The selective effect of procaine on the stretch reflex and tendon jerk of soleus muscle when applied to its nerve

Abstract

This paper describes a re-investigation into the mechanism of the selective action of local anaesthetics in paralysing muscle reflexes before affecting muscle power when they are injected into a muscle or applied to nerve. The problem has attracted little interest for the last 25 years, though it has important theoretical and practical implications for the understanding of muscle tone and movement.In 1919, Liljestrand & Magnus showed that the injection of 0 5-1 ml. of 1 % procaine into the triceps muscle of a decerebrate cat almost abolished the rigidity of that muscle without altering its response to stimulation of the brachial plexus or removing reflexes produced by turning the animal's head. Larger doses (4-8 ml.) were required to remove the last traces of tone and these also abolished the response to nerve stimulation, but not the response to direct faradic stimulation of the muscle. The experiments were performed as a preliminary to an investigation of the muscular spasm produced by tetanus toxin, and this was similarly abolished by small doses of procaine in the early stages of poisoning at a time when the spasm could still be removed by dorsal root section. They concluded that the action of procaine was to paralyse the muscle proprioceptor fibres before the motor fibres, as they, like Sherrington (1898), had shown that decerebrate rigidity was largely abolished by dorsal root section.Walshe (1924) used this method of intramuscular procaine injection to analyse the rigidity in patients with paralysis agitans. Appropriately graded injections into biceps or triceps muscles abolished the rigidity in these muscles alone, leaving them 'atonic, flabby and offering no resistance to passive stretch' and without a jerk. Meanwhile, the voluntary power of these muscles was unchanged and the freedom of voluntary movement greatly increased, though the tremor persisted. There were signs of slight ataxia and the injected muscles became 'painless [sic] to deep pressure or pinching'. Similar effects were 16-2

The human blink reflex

“…This can be explained only on the basis of differences in the central delay and is further evidence against the first reflex component being a proprioceptive monosynaptic reflex mediated by the fastest conducting afferent fibres. The conduction velocity of the afferent fibres Matthews and Rushworth (1957a, b) (Gassel and Diamontapolous, 1965 It has been reported previously that low frequency repetitive stimulation results in habituation of the second component of the blink reflex whereas the first component shows little or no change (Kugelberg, 1952;Rushworth, 1962;Gandiglio and Fra, 1967). This difference in the pattern of response led previous authors to believe that the first reflex component is a monosynaptic reflex.…”

Neuromuscular interaction in postural tone of the cat's isometric soleus muscle

“…The y excitation, without which there is very little sensitivity to stretch, sets up tension in the spindles and thus, as it were, elevates their frequency/extension curve at the lower end far above that of the denervated spindle (cf. Eldred et al 1953;Matthews & Rushworth, 1957). However, excitation is kept in check by tension-sensitive inhibitory reflexes on the y system, as pointed out above.…”

Proceedings of the Physiological Society

“…University Laboratory of Physiology, Oxford In cats decerebrated by mid-brain section the tonic stretch reflex of the soleus muscle is selectively abolished by applying procaine solution to the nerve to soleus. At the time when the reflex disappears the response of soleus to stimulation of its nerve central to the anaesthetized region is unaltered (Matthews & Rushworth, 1957). This effect was attributed to selective paralysis of the y efferents to the muscle spindles.…”

“…The methods were those used previously (Matthews & Rushworth, 1957), but the cats were 'decerebrated' by tying basilar and carotid arteries (common, external and 'internal'); the forebrain was later removed. The stretch reflex, 28 P SOCIETY, 19-20 JULY 1957 recorded myographically, had a large tonic component, and usually soleus showed 'active' tension at the resting length employed.…”