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Biomedical subjects

W R Ferrell

Publications and source records attributed to W R Ferrell.

At least 91 records · Page 5Linked to original sources
PubMed1986

Extravasation in the knee induced by antidromic stimulation of articular C fibre afferents of the anaesthetized cat.

Electrical stimulation of the cut distal end of the posterior articular nerve (p.a.n.) of the cat knee joint resulted in significant extravasation of plasma proteins and erythrocytes into the synovial cavity of the knee. This effect was mediated by group IV afferents (C fibres) since stimulation of p.a.n. suprathreshold for group II or III afferents but subthreshold for group IV afferents did not produce extravasation. Unmyelinated sympathetic efferent fibres in the joint nerve did not contribute to the extravasation and were responsible for a diminution of this response as shown by the enhanced extravasation occurring after adrenergic blockade. Plasma and erythrocyte extravasation was mediated by afferents containing substance P (SP), as demonstrated by the reversible abolition of extravasation when the substance P antagonist (D-Pro4,D-Trp7,9,10)-SP (4-11) was injected into the synovial cavity. In some animals it was observed that electrical stimulation of the cut distal end of p.a.n. in one limb resulted in extravasation in the contralateral knee joint. It is suggested that articular C fibre afferents could make a significant neurogenic contribution to the initiation or maintenance of inflammatory joint disease.

Anesthesia, General↗
PubMed1985

The influence of joint afferent discharge on locomotion, proprioception and activity in conscious cats.

Injection of local anaesthetic into the knee joint cavity in a series of 14 cats produced obvious abnormalities of posture and gait in half the animals. However, on employing a more sensitive testing procedure, 7 out of 8 animals exhibited reduced proprioceptive acuity after knee joint anaesthesia, and all animals tested showed marked reduction in motor activity after this procedure. Control procedures revealed that these effects were due to the local anaesthetic agent, and that this remained localized to the knee joint and did not diffuse out to block cutaneous and muscle afferents. Thus, joint afferents would appear to play a significant role in the regulation of posture and movement.

Anesthesia, Local↗
PubMed1985

Ascending and descending effects of joint afferent discharge on forelimb and hindlimb flexion reflex excitability in decerebrate cats.

In decerebrate cats with intact innervation of the fore- and hindlimbs, flexion reflexes are most easily elicited in forelimb muscles when the hindlimb is extended, and hindlimb flexion reflexes are most easily elicited when the forelimbs are extended. After intra-articular injection of local anaesthetic, this modulation of reflex excitability is abolished. Thus, in addition to their known segmental effects, joint afferents also exert significant ascending and descending effects on motoneurone excitability.

Animals↗
PubMed1985

Plasma extravasation in the cat knee-joint induced by antidromic articular nerve stimulation.

Antidromic electrical stimulation of C fibres in the cat knee-joint resulted in significant plasma extravasation into the synovial cavity in six out of seven cats. Preliminary findings suggest that this effect is mediated by Substance P. It is concluded that joint C fibre afferents could provide a neurogenic mechanism contributing towards the initiation or maintenance of inflammatory joint disease.

Animals↗
PubMed1985

Fluid compartmentation and articular mechanoreceptor discharge in the cat knee joint.

Experiments were performed to determine the effect of alteration of intra-articular pressure in different areas of the cat knee joint on the discharge of slowly adapting mechanoreceptors in the posterior region of the joint. At physiological (subatmospheric) pressures the anterior and posterior regions of the knee joint are not hydraulically continuous. However, at supra-atmospheric pressures between 2.5 and 9 cmH2O there is free communication between these areas. The discharge of receptors in the posterior region of the joint is influenced by intra-articular pressure changes in the posterior region when these are supra-atmospheric. However, pressure changes in the anterior region of the joint have little effect on the discharge of these receptors until free communication occurs between anterior and posterior regions. It is suggested that articular mechanoreceptors detect tension changes in collagen fibrils rather than volume changes of the joint capsule.

