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Effects of 1,8‐cineole on electrophysiological parameters of neurons of the rat superior cervical ganglion
Author(s) -
FerreiradaSilva Francisco W,
Barbosa Roseli,
MoreiraJúnior Luiz,
Dos SantosNascimento Tiago,
De OliveiraMartins Maria D,
CoelhodeSouza Andreli,
Cavalcante Francisco SA,
Ceccatto Vânia M,
De Lemos Telma LG,
Magalhães Pedro JC,
Lahlou Saad,
LealCardoso José H
Publication year - 2009
Publication title -
clinical and experimental pharmacology and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 103
eISSN - 1440-1681
pISSN - 0305-1870
DOI - 10.1111/j.1440-1681.2009.05188.x
Subject(s) - electrophysiology , depolarization , chemistry , blockade , niflumic acid , pharmacology , biophysics , medicine , biology , receptor , biochemistry
Summary1 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 (R i ) and altered the resting potential (E m ) 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 E m and the decrease in R i induced by 6 mmol/L 1,8‐cineole were unaltered by 200 µmol/L niflumic acid, a well known blocker of Ca 2+ ‐activated Cl − currents. 3 Significant correlations (Pearson correlation test) were found between changes in E m 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 E m 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.