The effects of myomodulin and structurally related neuropeptides on skeletal neuromuscular transmission in the locust.

1. The modulatory actions of myomodulin A on tension generated in the extensortibiae muscle of the locust hindleg by stimulation of the slow excitatory motoneurone (SETi) depend upon the frequency of stimulation. Myomodulin A has no consistent effect on the tension induced by the fast extensor motoneurone (FETi) or upon the myogenic rhythm present in the extensor. The effects of a range of structurally related neuropeptides have also been assessed. 2. At low frequencies of SETi stimulation (1 Hz and below), the predominant modulatory effects are increases in the amplitude, contraction rate and relaxation rate of twitch tension. At higher frequencies, where twitches summate but tetanus is incomplete (up to 20 Hz), these effects are superimposed upon an increase of maintained tension. 3. The modulatory actions of myomodulin-like peptides show some similarities to and some differences from the modulatory actions of octopamine, proctolin and FMRFamide-like neuropeptides in this preparation, but are likely to be mediated via a distinct set of receptors. 4. The results of the present study, taken together with the localization of myomodulin-like immunoreactivity in specific sets of neurones in the locust nervous system, suggest the presence of a novel modulatory system in insects that uses myomodulin-like neuropeptides. It also indicates that myomodulins, which were first identified in molluscs, may represent another interphyletic family of neuropeptides.

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The release of catecholamines from the adrenal medulla and its modulation by α2-adrenoceptors in the anaesthetized dog

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y87-093 ◽

1987 ◽

Vol 65 (4) ◽

pp. 550-557 ◽

Cited By ~ 12

Author(s):

Sylvain Foucart ◽

Réginald Nadeau ◽

Jacques de Champlain

Keyword(s):

Electrical Stimulation ◽

Adrenal Medulla ◽

Plasma Concentrations ◽

Splanchnic Nerve ◽

Feedback Mechanism ◽

Adrenal Vein ◽

Low Frequencies ◽

Negative Feedback Mechanism ◽

Frequency Of Stimulation ◽

Stimulation Of

The adrenal nerve of anaesthetized and vagotomized dogs was electrically stimulated (10 V pulses of 2 ms duration for 10 min) at frequencies of 1, 3, 10, and 25 Hz. There was a correlation between the frequency of stimulation and the plasma concentrations of epinephrine, norepinephrine, and dopamine in the adrenal vein, mainly after the 1st min of stimulation and the maximal concentration was reached sooner with higher frequencies of stimulation. Moreover, the relative percentage of catecholamines released in response to the electrical stimulation was not changed by the frequency of stimulation. To test the hypothesis that a local negative feedback mechanism mediated by α2-adrenoceptors exists in the adrenal medulla, the effects of the systemic administration of clonidine (α2-agonist) and yohimbine (α2-antagonist) on the concentrations of catecholamines in the adrenal vein were evaluated during the electrical stimulation of the adrenal nerve (5 V pulses of 2 ms duration for 3 min) at 3 Hz. Moreover, the effects of the systemic injections of more specific α2-agonist and antagonist (oxymetazoline and idazoxan) were tested on the release of catecholamines in the adrenal vein in response to electrical stimulation of the splanchnic nerve at 1 and 3 Hz frequencies. The injection of 0.5 mg/kg of yohimbine caused a significant increase in the concentrations of epinephrine and norepinephrine in the adrenal vein induced by the electrical stimulation of the adrenal nerve and the injection of 15 μg/kg of clonidine had no effects. In the second series of experiments, the injection of 2 μg/kg of oxymetazoline caused a significant decrease in the release of epinephrine and norepinephrine at 1 Hz, but similarly to clonidine, there were no changes at 3 Hz. In contrast, the release of epinephrine and dopamine in response to electrical stimulation of the splanchnic nerve was increased at 3 Hz after the injection of idazoxan, but not at 1 Hz. It is concluded that the adrenal medulla catecholamines secretion appears to be partly modulated by a presynaptic inhibitory mechanism that involves α2-adrenoceptors. The observation that agonists appear to be more efficient at low frequencies of stimulation while antagonists appear to be more efficient at higher frequencies could be explained by the possibility that adrenal medullary α2-receptors would be saturated at higher frequencies of stimulation.