Action Potentials↗
PubMed1985

The response of slowly adapting mechanoreceptors in the cat knee joint to tetanic contraction of hind limb muscles.

The effect of tetanic contraction of muscles acting at the cat knee joint on the discharge of various types of slowly adapting knee joint receptors was investigated. Contraction of a particular muscle could either increase, decrease or produce no alteration in the discharge of a given receptor. Whatever effects were produced by muscle contraction, these effects were always maximal at extremes of the flexion/extension range, and enhanced by limb movement. However, these receptors could not be induced to discharge at intermediate positions either by the passive tension or active contraction of muscles around the knee joint. It is concluded that muscle contraction does not increase the proportion of joint receptors (approximately 18%) which are known to spontaneously discharge at intermediate positions in the absence of significant muscle tone (Ferrell, 1980).

Action Potentials↗
PubMed1984

Response of slowly adapting articular mechanoreceptors in the cat knee joint to alterations in intra-articular volume.

Recordings were obtained from slowly adapting mechanoreceptors innervating the posterior aspect of the cat knee joint capsule. It was observed that, with rising intra-articular volume, initially both intra-articular pressure and the neural discharge increased. This increase was dependent on the rate of fluid accumulation within the joint. However, the joint nerve discharge invariably levelled out despite increasing intra-articular volume and pressure. This suggests that there exists some limit to capsular distension in the posterior joint region beyond which fluid is diverted to other areas of the knee joint.

Action Potentials↗
PubMed1983

Discharge characteristics of the elbow joint nerve of the cat.

Direct recordings were made from intact elbow joint nerves (EJN) in decerebrate cats. These multiunit recordings indicate that the EJN is a relatively pure articular nerve and does not contain significant numbers of muscle afferent fibres. In every cat the EJN exhibited a tonic discharge throughout a full range of elbow joint positions. The discharge was most intense when the elbow was extended to 165 degrees and least intense when the joint was held in midrange positions between 90 degrees and 120 degrees. There was a modest increase in discharge as the elbow was held in more flexed positions and activity at 30 degrees was about half of that at 165 degrees. Alterations in the tone of muscles around the joint did not affect the adapted EJN discharge at any angle.

Action Potentials↗
PubMed1982

The effect of elbow joint afferent discharge on transmission in forelimb flexion reflex pathways to biceps and triceps brachii in decerebrate cats.

The present experiments were performed to investigate the influence of elbow joint afferent discharge on the excitability of reflex arcs mediating flexion withdrawal and crossed extensor reflexes in the forelimb muscles of decerebrate cats. The excitability of flexion withdrawal and crossed extensor reflexes in forelimb muscles was shown to be modulated by elbow joint position. Flexion withdrawal reflexes were most easily elicited when the elbow was extended and crossed extensor reflexes were most easily elicited when the elbow was flexed. This modulation of transmission was not confined to reflex pathways projecting to muscles acting at the elbow but also included pathways to muscles acting at the wrist and shoulder in addition to muscles in the contralateral forelimb. The changing excitability of reflex pathways caused by elbow movement was unaltered by degloving the skin covering the joint and tenotomy of the medial head of triceps and the long head of biceps. However, modulation of reflex excitability by joint movement was totally abolished by local anaesthesia of the joint in an otherwise intact limb. Thus, the present experiments indicate that transmission in forelimb flexion reflex pathways can be powerfully influenced by elbow joint afferent discharge.

Animals↗
PubMed1981

Modulation of transmission in forelimb flexion reflex pathways by elbow joint afferent discharge in decerebrate cats.

In intact forelimbs in decerebrate cats, flexion reflexes are most easily elicited when the elbow joint is extended and extension reflexes are most easily elicited when the elbow joint is flexed. Abolition of sensory discharge arising from the elbow joint by intra-articular injection of local anaesthetic eliminates this modulation of reflex excitability. We conclude that elbow joint afferent discharge modulates the transmission in flexion reflex pathways to forelimb motoneurones.

Afferent Pathways↗
PubMed1981

The effect of knee joint afferent discharge on transmission in flexion reflex pathways in decerebrate cats.

