scholarly journals Stretch reflex gain in cat triceps surae muscles with compliant loads

2002 ◽  
Vol 545 (3) ◽  
pp. 1027-1040 ◽  
Author(s):  
Sophie J. De Serres ◽  
David J. Bennett ◽  
Richard B. Stein
Keyword(s):  
Stretch Reflex ◽  
Triceps Surae ◽  
Reflex Gain ◽  
Triceps Surae Muscles

Frequency analysis of stretch reflex and its main subsystems in triceps surae muscles of the cat.

1970 ◽  
Vol 33 (6) ◽  
pp. 713-749 ◽  
Author(s):  
N P Rosenthal ◽  
T A McKean ◽  
W J Roberts ◽  
C A Terzuolo
Keyword(s):  
Frequency Analysis ◽  
Stretch Reflex ◽  
Triceps Surae ◽  
Triceps Surae Muscles

scholarly journals Intrinsic Properties and Reflex Compensation in Reinnervated Triceps Surae Muscles of the Cat: Effect of Activation Level

2003 ◽  
Vol 90 (3) ◽  
pp. 1537-1546 ◽  
Author(s):  
Clotilde M.J.I. Huyghues-Despointes ◽  
Timothy C. Cope ◽  
T. Richard Nichols
Keyword(s):  
Mechanical Properties ◽  
Stretch Reflex ◽  
Full Range ◽  
Motor Units ◽  
Triceps Surae ◽  
Type I ◽  
Initial Stiffness ◽  
Decerebrate Cat ◽  
Reflex Action ◽  
Triceps Surae Muscles

The manner in which activation levels influence intrinsic muscular properties and contributions of the stretch reflex were studied in homogeneous soleus (SOL) and heterogeneous gastrocnemius (G) muscles in the decerebrate cat. Intrinsic mechanical properties were represented by the initial stiffness of the muscle, measured prior to reflex action, and by the tendency of the muscle to yield during stretch in the absence of the stretch reflex. Stiffness regulation by the stretch reflex was evaluated by measuring the extent to which reflex action reduces yielding and the extent to which stiffness depends on background force. Intrinsic mechanical properties were measured in muscles deprived of effective autogenic reflexes using the method of muscular reinnervation. Reinnervated muscles were recruited to force levels comparable to those achieved during natural locomotion. As force declined during crossed-extension reflexes in reinnervated and intact muscles, initial stiffness declined according to similar convex trajectories. The data did not support the hypothesis that, for a given force level, initial stiffness is greatest in populations of predominantly type I motor units. Incremental stiffness (Δ f/Δ l) of both G and SOL increased in the presence of the stretch reflex. Yielding of SOL (ratio of incremental to initial stiffness) substantially decreased in the presence of the stretch reflex over the full range of forces. In reflexive G, yielding significantly decreased for low to intermediate forces, whereas at higher forces, yielding was similar irrespective of the presence or absence of the stretch reflex. The stretch reflex regulates stiffness in both homogeneous and heterogeneous muscles.

scholarly journals Movement Reduces the Dynamic Response of Muscle Spindle Afferents and Motoneuron Synaptic Potentials in Rat

2004 ◽  
Vol 91 (5) ◽  
pp. 2164-2171 ◽  
Author(s):  
Valerie K. Haftel ◽  
Edyta K. Bichler ◽  
T. Richard Nichols ◽  
Martin J. Pinter ◽  
Timothy C. Cope
Keyword(s):  
Dynamic Response ◽  
Stretch Reflex ◽  
Muscle Spindles ◽  
Triceps Surae ◽  
History Dependence ◽  
Muscle Stretch ◽  
Initial Burst ◽  
Synaptic Potentials ◽  
Probable Effect ◽  
Triceps Surae Muscles