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Command Interneurons in the Crayfish Central Nervous System

Journal of Experimental Biology ◽

10.1242/jeb.46.2.249 ◽

1967 ◽

Vol 46 (2) ◽

pp. 249-261

Author(s):

H. L. ATWOOD ◽

C. A. G. WIERSMA

Keyword(s):

Central Nervous System ◽

Nervous System ◽

Temporal Pattern ◽

Motor Output ◽

Evoked Response ◽

Total Response ◽

Motor Effects ◽

Frequency Of Stimulation ◽

Stimulation Of

1. The motor effects evoked by stimulation of each of eight command fibres in the circumoesophageal commissures of the crayfish are described. 2. The fibres obtained appeared to have widespread connexions in all or most of the lower ganglia. For certain fibres the response was stronger on the homolateral side of the animal; for others it was symmetrical. 3. The frequency of stimulation of a command fibre generally had a pronounced influence on the speed of the evoked response. In addition, segments of the total response could be elicited selectively by alteration of the frequency and duration of stimulation. 4. Although the responses associated with most of the fibres were not sensitive to the fine temporal pattern of the applied stimulation, for one fibre the motor output depended clearly on the spacing of the stimulating pulses.

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Fructose 2,6-bisphosphate in rat skeletal muscle during contraction

Biochemical Journal ◽

10.1042/bj2230073 ◽

1984 ◽

Vol 223 (1) ◽

pp. 73-79 ◽

Cited By ~ 28

Author(s):

Y Minatogawa ◽

L Hue

Keyword(s):

Extensor Digitorum Longus ◽

Fold Increase ◽

Rat Skeletal Muscle ◽

Low Frequencies ◽

Contracting Muscle ◽

Glycolytic Intermediates ◽

Fructose 1,6 Bisphosphate ◽

Frequency Of Stimulation ◽

Stimulation Of

Fructose 2,6-bisphosphate and several glycolytic intermediates were measured in two rat muscles, extensor digitorum longus and gastrocnemius, which were electrically stimulated in situ. Both the duration and the frequency of stimulation were varied to obtain different rates of glycolysis. There was no relationship between fructose 2,6-bisphosphate content and the increase in tissue lactate in contracting muscle. However, in gastrocnemius stimulated at low frequencies (less than or equal to 5 Hz), there was a 2-fold increase in fructose 2,6-bisphosphate at 10s, followed by a return to basal values, whereas lactate increased only after 1 min of contraction. The concentrations of hexose 6-phosphates, fructose 1,6-bisphosphate and triose phosphates were all increased during the 3 min stimulation. During tetanus (frequencies greater than or equal to 10 Hz) fructose 2,6-bisphosphate was not increased, whereas glycolysis was maximally stimulated and resulted in an accumulation of tissue lactate, mostly from glycogen. The concentrations of hexose 6-phosphate increased continuously during the 1 min tetanus, whereas fructose 1,6-bisphosphate was increased at 10s and then decreased progressively. It therefore appears that fructose 2,6-bisphosphate does not play a role in the stimulation of glycolysis during tetanus; it may, however, be involved in the control of glycolysis when the muscles are stimulated at low frequencies for short periods of time.

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Effective Ultrasonic Stimulation in Human Peripheral Nervous System

10.1101/2021.04.22.440931 ◽

2021 ◽

Author(s):

Thomas Riis ◽

Jan Kubanek

Keyword(s):

