Prolonged time course for vibratory suppression of stretch reflex in the decerebrate cat

1981 ◽  
Vol 44 (1) ◽  
Author(s):  
W.Z. Rymer ◽  
Z. Hasan
Keyword(s):  
Stretch Reflex ◽  
Time Course ◽  
Decerebrate Cat ◽  
Prolonged Time

Nonlinear properties of stretch reflex studied in the decerebrate cat

1982 ◽  
Vol 47 (2) ◽  
pp. 179-192 ◽  
Author(s):  
J. W. Aldridge ◽  
R. B. Stein
Keyword(s):  
Electrical Stimulation ◽  
Neural Activity ◽  
Stretch Reflex ◽  
Time Course ◽  
Nonlinear Interactions ◽  
Motor Axons ◽  
Plantaris Muscle ◽  
Decerebrate Cat ◽  
Reflex Responses ◽  
Stimulation Of

1. Pairs of brief stretches or a series of stretches at random intervals (Poisson process) were applied to a slow (soleus) and a fast (plantaris) muscle in decerebrate cats to analyze the nonlinear effects of one stretch on the reflex responses to subsequent stretches. Neural activity, electromyogram (EMG), and force were recorded. The reflex responses due to stretch were compared with reflexes as a result of electrical stimulation of nerves. Nonlinearities of muscle were also examined in the absence of reflexes. Short-latency neural activity produced by the stimuli at all intervals studied was quite constant, so changes in sensory activity cannot account for the nonlinearities. Three phases of nonlinear interactions were observed, and mechanisms for these nonlinearities are suggested. 2. For short intervals (less than 100 ms) following a stretch the force and EMG produced by a second stretch is depressed. This early depression could be due to the after hyperpolarization of the motoneuron cel body or to synaptic mechanisms, since the depression of EMG is seen with electrical stimulation of Ia sensory, but not alpha-motor axons. In addition, a second stretch can disrupt the reflex contraction produced by the first stretch if it occurs at a time when new actomyosin bonds are not readily formed. Because of this force suppression, the total reflex force produced in response to two stretches may be less than the response to a single stretch. 3. For intervals between 100 and 300 ms the force and EMG produced by a second stretch is enhanced. This potentiation is also seen with electrical stimulation of large sensory but not motor axons and could result from a synchronization of motoneuronal excitability cycles. It is more prominent in the homogeneous (soleus) muscle than the mixed (plantaris) muscle, probably because the motoneuron cell bodies will reach a period of high excitability at more nearly the same time in the homogeneous muscle. 4. For longer intervals the force produced by a second stretch is reduced even when the EMG is close to control values. This late depression is also observed with electrical stimulation of cut motor axons and therefore arises from the contractile properties of muscles. 5. With a random series of stretches, the same time course of nonlinear interactions is observed. However, as the mean rate of the random stretches is increased, the average response of the reflex decreases. Thus, the stretch reflex will be most effective in correcting for occasional perturbations to a movement, rather than for continuously varying disturbances.

Pattern differences in experimental fevers induced by endotoxin, endogenous pyrogen, and prostaglandins

1988 ◽  
Vol 254 (4) ◽  
pp. R633-R640 ◽  
Author(s):  
A. Morimoto ◽  
T. Nakamori ◽  
T. Watanabe ◽  
T. Ono ◽  
N. Murakami
Keyword(s):  
Time Course ◽  
Interleukin 1 ◽  
Bacterial Endotoxin ◽  
Endogenous Pyrogen ◽  
Prolonged Time ◽  
Fever Onset ◽  
Long Latency ◽  
Low Concentrations ◽  
High Concentrations ◽  
Experimentally Induced

To distinguish pattern differences in experimentally induced fevers, we investigated febrile responses induced by intravenous (IV), intracerebroventricular (ICV), and intra-preoptic/anterior hypothalamic (POA) administration of bacterial endotoxin (lipopolysaccharide, LPS), endogenous pyrogen (EP), human recombinant interleukin-1 alpha (IL-1), and prostaglandins E2 and F2 alpha (PGE2 and PGF2 alpha). Intravenous LPS, EP, or IL-1 in high concentrations caused biphasic fever. In low concentrations, they induced only the first phase of fever. Latency to onset and time to first peak of fever induced by IV injection of LPS or EP were almost the same as those after ICV or POA injection of PGE2. Fever induced by ICV or POA administration of LPS, EP, IL-1, or PGF2 alpha had a long latency to onset and a prolonged time course. There were significant differences among the latencies to fever onset exhibited by groups that received ICV or POA injections of LPS, EP, or PGF2 alpha and by groups given IV injections of LPS or EP and ICV or POA injections of PGE2. Present observations indicate different patterns of fever produced by several kinds of pyrogens when given by various routes. These results permit us to consider the possibility that there are several mediators or multiprocesses underlying the pathogenesis of fever.