1. Changes in excitability of reflex arcs mediating flexion withdrawal ad crossed extensor reflexes have been examined in decerebrate cats. 2. The excitability of flexion withdrawal and crossed extensor reflexes was shown to be modulated by knee joint position. Flexion withdrawal reflexes were most easily elicited when the knee was extended and crossed extensor reflexes were most easily elicited when the knee was flexed. 3. The modulation of transmission was not confined to reflex pathways to muscles acting at the knee but also included pathways to muscles acting at the hip and ankle, as well as pathways to muscles in the contralateral limb. 4. The changing excitability of reflex pathways caused by movement of the knee joint was unrelated to the stretch applied to muscles acting at the knee and to cutaneous afferent discharge. Modulation of reflex excitability by joint movement was totally abolished by local anaesthesia of the knee joint in an otherwise intact limb. 5. The results of the present experiments indicate that transmission in flexion reflex pathways can be inhibited by knee joint afferent discharge.

Animals↗
PubMed1980

The effect of acute abolition of knee joint afferent discharge on postural reflexes in the conscious cat.

Injection of local anaesthetic into the knee joint space in a series of 5 cats produced obvious postural abnormalities in 3 animals. However, on employing a more sensitive test, all animals exhibited abnormalities of postural reflexes on abolishing knee joint afferent discharge. Control experiments indicated that this could not be attributed to the local anaesthetic diffusing locally out of the joint capsule and affecting muscle and cutaneous afferents around the knee joint.

Afferent Pathways↗
PubMed1980

The adequacy of stretch receptors in the cat knee joint for signalling joint angle throughout a full range of movement.

1. The present experiments were performed to resolve the discrepancy between the experiments of Boyd & Roberts (1953) in which receptors active at intermediate angles (mid range units) were frequently encountered, and the experiments of Burgess & Clark (1969) where mid range units were rarely encountered. 2. The discharge of knee joint afferents in the cat posterior articular nerve was recorded from both the dorsal roots and from the intact joint nerve. 3. No receptors were isolated which exhibited intermediate adaptation rates (similar to the "phasic" receptors described by Burgess & Clark, 1969). 4. The proportion of mid range units isolated in the present experiments (17.8%) was substantially larger than in the experiments of Burgess & Clark (4.8%). 5. Direct recordings from the posterior articular nerves of a series of cats revealed that there were always receptors tonically active at all intermediate positions. 6. Afferents from the popliteus muscle did not make a major contribution to the population of mid range units in the posterior articular nerve as removal of the popliteus muscle did not significantly alter the mean number of mid range units in the joint nerves of a series of nine cats. 7. Succinylcholine (SCh) in low doses (0.05-0.1 mg/kg) was found not to be specific for spindle afferents as these doses of SCh could elevate the resting discharge of mid range units of true articular origin. 8. It is concluded that slowly adapting joint receptors can adequately signal joint angle throughout the full normal range of movement and hence could make an important contribution to position sense.

Adaptation, Physiological↗
PubMed1980

The effect of suxamethonium on the response to stretch of Golgi tendon organs in the cat.

1. The effects of intra-arterial infusion of suxamethonium (succinylcholine, SCh) on the response to stretch of Golgi tendon organs in the soleus muscle of the cat have been studied. 2. SCh infusion produced a gradual facilitation of the discharge of tendon organs with low thresholds to passive muscle stretch, but had no detectable effect on tendon organs with high thresholds to stretch. 3. The time course of excitation and recovery of low-threshold tendon organs after SCh infusion was much longer than that of muscle spindle primary and secondary sensory endings. 4. Control experiments showed that there was no change in the passive tension of the soleus muscle during SCh infusion, thus excluding the possibility that the excitation of the low-threshold tendon organs is caused by an increase in passive muscle tension. 5. These findings complement recent observations that SCh can excite receptors other than those in muscle spindles, and indicate that SCh activation on its own may not be a sufficient criterion on the basis of which to identify muscle spindle afferent axons.

Action Potentials↗