Among the mechanisms that may result in modulation of the stretch reflex by the recent history of muscle contraction is the history dependence observed under some conditions in the response properties of muscle spindles. The present study was designed to test one report that in successive trials of muscle stretch-release, spindle afferent firing during stretch, i.e., the dynamic response shows no history dependence beyond the initial burst of firing at stretch onset. Firing responses of spindle afferents were recorded during sets of three consecutive trials of triangular stretch-release applied to triceps surae muscles in barbiturate-anesthetized rats. All 69 spindle afferents fired more action potentials (spikes) during the dynamic response of the first trial, excluding the initial burst, than in the following two trials. The reduced dynamic response (RDR) was nearly complete after trial 1 and amounted to an average of ∼12 fewer spikes (16 pps slower firing rate) in trial 3 than in trial 1. RDR was sensitive to the interval between stretch sets but independent of stretch velocity (4–32 mm/s). RDR was reflected in the synaptic potentials recorded intracellularly from 16 triceps surae α-motoneurons: depolarization during muscle stretch was appreciably reduced after trial 1. These findings demonstrate history dependence of spindle afferent responses that extends throughout the dynamic response in successive muscle stretches and that is synaptically transmitted to motoneurons with the probable effect, unless otherwise compensated, of modulating the stretch reflex.

Dynamic Force Responses in Electrically Stimulated Triceps Surae Muscles: Effects of Fatigue and Temperature

1999 ◽  
Vol 23 (5) ◽  
pp. 436-439 ◽  
Author(s):  
Dietmar Rafolt ◽  
Eugen Gallasch ◽  
Winfried Mayr ◽  
Hermann Lanmuller
Keyword(s):  
Triceps Surae ◽  
Dynamic Force ◽  
Triceps Surae Muscles

Receptor Mechanisms Underlying Heterogenic Reflexes Among the Triceps Surae Muscles of the Cat

1999 ◽  
Vol 81 (2) ◽  
pp. 467-478 ◽  
Author(s):  
T. Richard Nichols
Keyword(s):  
Triceps Surae ◽  
Spinal Reflex ◽  
Medial Gastrocnemius ◽  
Entire Group ◽  
Passive Components ◽  
Mechanical Coupling ◽  
Golgi Tendon Organs ◽  
Reflex Pathways ◽  
Tendon Organs ◽  
Triceps Surae Muscles

Receptor mechanisms underlying heterogenic reflexes among the triceps surae muscles of the cat. The soleus (S), medial gastrocnemius (MG), and lateral gastrocnemius (LG) muscles of the cat are interlinked by rapid spinal reflex pathways. In the decerebrate state, these heterogenic reflexes are either excitatory and length dependent or inhibitory and force dependent. Mechanographic analysis was used to obtain additional evidence that the muscle spindle primary ending and the Golgi tendon organ provide the major contributions to these reflexes, respectively. The tendons of the triceps surae muscles were separated and connected to independent force transducers and servo-controlled torque motors in unanesthetized, decerebrate cats. The muscles were activated as a group using crossed-extension reflexes. Electrical stimulation of the caudal cutaneous sural nerve was used to provide a particularly strong activation of MG and decouple the forces of the triceps surae muscles. During either form of activation, the muscles were stretched either individually or in various combinations to determine the strength and characteristics of autogenic and heterogenic feedback. The corresponding force responses, including both active and passive components, were measured during the changing background tension. During activation of the entire group, the excitatory, heterogenic feedback linking the three muscles was found to be strongest onto LG and weakest onto MG, in agreement with previous results concerning the strengths of heteronymous Ia excitatory postsynaptic potentials among the triceps surae muscles. The inhibition, which is known to affect only the soleus muscle, was dependent on active contractile force and was detected essentially as rapidly as length dependent excitation. The inhibition outlasted the excitation and was blocked by intravenous strychnine. These results indicate that the excitatory and inhibitory effects are dominated by feedback from primary spindle receptors and Golgi tendon organs. The interactions between these two feedback pathways potentially can influence both the mechanical coupling between ankle and knee.

