Effects of bupivacaine and ropivacaine on high-voltage-activated calcium currents of the dorsal horn neurons in newborn rats

Bg. Liu et al., Effects of bupivacaine and ropivacaine on high-voltage-activated calcium currents of the dorsal horn neurons in newborn rats, ANESTHESIOL, 95(1), 2001, pp. 139-143
Citations number
Categorie Soggetti
Aneshtesia & Intensive Care","Medical Research Diagnosis & Treatment
Journal title
ISSN journal
0003-3022 → ACNP
Year of publication
139 - 143
SICI code
Background: Local anesthetics, such as bupivacaine, have been reported to b lock calcium currents in primary sensory neurons and to interfere with the release of neurotransmitters in central nervous system neurons. However, it is unknown whether local anesthetics affect the calcium current activity o f central nervous system neurons. Methods: Using a traditional whole cell voltage clamp technique, effects of bupivacaine and ropivacaine on high-voltage activated calcium currents (HV A-Ic(a)) were investigated in enzymatically dissociated dorsal horn neurons of neonatal rats. Calcium currents were evoked by testing pulses from a ho lding potential of -90 to 0 mV, Results: Bupivacaine significantly reduced HVA-Ic(a) in a dose-dependent ma nner. The peak HVA-Ic(a) decreased by 24.5 +/- 2,5, 32.0 +/- 6.8, 59.4 +/- 6,2, 88.3 +/- 1.5, and 91.6 +/- 1.1% in response to 10, 30, 50, 100 and 200 muM bupivacaine, respectively. Unlike bupivacaine, ropivacaine markedly in creased HVA-Ic(a) at lower concentrations (< 50 muM) but decreased HVA-Ic(a ) at higher concentrations (greater than or equal to 50 muM), The percent i ncreases in peak HVA-Ic, induced by 10 and 30 muM ropivacaine were 95 +/- 1 9.1 and 41.6 +/- 8.3%, respectively. The percent decreases in response to 5 0, 100, and 200 muM ropivacaine were 21.1 +/- 2.1, 63.2 +/- 6.0 and 79.1 +/ - 7.6%, respectively. Results indicate that the inhibitory potency of ropiv acaine on HVA-Ic(a) was significantly lower than that of bupivacaine at the same concentrations. Conclusions: The current study showed that bupivacaine inhibited HVA-Ic, re corded from dorsal horn neurons and that ropivacaine increased HVA-Ic, at l ower concentrations but decreased HVA-Ic, at higher concentrations. The inh ibitory potency of ropivacaine was lower than that of bupivacaine, Inhibiti on of calcium currents of central nervous system neurons may be related to the systemic neurotoxic effects of local anesthetics (e.g., convulsions, se izures).