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. Author manuscript; available in PMC: 2013 Jul 27.
Published in final edited form as: Anesthesiology. 2006 Jul;105(1):160–168. doi: 10.1097/00000542-200607000-00026

Table 1.

Injury Effects on AP Parameters and ICa

Command Current Clamp
Voltage Clamp:
Square Wave
Voltage Clamp: AP Waveform
Cell Size Injury
Model		 n APdur50, ms APthresh, mV AHPampl, mV AHPdur50, ms AHPτ, ms Gmax, pS/pF Ipeak, pA/pF Charge Transfer,
fC/μm2
Small Control 20 4.4 ± 0.4 −10.1 ± 2.0 −15.8 ± 1.5 38.3 ± 4.8 55.7 ± 9.5 3.7 ± 0.3 −249.9 ± 19.8 4.66 ± 0.20
SNL L4 20 5.0 ± 0.5 −11.5 ± 2.2 −16.6 ±1.2 34.3 ± 7.3 41.0 ± 10.6 3.1 ± 0.4 −220.3 ± 29.1 4.08 ± 0.52
SNL L5 19 14.8 ± 0.5* −14.7 ± 1.8* −14.9 ± 1.4 42.7 ± 7.2 53.2 ± 12.2 2.3 ± 0.2* −143.1 ± 17.2* 2.76 ± 0.40*
Medium Control 20 3.4 ± 0.5 −20.2 ± 2.0 −15.3 ± 1.1 70.2 ± 10.4 121.2 ± 21.7 3.5 ± 0.4 −180.0 ± 19.5 4.06 ± 0.47
SNL L4 14 4.6 ± 1.1 −22.4 ± 3.4 −9.1 ± 1.8* 45.4 ± 11.3 70.8 ± 15.9 2.6 ± 0.4 −114.1 ± 21.6* 2.52 ± 0.57*
SNL L5 24 6.4 ± 1.1* −19.4 ± 1.7 −10.9 ± 0.8* 20.8 ± 2.9* 29.6 ± 4.9* 2.2 ± 0.3* −113.6 ± 16.5* 2.54 ± 0.37*
Large Control 16 3.6 ± 1.4 −16.7 ± 3.2 −14.9 ± 1.2 90.5 ± 14.1 181.6 ± 23.6 3.9 ± 0.5 −192.2 ± 21.4 5.39 ± 1.64
SNL L4 13 2.3 ± 0.3 −20.8 ± 3.2 −15.4 ± 1.8 53.0 ± 14.8* 94.8 ± 29.5* 2.4 ± 0.5* −104.0 ± 30.4* 2.05 ± 0.76*
SNL L5 12 3.1 ± 0.5 −17.7 ± 2.1 −10.5 ± 1.3* 57.7 ± 19.8* 115.5 ± 46.3* 2 3 ± 0 5* −105.3 ± 26.1* 1.87 ± 0.51*

Injury prolonged action potential (AP) in small and medium neurons, whereas afterhyperpolarization (AHP) was decreased in medium and large cells in response to current clamp command protocols. Every group lost Ca2+ current (ICa) in response to voltage clamp command protocols after injury. Neurons grouped by cell size and injury model were analyzed by comparison with “control” neurons from skin-sham operated rats. Means compared with analysis of variance and Bonferroni post hoc, except in large cell voltage clamp data, where nonparametric Kruskal-Wallis with Dunn post hoc comparisons were used to account for signal saturation. See Materials and Methods.

*

P < 0.05 vs. control; no other comparisons among injury groups were significant.

AHPampl = amplitude of hyperpolarization below resting membrane potential after AP; AHPdur50 = duration at 50% of AHP; AHPτ = time constant of recovery from AHP; APdur50 = duration at 50% of AP; APthresh = inflection on upstroke of AP; charge transfer = integral of area under current wave representing total Ca2+ charge transferred in response to standardized AP waveform expressed as coulombs per area of cell membrane; Gmax = maximum Boltzmann conductance in response to stepwise increments in 200-ms test pulse from holding potential of −90 mV; Ipeak = peak inward ICa in response to standardized AP waveform; SNL = spinal nerve ligation.

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