Sympathetic effects on spontaneous activity in bovine mesenteric lymphatics

1984 ◽  
Vol 247 (4) ◽  
pp. H610-H615
Author(s):  
T. Ohhashi ◽  
T. Azuma
Keyword(s):  
Spontaneous Activity ◽  
Inhibitory Effect ◽  
Lymph Vessel ◽  
Autonomic Nerves ◽  
Inhibitory Influence ◽  
Nerve Terminals ◽  
Pacemaker Cells ◽  
Excitatory Effect ◽  
Transmural Stimulation ◽  
Spontaneous Contractions

To investigate the effects of autonomic nerves on the spontaneous activity, responses of valvular and intervalvular segments of isolated bovine mesenteric lymphatics to 60-strains of pulses (50 V for 0.5 ms at 2 Hz) have been studied under the influence of various drugs. There was a marked difference in response to transmural stimulation between the valvular and intervalvular segments. In the valvular segment, the stimulation arrested the spontaneous activity. However, the rhythm of spontaneous contractions was markedly accelerated during the stimulation in the intervalvular segment. Both inhibitory and excitatory effects were completely blocked by tetrodotoxin and guanethidine, potentiated by cocaine, and unaffected by hexamethonium and atropine. Propranolol blocked the inhibitory effect of the stimulation in the valvular segment. Pretreatment of the intervalvular segment with phentolamine converted the normal excitatory effect of the stimulation into an inhibitory influence. No change in rhythm was brought about by the stimulation in the presence of propranolol and phentolamine in either segment. These results suggest that transmural electrical stimulation causes the release of norepinephrine from postganglionic sympathetic nerve terminals in the vicinity of pacemaker cells and that beta-adrenoceptors are predominant in the valvular region of the lymph vessel.

Inhibition and Rhythmic Activity of the Circular Muscles of Calliactis Parasitica (Couch)

1960 ◽  
Vol 37 (4) ◽  
pp. 812-831
Author(s):  
D. W. EWER
Keyword(s):  
Electrical Stimulation ◽  
Spontaneous Activity ◽  
Low Frequency ◽  
Rhythmic Activity ◽  
Inhibitory Effect ◽  
Low Frequency Stimulation ◽  
Double Response ◽  
Frequency Stimulation ◽  
Spontaneous Contractions ◽  
Stimulation Of

1. The responses to electrical stimulation of isolated rings of the column and pedal disk of Calliactis are described. Such rings make slow spontaneous contractions which are frequently rhythmical, the interval between contractions normally being 7-20 min. 2. Continuous low-frequency stimulation inhibits spontaneous activity of rings from the pedal disk and also of fresh rings from more adoral regions of the column. Older rings from the mid-column respond to such stimulation by a tetanic contraction. 3. The latency of response to electrical stimulation of pedal rings is of the order of 120 sec. This latency is not affected by stimulation frequency but is prolonged by increase in the number of shocks applied. 4. Stimulation of a pedal ring at the onset of a contraction prevents the further development of this contraction, while stimulation as a contraction reaches its maximum is followed by more rapid relaxation than in unstimulated controls. 5. Mid-column rings when freshly prepared show a latency of the order of 120 sec. As the preparation ages, a double response to stimulation appears; the first response has a latency of about 30-40 sec. and presently becomes the only type of response shown. 6. If two sets of stimuli are applied to a mid-column ring, the magnitude of response to the second set increases as the time between stimulations increases. With long intervals an almost total contraction is obtained in response to a single shock. 7. The effect of intercalated stimuli upon the rhythm of spontaneous activity is studied. The effect is very variable and it is suggested that this is the result of electrical stimulation having both an excitatory and an inhibitory effect. 8. The very long latent periods characteristic of pedal rings and the rhythmic activity of these preparations are interpreted as interactions of excitation and inhibition.

