Search results for "nifedipine"

Arginine vasopressin, via activation of post-junctional V1 receptors, induces contractile effects in mouse distal colon

2013

The aim of this study was to analyze whether arginine vasopressin (AVP) may be considered a modulator of intestinal motility. In this view, we evaluated, in vitro, the effects induced by exogenous administration of AVP on the contractility of mouse distal colon, the subtype(s) of receptor(s) activated and the action mechanism. Isometric recordings were performed on longitudinal and circular muscle strips of mouse distal colon. AVP (0.001 nM-100 nM) caused concentration-dependent contractile effects only on the longitudinal muscle, antagonized by the V1 receptor antagonist, V-1880. AVP-induced effect was not modified by tetrodotoxin, atropine and indomethacin. Contractile response to AVP was…

Mode and mechanism of neurotensin action in rat proximal colon

1997

Abstract This study examined the mechanism of action of neurotensin on intraluminal pressure in rat proximal colon. The direct and indirect contractile response to neurotensin (100 nM) was abolished in Ca 2+ -free solution, and was antagonized by nifedipine (1–5–10 nM) and potentiated by Bay K 8644 (methyl 1,4-dihydro-2,6-dimethyl-3-nitro-4-(2-trifluoromethylphenyl)-pyridine-5-carboxylate) (10–100–1000 nM). Neurotensin, in the presence of nifedipine (10 nM) and atropine (1 μM), induced a tetrodotoxin-insensitive inhibitory effect, which was antagonized by SR 48692 (2[(1-(7-chloro-4-quinolinyl)-5-(2,6-dimethoxy-phenyl)pyrazol-3-yl) carbonyl amino]tricyclo (3.3.1.1. 3.7 ) decan-2-carboxylic a…

Metabolic effects of enalapril and nifedipine in diabetic hypertensives

1991

Effects of Nifedipine on Blood Pressure, Arterial Compliance and Left Ventricular Mass in Elderly Patients with Isolated Systolic Hypertension

1989

The aim of this study was to evaluate the effects of acute and chronic administration of slow-release nifedipine (SRN) on blood pressure (BP), aortic index (AI), average wall stress (AWS), left ventricular mass (LVM), and other hemodynamic parameters in elderly patients with isolated systolic hypertension (ISH) (systolic blood pressure [SBP] > 175 mmHg). We studied 10 patients (mean age 73.7 ± 5.6 years) in which after a washout period, in basal conditions, 3 h after the administration of SRN (20 mg), and 180 days after chronic therapy (40 mg daily), we evaluated the changes of BP, HR, AI, AWS, LVM, and other parameters obtained by means of echocardiography. After SRN we observed a signific…

Biowaiver Monographs for Immediate-Release Solid Oral Dosage Forms: Nifedipine

2015

Literature data relevant to the biopharmaceutical properties of the active pharmaceutical ingredient (API) nifedipine are reviewed to evaluate whether a waiver of in vivo bioequivalence (BE) testing of immediate-release (IR) dosage forms formulated as tablets and soft gelatin capsules is warranted. Nifedipine's solubility and permeability, its therapeutic use and index, pharmacokinetics, food drug interactions, and any reported BE/bioavailability problems were all taken into consideration. Solubility and BA data indicate conclusively that nifedipine is a class II substance of biopharmaceutics classification system (BCS) and that the formulation of drug product plays a key role on the dissol…

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…

Role of Ca2+-Activated K+ Channels on Adrenergic Responses of Human Saphenous Vein

2006

Background We studied the participation of K + channels on the adrenergic responses in human saphenous veins as well as the intervention of dihydropyridine-sensitive Ca 2+ channels on modulation of adrenergic responses by K + channels blockade. Methods Saphenous vein rings were obtained from 40 patients undergoing coronary artery bypass surgery. The vein rings were suspended in organ bath chambers for isometric recording of tension. Results Iberiotoxin (10 −7 mol/L), an inhibitor of large conductance Ca 2+ -activated K + channels, and charybdotoxin (10 −7 mol/L), an inhibitor of both large and intermediate conductance Ca 2+ -activated K + channels, enhanced the contractions elicited by elec…