Search results for "choline"
showing 10 items of 1138 documents
Uptake and storage of choline by rat brain: influence of dietary choline supplementation.
1991
In order to elucidate the regulation of the levels of free choline in the brain, we investigated the influence of chronic and acute choline administration on choline levels in blood, CSF, and brain of the rat and on net movements of choline into and out of the brain as calculated from the arteriovenous differences of choline across the brain. Dietary choline supplementation led to an increase in plasma choline levels of 50% and to an increase in the net release of choline from the brain as compared to a matched group of animals which were kept on a standard diet and exhibited identical arterial plasma levels. Moreover, the choline concentration in the CSF and brain tissue was doubled. In th…
Choline Metabolism and Risk of Atrial Fibrillation and Heart Failure in the PREDIMED Study
2020
Abstract Background Few studies have examined the associations of trimethylamine-N-oxide (TMAO) and its precursors (choline, betaine, dimethylglycine, and L-carnitine) with the risk of atrial fibrillation (AF) and heart failure (HF). This study sought to investigate these associations. Methods Prospective associations of these metabolites with incident AF and HF were examined among participants at high cardiovascular risk in the PREDIMED study (PREvención con DIeta MEDiterránea) after follow-up for about 10 years. Two nested case-control studies were conducted, including 509 AF incident cases matched to 618 controls and 326 HF incident cases matched to 426 controls. Plasma levels of TMAO an…
Apparent vs real effects of scopolamine on the learning of an active avoidance task.
1996
The effects of scopolamine hydrobromide (0.5 and 2 mg/ kg) administered intraperitoneally to Balb/c male mice before or after training in active avoidance were explored in four training sessions and in a subsequent test session, free of drug. Animals given scopolamine prior to training performed better than controls, an effect that was reversed in the session free of drug. However, a deeper analysis of the data permits us to interpret this increment in the number of avoidance responses as a consequence of the increase in activity produced by the drug and not as learning. In the animals injected with scopolamine after sessions no effects were observed. In conclusion, the results of the prese…
Angiotensin II contractile effects in mouse colon: role for pre- and post-junctional AT1A receptors
2013
Aim This study investigates whether a local renin–angiotensin system (RAS) exists in mouse colon and whether angiotensin II (Ang II) may play a role in the regulation of the contractile activity. Methods Isometric recordings were performed in vitro on the longitudinal muscle of mouse proximal and distal colon. Transcripts encoding for RAS components were investigated by RT-PCR. Results Ang II caused, in both preparations, a concentration-dependent contractile effect, antagonized by losartan, AT1 receptor antagonist, but not by PD123319, AT2 receptor antagonist. The combination of losartan plus PD123319 caused no change on the Ang II-induced contraction than losartan alone. Tetrodotoxin, neu…
Effect of verapamil and diltiazem on isolated gastro-oesophageal sphincter of the rat
1985
Abstract The effect of verapamil and diltiazem on the contraction induced by agonists on the rat lower oesophageal sphincter in-vitro has been studied. Both calcium entry blockers inhibited the contractile response to acetylcholine, carbachol and KCl. The potency of the inhibitory action was diltiazem > verapamil. The results give substance to the use of calcium entry blockers in the treatment of oesophageal spasm.
Effects of Ca2+ channel antagonists in guinea-pig normal and skinned gall bladder.
1993
CaCl2 (0.01-50 mM, in K(+)-depolarized tissues), KCl (0.1-100 mM) and acetylcholine (1 nM-10 mM) produced concentration-dependent contractions of guinea-pig isolated gall bladder. Nifedipine (1-100 microM), verapamil (1-100 microM), diltiazem (1-100 microM), cinnarizine (1-100 microM), and flunarizine (1-100 microM) each produced a concentration-related inhibition of the log concentration-effect curve for CaCl2. The rank order of potencies of these antagonists, measured as the IC50 against Ca2+ (50 mM)-induced contraction of depolarized gall bladder, was diltiazem (0.25 microM)or = verapamil (0.8 microM) approximately nifedipine (1.2 microM)cinnarizine (25 microM) approximately flunarizine …
Role of endothelium in the responses to noradrenaline in normal and sensitized guinea-pig aorta
1993
1. The pharmacological reactivity of sensitized blood vessels has been less studied than that of the airways. Aorta rings were obtained from normal (non-sensitized) and actively sensitized guinea-pigs, and prepared for isometric recording of tension changes. 2. Noradrenaline (10 nM-0.1 mM), histamine (0.1 microM-0.1 mM) and KCl (10-100 mM) produced concentration-related contractions of normal tissues. Removal of endothelium resulted in a marked leftward and upward shift of the concentration-response curve for noradrenaline but it did not alter histamine- or KCl-induced responses. Pretreatment with L-NG-nitroarginine (L-NOARG, 30 microM), haemoglobin (5 microM) or ibuprofen (10 microM) enhan…
Modulatory role of magnesium on the contractile response of rat aorta to several agonists in normal and calcium-free medium.
1993
Abstract Acute withdrawal of external Mg2+ increased basal tone of rat isolated aorta incubated in the presence of Ca2+. Above normal levels of Mg2+ (1–4 Mm) inhibited basal tone while much higher levels of the divalent cation (64–256 Mm) evoked contractile responses regardless of the presence of Ca2+. Contractile responses to noradrenaline (1μm) and KCl (80 Mm) were inhibited by addition of cumulative concentrations of Mg2+. Acetylcholine-induced contractions in the presence of physiological concentrations of Mg2+ (1 Mm) decreased gradually to the basal tone, but a sustained contraction was observed in the absence of this ion. In Ca2+-free medium, acetylcholine-induced phasic responses ind…
Spontaneous electromechanical activity in the rat duodenumin vitro
1990
Isolated rat duodenum shows spontaneous mechanical and electrical activities. Mechanical activity consists in changes both in endoluminal pressure and in isometric tension. Electrical activity is characterized by slow waves with superimposed bursts. This spontaneous activity is tetrodotoxin (TTX) resistant and therefore it is myogenic in origin. Indeed, TTX pretreatment, even in the presence of atropine and guanethidine, caused an increase in amplitude and in frequency of the electrical and mechanical activities. This finding indicates the presence of tonically active inhibitory intramural non adrenergic, non cholinergic (NANC) nerves. Duodenal longitudinal strips showed a spontaneous mecha…
Antagonist discrimination between subtypes of tachykinin receptors in the guinea-pig ileum.
1986
1. The effects of substance P and eledoisin on spontaneous and electrically-evoked release of [3H]acetylcholine, and on smooth muscle were studied in the guineapig myenteric plexus-longitudinal muscle preparation preloaded with [3H]choline. Substance P and eledoisin caused transient increases in spontaneous release of [3H]acetylcholine and in longitudinal muscle tone. Both tachykinins were equipotent in contracting the muscle, but eledoisin was more potent than substance P in eliciting [3H]acetylcholine release. The release caused by substance P was enhanced in the presence of naloxone and scopolamine which suggests that the release is modulated through opioid and muscarinic receptors. 2. S…