Properties of the trochanteral hair plate and its function in the control of walking in the cockroach

1976 ◽  
Vol 64 (1) ◽  
pp. 233-249 ◽  
Author(s):  
R. K. Wong ◽  
K. G. Pearson
Keyword(s):  
Inhibitory Effect ◽  
Short Latency ◽  
Inhibitory Influence ◽  
Type I ◽  
Type Ii ◽  
Step Cycle ◽  
Excitatory Effect ◽  
Physiological Properties ◽  
Hair Sensilla ◽  
Leg Movement

1. The physiological properties of the group of long hair sensilla of the trochanteral hair plate in the cockroach metathoracic leg were studied. The sensilla were divided into type I and type II according to their responses to imposed displacements. 2. Type I hair sensilla responded to dynamic displacements whereas type II hair sensilla responded to both dynamic and static displacements. The hair sensilla are normally excited by phasic flexion movements of the femur near the end of leg protraction. 3. Activity in the trochanteral hair plate afferents had a short latency excitatory effect on the motoneurone producing slow extension movements of the femur and an inhibitory effect on the femur flexor motoneurones. 4. Removal of the trochanteral hair plate in one leg caused overstepping of that leg in a walking animal due to exaggerated flexion of the femur. This change in leg movement can be explained by the removal of the inhibitory influence from the hair plate afferents to the femur flexor motoneurones. 5. We conclude that one function of the trochanteral hair plate is to limit femur flexion during a step cycle.

Some effects of superior laryngeal nerve stimulation on sympathetic preganglionic neuron firing

1979 ◽  
Vol 57 (10) ◽  
pp. 1073-1081 ◽  
Author(s):  
Urs Gerber ◽  
Canio Polosa
Keyword(s):  
Firing Pattern ◽  
Superior Laryngeal Nerve ◽  
Inhibitory Effect ◽  
Laryngeal Nerve ◽  
Depressant Effect ◽  
Excitatory Effect ◽  
Sympathetic Preganglionic Neurons ◽  
Preganglionic Neurons ◽  
Phrenic Motoneurons ◽  
Frequency Of Stimulation

Repetitive electrical stimulation of afferent fibers in the superior laryngeal nerve (SLN) evoked depressant or excitatory effects on sympathetic preganglionic neurons of the cervical trunk in Nembutal-anesthetized, paralyzed, artificially ventilated cats. The depressant effect, which consisted of suppression of the inspiration-synchronous discharge of units with such firing pattern, was obtained at low strength and frequency of stimulation (e.g. 600 mV, 30 Hz) and was absent at end-tidal CO2 values below threshold for phrenic nerve activity. The excitatory effect required higher intensity and frequency of stimulation and was CO2 independent. The depressant effect on sympathetic preganglionic neurons with inspiratory firing pattern seemed a replica of the inspiration-inhibitory effect observed on phrenic motoneurons. Hence, it could be attributed to the known inhibition by the SLN of central inspiratory activity, if it is assumed that this is a common driver for phrenic motoneurons and some sympathetic preganglionic neurons. The excitatory effect, on the other hand, appears to be due to connections of SLN afferents with sympathetic preganglionic neurons, independent of the respiratory center.

A Quantitative Study of the Behaviour of the Male Mormoniella Vitripennis (Walker) (Hymenoptera, Pteromalidae) Towards Two Constant Stimulus-Situations

Behaviour ◽  
1961 ◽  
Vol 18 (4) ◽  
pp. 288-311 ◽  
Author(s):  
Robert Barrass
Keyword(s):  
Nervous Activity ◽  
Specific Effect ◽  
Inhibitory Effect ◽  
Constant Stimulus ◽  
Receptive Female ◽  
Short Term ◽  
Excitatory Effect ◽  
Time Intervals ◽  
Almost All ◽  
Term Response

Abstract1. The method of dual quantification was used to study the effect of courtship of both receptive and non-receptive females on the subsequent behaviour of the male Mormoniella vitripennis. 2. The male's responsiveness to successive non-receptive females waned when the time between presentations was short. The extent of this waning was less with longer time intervals. 3. When many females were presented to a male one after another the male courted almost all of them if they were receptive females but only a few if they were non-receptive females. 4. A single courtship of either a receptive or a non-receptive female had a similar effect on the male's subsequent behaviour and recovery occurred in a similar way. 5. Courtship of 20 non-receptive females reduced the male's response to further females more than did courtship of 20 receptive females. 6. The significance of these observations is discussed with reference to the use of dummy animals and to the recent ethological concepts of reaction specific energy, motivational impulses, specific action potentiality and consummatory act. 7. An endogenous central nervous influence on the male's readiness to respond is postulated. Courtship has a short-term response-specific effect (receptive or non-receptive females) and an inhibitory stimulus-specific effect (non-receptive females). With receptive females the inhibitory effect is absent and/or mating has an excitatory effect. The stimuli provided by a receptive female must direct nervous activity rather than release a limited amount of stored energy.