scholarly journals Stretch Reflex Latencies in Spastic Hemiparetic Subjects are Prolonged After Transcutaneous Electrical Nerve Stimulation

1993 ◽  
Vol 20 (2) ◽  
pp. 97-106 ◽  
Author(s):  
Christina W.Y. Hui-Chan ◽  
Mindy F. Levin
Keyword(s):  
Nerve Stimulation ◽  
Transcutaneous Electrical Nerve Stimulation ◽  
Stretch Reflex ◽  
Time Course ◽  
Dorsal Column ◽  
Electrical Nerve Stimulation ◽  
Reflex Excitability ◽  
Reflex Threshold ◽  
Repetitive Electrical Stimulation

ABSTRACT:Low-intensity repetitive electrical stimulation such as dorsal column and transcutaneous electrical nerve stimulation (TENS) reportedly decreases spasticity and improves voluntary motor control. However, the mechanisms mediating these effects are unclear. Recent findings suggest that spasticity may be characterized more appropriately by a decrease in the stretch reflex threshold than by an increase in gain. Our objectives were: (1) to examine possible changes in stretch reflex excitability following 45 min of TENS, (2) to map out the time course of possible post-stimulation effects via both latency and magnitude (amplitude or area) measurements, and (3) to determine the role of segmental versus non-segmental mechanisms involved in mediating these changes. The effects of 45 min of segmentally and heterosegmentally applied TENS on lower limb reflexes in ten spastic hemiparetic subjects were contrasted with those resulting from placebo stimulation. We found that both segmentally and heterosegmentally applied TENS caused an immediate increase in soleus H reflex latencies that was evident for up to 60 minutes post-stimulation in over 75% of the subjects. Similar increases for up to 60 and 40 minutes post-stimulation was noted for the stretch reflex latencies in 50% and 67% of the subjects respectively for segmental and heterosegmental stimulation. These results suggested that manipulation of segmental and heterosegmental afférents for 45 min may lead to a decrease of the otherwise augmented stretch reflex excitability accompanying hemiparetic spasticity.

Mechanical analysis of heterogenic inhibition between soleus muscle and the pretibial flexors in the cat

1991 ◽  
Vol 66 (4) ◽  
pp. 1139-1155 ◽  
Author(s):  
T. R. Nichols ◽  
D. Koffler-Smulevitz
Keyword(s):  
Stretch Reflex ◽  
Metatarsophalangeal Joint ◽  
Reciprocal Inhibition ◽  
Mechanical Analysis ◽  
Initial State ◽  
Stretch Reflexes ◽  
Decerebrate Cat ◽  
Intravenous Injections ◽  
Activation Level ◽  
Length Changes

1. The role of proprioceptive pathways linking the direct antagonists soleus (S) and tibialis anterior (TA) muscles in governing the mechanical properties of the ankle joint were studied in the decerebrate cat. Actions of these heterogenic pathways were compared with those between S and extensor digitorum longus (EDL), a muscle that also acts at the metatarsophalangeal joint. These neurally mediated interactions between S and either TA or EDL were studied by applying controlled length changes to the isolated tendons of pairs of these muscles and recording the resulting changes in force. The muscles were activated with the use of electrically evoked crossed-extension reflexes, flexion reflexes, and brain stem stimulation. 2. Heterogenic inhibition from TA or EDL onto S was well developed whether S was initially quiescent or activated by a crossed-extension reflex. The inhibition persisted for the duration of the stretch of TA or EDL. During a crossed-extension reflex, TA did not generate background force, but brief stretch reflexes could be obtained. During flexion reflexes, stretch reflexes in S were usually abolished, and heterogenic inhibition from S to TA was weak or absent. 3. The strength of the heterogenic inhibition onto S was dependent on the initial length and activation level of TA and EDL. Changes in flexor length or activation level per se did not alter the background force or strength of the stretch reflex in S. Even taking into account the variation of strength of inhibition with the initial state of the muscle of origin, the strength of the inhibition was stronger from TA to S than the other way around. 4. The contributions of heterogenic inhibition from TA and EDL to S were independent in the sense that these components summed linearly with each other and with the autogenic reflex in S. In addition, the magnitude of the inhibition from TA to S was proportional to the amplitude of stretch for low to intermediate levels of initial force in S. The inhibition appeared to affect the mechanical responses of S essentially as rapidly as the stretch reflex in this muscle. 5. The heterogenic inhibition from TA to S was reduced or abolished by intravenous injections of strychnine but unaffected by injections of picrotoxin or bicuculline. These results, together with the observation that the inhibition sums linearly with the stretch reflex, suggest that the mechanism of this heterogenic inhibition is glycinergic and postsynaptic and, therefore, may include Ia-disynaptic reciprocal inhibition.(ABSTRACT TRUNCATED AT 400 WORDS)