Estrogen attenuates the cardiovascular and ventilatory responses to central command in cats

2002 ◽  
Vol 92 (4) ◽  
pp. 1635-1641 ◽  
Author(s):  
Shawn G. Hayes ◽  
Nicolas B. Moya Del Pino ◽  
Marc P. Kaufman
Keyword(s):  
Triceps Surae ◽  
Central Command ◽  
Neuronal Function ◽  
Ventilatory Responses ◽  
Exercise Pressor Reflex ◽  
Arterial Blood ◽  
Static Contraction ◽  
17Β Estradiol ◽  
Pressor Reflex ◽  
Triceps Surae Muscles

Static exercise is well known to increase heart rate, arterial blood pressure, and ventilation. These increases appear to be less in women than in men, a difference that has been attributed to an effect of estrogen on neuronal function. In decerebrate male cats, we examined the effect of estrogen (17β-estradiol; 0.001, 0.01, 0.1, and 1.0 μg/kg iv) on the cardiovascular and ventilatory responses to central command and the exercise pressor reflex, the two neural mechanisms responsible for evoking the autonomic and ventilatory responses to exercise. We found that 17β-estradiol, in each of the three doses tested, attenuated the pressor, cardioaccelerator, and phrenic nerve responses to electrical stimulation of the mesencephalic locomotor region (i.e., central command). In contrast, none of the doses of 17β-estradiol had any effect on the pressor, cardioaccelerator, and ventilatory responses to static contraction or stretch of the triceps surae muscles. We conclude that, in decerebrate male cats, estrogen injected intravenously attenuates cardiovascular and ventilatory responses to central command but has no effect on responses to the exercise pressor reflex.

Production of hydroxyl radicals in contracting skeletal muscle of cats

1996 ◽  
Vol 81 (3) ◽  
pp. 1197-1206 ◽  
Author(s):  
C. A. O'Neill ◽  
C. L. Stebbins ◽  
S. Bonigut ◽  
B. Halliwell ◽  
J. C. Longhurst
Keyword(s):  
Skeletal Muscle ◽  
Triceps Surae ◽  
Oxygen Species ◽  
Static Contraction ◽  
Maximal Tension ◽  
Cumulative Production ◽  
Triceps Surae Muscles ◽  
Specific Species

Reactive oxygen species increase during exhaustive contraction of skeletal muscle, but characterization of the specific species involved and their rates of production during nonexhaustive muscle contraction have not been investigated. We hypothesized that the production rate of hydroxyl radical (.OH) increases in contracting muscle and that this rate is attenuated by pretreatment with deferoxamine (Def) or dimethylthiourea (DMTU). We measured the rate of production of .OH before, during, and after 5 min of intermittent static contraction of the triceps surae muscles in cats (n = 6) using the formation of p-, m-, and o-tyrosines by hydroxylation of phenylalanine. L-Phenylalanine (30 mg/kg i.v.) was administered to each animal 3 min before contraction. Blood samples were collected from the popliteal vein 1 min before contraction; 1, 3, and 4.5 min during contraction; and 1 min after contraction. During and after contraction, the cumulative production rates of p-, m-, and o-tyrosines were elevated by 42.84 +/- 5.41, 0.25 +/- 0.04, and 0.21 +/- 0.03 nmol.min-1.g-1, respectively, compared with noncontracting triceps surae muscles. Pretreatment with Def (10 mg/kg i.v.; n = 5) or DMTU (10 mg/kg i.v.; n = 4) decreased the cumulative rates of production of p-, m-, and o-tyrosines during and after contraction. Additionally, the rate of tyrosine production increased in proportion to the percentage of maximal tension developed by the triceps surae muscles. These results directly demonstrate that .OH is produced in vivo in the skeletal muscle of cats during intermittent static contraction and that production can occur before the onset of fatigue.

