The enzymatic complex Nicotinamide Adenine Dinucleotide Phosphate (NADPH) oxidase (NOx) may be the principal source of reactive oxygen species (ROS). The NOX2 and NOX4 isoforms are tissue-dependent and are differentially expressed in slow-twitch fibers (type I fibers) and fast-twitch fibers (type II fibers) of skeletal muscle, making them different markers of ROS metabolism induced by physical exercise. The aim of this study was to investigate NOx signaling, as a non-adaptive and non-cumulative response, in the predominant fiber types of rat skeletal muscles 24 h after one strenuous treadmill exercise session. The levels of mRNA, reduced glycogen, thiol content, NOx, superoxide dismutase, catalase, glutathione peroxidase activity, and PPARGC1α and SLC2A4 gene expression were measured in the white gastrocnemius (WG) portion, the red gastrocnemius (RG) portion, and the soleus muscle (SOL). NOx activity showed higher values in the SOL muscle compared to the RG and WG portions. The same was true of the NOX2 and NOX4 mRNA levels, antioxidant enzymatic activities, glycogen content. Twenty-four hours after the strenuous exercise session, NOx expression increased in slow-twitch oxidative fibers. The acute strenuous exercise condition showed an attenuation of oxidative stress and an upregulation of antioxidant activity through PPARGC1α gene activity, antioxidant defense adaptations, and differential gene expression according to the predominant fiber type. The most prominent location of detoxification (indicated by NOX4 activation) in the slow-twitch oxidative SOL muscle was the mitochondria, while the fast-twitch oxidative RG portion showed a more cytosolic location. Glycolytic metabolism in the WG portion suggested possible NOX2/NOX4 non-regulation, indicating other possible ROS regulation pathways.

The effects on isolated guinea‐pig ileum of the essential oil of Croton zehntneri (CZEO) and of its main constituent estragole (57% of CZEO by weight) were studied. CZEO and estragole (0.1–100 μg/mL) decreased the tonus in 56% and 61.5%, respectively, of the muscles. At concentrations above 10 μg/mL, they induced spontaneous rhythmic movements of small amplitude (less than 11% of the potassium contraction peak to peak). At concentrations from 1 to 100 μg/mL and with similar potencies, these agents blocked the contractions induced by acetylcholine, histamine and 50 mM K+ and caused relaxation of already established potassium contractures. Tested separately, CZEO, estragole and anethole (28% of CZEO by weight) blocked the contraction induced by Ca++ in the presence of 50 mM K+, but CZEO was more potent than estragole or anethole in blocking the Ca++‐induced contractions than those induced by K+. With large increases in the agonist concentration, the action of the oils on the contractions induced by Ca++ was reversible; however, their effect on contractions induced by histamine or ACh was not. The data show that the essential oil of Croton zehntneri has an effect on intestinal smooth muscle that is predominantly antispasmodic, and attributable in part to the effect of estragole, a major constituent. © 1997 John Wiley & Sons, Ltd.

The effects of methyleugenol (ME) on guinea-pig isolated ileum were studied. ME reversibly relaxed basal tonus (EC 50 of 52.2 18.3 m mM), an action unaltered by 0.5 m mM tetrodotoxin or 0.5 mM hexamethonium, and relaxed the ileum precontracted with 60 mM KCl. ME slightly hyperpolarised the ileum from ± 57.3 to ± 62.8 mV but had no effect in depolarised tissues. ME inhibited contractions induced by ACh, histamine and KCl with IC 50 values of approximately 82, 124, and 65 m mM, respectively. Our results suggest that ME induces relaxation of guinea-pig ileum by a direct action on smooth muscle via a mechanism largely independent of alterations of membrane potential (E m ).

Environmentally relevant doses of inhaled diesel particles elicit pulmonary inflammation and impair lung mechanics. Eugenol, a methoxyphenol component of clove oil, presents in vitro and in vivo anti-inflammatory and antioxidant properties. Our aim was to examine a possible protective role of eugenol against lung injuries induced by diesel particles. Male BALB/c mice were divided into four groups. Mice received saline (10 μl in; CTRL group) or 15 μg of diesel particles DEP (15 μg in; DIE and DEUG groups). After 1 h, mice received saline (10 μl; CTRL and DIE groups) or eugenol (164 mg/kg; EUG and DEUG group) by gavage. Twenty-four hours after gavage, pulmonary resistive (ΔP1), viscoelastic (ΔP2) and total (ΔPtot) pressures, static elastance (Est), and viscoelastic component of elastance (ΔE) were measured. We also determined the fraction areas of normal and collapsed alveoli, amounts of polymorpho- (PMN) and mononuclear cells in lung parenchyma, apoptosis, and oxidative stress. Est, ΔP2, ΔPtot, and ΔE were significantly higher in the DIE than in the other groups. DIE also showed significantly more PMN, airspace collapse, and apoptosis than the other groups. However, no beneficial effect on lipid peroxidation was observed in DEUG group. In conclusion, eugenol avoided changes in lung mechanics, pulmonary inflammation, and alveolar collapse elicited by diesel particles. It attenuated the activation signal of caspase-3 by DEP, but apoptosis evaluated by TUNEL was avoided. Finally, it could not avoid oxidative stress as indicated by malondialdehyde.

This study was undertaken to assess the effects of eugenol (EUG) on tracheal muscle (TM) and the putative mechanisms underlying these effects. Cumulatively increasing concentrations (1-1000 μm) of EUG did not affect the resting tonus of TM. However, EUG (1-2000 μm) reduced the contractions induced by electrical field stimulation (IC(50) = 842.3 ± 52.7 μm), an effect that was unaltered by either 10 μm montelukast (IC(50) = 816.1 ± 70.1 μm) or 2 μm indomethacin (IC(50) = 693.1 ± 170.8 μm). EUG also completely relaxed the sustained contractile responses to 80 mM K(+) (IC(50)  = 597.3 ± 60.6 μm) and 1 μm carbamoylcholine (IC(50) = 571.3 ± 148.8 μm), an effect that was unaltered by indomethacin (2 μm). Under Ca(2+) -free conditions, EUG reduced the ACh-induced contractions (IC(50) = 703.4 ± 256.1 μm), the CaCl₂ -induced contractions in preparations pretreated with 60 μm ACh in the presence of nifedipine, and the Ba(2+) -induced contractions in preparations depolarized with K(+) . In tracheal preparations maintained in Ca(2+) -containing solution, EUG (300-2000 μm) relaxed the contractile response to phorbol dibutyrate (1 μm), an activator of protein kinase C. It is concluded that in TM, EUG induces a myogenic antispasmodic effect (not modulated by arachidonic acid derivatives) either through various mechanisms almost with the same pharmacological potency or via an action on a step common to all of them. These mechanisms seem to include blockade of voltage- and receptor-operated Ca(2+) channels, IP₃ -induced Ca(2+) release from sarcoplasmic reticulum and reduction of the sensitivity of contractile proteins to Ca(2+) .