Effect of Vitamin B complex on discharge of the afferent nerve of cat soleus muscle under ischemic conditions

Abstract

The discharge in afferent nerves of cat soleus muscle was recorded in Nembutal anesthetized animals. The frequency of discharges in the soleus muscle nerve was found to increase after tetanic contraction of the muscle either under ischemic or non-ischemic conditions. Two cases which had been associated with the augmentation of the discharge followed by tetanic contractions of soleus muscle exhibited excitation, i. e., increase in discharge frequency, due to an intraarterial injection of 10% NaCl solution, whereas no such excitation with the injection of 10% NaCl, was observed in two other cases which showed no post-tetanic potentiation. Increase in discharge frequency recorded from single nerve fibres, after tetanic contractions of soleus muscle under an ischemic condition, was demonstrated in one out of 11 fibres of group I, 2 fibres out of 20 in group II and one fibre out of 11 in group III. The increase seen in groups I and II were of a transient type, and that in group III was a lasting type which continued for more than 8 min. Although a vitamin B complex (the combination of thiamine monophosphate disulfide 107.3 mg, pyridoxine hydrochloride 100 mg and cyano-cobalamine 1 mg), dissolved in 20% glucose solution, tended to enhance spontaneous discharge in the soleus muscle nerve, the post-tetanic potentiation of the discharge was significantly suppressed by this combined administration. The vitamin B complex dissolved in Ringer's solution also showed actions similar to, but weaker than, those of the complex dissolved in the glucose solution. These results suggest that vitamin B complex may effectively be used for the relief of muscular pain under ischemic conditions.