Gadolinium attenuates exercise pressor reflex in cats

2001 ◽  
Vol 280 (5) ◽  
pp. H2153-H2161 ◽  
Author(s):  
Shawn G. Hayes ◽  
Marc P. Kaufman
Keyword(s):  
Pressor Response ◽  
Oxygen Demand ◽  
Muscle Afferents ◽  
Triceps Surae ◽  
Mechanical Stimuli ◽  
Group Iii ◽  
Exercise Pressor Reflex ◽  
Static Contraction ◽  
Pressor Reflex ◽  
Triceps Surae Muscles

The exercise pressor reflex, which arises from the contraction-induced stimulation of group III and IV muscle afferents, is widely believed to be evoked by metabolic stimuli signaling a mismatch between blood/oxygen demand and supply in the working muscles. Nevertheless, mechanical stimuli may also play a role in evoking the exercise pressor reflex. To determine this role, we examined the effect of gadolinium, which blocks mechanosensitive channels, on the exercise pressor reflex in both decerebrate and α-chloralose-anesthetized cats. We found that gadolinium (10 mM; 1 ml) injected into the femoral artery significantly attenuated the reflex pressor responses to static contraction of the triceps surae muscles and to stretch of the calcaneal (Achilles) tendon. In contrast, gadolinium had no effect on the reflex pressor response to femoral arterial injection of capsaicin (5 μg). In addition, gadolinium significantly attenuated the responses of group III muscle afferents, many of which are mechanically sensitive, to both static contraction and to tendon stretch. Gadolinium, however, had no effect on the responses of group IV muscle afferents, many of which are metabolically sensitive, to either static contraction or to capsaicin injection. We conclude that mechanical stimuli arising in contracting skeletal muscles contribute to the elicitation of the exercise pressor reflex.

Response to sudden torques about ankle in man. II. Postmyotatic reactions

1980 ◽  
Vol 43 (1) ◽  
pp. 86-101 ◽  
Author(s):  
G. L. Gottlieb ◽  
G. C. Agarwal
Keyword(s):  
Tibialis Anterior ◽  
Stretch Reflex ◽  
Reaction Times ◽  
Tonic Contraction ◽  
Triceps Surae ◽  
Afferent Pathways ◽  
Triggered Reaction ◽  
Applied Torque ◽  
Significant Difference ◽  
The Subject

1. Torques were applied to dorsiflex or plantarflex the ankle joint of normal human subjects who were instructed to react to them in various ways. Myoelectric and mechanical responses were recorded and analyzed. 2. Myoelectric responses in triceps surae or tibialis anterior with times of onset between 100 and 200 ms are conditional on the instruction to the subject and not the direction of the applied torque. These responses are termed postmyotatic responses. 3. The latency of the postmyotatic response is the same in both triceps surae and tibialis anterior. It is not dependent on the direction of the applied torque and consequently is not a "stretch reflex," but a triggered reaction. 4. When the subject is sitting relaxed and instructed to resist the applied torque, the magnitude of the postmyotatic response is highly and linearly correlated with the rate of ankle rotation produced by the disturbing torque. 5. Tonic contraction of the muscles prior to the onset of a stretching torque has only a slight effect on the magnitude of the postmyotatic response and usually reduces it. Prior tonic contraction of the antagonist also has a modest effect in reducing the response. 6. Instructing the subject to resist a torque as quickly and strongly as possible increases the magnitude of the postmyotatic response but has little effect on its linear functional relationship to the magnitude of the mechanical stimulus. 7. The postmyotatic response, although voluntary and kinesthetically triggered, is not completely equivalent to a visually triggered voluntary reaction because under experimental situations designed to measure simple reaction times and choice reaction times of the postmyotatic response, no significant difference is found between the two conditions. 8. It is suggested that the peripheral afferent pathways of the stretch reflex play a dual role in determining postmyotatic responses. First, they provide to supraspinal centers one early proprioceptive signal about limb perturbation that can trigger a previously selected mode of response. Second, they modulate that response by convergence, at the segmental level, of peripheral afferent signals with the descending command signals.

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