Search results for "Caffeine"
showing 10 items of 118 documents
Evidence that depletion of internal calcium stores sensitive to noradrenaline elicits a contractile response dependent on extracellular calcium in ra…
1993
1. Noradrenaline 1 microM induced a contractile response in rat isolated aorta in the presence or in the absence of extracellular Ca2+ with depletion of intracellular Ca2+ stores. Thereafter, during incubation in the presence of Ca2+, an increase in the resting tone was observed. Such a contractile response did not occur after exposure to caffeine or 5-hydroxytryptamine. 2. This increase in tension was inhibited in a concentration-dependent manner by alpha-adrenoceptor antagonists (prazosin, phentolamine and yohimbine), the non-specific relaxing compound, papaverine and by the Ca(2+)-entry blocker, nifedipine. Therefore, this contractile process is related to depletion of Ca2+ stores sensit…
Actions of alpha-adrenoceptor blocking agents on two types of intracellular calcium stores mobilized by noradrenaline in rat aorta.
1993
In isolated rat aortic strips noradrenaline induces a biphasic contractile response in Ca-free medium, associated with two different intracellular calcium pools, one of which is common to caffeine. We analyzed the mechanisms involved in the depletion and repletion of both intracellular Ca pools sensitive to noradrenaline in different experimental procedures in presence of prazosin, phentolamine and yohimbine. At 37 degrees C the alpha-adrenergic blocking agents inhibited contractile responses to noradrenaline in Ca-free medium, with prazosin being highly selective. alpha 2-adrenoceptors probably do not participate in the release of Ca from internal stores, as no contractile response was obs…
Binding of urate and caffeine to hemocyanin of the lobster Homarus vulgaris (E.) as studied by isothermal titration calorimetry.
2000
Hemocyanin serves as an oxygen carrier in the hemolymph of the European lobster Homarus vulgaris. The oxygen binding behavior of the pigment is modulated by metabolic effectors such as lactate and urate. Urate and caffeine binding to 12-meric hemocyanin (H. vulgaris) was studied using isothermal titration calorimetry (ITC). Binding isotherms were determined for fully oxygenated hemocyanin between pH 7.55 and 8.15. No pH dependence of the binding parameters could be found for either effector. Since the magnitude of the Bohr effect depends on the urate concentration, the absence of any pH dependence of urate and caffeine binding to oxygenated hemocyanin suggests two conformations of the pigme…
Pharmacological Neuroenhancement: Substances and Epidemiology
2013
Pharmacological neuroenhancement (PN) refers to the general use of psychoactive substances with the purpose of cognitive enhancement (e.g. enhancement of vigilance, concentration, memory or mood) by healthy subjects. Substances for PN include Over-the-Counter- (OTC-) substances such as coffee, caffeinated drinks/energy drinks, caffeine tablets and Ginkgo biloba as well as prescription drugs and illicit drugs (e.g. (psycho-) stimulants). “Brain doping” refers to the illicit use of a subcategory of these substances. On the one hand, this subcategory includes prescription drugs for the treatment of attention deficit/hyperactivity disorder (ADHD), sleep disorders, Alzheimer’s disease and depres…
Assessing the Differential Affinity of Small Molecules for Noncanonical DNA Structures
2012
The targeting of higher-order DNA structures has been thoroughly developed with G-quadruplex DNA but not with other structures like branched DNA (also known as DNA junctions). Because these alternative higher-order DNA architectures might be of high biological relevance, we implemented a high-throughput version of the FRET melting assay that enabled us to map the interactions of a candidate with four different DNA structures (duplex- and quadruplex DNA, three- and four-way junctions) in a rapid and reliable manner. We also introduce a novel index, the BONDS (branched and other noncanonical DNA selectivity) index, to conveniently quantify this differential affinity.
An Aqueous Extract of Ilex paraguariensis Reduces Carrageenan-Induced Edema and Inhibits the Expression of Cyclooxygenase-2 and Inducible Nitric Oxid…
2014
Mate (Ilex paraguariensis) is a highly popular herbal beverage in South America due to its high content of caffeine. Its hypolipidemic and antioxidant properties are of increasing interest in the treatment of cardiovascular disorders and for weight control. In the present study, we show for the first time both the local and systemic anti-inflammatory effects of an aqueous extract of mate in three classic in vivo models, namely acute and chronic 12-O-tetradecanoylphorbol 13-acetate-induced mouse ear edema and acute carrageenan-induced mouse paw edema. Caffeine, rutin, chlorogenic acid, 3,5-dicafeoyl quinic acid, and 4,5-dicafeoyl quinic acid, accompanied by a complex mixture of other simple …
Influence of different coffee drinks preparations on ochratoxin A content and evaluation of the antioxidant activity and caffeine variations.
2011
Coffee is one of the most frequently consumed beverages in North America and Europe. It is well known that coffee contains caffeine and that coffee beans can be contaminated by Ochratoxin A (OTA). The operating conditions however affect OTA and caffeine extraction from the roasted coffee. OTA content found in the beverages can be greater than that found in the roasted coffee used to prepare it, representing a potential OTA related risk factor for the human health. Moreover the coffee beans and coffee based beverages have an anti oxidant activity. This study investigates the OTA content, the amount of caffeine, and the antioxidant activity in five different preparations: American coffee, Mok…
Effects of Alcohol, Coffee, and Tobacco, Alone or in Combination, on Physiological Parameters and Anxiety in a Young Population
2012
The objective was to evaluate the effects of a single dose of alcohol, caffeine, and nicotine, alone or in combination, on physiological parameters (systolic and diastolic blood pressure [SBP and DBP] and heart rate [HR]) and state-trait anxiety in healthy young volunteers.The procedure reproduces the conditions under which the subjects (Intake of alcohol or alcohol-nicotine reduced DBP. Comparisons between control and combined treatment (coffee-alcohol-nicotine) groups revealed a decrease in HR in the former group but not in the latter. The coffee consumers alone exhibited a tendency toward an increase in SA, while the control group showed a tendency toward a decrease in this measure. When…
Effects of caffeine intake on the pharmacokinetics of melatonin, a probe drug for CYP1A2 activity
2003
Aims The aim of this study was to assess the influence of concomitant caffeine intake on the pharmacokinetics of oral melatonin, a probe drug for CYP1A2 activity. Methods Twelve healthy subjects, six smokers and six nonsmokers, were given melatonin (6 mg) either alone or in combination with caffeine (3 × 200 mg). Blood samples for the analysis of melatonin or caffeine and paraxanthine were taken from 1 h before until 6 h after intake of melatonin. Subjects were genotyped with respect to the CYP1A2*1F (C734A) polymorphism. Results When caffeine was coadministered the Cmax and AUC of melatonin were increased on average by 142% (P = 0.001, confidence interval on the difference 44, 80%) and …
Vasodilator Effects of Liriodenine and Norushinsunine, Two Aporphine Alkaloids Isolated from <i>Annona cherimolia,</i>in Rat Aorta
1995
The effect of two aporphines, liriodenine and norushinsunine, isolated from Annona cherimolia, were studied in the rat aorta in order to examine their mechanism of action. Both alkaloids (10–7–10–4 mol/l) showed relaxant effects on the contractions elicited by 10–6 mol/l noradrenaline (NA) or 80 mmol/l KC1, but, while liriodenine showed a nonspecific relaxant action on both spasmogens, norushinsunine was more potent on KC1-induced contraction. In Ca2+-free medium, both alkaloids (0.1 mmol/l) inhibited the responses elicited by NA, but not those elicited by caffeine. This inhibitory action occurred when the alkaloids were present during the release of the Ca2+ internal stores or during the r…