Electromyographic responses elicited by cutaneous and mixed nerve stimulation in human tibialis anterior muscle

Summary The rectified and averaged myoelectrical responses of the anterior tibial muscle to stimulation of the posterior tibial, peroneal and sural nerves at the ankle were recorded during a weak isometric contraction in man. The stimulation of the posterior tibial nerve elicited two excitatory phases (short and long latency excitations) at 40 ms and 78 ms latencies, respectively, separated by a phase of reduced activity. With peroneal and sural nerve stimulation such triphasic responses were less consistent; only a monophasic inhibitory response occurred in some recordings. These results indicate that well-identifiable responses with distinct latencies can be obtained in human leg muscle with cutaneous and mixed nerve stimulation distal to the muscle.This work was supported by the Council of Physical Education and Sport (Ministry of Education), Finland.     

Effect of nerve stimulation on rat skeletal muscle. A study of plasma membrane

Summary The gastrocnemius muscle of the rat showed no morphological, histometric or plasma membrane changes, after sciatic nerve stimulation with a 5 mA current for 30 to 60 min, 10 mA for 30 min and 15 mA for 5 min. However, 10 mA for 60 and 200 min gave rise to mitochondrial and plasma membrane abnormalities. These changes were absent after a rest period. The results indicated the sciatic nerve stimulation at 10 mA for 60 and 200 min caused reversible changes in the rat skeletal muscle mitochondria and plasma membrane.     

Effect of nerve stimulation on rat skeletal muscle. A study of plasma membrane

The gastrocnemius muscle of the rat showed no morphological, histometric or plasma membrane changes, after sciatic nerve stimulation with a 5mA current for 30 to 60 min, 10 mA for 30 min and 15 mA for 5 min. However, 10 mA for 60 and 200 min gave rise to mitochondrial and plasma membrane abnormalities. These changes were absent after a rest period. The results indicated that the sciatic nerve stimulation at 10 mA for 60 and 200 min caused reversible changes in the rat skeletal muscle mitochondria and plasma membrane.     

Synkinesis in hemifacial spasm: results of recording intracranially from the facial nerve

We show evidence that the motonucleus of the facial nerve is involved in producing the synkinesis in patients with hemifacial spasm. These results were obtained by recording from the intracranial portion of the facial nerve and from the orbicularis oculi muscle in patients operated upon for hemifacial spasm during electrical stimulation of the mandibular branch of the facial nerve. Also, the electromyographic response from the same muscle was recorded when the facial nerve was electrically stimulated at a location near the brainstem. The results show that it is unlikely that the symptoms of patients with hemifacial spasm can be explained on the basis of ephaptic transmission at the site of lesion of the facial nerve.     

Synkinesis in hemifacial spasm: results of recording intracranially from the facial nerve

Summary We show evidence that the motonucleus of the facial nerve is involved in producing the synkinesis in patients with hemifacial spasm. These results were obtained by recording from the intracranial portion of the facial nerve and from the orbicularis oculi muscle in patients operated upon for hemifacial spasm during electrical stimulation of the mandibular branch of the facial nerve. Also, the electromyographic response from the same muscle was recorded when the facial nerve was electrically stimulated at a location near the brainstem. The results show that it is unlikely that the symptoms of patients with hemifacial spasm can be explained on the basis of ephaptic transmission at the site of lesion of the facial nerve.     

Evidence to support the hypothesis that ATP is a co-transmitter in rat vas deferens

Application of exogenous ATP or of noradrenaline (NA) produced responses in bisected rat vas deferens which mimicked the biphasic responses to nerve stimulation, and these actions were modified by nifedipine and verapamil in a manner similar to the modification of the 2 phases of the responses of the vas to nerve stimulation. It is proposed that sufficient evidence now exists to support the hypothesis that in this tissue, ATP is released along with NA from the motor nerves and that ATP may indeed be a co-transmitter.     

Reticular potentials evoked by electrical stimulation of individual semicircular canals.

Responses of pontine reticular formation neurons following single shock electrical stimulation of single semicircular canals were recorded with tungsten microelectrodes in 40 curarized guinea-pigs. The field and unitary potentials obtained from 62 reticular sites, exhibited latency values ranging from 0.3 to 2.5 msec. The early latencies (0.3-0.5 msec) have been interpreted as responses mediated by primary vestibular fibres projecting directly to the reticular substance.     

Reticular potentials evoked by electrical stimulation of individual semicircular canals

Summary Responses of pontine reticular formation neurons following single shock electrical stimulation of single semicircular canals were recorded with tungsten microelectrodes in 40 curarized guinea-pigs. The field and unitary potentials obtained from 62 reticular sites, exhibited latency values ranging from 0.3 to 2.5 msec. The early latencies (0.3–0.5 msec) have been interpreted as responses mediated by primary vestibular fibres projecting directly to the reticular substance.This work was supported by a grant of CNR.     

Supernormal responses to premature stimulation in Ca-dependent action potentials.

The responses of Ca-dependent action potentials to premature stimulation were studied in the isolated canine ventricular muscle. When very premature stimuli were applied, supernormally augmented responses with propagation occurred, while responses with long preceding intervals were small and not conducted.     

