Abstract Abstract AIM:To study the effects of magnolol and honokiol on isolated smooth muscle of gastrointestinal tract and their relationship with Ca 2+ , and on the gastric emptying and the intestinal propulsive activity in mice. METHODS:Routine experimental methods using isolated gastric fundus strips of rats and isolated ileum segments of guinea pigs were adopted to measure the smooth muscle tension. The effects of magnolol 10 -3 , 10 -4 , 10 -5 mol/L, and honokiol 10 -4 , 10 -5 , 10 -6 mol/L on the contractility of gastric fundus strips of rats and ileum of guinea pigs induced by acetylcholine (Ach) and 5-hydroxytryptamine (5-HT) was assessed respectively. The method using nuclein and pigment methylene blue was adopted to measure the gastric retention rate of nuclein and the intestinal propulsive ratio of a nutritional semi-solid meal for assessing the effect of magnolol and honokiol (0.5, 2, 20 mg/kg) on gastric emptying and intestinal propulsion. RESULTS:Magnolol and honokiol significantly inhibited the contractility of isolated gastric fundus strips of rats treated with Ach or 5-HT and isolated ileum guinea pigs treated with Ach or CaCl 2 , and both of them behaved as non-competitive muscarinic antagonists. Magnolol and honokiol inhibited the contraction induced by Ach in Ca 2+ -free medium and extracellular Ca 2+ -dependent contraction induced by Ach. Each group of magnolol and honokiol experiments significantly decreased the residual rate of nuclein in the stomach and increased the intestinal propulsive ratio in mice. CONCLUSION:The inhibitory effect of magnolol and honokiol on contractility of the smooth muscles of isolated gastric fundus strips of rats and isolated ileum of guinea pigs is associated with a calcium-antagonistic effect. Magnolol and honokiol can improve the gastric emptying of a semi-solid meal and intestinal propulsive activity in mice. © 2005The WJG Press and Elsevier Inc. All rights reserved. Key words: Magnolol and honokiol; Gastrointestinal movementZhang WW, Li Y, Wang XQ, Tian F, Cao H, Wang MW, Sun QS. Effects of magnolol and honokiol derived from traditional Chinese herbal remedies on gastrointestinal movement. World

No abstract

Iron (Fe) is a critical nutrient in marine systems and the organic complexation of Fe is a central factor of the marine biogeochemistry of Fe. In the present study, total dissolved Fe and its organic speciation were measured in filtered seawater samples (<0.2 µm) collected along three surface transects across the subtropical (ST) front, east of New Zealand, in austral spring (October 2000). Total dissolved Fe concentrations were low (∼0.1 nm) in the subantarctic (SA) waters. The highest Fe concentration (∼0.8 nm) was observed at the mixing boundary north of the Subtropical Convergence (STC) and then decreased relatively quickly both southward and northward. Cathodic stripping voltammetry was used to determine Fe speciation. The dissolved Fe(iii) was fully complexed (>99.9%) by natural organic ligands, which were found to occur in excess of the dissolved Fe concentration at 1.29 ± 0.33 nm (equivalent to an excess over Fe of ∼1.0 nm), and with a complex stability of log K FeL,Fe 3+ = 22.67 ± 0.22. The total ligand concentrations were consistently higher (∼0.5 nm) in the ST and STC waters than in the SA waters. Our Fe data imply that the regional currents may be an important vehicle for transporting the elevated Fe across the front.

No abstract

No abstract