Time Course of the Soleus M Response and H Reflex after Lidocaine Tibial Nerve Block in the Rat

Table 1

Mean (±standard deviation) of latencies and amplitudes of M responses and H responses expressed in relation to the maximum M response, measured in prone conscious rats and then rats anaesthetised by intraperitoneal ketamine and placed in the lateral supine position before (pre) and after (post) lidocaine injection during the plateau phase. Finally, the two right-hand columns indicate the values recorded before (pre) and after (post) injection of placebo under the same conditions as those used for lidocaine injection. The post-lidocaine latency of the H reflex corresponds to the mean latency of the H reflexes persisting on several paws after lidocaine injection. The “pre-lidocaine” column shows statistical comparison of the values obtained in “conscious rats” and “pre-lidocaine”, while the “post-lidocaine” column shows statistical comparison of  “pre-lidocaine” and “post-lidocaine” values. No statistically significant difference was observed between “preplacebo” and “postplacebo” values.

	Conscious rats (𝑛=22)	Anaesthetised rats (𝑛=22)
		Lidocaine (𝑛=18)		Placebo (𝑛=4)
		Pre	Post	Pre	Post
Latency (ms)
M response	1.1 ± 0.1	1.7 ± 0.5**	1.7 ± 0.6	1.7 ± 0.3	1.7 ± 0.4
H reflex	5.9 ± 0.4	7.7 ± 1.1**	7.7 ± 1.0	7.7 ± 0.8	7.7 ± 0.9
Amplitude of M response (mV)	39.2 ± 7.5	35.4 ± 6.6	19.1 ± 6.4***	35.3 ± 3.2	35.4 ± 3.9
Hmax/Mmax (%)	47.1 ± 15.1	38.5 ± 10.8***	0.0 ± 0.2***	38.2 ± 4.3	38.1 ± 3.9

**Highly significant difference (𝑡-test; 𝑃<0.01). ***Very highly significant difference (𝑡-test; 𝑃<0.001).