Role played in man by myelinated fibers of different diameters for the evocation of a nociceptive flex reflex and the accompanying pain sensation]

Using simultaneous recordings we have made in Man a comparative study of: the sural nerve afferent volley, the nociceptive flexor reflex of a muscle of the lower limb and the associated painful sensation. Two types of stimulations were used, a single short duration electric stimulus, and a train of electric shocks (100/sec). With a single stimulus, the nociceptive flexor reflex and the painful sensation develop only when A delta fibers are recruited. On the other hand, when the stimulations are given by trains the nociceptive flexor reflex and the painful sensation can develop with a stimulus sub-liminar to the threshold of A delta fibers, when A alpha fibers are recruited. When the stimulus activate both A alpha and A delta fibers, the flexion reflex and the pain disappear when a selective blockade of the A delta group is exerted by means of Lidocain.     

Existence of a non-retinotopic contralateral retino-tectal visual projection in the normal frog Rana esculenta L]

In the Frog, after unilateral optic nerve and tract section, contralateral visual responses were recorded in the tectum ipsilateral to the section. These responses were elicited by stimulation of a unique spatial region located near the projection of the contralateral eye optic axis and could be randomly recorded on the tectal surface. The possible pathways and the role of such retino-tectal afferences are discussed.     

Mediation by nitric oxide of neurally-induced human cerebral artery relaxation

Human cerebral artery strips relaxed in response to non-adrenergic, non-cholinergic vasodilator nerve stimulation by electrical pulses or nicotine. The relaxation response was abolished by treatment with N^G-nitro-L-arginine, a nitric oxide synthase inhibitor; the inhibitory effect was reversed by L-, but not D-, arginine. Nitric oxide-induced relaxation was unaffected. These findings support the hypothesis that nitric oxide plays a crucial role, possibly as neurotransmitter, in transmitting information from vasodilator nerve to smooth muscle in human cerebral arteries.     

Latency of taste nerve signals in frog (Rana catesbeiana).

The latency of frog gustatory neural impulses to 1.0 M NaCl was a mean of 86 msec. Electrical stimulation of taste cell membranes produced gustatory neural impulses with the mean 5 msec latency. It is concluded that most of the 86 msec latency of taste nerve responses to 1.0 N NaCl is due to the latency of taste receptor potential following the onset of gustatory stimulation.     

The effect of halothane on the action of alcuronium in the dog.

The effect of halothane on the action of alcuronium on neuromuscular transmission was studied in the intact dog. Electrical and mechanical evoked responses from stimulation of the ulnar nerve were recorded. The administration of 0.5% halothane prolonged the duration of action of alcuronium by about 50%.     

Hyperventilation and inhibitory synapses.

Injection of a subconvulsive dose of strychnine (which blocked the inhibitory synapses) increases respiratory muscle activity evoked by stimulation of a sciatic nerve as well as by inhalation of hypercapnic gas mixture. Thus the inhibitory synapses prevent an excessive hyperventilation.     

Bestimmung der optimalen Reizparameter bei Reizung des aszendierenden retikulären Systems

Summary For the initiation of an arousal reaction, the stimulation of the reticular activating system by square waves of frequencies varying from 50 to 400 c/s was studied. To evaluate the stimulation efficiency, the initial frequency of the rhinencephalic arousal reaction was used. The optimal stimulus frequency depends on the duration of the pulses. The optimal frequency was found to be 200 c/s at a pulse duration of 0.5 ms and 100 c/s at a pulse duration of 1.5 ms.     

Hyperventilation and inhibitory synapses

Summary Injection of a subconvulsive dose of strychnine (which blocked the inhibitory synapses) increases respiratory muscle activity evoked by stimulation of the sciatic nerve as well as by inhalation of hypercapnic gas mixture. Thus the inhibitory synapses prevent an excessive hyperventilation.     

The effect of halothane on the action of alcuronium in the dog

Summary The effect of halothane on the action of alcuronium on neuromuscular transmission was studied in the intact dog. Electrical and mechanical evoked responses from stimulation of the ulnar nerve were recorded. The administration of 0.5% halothane prolonged the duration of action of alcuronium by about 50%.We are indebted to Professor A. Mueller for facilities, help and encouragement. R.S. Jones was the holder of a Royal Society European Exchange Fellowship.     

Role of metallothioneins in peripheral nerve function and regeneration

The physiological role of the metallothionein (MT) family of proteins during peripheral nerve injury and regeneration was examined in Mt1+ 2 and Mt3 knockout (KO) mice. To this end, the right sciatic nerve was crushed, and the regeneration distance was evaluated by the pinch test 2-7 days postlesion (dpl) and electrophysiologically at 14 dpl. The quality of the regeneration was assessed by light microscopy and immunohistochemical methods. The results show that the regeneration distance was greater in the Mt3 KO than in the Mt1+ 2 KO mice, whereas control mice showed intermediate values. Moreover, the number of regenerating axons in the distal tibial nerve was significantly higher in Mt3KO mice than in the other two strains at 14 dpl. Immunoreactive profiles to protein gene product 9.5 were present in the epidermis and the sweat glands of the plantar skin of the hindpaw of the Mt3 KO group. The improved regeneration observed with the Mt3 KO mice was confirmed by compound nerve action potentials that were recorded from digital nerves at 14 dpl only in this group. We conclude that Mt3 normally inhibits peripheral nerve regeneration.     

Comparison of the responsiveness of isolated arteries and veins taken from the same dogs 17 days apart

Summary The present experiments demonstrate that isolated arteries and veins taken from the same dogs before and after an interval of 17 days show comparable responses to adrenergic nerve stimulation, exogenous norepinephrine and depolarizing solution. They provide an acceptable model for the in vitro study of chronic influences on canine vascular responsiveness.