Inhibitory actions of eugenol on rat isolated ileum

Abstract: The effects of eugenol (1-2000 mM) on rat isolated ileum were studied. Eugenol relaxed the basal tonus (IC 50 83 mM) and the ileum precontracted with 60 mM KCl (IC 50 162 mM), an action unaltered by 0.5 mM tetrodotoxin, 0.2 mM N G -nitro-L-arginine methyl ester, 0.5 mM hexamethonium, and 1 mM indomethacin. Eugenol did not alter the resting transmembrane potential (E m ) of the longitudinal muscle layer under normal conditions (5.0 mM K + ) or in depolarised tissues. Eugenol reversibly inhibited contractions induced by submaximal concentrations of acetylcholine (ACh) and K + (40 mM) with IC 50 values of approximately 228 and 237 mM, respectively. Eugenol blocked the component of ACh-induced contraction obtained in Ca 2+ -free solution (0.2 mM EGTA) or in the presence of nifedipine (1 mM). Our results suggest that eugenol induces relaxation of rat ileum by a direct action on smooth muscle via a mechanism largely independent of alterations of E m and extracellular Ca 2+ influx. Key words: essential oil, eugenol, ileum, smooth muscle, antispasmodic. Résumé : On a examiné les effets de l'eugénol (1-2000 mM) sur l'iléon isolé de rat. L'eugénol a provoqué une relaxation du tonus basal (CI 50 83 mM) et de l'iléon précontracté avec 60 mM KCl (CI 50 162 mM); cet effet n'a pas été modifié par 0,5 mM tétrodotoxine, 0,2 mM N G -nitro-L-arginine méthyl ester, 0,5 mM hexaméthonium et 1 mM indométhacine. L'eugénol n'a pas modifié le potentiel transmembranaire (E m ) au repos de la couche musculaire longitudinale dans des conditions normales (5,0 mM K + ) ou dans les tissus dépolarisés. Il a inhibé de manière réversible les contractions induites par des concentrations submaximales d'acétylcholine (ACh) et de K + (40 mM) avec des valeurs de CI 50 d'approximativement 228 et 237 mM respectivement. Il a bloqué la composante de la contraction induite par l'ACh dans une solution sans Ca 2+ (0,2 mM EGTA) ou en présence de nifédipine (1 mM). Nos résultats donnent à penser que l'eugénol provoque une relaxation de l'iléon de rat en agissant directement sur le muscle lisse par l'intermédiaire d'un mécanisme largement indépendant des modifications du potentiel E m et de l'influx de Ca 2+ extracellulaire

Characterisation of microbial attack on archaeological bone

As part of an EU funded project to investigate the factors influencing bone preservation in the archaeological record, more than 250 bones from 41 archaeological sites in five countries spanning four climatic regions were studied for diagenetic alteration. Sites were selected to cover a range of environmental conditions and archaeological contexts. Microscopic and physical (mercury intrusion porosimetry) analyses of these bones revealed that the majority (68%) had suffered microbial attack. Furthermore, significant differences were found between animal and human bone in both the state of preservation and the type of microbial attack present. These differences in preservation might result from differences in early taphonomy of the bones. © 2003 Elsevier Science Ltd. All rights reserved