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Bischoff, U; Bräu, ME; Vogel, W; Hempelmann, G; Olschewski, A.
Local anaesthetics block hyperpolarization-activated inward current in rat small dorsal root ganglion neurones.
BRIT J PHARMACOL 2003 139: 1273-1280. [OPEN ACCESS]
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Authors Med Uni Graz:
Olschewski Andrea

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Number of Figures: 6
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(1) Hyperpolarizing voltage steps evoke slowly activating inward currents in a variety of neurones and in cardiac cells. This hyperpolarization-activated inward current (I(h)) is thought to play a significant role in cell excitability, firing frequency, or in setting of the resting membrane potential in these cells. We studied the effects of lidocaine, mepivacaine, QX-314 and bupivacaine as well as its enantiomers on I(h) in the membrane of dorsal root ganglion neurones (DRG). (2) The patch-clamp technique was applied to small dorsal root ganglion neurones identified in 200 micro M thin slices of young rat DRGs. Under voltage-clamp conditions, the whole-cell I(h) current was recorded in the presence of different concentrations of the local anaesthetics. In current-clamp mode the resting membrane potential and the voltage response of DRG neurones to injected current pulses were investigated. (3) I(h) was reversibly blocked by bupivacaine, lidocaine and mepivacaine applied externally in clinically relevant concentrations. Concentration-response curves gave half-maximum inhibiting concentrations of 55, 99 and 190 micro M, respectively. Bupivacaine block of the I(h) current was not stereoselective. No significant effect was observed when QX-314 was applied to the external surface of the membrane. (4) In current-clamp experiments 60 micro M bupivacaine slightly hyperpolarized the membrane. The membrane stimulation by low-amplitude current pulses in the presence of bupivacaine showed an increase of the hyperpolarizing responses. (5) Our findings suggest an important role of the I(h)-block by local anaesthetics in the complex mechanism of drug action during epidural and spinal anaesthesia.
Find related publications in this database (using NLM MeSH Indexing)
Anesthetics, Local - pharmacology
Animals - pharmacology
Bupivacaine - pharmacology
Dose-Response Relationship, Drug - pharmacology
Electrophysiology - pharmacology
Ganglia, Spinal - cytology
Inhibitory Concentration 50 - cytology
Ion Channels - antagonists and inhibitors
Lidocaine - analogs and derivatives
Mepivacaine - pharmacology
Neurons - drug effects
Pyrimidines - pharmacology
Rats - pharmacology
Research Support, Non-U.S. Gov't - pharmacology
Tetraethylammonium - pharmacology
Time Factors - pharmacology

Find related publications in this database (Keywords)
ion channels
cationic current
sensory neurones
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