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PubMedDate not supplied

[Mechanisms of change in the tonus of depolarized smooth muscle (guinea pig taenia coli) during application of a hyperpolarizing current].

Using double sucrose-gap technique three types of contractile responses of depolarized smooth muscle (guinea-pig taenia-coli) current-induced hyperpolarization were investigated: 1) contractions, 2) relaxations and 3) biphasic responses (relaxation followed by contraction). Every preparation generated generally only one type of responses (of different amplitude) when passing the currents of various strength. These responses were attributed to the changes of calcium fluxes through the cellular membranes under hyperpolarization. The phenomena observed were analysed on the mathematical model. Quantitative analysis showed that description of calcium current changes with equations of Hogkin-Huxley types was not sufficient; the model predicts the existence of non-inactivating channels in the smooth muscle cellular membrane. This very assumption allows to describe correctly all three types of cintractile responses.

Animals↗
PubMed1992

Some pharmacological properties of the oviduct muscularis of the stable fly Stomoxys calcitrans.

1. Spontaneous and rhythmic contractions were measured in 80% of the preparations of the stable fly oviduct which were separated from the central nervous system and other tissues. Measurements of the changes in the amplitude and frequency of contractions and changes in the baseline tonus were taken separately, even though they often occurred together during chemical treatments. 2. L-glutamate, at a concentration of 10(-4) to 10(-3) M, caused an increase in the frequency of contractions and in muscle tonus. Contraction frequency showed the highest percentage of change while amplitude and tonus had lower values. 3. The excitation threshold for proctolin on the oviduct was between 10(-13) and 10(-10) M. The initial responses to the peptide showed increases in the amplitude, frequency, and tonus of muscle contractions. However, tonic changes dominated the response profile when the concentration reached 10(-10) or 10(-9) M. In 12 experiments in which the oviduct was exposed to 10(-7) M leucomyosuppressin, no change in the amplitude, frequency, or tonus of muscle contractions was detected. 4. Octopamine caused an inhibition of spontaneous muscle contractions of the oviduct. Spontaneous contractions showed a graded drop in activity over the concentration range tested (10(-8)-10(-6) M). Also 57% of the preparations tested showed a substantial drop in baseline tonus after the addition of octopamine. 5. Stable fly oviducts exposed to extracts from the male reproductive tract showed a noticeable change in the amplitude frequency and tonus of muscle contraction at levels of 2 to 3 equivalents.

Animals↗
PubMed1989

Sleep tonus inversion: a feature of juvenile dystonic parkinsonism.

Polysomnographic monitoring of a 16-year-old girl suffering from dopa-responsive dystonic parkinsonism showed a change in the distribution of muscle activity in thigh muscles during different stages of sleep. The hamstring muscles were hypertonic at sleep onset compared with the vastus lateralis of the quadriceps muscles. At the third sleep cycle of each of the 2 nights, the time at which sleep benefit becomes clinically evident, the hypertonia in the hamstring muscles was reversed and the vastus lateralis became more hypertonic. It is suggested that the muscle tonus inversion marks the moment at which the sleep process alleviates the dystonic parkinsonian state manifested at wakefulness as a circardian fluctuation. According to our data, the flexor-extensor tonus inversion during sleep was not yet described in the literature, and may be an associated feature of dopa-responsive dystonic parkinsonism.

Adolescent↗
PubMed1998

Effects of neonatal hypoxia on the medulla-spinal cord descending neurons.

Hypoxic changes in the medulla-spinal cord descending neurons were studied morphologically using a retrograde neurotracer, choleratoxin B subunit (CTb). On postnatal day 7, Sprague-Dawley rats were subjected to a hypoxic load of 8% oxygen for 5 hours. In the rats that survived, CTb was injected into the lumbar enlargement at postnatal day 26, and they were killed at postnatal day 28 for histologic analysis. Retrograde transported CTb was visualized by immunohistochemistry. The results were compared with those obtained from control rats. In the control rats, CTb-positive cells were observed in the nucleus reticularis gigantocellularis, nucleus reticularis magnocellularis, nucleus raphe magnus, nucleus raphe obscurus, and nucleus raphe pallidus. In the hypoxic rats, although CTb-positive cells were detected in the same areas as the control rats, there was a noteworthy decrease in the number of CTb-positive cells in all areas, and there were many cells with hypoxic degeneration. In all of the nuclei a marked decrease in the number of CTb-positive cells was observed. Because medulla-spinal cord descending neurons have important roles in the regulation of postural muscle tone, these results may account for the pathophysiology of abnormal muscle tonus accompanying hypoxic brain damage.

Animals↗
PubMed2005

Discharge of identified orexin/hypocretin neurons across the sleep-waking cycle.