Interaction of Vestibular and Proprioceptive Reflexes in the Decerebrate Cat

1956 ◽  
Vol 185 (3) ◽  
pp. 607-613 ◽  
Author(s):  
Werner P. Koella ◽  
Hiroyuki Nakao ◽  
Robert L. Evans ◽  
Jun Wada
Keyword(s):  
Stretch Reflex ◽  
Muscle Spindles ◽  
Longitudinal Axis ◽  
Strain Gauges ◽  
Vestibular Apparatus ◽  
Triceps Brachii ◽  
Decerebrate Cat ◽  
Proprioceptive Reflexes ◽  
The Difference ◽  
Decerebrate Cats

The quantitative interrelation between stretch, tension and position in space was studied in decerebrate cats. The tension produced by the isolated M. triceps brachii was recorded by means of strain gauges. It was found that the tension increment, produced by a particular stretch, increases as the preparation is turned from the prone to the supine position around its longitudinal axis. The proportion between the tensions produced by a series of two or more different stretches, however, stays constant under these conditions. It was shown, furthermore, that the effect of a change in position upon the degree of rigidity—i.e., the difference between the tensions in the prone and in the supine positions—is the greater the greater the initial stretch. A quantitative analysis of the results disclosed that the vestibular factor and the proprioceptive factor are related in a multiplicative manner. These experiments show that the vestibular apparatus and the muscle spindles exert their influence not in an isolated and independent, but a quantitatively interdependent manner. The results of the present work together with the findings of other authors (Granit) give strength to the argument that the vestibular apparatus controls the stretch reflex activity in an indirect manner, i.e., over the ‘by-pass’ of the gamma-efferents.

Effect of anesthetic on sympathetic responses evoked from cerebellar uvula in decerebrate cats

1992 ◽  
Vol 263 (4) ◽  
pp. H1285-H1291 ◽  
Author(s):  
J. F. Paton ◽  
M. P. Gilbey
Keyword(s):  
Time Course ◽  
Pressor Response ◽  
Conditioning Stimulus ◽  
Sympathetic Nerves ◽  
Decerebrate Cat ◽  
Test Response ◽  
Recovery From Anesthesia ◽  
Decerebrate Cats ◽  
Train Stimulation ◽  
Stimulation Of

The sympathetic mechanisms involved in the conversion of the tachycardia-pressor response evoked by electrical stimulation of the uvula (lobule IX of the posterior cerebellar cortex) in the unanesthetized decerebrate cat to a bradycardia-depressor response in the same, but anesthetized preparation, were investigated. Sympathoexcitation was produced in the inferior cardiac and renal sympathetic nerves in response to short train stimulation (2-5 pulses, 100-500 Hz) of the uvula in the unanesthetized decerebrate cat, and when paired stimuli (conditioning and test) were applied, the test-evoked potential in both nerves was similar to the response elicited by the conditioning stimulus. Anesthetic administered to these same animals caused the test response in both sympathetic nerves to be greatly decreased, yet the conditioning response was unchanged. The attenuation of the test response by the conditioning stimulus diminished during recovery from anesthesia. The recovery of the test response paralleled the time course of the return of the tachycardia-pressor effect evoked by long train stimulation of the uvula. It appears that anesthesia does not block the sympathoexcitatory response but acts to augment sympathoinhibitory processes associated with uvula stimulation; some possible mechanisms are discussed.

