The action of local hormones

1950 ◽  
Vol 137 (888) ◽  
pp. 292-300 ◽  
Keyword(s):  
Primary Amine ◽  
General Circulation ◽  
Sympathetic Nerves ◽  
Blood Stream ◽  
The Other ◽  
Adrenergic Nerves ◽  
Important Advance ◽  
Unknown Substance ◽  
Stimulation Of

In order to account for the resemblance between the actions of sympathetic nerves and those of adrenaline, Elliott (1904) suggested that sympathetic nerves might act by liberating adrenaline. Discussing this theory Barger & Dale (1910) came to the conclusion that the actions of sympathetic nerves did not resemble those of adrenaline so closely as they did those of the corresponding primary amine now known as noradrenaline. Loewi’s demonstration that some sympathetic nerves do actually liberate a substance like adrenaline was published in 1921. Cannon & Rosenblueth (1937) obtained evidence that stimulation of the sympathetic nerves in a cat led to the liberation into the blood stream of a variable mixture of two substances. They supposed that one of those substances had purely excitor effects and the other purely inhibitor effects, and they called them sympathin E and sympathin I. The discovery that two substances were involved was an important advance, but it now seems likely that the two substances are adrenaline and noradrenaline, and since neither of these has purely excitor or purely inhibitor effects the terms sympathin E and Sympathin I should be forgotten. The word sympathin is a convenient label for the substances specifically liberated by adrenergic nerves and may perhaps survive with this meaning. The reason for the slow advance of knowledge about these substances is that the quantities available for study are small. The evidence is still almost entirely pharmacological, since no other methods are sensitive enough. The distinction between adrenaline and noradrenaline has depended on the use of parallel quantitative tests using tissues with different values for the ratio of the activities of these two drugs. If the unknown substance is adrenaline it should match the same amount of adrenaline by any test. It was by using this criterion and studying the effect on distant organs of substances liberated into the general circulation that Cannon & Rosenblueth showed that adrenaline was not the only substance liberated. Their results were such as might be produced by the liberation of a mixture of adrenaline and noradrenaline, but they did not adopt this explanation which was first published by Bacq (1933).

The Turnover in Normal Dogs of Prothrombin and Its Fragments; Effect of Induced Intravascular Coagulation

1979 ◽  
Vol 42 (02) ◽  
pp. 548-555 ◽  
Author(s):  
Charles A Owen ◽  
Kenneth G Mann ◽  
Frederic C McDuffie
Keyword(s):  
Close Agreement ◽  
Blood Stream ◽  
The Other ◽  
Normal Adult ◽  
Capillary Barrier ◽  
Prothrombin Fragment ◽  
Intravascular Coagulation ◽  
Dog Brain

SummaryWhen 125I-labeled canine prothrombin was given to normal adult dogs intravenously, it was calculated that 240% of the plasma prothrombin crossed the capillary barrier per day, 410% of the interstitial prothrombin returned to the blood stream daily, and 79% of the plasmatic prothrombin was catabolized per day. These data are in close agreement with those observed for bovine prothrombin in calves by Takeda (1970).When derived from normal dog prothrombin, prethrombin-1 is a mixture of 2 polypeptides, one larger than the other, and both present in about equal amounts. The longer peptide, “prethrombin-1-long,” was catabolized twice as fast as prothrombin, and the shorter, “prethrombin-1-short,” 4 times faster. Prothrombin fragment-1 was catabolized by the normal dog still more rapidly.The catabolism of prothrombin was not accelerated in 3 dogs receiving continuous infusions of a thromboplastic emulsion of dog brain. Nor was the level of prothrombin in their plasma remarkably altered.

