Effects of 1,8-cineole on electrophysiological parameters of neurons of the rat superior cervical ganglion |
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Authors: | Francisco W Ferreira-da-Silva,Roseli Barbosa,Luiz Moreira-Jú nior,Tiago dos Santos-Nascimento,Maria D de Oliveira-Martins,relina N Coelho-de-Souza,Francisco SA Cavalcante,Vâ nia M Ceccatto,Telma LG de Lemos,Pedro JC Magalhã es,Saad Lahlou, José H Leal-Cardoso |
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Affiliation: | Laboratory of Electrophysiology, Superior Institute of Biomedical Sciences, Campus of Itaperi, State University of Ceará;, Laboratory of Biotransformation and Natural Products, Organic and Inorganic Chemistry Department, Campus of Pici;and Department of Physiology and Pharmacology, School of Medicine, Campus of Porangabussu, Federal University of Ceará, Fortaleza, Ceará, Brazil |
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Abstract: | ![]()
- 1 1,8‐Cineole is a non‐toxic small terpenoid oxide believed to have medicinal properties in folk medicine. It has been shown to have various pharmacological effects, including blockade of the compound action potential (AP). In the present study, using intracellular recording techniques, we investigated the effects of 1,8‐cineole on the electrophysiological parameters of neurons of the superior cervical ganglion (SCG) in rats.
- 2 1,8‐Cineole (0.1–6 mmol/L) showed reversible and concentration‐dependent effects on various electrophysiological parameters. At 3 and 6 mmol/L, but not at 0.1 and 1 mmol/L, 1,8‐cineole significantly diminished the input resistance (Ri) and altered the resting potential (Em) to more positive values. At 6 mmol/L, 1,8‐cineole completely blocked all APs within 2.7 ± 0.6 min (n = 12). In neurons exposed to 3 and 1 mmol/L 1,8‐cineole, the effects regarding excitability varied from complete AP blockade to minor inhibition of AP parameters. The depolarization of Em and the decrease in Ri induced by 6 mmol/L 1,8‐cineole were unaltered by 200 µmol/L niflumic acid, a well known blocker of Ca2+‐activated Cl? currents.
- 3 Significant correlations (Pearson correlation test) were found between changes in Em and decreases in AP amplitude (r = –0.893; P < 0.00282) and maximum ascendant inclination (r = –0.799; P < 0.0173), but not for maximum descendant inclination (r = 0.598; P < 0.117). Application of current to restore the transmembrane potential equal to control Em values in the presence of 6 mmol/L 1,8‐cineole resulted in the partial recovery of AP.
- 4 The present study shows that 1,8‐cineole effectively blocks the excitability of SCG neurons, probably through various mechanisms, one of which acts indirectly via depolarization of the neuronal cytoplasmatic membrane.
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Keywords: | action potential autonomic nervous system 1,8-cineole essential oils intracellular recording technique superior cervical ganglia |
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