Nervous System ◽

Peripheral Nervous System ◽

Low Frequency ◽

Controlled Study ◽

Excitable Cells ◽

Low Frequencies ◽

Ultrasound Frequency ◽

Nociceptive Responses ◽

Ultrasonic Stimulation ◽

Stimulation Of

AbstractObjectiveLow-intensity ultrasound can stimulate excitable cells in a noninvasive and targeted manner, but which parameters are effective has remained elusive. This question has been difficult to answer because differences in transducers and parameters—frequency in particular—lead to profound differences in the stimulated tissue volumes. The objective of this study is to control for these differences and evaluate which ultrasound parameters are effective in stimulating excitable cells.MethodsHere, we stimulated the human peripheral nervous system using a single transducer operating in a range of frequencies, and matched the stimulated volumes with an acoustic aperture.ResultsWe found that low frequencies (300 kHz) are substantially more effective in generating tactile and nociceptive responses in humans compared to high frequencies (900 kHz). The strong effect of ultrasound frequency was observed for all pressures tested, for continuous and pulsed stimuli, and for tactile and nociceptive responses.ConclusionThis prominent effect may be explained by a mechanical force associated with ultrasound. The effect is not due to heating, which would be weaker at the low frequency.SignificanceThis controlled study reveals that ultrasonic stimulation of excitable cells is stronger at lower frequencies, which guides the choice of transducer hardware for effective ultrasonic stimulation of the peripheral nervous system in humans.

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Frequency arrangement in anterior ectosylvian auditory cortex of dog

American Journal of Physiology-Legacy Content ◽

10.1152/ajplegacy.1962.203.1.185 ◽

1962 ◽

Vol 203 (1) ◽

pp. 185-193 ◽

Cited By ~ 12

Author(s):

Archie R. Tunturi

Keyword(s):

Nervous System ◽

Auditory Cortex ◽

Evoked Potentials ◽

Frequency Pattern ◽

Low Frequencies ◽

General Arrangement ◽

Threshold Data ◽

Human Hearing ◽

Stimulation Of

The anterior ectosylvian (AES) area was studied with local applications of strychnine and stimulation of the ear with known frequencies. The threshold spikes for various frequencies were determined to locate the connections to the area. It was found that low frequencies produced spikes ventrocaudally and higher frequencies produced spikes dorsocephalically. Each patch responded to a wider band of frequencies than observed in other areas. The same general arrangement, although less distinct, was obtained for both AES and MES (middle ectosylvian) areas in the lightly anesthetized dog, using only the evoked potentials as indicators. Considerable variation was found between animals and this variation was thought to be due to development of the nervous system. It was found that a sulcus generally separated the AES and MES areas. Other branch sulci of the ectosylvian sulcus penetrated the MES area, distorting the frequency pattern for sounds. The threshold data for the anesthetized dog in the AES and MES areas agree in absolute values to the minimum audible pressure levels for human hearing.

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The Modulatory Actions of FMRFamide and Related Peptides on Locust Skeletal Muscle

Journal of Experimental Biology ◽

10.1242/jeb.126.1.403 ◽

1986 ◽

Vol 126 (1) ◽

pp. 403-422 ◽

Cited By ~ 1

Author(s):

PETER D. EVANS ◽

CAMILLA M. MYERS

Keyword(s):

Slow Muscle ◽

Motor Neurone ◽

Muscle Fibres ◽

Relaxation Rates ◽

Receptor System ◽

Low Frequencies ◽

Slow Muscle Fibres ◽

Slow Twitch ◽

Frequency Of Stimulation ◽

Stimulation Of

1. The modulatory actions of FMRFamide and related peptides on tension generated in the extensor-tibiae muscle of the locust hindleg by stimulation of the slow excitatory motor neurone (SETi) depend upon the frequency of stimulation of SETi. They have no effect on the tension induced by the fast motor neurone (FETi) or upon the myogenic rhythm present in this muscle. 2. At low frequencies of SETi stimulation (1Hz and below) the predominant modulatory effects are increases in the amplitude, contraction rates and relaxation rates of twitch tension. At higher frequencies, where twitches summate but tetanus is incomplete (up to 20 Hz) these effects are superimposed upon an increase of maintained tension. 3. FMRFamide increases the amplitude and relaxation rate of slow twitch tension by different amounts in different regions of the extensor muscle. It is likely that the effects of FMRFamide are restricted to slow muscle fibres that are innervated by SETi but not FETi. 4. The modulatory actions of FMRFamide on SETi-induced tension are additive to, but do not potentiate, the modulatory actions of octopamine and proctolin in this muscle. The actions of FMRFamide show some similarities with the modulatory actions of octopamine in this preparation but they are mediated by an independent receptor system that does not change cyclic nucleotide levels. Other actions of FMRFamide are similar to the actions of proctolin.

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