EFFECT OF ACTINOMYCIN D ON TSH-INDUCED STIMULATION OF THYROIDAL PROTEIN SYNTHESIS IN THE RAT

1974 ◽  
Vol 77 (1) ◽  
pp. 64-70 ◽  
Author(s):  
Gustav Wägar
Keyword(s):  
Protein Synthesis ◽  
Actinomycin D ◽  
The Other ◽  
Leucine Incorporation ◽  
Short Term ◽  
Other Hand ◽  
Thyroid Glands ◽  
Translational Level ◽  
Stimulation Of

ABSTRACT Whether the short-term regulation of thyroidal protein synthesis by TSH occurs at the transcriptional or the translational level was tested by measuring the effect of actinomycin D (act D) on the TSH-induced stimulation of L-14C-leucine incorporation into the thyroidal proteins of rats. TSH was injected 6 h before the rats were killed. The thyroid glands were then removed and incubated in vitro in the presence of L-14C-leucine for 2 h. The pronounced stimulation of leucine incorporation in the TSH-treated animals was depressed as compared with controls but still significant even when the animals had been pre-treated with 100 μg act D 24 and 7 h before sacrifice. On the other hand, act D strongly decreased incorporation of 3H-uridine into RNA. Short-term regulation of thyroidal protein synthesis by TSH appears to be partly but not wholly dependent on neosynthesis of RNA. Hence regulation may partly occur at the translation level of protein synthesis.

scholarly journals Receptor-operated Ca2+ channels in gastric parietal cells: gastrin and carbachol induce Ca2+ influx in depleting intracellular Ca2+ stores

1993 ◽  
Vol 289 (1) ◽  
pp. 117-124 ◽  
Author(s):  
S Roche ◽  
J P Bali ◽  
R Magous
Keyword(s):  
Steady State ◽  
Receptor Activation ◽  
Parietal Cells ◽  
The Other ◽  
Bivalent Cation ◽  
Gtp Binding ◽  
Gastric Parietal Cells ◽  
Type Receptor ◽  
Ca2 Channels ◽  
Stimulation Of

The mechanism whereby gastrin-type receptor and muscarinic M3-type receptor regulate free intracellular Ca2+ concentration ([Ca2+]i) was studied in rabbit gastric parietal cells stimulated by either gastrin or carbachol. Both agonists induced a biphasic [Ca2+]i response: a transient [Ca2+]i rise, followed by a sustained steady state depending on extracellular Ca2+. Gastrin and carbachol also caused a rapid and transient increase in Mn2+ influx (a tracer for bivalent-cation entry). Pre-stimulation of cells with one agonist drastically decreased both [Ca2+]i increase and Mn2+ influx induced by the other. Neither diltiazem nor pertussistoxin treatment had any effect on agonist-stimulated Mn2+ entry. Thapsigargin, a Ca(2+)-pump inhibitor, induced a biphasic [Ca2+]i increase, and enhanced the rate of Mn2+ entry. Preincubation of cells with thapsigargin inhibits the [Ca2+]i increase as well as Mn2+ entry stimulated by gastrin or by carbachol. Thapsigargin induced a weak but significant increase in Ins(1,4,5)P3 content, but this agent had no effect on the agonist-evoked Ins(1,4,5)P3 response. In permeabilized parietal cells, Ins(1,4,5)P3 and caffeine caused an immediate Ca2+ release from intracellular pools, followed by a reloading of Ca2+ pools which can be prevented in the presence of thapsigargin. We conclude that (i) gastrin and carbachol mobilize common Ca2+ intracellular stores, (ii) Ca2+ permeability secondary to receptor activation involves neither a voltage-sensitive Ca2+ channel nor a GTP-binding protein from the G1 family, and (iii) agonists regulate common Ca2+ channels in depleting intracellular Ca2+ stores.

Peripheral muscarinic control of norepinephrine release in the cardiovascular system

1980 ◽  
Vol 239 (6) ◽  
pp. H713-H720 ◽  
Author(s):  
E. Muscholl
Keyword(s):  
Physiological Role ◽  
Sympathetic Nerves ◽  
Adrenergic Nerve ◽  
Sequence Of Events ◽  
Adrenergic Response ◽  
Adrenergic Nerve Terminals ◽  
Muscarinic Cholinergic ◽  
Related Compounds ◽  
Stimulation Of