Influence of Codisposal of Municipal Solid Waste and Olive Vegetation Water on the Anaerobic Digestion of a Sanitary Landfill

1993 ◽  
Vol 27 (2) ◽  
pp. 261-271 ◽  
Author(s):  
R. Cossu ◽  
N. Blakey ◽  
P. Cannas
Keyword(s):  
Municipal Solid Waste ◽  
Solid Waste ◽  
Research Study ◽  
Inhibitory Effect ◽  
Organic Load ◽  
Sanitary Landfill ◽  
Inhibitory Influence ◽  
Vegetation Water ◽  
Waste Degradation ◽  
Very High

A research study was carried out aiming to investigate the possibility of treatment of vegetation water in a anaerobic digester like a sanitary landfill. This vegetation water originates from olive oil production. The results, obtained from lysimeters filled with Municipal Solid Waste, show very high gasification and reduction of the organic load of vegetation water, with no inhibitory effect on waste degradation processes providing the vegetation water is added to an active methanogenic system or buffering the landfill system during the acid phase. The inhibitory influence of compounds, like polyphenols, which can be present in vegetation water in large amounts, has been studied.

scholarly journals The metabolism of amiodarone by various CYP isoenzymes of human and rat, and the inhibitory influence of ketoconazole

2008 ◽  
Vol 11 (1) ◽  
pp. 147 ◽  
Author(s):  
Marwa E. Elsherbiny ◽  
Ayman O.S. El-Kadi ◽  
Dion R. Brocks
Keyword(s):  
Cytochrome P450 ◽  
Inhibitory Effect ◽  
Intrinsic Clearance ◽  
Significant Inhibition ◽  
Inhibitory Influence ◽  
Relative Kinetic ◽  
Cyp Isoforms ◽  
High Concentrations ◽  
In Vivo Administration

PURPOSE. To evaluate the metabolism of amiodarone (AM) to desethylamiodarone (DEA) by selected human and rat cytochrome P450, and the inhibitory effect of ketoconazole (KTZ). METHODS. Some important CYP isoenzymes (rat CYP1A1, 1A2, 2C6, 2C11, 2D1, 2D2, and 3A1 and human CYP1A1, 1A2, 2D6 and 3A4) were spiked with various concentrations of AM to determine the relative kinetic parameters for formation of DEA in the presence and absence of various concentrations of KTZ. RESULTS. The formation of DEA was observed when AM was exposed to each of the CYP tested, although the rates were varied. Human CYP1A1 followed by 3A4 had the highest intrinsic clearance (CLint) for DEA formation whereas in rat, CYP2D1 followed by CYP2C11 had the highest CLint. Human and rat CYP1A2 seemed to have the lowest CLint. At high concentrations of AM and KTZ, near those expected in vivo, significant inhibition of all isoforms except for rat CYP1A2 was observed. At lower concentration ranges of both drugs, the inhibitory constant was determined. At these levels, KTZ was found to potently inhibit human CYP1A1 and 3A4 and rat 2D2 and 1A1. CONCLUSION. Human CYP1A1 and 3A4 and rat CYP2D1 and 2C11 were most efficient in converting AM to DEA. For DEA formation, the in vivo administration of KTZ could inhibit other CYP isoforms besides CYP3A in human and rat.

