Search results for "Calcium Channel Blockers"
showing 10 items of 102 documents
Effect of the CB1 cannabinoid agonist WIN 55212-2 on the acquisition and reinstatement of MDMA-induced conditioned place preference in mice
2010
AbstractBackgroundNumerous reports indicate that MDMA users consume other psychoactive drugs, among which cannabis is one of the most common. The aim of the present study was to evaluate, using the conditioned place preference, the effect of the cannabinoid agonist WIN 55,212-2 on the rewarding effects of MDMA in mice.MethodsIn the first experiment adolescent mice were initially conditioned with 1.25, 2.5 or 5 mg/kg of MDMA or 0.1 or 0.5 mg/kg of WIN and subsequently with both drugs. Reinstatement of the extinguished preference by priming doses was performed in the groups that showed CPP. In the second experiment, animals were conditioned with 2.5 or 5 mg/kg of MDMA and, after extinction, r…
Capacitative Ca2+ entry associated with α1-adrenoceptors in rat aorta
1997
In rat aorta, depletion of internal Ca2+ stores by addition of noradrenaline (1 microM) induces a biphasic response (an initial phasic response and a tonic one) mediated by two different intracellular Ca2+ pools. This response cannot be repeated, suggesting a depletion of internal Ca2+ stores sensitive to noradrenaline. In absence of the agonist, this depletion is the signal for the entry of extracellular Ca2+, not only to refill the stores but also, under our experimental conditions, to activate the contractile proteins thus inducing an increase in the resting tone (IRT) that constitutes functional evidence of this Ca2+ entry. The ionic channels involved in the mechanism of the IRT have be…
Arginine Vasopressin Enhances Sympathetic Constriction Through the V 1 Vasopressin Receptor in Human Saphenous Vein
1998
Background —Arginine vasopressin (AVP) not only acts directly on blood vessels through V 1 receptor stimulation but also may modulate adrenergic-mediated responses in animal experiments in vivo and in vitro. The aim of the present study was to investigate whether AVP can contribute to an abnormal adrenergic constrictor response of human saphenous veins. Methods and Results —Saphenous vein rings were obtained from 32 patients undergoing coronary artery bypass surgery. The vein rings were suspended in organ bath chambers for isometric recording of tension. AVP (3×10 −9 mol/L) enhanced the contractions elicited by electrical field stimulation at 1, 2, and 4 Hz (by 80%, 70%, and 60%, respectiv…
Relaxant activity of three aporphine alkaloids from Annona cherimolia on isolated aorta of rat.
1995
Abstract In the present study we tested the relaxant effect of three aporphine alkaloids—roemerine, anonaine and dehydroroemerine—isolated from the roots of Annona cherimolia, on isolated strips of rat thoracic aorta. All compounds completely relaxed KCl- and noradrenaline-induced contractions with different potencies depending on their structural characteristics. The experiments, carried out in Ca2+-free medium using two different agonists (noradrenaline and caffeine) which mobilize calcium intracellularly by different mechanisms of action, showed that the alkaloids made no contribution to intracellular calcium processes. The present study provides evidence that the relaxant effects produc…
Effects of menthol on circular smooth muscle of human colon: Analysis of the mechanism of action.
