Anesth Analg 2008; 106:1778-1783
© 2008 International Anesthesia Research Society
doi: 10.1213/ane.0b013e318172c3a2
ANESTHETIC PHARMACOLOGY
The Local Anesthetic Butamben Inhibits Total and L-Type Barium Currents in PC12 Cells
Laurentius J.A. Rampaart, MD,
Jeroen P. Beekwilder, MSc,
Gertrudis Th.H. van Kempen, BSc,
Rutgeris J. van den Berg, PhD, and
Dirk L. Ypey, PhD
From the Department of Neurophysiology, Leiden University Medical Center (LUMC), Leiden, The Netherlands.
Address correspondence to Dirk L. Ypey, PhD, Department of Cardiology (C5-27), Leiden University Medical Center (LUMC), Postbox 9600, 2300 RC Leiden, The Netherlands. Address e-mail to D.L.Ypey{at}LUMC.NL.
BACKGROUND: Butamben or n-butyl-p-aminobenzoate is a long-acting experimental local anesthetic for the treatment of chronic pain when given as an epidural suspension. We have investigated whether Cav1.2/L-type calcium channels may be a target of this butamben action.
METHODS: The effect of butamben on these channels was studied in undifferentiated rat PC12-cells with the whole-cell patch-clamp technique in voltage-clamp. Ba2+ ions were used as the charge carriers in the calcium channel currents, whereas K+ currents were removed using K+ free solutions.
RESULTS: Butamben 500 µM reversibly suppressed the total whole-cell barium current by 90% ± 3% (n = 15), whereas 10 µM nifedipine suppressed this barium current by 75% ± 7% (n = 6). Preexposure to butamben followed by washout decreased the inhibition by nifidepine to 47% ± 5% (n = 10). These suppressive effects were not due to the measurement procedure and the drug vehicles in the solutions (<0.1% ethanol; n = 6).
CONCLUSIONS: Butamben inhibits the total barium current through expressed calcium channel types in PC12 cells, including Cav1.2/L-type channels. Because Cav1.2 channels may also occur in human nociceptive C fibers, this result allows the possibility that these L-type channels are involved in the analgesic action of butamben.
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