Cardioregulatory properties of the abdominal ganglia in Limulus

1970 ◽  
Vol 48 (6) ◽  
pp. 333-341 ◽  
Author(s):  
R. Von Burg ◽  
W. C. Corning
Keyword(s):  
Central Nervous System ◽  
Heart Rate ◽  
Nervous System ◽  
Heart Function ◽  
Inhibitory Effect ◽  
Bioelectrical Activity ◽  
Inhibitory Influence ◽  
Dorsal Nerves

The abdominal ganglia of the Limulus central nervous system exert a net inhibitory effect on heart rate. This influence is mediated mainly by the dorsal nerves in the first three ganglia. When the dorsal nerves are sectioned, cardioacceleration results; when these nerves are stimulated, a reduction in rate is obtained. However, cardioaccelerators can be unmasked by splitting a ganglion. This selectively removes the inhibitory output, leaving only a cardioaccelerator influence. Inhibition of bioelectrical activity in the intact abdominal ganglia with GABA also resulted in an increased heart rate, confirming their net inhibitory influence on heart function. Possible models of abdominal ganglia organization are discussed.

scholarly journals Inhibitory effect of alcohol on ghrelin secretion in normal man

2005 ◽  
Vol 152 (5) ◽  
pp. 743-747 ◽  
Author(s):  
Jan Calissendorff ◽  
Olle Danielsson ◽  
Kerstin Brismar ◽  
Sven Röjdmark
Keyword(s):  
Drinking Water ◽  
Venous Blood ◽  
Serum Levels ◽  
Underlying Mechanism ◽  
Inhibitory Effect ◽  
Inhibitory Influence ◽  
Normal Man ◽  
Obese Subjects ◽  
Ghrelin Secretion ◽  
Serum Ghrelin

Background: Human appetite is stimulated by alcohol but the underlying mechanism is unknown. It is possible that hunger-stimulating hormones are mediators of this effect of alcohol. Ghrelin stimulates hunger, but how alcohol affects human ghrelin secretion has never been studied before. Objective: To investigate whether alcohol ingestion exerts an acute influence on serum ghrelin concentrations in healthy subjects. Subjects and design: Eight healthy non-obese subjects participated in the study. All were investigated on two occasions (experiments A and B). Alcohol (0.55 g ethanol/kg body weight) was ingested in experiment A, and drinking-water in experiment B. Venous blood was collected before, and 30 and 60 min after consumption of the drinks. Serum concentrations of ghrelin, cortisol and ethanol were determined and neuropeptide Y (NPY) concentrations were determined in plasma. Results: Alcohol lowered the ghrelin level by 13.9±5.0% at 30 min and by 17.5±2.6% at 60 min, in contrast to drinking-water which was without significant effect. Serum levels of cortisol and insulin were similar after alcohol and water as was plasma NPY. Conclusion: Alcohol has an acute inhibitory influence on human ghrelin secretion but no measurable effect on the secretion of NPY and cortisol. Hence, none of these hormones mediate the orexigenic effect of the drug.

Sources and implications of basal nitric oxide in spontaneous contractions of guinea pig taenia caeci

2003 ◽  
Vol 285 (4) ◽  
pp. G747-G753 ◽  
Author(s):  
Catalina Caballero-Alomar ◽  
Carmen Santos ◽  
Diego Lopez ◽  
M. Teresa Mitjavila ◽  
Pere Puig-Parellada
Keyword(s):  
Nitric Oxide ◽  
Guinea Pig ◽  
Inhibitory Effect ◽  
No Production ◽  
Paramagnetic Resonance ◽  
Synthase Inhibitor ◽  
Spontaneous Contractions ◽  
Electron Paramagnetic

We examined in vitro the source and role of basal nitric oxide (NO) in proximal segments of guinea pig taenia caeci in nonadrenergic, noncholinergic (NANC) conditions. Using electron paramagnetic resonance (EPR), we measured the effect of the NO synthase inhibitor NG-nitro-l-arginine methyl ester (l-NAME, 10–4 M), the neuronal blocker tetrodotoxin (TTX, 10–6 M), or both on spontaneous contractions and on the production of basal NO. Both l-NAME and TTX, when tested alone, increased the amplitude and frequency of contractions. NO production was abolished by l-NAME and was inhibited by 38% by TTX. When tested together, l-NAME in the presence of TTX or TTX in the presence of l-NAME had no further effect on the amplitude or frequency of spontaneous contractions, and the NO production was inhibited. These findings suggest that basal NO consists of TTX-sensitive and TTX-resistant components. The TTX-sensitive NO has an inhibitory effect on spontaneous contractions; the role of TTX-resistant NO is unknown.

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