2014
Abstract Menthol is the major constituent of peppermint oil, an herbal preparation commonly used to treat nausea, spasms during colonoscopy and irritable bowel disease. The mechanism responsible for its spasmolytic action remains unclear. The aims of this study were to investigate the effects induced by menthol on the human distal colon mechanical activity in vitro and to analyze the mechanism of action. The spontaneous or evoked-contractions of the circular smooth muscle were recorded using vertical organ bath. Menthol (0.1 mM–30 mM) reduced, in a concentration-dependent manner, the amplitude of the spontaneous contractions without affecting the frequency and the resting basal tone. The in…
Nifedipine improves blood flow and oxygen supply, but not steady-state oxygenation of tumours in perfusion pressure-controlled isolated limb perfusio…
2002
Isolated limb perfusion allows the direct application of therapeutic agents to a tumour-bearing extremity. The present study investigated whether the dihydropyridine-type Ca2+-channel blocker nifedipine could improve blood flow and oxygenation status of experimental tumours during isolated limb perfusion. Perfusion was performed by cannulation of the femoral artery and vein in rats bearing DS-sarcoma on the hind foot dorsum. Perfusion rate was adjusted to maintain a perfusion pressure of 100–140 mmHg throughout the experiment. Following equilibration, nifedipine was continuously infused for 30 min (8.3 μg min−1 kg−1 BW). During constant-pressure isolated limb perfusion, nifedipine can signi…
Calcium antagonist properties of cinnarizine, trifluoperazine and verapamil in guinea-pig normal and skinned trachealis muscle.
1990
In guinea-pig trachealis, depolarized by a K(+)-rich medium, Ca2+ (0.01-10 mM) caused concentration-related spasm. Verapamil (0.5-5 microM), cinnarizine (10-100 microM) and trifluoperazine (16-160 microM) each produced concentration-dependent antagonism of Ca2+ characterized by a rightward and downward displacement of the log concentration-effect curve for Ca2+. The rank order of potencies of these antagonists, measured as the IC75 against Ca2+ (10 mM)-induced contraction of depolarized trachea, was verapamil (5.6 microM) greater than cinnarizine (59 microM) greater than trifluoperazine (91 microM). In skinned trachea, verapamil in concentrations up to 100 microM did not modify the concentr…
Pretreatment with potent P-glycoprotein ligands may increase intestinal secretion in rats.
2001
The expression of P-glycoprotein is induced in cell cultures upon exposure to various inducers. Therefore, the aim of the present study was to evaluate the in-vivo relevance of this observation, i.e. the influence of chronic pretreatments with selected drugs -- all of which are ligands to P-glycoprotein (P-gp) as demonstrated in radioligand binding studies and all of which have some or a considerable effect on P-gp expression in Caco-2 cells -- on the effective intestinal permeabilities of the model compound talinolol in rats employing in-situ single-pass intestinal perfusion of three different gut segments. Talinolol was selected, because it shows high selectivity for one of the exsorptive…
Effects of Calcium Antagonists on Rat Normal and Skinned Fundus
1992
Abstract Calcium chloride (CaCl2) (0·1−25 Mm, in K+-depolarized tissue), KCl (10−112 Mm) and acetylcholine (1 × 10−9 m−1 Mm) produced concentration-dependent contractions of rat isolated fundus. Verapamil (0·01−100 μm), cinnarizine (1−100 μm), trifluoperazine (10−500 μm) and dantrolene (50−250 μm) each produced a concentration-related rightward and downward shift of the log concentration-effect curve for CaCl2. The rank order of potencies of these antagonists, measured as the IC50 against Ca2+ (25 Mm)-induced contraction of depolarized fundus, was verapamil (2.5 μm) > cinnarizine (8·7 μm) > trifluoperazine (85·1 μm) > dantrolene (> 250 μm). Cinnarizine (0·5 Mm) a…
Combination of alpha lipoic acid and gabapentin, its efficacy in the treatment of burning mouth syndrome : a randomized, double-blind, placebo contro…
2010
Burning Mouth Syndrome (BMS) is a disease that manifests as burning in the tongue or in any area of the oral mucosa, in the absence of clinically verifiable injuries. Objectives: To verify the efficacy of alpha lipoic acid (ALA) and gabapentin (GABA), used individually and jointly, to reduce the burning in patients with burning mouth and establish a drug therapy for the BMS. Study Design: During April and May 2008, we conducted a randomized, double-blind, placebo-controlled trial in the Department of Clinical Stomatology, Faculty of Dentistry, Rosario, Argentina. The gathering of patients was between those ones with BMS who were treated in our service between March 2003 and March 2008 witho…