Onset of relaxation in cardiac muscle segments

1983 ◽  
Vol 245 (4) ◽  
pp. H610-H615
Author(s):  
J. F. Rondinone ◽  
D. A. Martyn ◽  
L. L. Huntsman
Keyword(s):  
Feedback Control ◽  
Cardiac Muscle ◽  
Time Course ◽  
Segment Length ◽  
Isometric Contractions ◽  
Papillary Muscles ◽  
Initial Length ◽  
Short Segment ◽  
Prolonged Time ◽  
Active Segment

The onset of relaxation has been studied in undamaged central segments of isolated ferret papillary muscles at 27 degrees C, 12 beats/min. A technique that provides a signal proportional to the length of a chosen segment was used to assess segment velocity and length. Feedback control was employed to obtain segment isometric contractions. At a variety of times during segment isometric twitches, rapid load clamps were imposed using a range of loads from resting force to greater than half peak developed force. For the purposes of this study, the onset of relaxation was defined as occurring when active segment shortening ceased and elongation began (i.e., Vseg = 0). Early load clamps to low loads resulted in V = 0 at comparatively short segment lengths and early times. Later load clamps caused zero velocity to occur at longer segment lengths and later times. The V = 0 points in fact formed a line in the segment length-time plane. Contractions clamped to higher loads exhibited reduced shortening and a prolonged time course so that the V = 0 points showed the same dependence on length and time. Remarkably, all the variations of load-clamp load, time, and initial length yielded V = 0 points that were intermixed along a single line. Increasing or decreasing extracellular Ca2+ caused the V equal to O points to shift to later times and shorter segment lengths or earlier times and longer segment lengths, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of cold-induced muscle spindle secondary activity on monosynaptic and stretch reflexes in the decerebrate cat

1979 ◽  
Vol 57 (6) ◽  
pp. 606-614 ◽  
Author(s):  
C. E. Chapman ◽  
W. J. Michalski ◽  
J. J. Séguin
Keyword(s):  
Muscle Spindle ◽  
Stretch Reflex ◽  
Synergistic Effects ◽  
Medial Gastrocnemius ◽  
Monosynaptic Reflex ◽  
Lateral Gastrocnemius ◽  
Stretch Reflexes ◽  
Decerebrate Cat ◽  
Muscle Cooling ◽  
Decerebrate Cats

The effects of muscle spindle secondary ending activity on the stretch reflex were studied in unanesthetized decerebrate cats. Activation of secondary endings was accomplished by reducing the muscle temperature. This has been shown to cause a sustained asynchronous discharge from secondary endings. Cooling of the medial gastrocnemius or lateral gastrocnemius–soleus muscles caused an increase in the phasic and tonic components of their stretch reflexes. Cooling of the relaxed medial gastrocnemius muscle caused similar increases in the components of the stretch reflex of the synergistic lateral gastrocnemius–soleus muscle and an increase in its monosynaptic reflex. It was concluded that the facilitatory autogenetic and synergistic effects of muscle cooling on the stretch and monosynaptic reflexes were brought about by activity in group II afferents from muscle spindle secondary endings and could not be ascribed to any other type of muscle receptor. These results support the concept of an excitatory role for the secondary endings of the muscle spindle in the stretch reflex of the decerebrate cat.

Synthesis and Properties of "Hormonogene" and "Inhibitorogene" Type Oxytocin Analogs

1992 ◽  
Vol 57 (6) ◽  
pp. 1345-1351 ◽  
Author(s):  
B. C. Pal ◽  
Jiřina Slaninová ◽  
Tomislav Barth ◽  
Jerzy Trojnar ◽  
Michal Lebl
Keyword(s):  
Amino Acid ◽  
Inhibitory Action ◽  
Time Course ◽  
Solid Phase ◽  
Prolonged Time ◽  
Prolonged Effect ◽  
In Vivo Tests

Nα-Glycyl, diglycyl and triglycyl [2-D and [2-L-p-ethylphenylalanine]oxytocin analogs were synthesized by the solid phase technology utilizing racemic p-ethylphenylalanine. Analogs containing this amino acid of D-configuration were shown to be weak uterotonic antagonists both in vitro and in vivo tests; the compound containing triglycyl residue in position 1 was shown to have prolonged time course of inhibitory action. Analogs containing the L-amino acid were shown to be inhibitors of uterotonic activity of oxytocin in vitro, but uterotonic agonists with prolonged effect in vivo.

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