Although maintained by multiple arousal systems, wakefulness falters if orexin (hypocretin), orexin receptors, or orexin neurons are deficient; narcolepsy results with hypersomnolence or sudden onset of rapid eye movement sleep [or paradoxical sleep (PS)] and loss of muscle tonus. To learn how orexin neurons maintain wakefulness, we recorded neurons in head-fixed rats across the sleep-waking cycle and then labeled them with Neurobiotin to identify them by immunohistochemistry. We show that identified orexin neurons discharge during active waking, when postural muscle tone is high in association with movement, decrease discharge during quiet waking in absence of movement, and virtually cease firing during sleep, when postural muscle tone is low or absent. During PS, they remain relatively silent in association with postural muscle atonia and most often despite phasic muscular twitches. They increase firing before the end of PS and thereby herald by several seconds the return of waking and muscle tone. The orexin neurons would thus stimulate arousal, while antagonizing sleep and muscle atonia.

Action Potentials↗
PubMed1986

A prospective study of inhibitive casting as an adjunct to physiotherapy for cerebral-palsied children.

The effect of a three-week course of inhibitive casting and neurodevelopmental therapy on the static muscle tonus, developmental skills, passive range of ankle dorsiflexion and gait pattern was determined in 32 cerebral-palsied children. Two weeks after treatment, passive range of ankle dorsiflexion and foot-floor contact in walking had improved significantly but there was no significant change in the static muscle tone or developmental skills. After five months the improvements in ankle dorsiflexion and walking pattern were no longer evident. Further objective studies to determine the effect of 'inhibitive casting' are necessary before the modality is used indiscriminately.

Ankle↗
PubMedDate not supplied

Thermoregulatory cold-defense deficits in rats with preoptic/anterior hypothalamic lesions.

This paper discusses the course of recovery from the thermoregulatory deficits produced in rats by electrolytic lesions in the preoptic/anterior hypothalamic area. Severe damage rendered rats ectothermic, that is unable to maintain their body temperatures at normal levels unless they were incubated at an ambient temperature of 30 degrees C. Less severe damage produced rats that maintained subnormal but stable body temperatures at 23 degrees C, but that did not increase metabolic rate or shiver and whose body temperatures dropped drastically in the cold (5 degrees C). As the animals recovered, nonshivering thermogenesis returned. Eventually the rats became excessively hyperthermic in normal room temperatures, due to very high metabolic rates. They were still unable to shiver or increase metabolic rate further in the cold and were therefore still unable to prevent a large drop in body temperature. Muscle tonus and shivering recovered gradually, and oxygen consumption returned to near normal levels. The data are described in terms of levels of integration of the nervous control of thermoregulation.

Animals↗
PubMed1996

Head and body positions affect thermoregulatory tonus in deltoid muscles.

Electromyograms (EMGs) were recorded from both deltoid muscles (DMs) when subjects were sitting, standing, and bending the head laterally at different cold sensations to clarify the role of head and body positions in the thermoregulatory tonus. At room temperature (22 degrees C), neither EMG related to thermoregulatory muscle tonus (TMT) nor were changes in EMG intensity observed during changes in posture. At a cold temperature (5 degrees C), when the subjects felt slightly cold or cold, the averaged surface EMG intensity of TMT was approximately 2-3 microV during sitting with the head held upright. The EMG of TMT was 7.23 +/- 2.99 microV in subjects sitting with the head upright when feeling cold and extremely cold and increased to 14.75 +/- 5.15 microV (P < 0.01) when the subjects stood at ease and to 19.96 +/- 11.01 microV (P < 0.01) when the subjects stood on tiptoes. Lateral head bending in subjects standing at ease and feeling extremely cold increased the EMG 40-60% (P < 0.01) in the contralateral DM without any significant effect on the ipsilateral DM. The results suggest that in humans TMT is influenced by tonic postural reflexes.

Adult↗
PubMedDate not supplied

[Assessment of changes in physiological status of alcohol-dependent patients in the course of 10-day detoxication treatment].

Heart rate, respiratory rate, postural muscle tone and tapping in 14 alcohol dependent patients (type II ac. Cloninger) during 10 days of detoxification were investigated. Despite subjective mood increased, no longer observed were tachycardia and clinical symptoms of alcohol withdrawal; increased muscle tonus and faster respiration rhythm were observed. The observed physiological changes in alcohol dependent patients after 10 days of abstinence suggest that continuation of pharmacotherapy and psychotherapy after detoxification in acute alcohol withdrawal is recommended.

Adult↗
PubMed1975

The effect of berotec (Th 1165a) on spontaneous and induced uterine activity in the pregnant baboon.

Berotec (Th 1165a), a specific beta-adrenergic agent, has been found to be a more potent agent than metaproterenol in the inhibition of uterine activity in animals and human beings. The effect of berotec on spontaneous (postinduced) and induced uterine activity in the pregnant baboon near term was investigated. Berotec administered intravenously in a dose of 5 mug per minute consistently and significantly reduced spontaneous uterine activity as well as uterine activity by either oxytocin or prostaglandin F2-alpha. The frequency of contractions was consistently reduced whereas the effect on the amplitude of contractions was less marked. There was no reduction of the baseline muscle tonus. Berotec infusion produced a marked increase in the maternal heart rate, averaging 40 beats per minute. Berotec appears to be a potent inhibitor of spontaneous, oxytocin-induced, and prostaglandin-induced uterine activity in the pregnant baboon, but it has considerable cardiovascular side effects.

