ATP) channel modulators on acetylcholine release from guinea-pig isolated atria and small intestine.
2002
The effects of K(ATP) channel blockers (glibenclamide, HMR 1883, HMR 1372) and openers (cromakalim, pinacidil, diazoxide) on the electrically-evoked (5 Hz) release of [(3)H]acetylcholine were studied in isolated guinea-pig atria and myenteric plexus-longitudinal muscle preparations which had been preincubated with [(3)H]choline. Atria: Cromakalim (0.3 microM and 1 microM), pinacidil (10 microM) and diazoxide (30 microM) significantly reduced the stimulation-evoked release of [(3)H]acetylcholine. The inhibition produced by cromakalim and pinacidil was prevented by 1 microM of either HMR 1883, HMR 1372 or glibenclamide. The blockers alone significantly increased the release at concentrations …
EFFECTS OF CROMAKALIM (BRL-34915) IN TRACHEA ISOLATED FROM ACTIVELY SENSITIZED GUINEA-PIGS
1993
Abstract The effects of cromakalim were examined in tracheal strips isolated from normal (unsensitized) guinea-pigs and from animals actively sensitized to bovine serum albumin. Sensitized tracheae exhibited hyper-responsiveness to KCl, acetylcholine and histamine. In normal and sensitized tracheae, cromakalim (0·01–10 μm) produced a concentration-related suppression of spontaneous tone. The ability of cromakalim to relax tracheal strips was reduced when tone was raised by KCl (25 Mm), acetylcholine (0·1 Mm) or histamine (0·1 Mm) and lost against KCl (120 Mm)-induced spasm. Procaine (5 Mm) abolished the relaxant effect of cromakalim whilst tetraethylammonium (8 Mm) was without effect. These…
Effects of cromakalim on acetylcholine release and smooth muscle contraction in guinea-pig small intestine
1989
The effects of the potassium channel opener cromakalim on smooth muscle contraction and 3H-acetyl-choline release were studied simultaneously in guinea-pig longitudinal muscle myenteric plexus preparations which had been preincubated with 3H-choline. Cromakalim (10 mumol/l) inhibited more markedly the smooth muscle contractions caused by the release of endogenous acetylcholine (via electrical stimulation or via activation of nicotine- and 5-HT3-receptors) than contractions induced by pilocarpine. Cromakalim (10 mumol/l) did not affect the release of 3H-acetylcholine evoked by electrical stimulation or by stimulation of nicotine- and 5-HT3-receptors. In contrast, the release of 3H-acetylchol…
alpha-Bungarotoxin, kappa-bungarotoxin, alpha-cobratoxin and erabutoxin-b do not affect [3H]acetylcholine release from the rat isolated left hemidiap…
1995
Endplate preparations of the rat left hemidiaphragm were incubated with [3H]choline to label neuronal transmitter stores. Nerve evoked release of newly-synthesized [3H]acetylcholine was measured in the absence of cholinesterase inhibitors to investigate whether snake venom neurotoxins by blocking presynaptic nicotinic autoreceptors affect evoked transmitter release. Contractions of the indirectly stimulated hemidiaphragm were recorded to characterize the blocking effect of alpha-neurotoxins at the post-synaptic nicotinic receptors. Neither the long chain neurotoxins alpha-cobratoxin (1 microgram ml-1) and alpha-bungarotoxin (5 microgram ml-1) nor the short chain neurotoxin erabutoxin-b (0.1…
Muscarinic Properties of Compounds Related to Arecaidine Propargyl Ester
2011
A series of new analogues of the arecaidine propargyl ester (CAS 35516-99-5, APE, 1a) with alcohols consisting of 4 or 5 carbon atoms were investigated at muscarinic receptor subtypes. The muscarinic activity of the quaternary and tertiary salts of the APE-related compounds were assayed on the isolated guinea-pig ileum (M 3 receptor subtype) and guinea-pig left atria (M 2 receptor subtype) as well as on rabbit isolated vas deferens (M 1 receptor subtype). The structural variations made in the APE molecule, replacing the triple bond in the ester side chain with structures such as double bond, an allene moiety, a single bond, a cyclopropyl group or two triple bonds should alter the selectivit…
Altered electrical activity in colonic smooth muscle cells from dystrophic (mdx) mice
2001
Because the colon from dystrophic (mdx) mice shows an altered motor pattern, probably due to neural disorders, our aim was to examine the electrophysiological properties of muscle cells and the functionality of nitrergic transmission in circular muscle from normal and mdx colon. Normal colonic cells (resting membrane potential [RMP] about -50 mV) showed spontaneous hyperpolarizations (inhibitory junction potentials; IJPs) and cyclic slow depolarizations were sometimes recorded. Mdx colon had a depolarized RMP (about -36 mV) and spontaneous IJPs, but the cyclic activity was never observed. In the normal colon, Nomega-nitro-L-arginine methyl ester (L-NAME) induced depolarization and abolished…
Modification of the rat aortic wall during ageing; possible relation with decrease of peptidergic innervation.
2002
Structural changes of the male rat aorta were followed from birth to old age in male and female rats. In males, the vessel media width and area progressively increase concomitantly with a decrease of nuclei density during ageing, suggesting an hypertrophy of the smooth muscle cells. These correlations were however not evidenced in females. TUNEL-positive cells were found in media of 4 and 6 months in both sexes, mainly on the luminal side and in the adventitia. When biochemical markers were investigated with immunohistochemistry, media was uniformly stained by the anti-vimentin and anti-alpha-smooth actin at all stages investigated. On the contrary, the surface of media stained with anti-de…
Role of the Endothelium in the Relaxation Induced by Propofol and Thiopental in Isolated Arteries from Man
1997
Abstract Induction of anaesthesia with intravenous propofol and thiopental is often accompanied by hypotension. This study evaluates whether propofol and thiopental induce relaxation of isolated arteries from man and whether this effect is modulated by the endothelium. Mesenteric artery rings (with and without endothelium) from 12 patients were placed in organ baths and precontracted with phenylephrine before addition of propofol (10−3 M) or thiopental (10−3 M). Relaxation induced by propofol and thiopental was evaluated for rings with intact endothelium in the presence of the nitric oxide synthase inhibitor NG-nitro-l-arginine methyl ester (l-NAME; 10−4 M) or the cyclooxygenase inhibitor i…