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Table 1 Intrinsic electrogenic properties of small-sized DRG neurons in naïve, PBS-, HK-, and MRMT-1-rats

From: Enhanced excitability of small dorsal root ganglion neurons in rats with bone cancer pain

  

RMP

Rin

CT

TP

TP rise rate

AP amplitude

AP overshot

AP duration

AHP amplitude

AHP80% duration

AP frequency

  

mV

MΩ

pA

mV

v/s

mV

mV

ms

mV

ms

Spikes/s

CT

< 50

pA

Naïve

-50.6 ± 0.5 (29)

654.0 ± 20.1 (33)

29.8 ± 2.0 (29)

-27.6 ± 0.8 (38)

0.8 ± 0.1 (30)

101.8 ± 1.9 (34)

55.9 ± 1.4 (34)

44.6 ± 2.9 (30)

19.2 ± 0.8 (40)

17.6 ± 1.1 (35)

20.5 ± 1.8 (30)

 

PBS

-50.3 ± 0.7 (18)

634.5 ± 28.5 (13)

28.9 ± 2.2 (18)

-27.8 ± 0.8 (29)

0.7 ± 0.1 (24)

103.4 ± 1.8 (24)

55.5 ± 1.6 (24)

43.2 ± 2.6 (23)

18.9 ± 1.3 (25)

17.7 ± 1.4 (21)

20.6 ± 2.3 (14)

 

MRMT-1

-45.6 ± 0.5 (52) ***

546.3 ± 15.3 (60) ***

20.9 ± 1.5 (44) ***

-30.7 ± 0.6 (55) **

0.9 ± 0.1 (45) *

94.2 ± 1.9 (55) **

45.7 ± 1.9 (47) ***

34.3 ± 1.4 (54) ***

14.7 ± 0.7 (51) ***

14.6 ± 0.6 (49) *

31.4 ± 1.9 (32) ***

 

HK

-50.5 ± 0.6 (13)

638.1 ± 24.9 (19)

28.9 ± 2.4 (13)

-26.6 ± 1.0 (23)

0.7 ± 0.1 (13)

102.6 ± 2.6 (16)

54.7 ± 1.7 (16)

44.7 ± 3.1 (16)

19.7 ± 1.3 (11)

18.2 ± 1.7 (13)

20.3 ± 2.6 (12)

 

Naïve

-51.7 ± 1.1 (12)

593.0 ± 22.3 (14)

85.0 ± 3.3 (13)

-20.1 ± 0.7 (19)

1.9 ± 0.2 (11)

104.7 ± 3.4 (17)

55.1 ± 1.9 (17)

24.5 ± 2.1 (15)

19.7 ± 1.5 (16)

10.6 ± 1.4 (16)

10.5 ± 1.7 (15)

CT50 ~100 pA

PBS

-51.1 ± 0.6 (7)

594.6 ± 25.4 (6)

86.4 ± 4.0 (7)

-19.9 ± 1.5 (6)

2.0 ± 0.3 (5)

105.1 ± 4.3 (6)

56.5 ± 3.1 (6)

24.0 ± 1.9 (6)

20.2 ± 2.6 (7)

11.2 ± 1.7 (7)

13.8 ± 2.2 (6)

 

HK

-52.6 ± 1.5 (11)

596.9 ± 26.4 (7)

85.5 ± 2.7 (11)

-20.0 ± 1.1 (10)

2.0 ± 0.2 (10)

104.0 ± 2.4 (10)

56.0 ± 2.6 (9)

24.0 ± 1.7 (8)

19.7 ± 2.1 (8)

10.7 ± 1.5 (9)

12.2 ± 3.4 (9)

 

MRMT-1

-48.6 ± 0.5 (16) **

486.5 ± 25.8 (17) **

72.2 ± 4.0 (16) *

-23.4 ± 1.0 (17) **

2.3 ± 0.2 (14)

98.7 ± 2.6 (17)

46.1 ± 2.9 (15) *

22.1 ± 1.2 (17)

14.4 ± 1.3 (17) *

11.4 ± 1.0 (17)

19.3 ± 3.2 (12) *

CT

> 100

pA

Naïve

-54.6 ± 2.1 (7)

550.5 ± 40.8 (9)

157.9 ± 12.6 (7)

-16.6 ± 1.0 (8)

5.4 ± 1.1 (5)

103.7 ± 3.6 (7)

54.1 ± 3.3 (5)

17.5 ± 3.2 (6)

10.8 ± 1.3 (8)

6.3 ± 0.6 (6)

7.1 ± 3.4 (8)

 

PBS

-54.1 ± 1.9 (7)

556.6 ± 35.3 (7)

158.6 ± 14.6 (7)

-18.8 ± 0.8 (9)

5.1 ± 0.7 (5)

107.9 ± 4.8 (7)

56.7 ± 3.7 (6)

15.1 ± 1.1 (6)

10.9 ± 1.8 (6)

6.1 ± 0.5 (5)

6.8 ± 2.9 (8)

 

HK

-54.2 ± 1.6 (6)

552.0 ± 28.5 (6)

163.3 ± 13.2 (6)

-17.0 ± 1.2 (7)

5.1 ± 1.2 (5)

106.9 ± 6.3 (7)

56.2 ± 2.4 (6)

17.0 ± 4.6 (6)

10.6 ± 1.8 (6)

6.3 ± 0.6 (6)

7.3 ± 2.6 (6)

 

MRMT-1

-51.2 ± 0.9 (13)

508.1 ± 24.9 (12)

161.7 ± 16.6 (9)

-20.2 ± 1.4 (9)

5.0 ± 0.9 (7)

103.3 ± 4.9 (10)

54.9 ± 2.6 (8)

13.9 ± 1.4 (9)

9.0 ± 1.39 (10)

6.3 ± 0.9 (7)

10.0 ± 4.3 (8)

  1. Values are presented as mean ± S.E.M with the number given in parentheses. *p < 0.05, **p < 0.01,***p < 0.001, as compared with HK groups, two-tailed Student's t-test. RMP: resting membrane potential; Rin: membrane input resistance; CT: the depolarized current threshold for evoking the 1st action potential; TP: threshold potential; AHP: afterhyperpolarization; AHP80% duration: AHP duration at 80% repolarization (AHP80%);
  2. AP: action potential. Note that implantation of MRMT-1 tumor cells into the tibial canal in rats increased the cells excitability in low (CT < 50 pA)-, medium (CT: 50 - 100 pA)-, but not high (CT > 100 pA)-firing threshold DRG neurons as assessed by the intrinsic electrogenic parameters.