Adrenergic beta-Agonists↗
PubMed1976

Cyclic EEG and motility patterns during sleep in restrained infant rats.

When restrained in a quasi-fetal position, infant rats (2--3 weeks old) remain for an extended period in a sleep-like state as judged by polygraphic criteria. Moreover, they become very difficult to arouse by sensory stimuli, and show a level of spontaneous motility considerably higher than is normally found at this age during sleep. Phasic generalized body movements, which are often quite stereotyped, occur in trains at regular intervals, against a low background level of neck muscle tonus. The amplitude of the cortical EEG, especially in the delta band, is negatively correlated with the frequency of spontaneous motor burst activity. It is suggested that these REM-like "rapid body movements" in immature mammals may well represent a transitional stage between fetal behavior patterns and sleep motility in the adult organism.

Age Factors↗
PubMed1997

[Effects of melatonin and diazepam on the eye movement and postural muscle tone in decerebrate cats].

We studied the effects of melatonin and diazepam on eye movement and muscle activity in decerebrate cats, and results were compared with those obtained from carbachol injection into the pontine reticular formation which was supposed to be a model of REM sleep. In precollicular postmammillary decerebrate cats, the horizontal eye movement and the activity of bilateral triceps surae muscles were recorded under three conditions: (1) microinjection of carbachol into the rostral pontine reticular formation; (2) intravenous administration melatonin; and (3) diazepam. Both rapid eye movement and reduction of muscle activity were induced by carbachol injection, while only reduction of muscle activity was induced by diazepam administration. Neither rapid eye movement nor reduction of muscle activity was induced by melatonin administration in this animal preparation. From these results, we speculated that the inhibitory effect of diazepam on muscle tonus was not manifested through activation of the brainstem REM generating system. It is known that the melatonin receptors are located in several sites of central nervous system, such as suprachiasmatic nucleus, and not in the brainstem and spinal cord. The present results of melatonin administration may support this fact in view of behavioral aspects.

Animals↗
PubMed1986

[Dyskinetic syndrome following the use of metoclopramide].

The relation to the wide use of metoclopramide side effects are rare. These concern the extrapyramidal-motor system among others in form of dyskinetic syndrome. At the instance of a 15-year-old boy the dramatic course with cramp-like increases of the muscle tonus and compulsive movements in head and shoulder region are described. The knowledge of these medicament-induced symptoms is of differential-diagnostic importance to avoid false diagnose and to act with a definite aim. In easier forms of a dyskinetic syndrome suffices the discontinuation of the metoclopramide medication, in more severe cases proves the use of antiparkinsonian agents.

Adolescent↗
PubMed1977

[The influence of vasodilatators on intraocular pressure and blood pressure (author's transl)].

The influence of different vasodilatators on blood pressure and intraocular pressure has been tested in animal experiments. For that purpose substances with alphasympathicolytic effect (Hydergin, Trental) have been tested as well as substances which are of direct influence on the muscles. In all cases a decrease of the blood pressure was noticed. Furthermore in most of the cases an increase of the intraocular pressure could be seen. This is due to a direct dilatation of ocular vessels. The effects were short-lived and reversible. We tried to find an explanation for the variations of intraocular pressure during the decrease of blood pressure. The low transmural pressure (PTM) and the corresponding low starting point of the muscle tonus seemed to be responsible for this phenomenon. Without doubt the starting point of the blood pressure, the dose, and the cardiac ability for compensation are of great influence in the development of the curve. Only a sufficiently high blood pressure is able to dilate the ocular vessels, so that one has to draw therapeutic conclusions from the constellation blood pressure/intraocular pressure before deciding on treatment.

Animals↗
PubMed2003

[Kinesiologic assessment of motor development dynamic in premature children until the expected term of delivery].

BACKGROUND: Kinesiologic assessment is included in the neurological examination and the kinesiologic findings may be used as a valuable criterion in assessment of the motor development dynamics. METHODS: The experimental group consisted of twenty-one preterm children (11 boys and 10 girls) born between 28th and 36th week of gestational age. All children were examined every two weeks till the expected term of delivery. Examinations included neurological-kinesiological assessment based on selected parameters of spontaneous or forced movement, muscle tonus, primitive reflexology and postural reactivity and screening scores according to Touwen and Salokorpi. RESULTS: When comparing the results obtained in the examined sample of children, using examination records and screening scores according to Touwen and Salokorpi, the neurological-kinesiological appeared as the best to be applied to the clinical practice. The criteria of rehabilitation applied, proved to be very effective. CONCLUSIONS: Despite the diagnosis based on the kinesiological assessment cannot be determined, further precision of the specific features of the kinesiological picture in these children, as a parameter of the motor development dynamics, is needed, as it will allow for subsequent evaluation of the therapy applied.

Child Development↗