Activation of muscarinic cholinergic receptors located at the terminal adrenergic nerve fiber inhibits the process of exocytotic norepinephrine (NE) release. This neuromodulatory effect of acetylcholine and related compounds has been discovered as a pharmacological phenomenon. Subsequently, evidence for a physiological role of the presynaptic muscarinic inhibition was obtained on organs known to be innervated by the autonomic ground plexus (Hillarp, Acta. Physiol. Scand. 46, Suppl. 157: 1-68, 1959) in which terminal adrenergic and cholinergic axons run side by side. Thus, in the heart electrical vagal stimulation inhibits the release of NE evoked by stimulation of sympathetic nerves, and this is reflected by a corresponding decrease in the postsynaptic adrenergic response. On the other hand, muscarinic antagonists such as atropine enhance the NE release evoked by field stimulation of tissues innervated by the autonomic ground plexus. The presynaptic muscarine receptor of adrenergic nerve terminals probably restricts the influx of calcium ions that triggers the release of NE. However, the sequence of events between recognition of the muscarinic compound by the receptor and the process of exocytosis still remains to be clarified.

On Research and Other Matters

1922 ◽  
Vol 26 (140) ◽  
pp. 325-330
Author(s):  
S. Heckstall Smith
Keyword(s):  
British Empire ◽  
Air Force ◽  
The Other ◽  
Other Hand ◽  
Secretary Of State ◽  
The Press ◽  
The Subject ◽  
Stimulation Of

If the thought of another war troubles you, then don't read this article. If you would rather say to yourself as the Secretary of State said to the Air Conference, “ There won't be another war for ten years, so why worry? ” then no doubt you will think with him that it is better to let other nations have alk the bother and expense of trying to advance; after all, we are jolly fine fellows and can soon pick up. If, on the other hand, you have imagination which gives you a nasty queasy sensation when you think of what might be, then perhaps the following notes, albeit disjointed and mostly stale, may at least conjure up in you thoughts of your own on the subject. This is all that is needed to help, our advancement in the air–the stimulation of spoken and written thoughts by the British nation, for if every taxpayer in the British Empire says “ Air Force,” then the Press and Parliament will say it too.

Localization of Stereotactic Targets by Microrecording of Thalamic Somatosensory Evoked Potentials

Neurosurgery ◽  
1991 ◽  
Vol 28 (2) ◽  
pp. 223-230 ◽  
Author(s):  
Fumio Shima ◽  
Takato Morioka ◽  
Shozo Tobimatsu ◽  
Omiros Kavaklis ◽  
Motohiro Kato ◽  
...  
Keyword(s):  
Evoked Potentials ◽  
Median Nerve ◽  
Somatosensory Evoked Potentials ◽  
Practical Method ◽  
The Other ◽  
Basal Region ◽  
Thalamic Nuclei ◽  
Median Nerve Stimulation ◽  
Lower Amplitude ◽  
Stimulation Of

Abstract To improve the localization of stereotactic targets, somatosensory evoked potentials (SEPs) were recorded from the thalamus and subthalamic area using a specially designed semimicroelectrode in 61 patients and a conventional “macroclectrode” in 17 patients. By means of the semimicroelectrode, median nerve stimulation evoked two distinct SEPs, consisting of a diphasic wave with a huge positivity restricted to the nucleus ventrocaudalis (Vc) and a triphasic wave of lower amplitude with a major negativity in the ventral part of the nucleus ventrointermedius (Vim) and nucleus ventrooralis posterior (Vop) as well as the subthalamic lemniscal pathway. The Vim-Vc junction could thus be clearly delineated by an abrupt transition of SEPs from one type to the other with a precision of 1 mm. The parvicellular part of the Vc (Vcpc). situated in its basal region, was distinguishable from the Vc proper by a significant reduction of the positivity elicited by stimulation of the median nerve and by a rapid growth of a diphasic SEPs to stimulation of the posterior tibial nerve. In the other thalamic nuclei, stimulation of the median nerve elicited triphasic SEPs of a very small amplitude, suggesting a volume conduction current from the lemniscal pathway. With the macroclectrode, the positivity in the Vc was sensitive to electrode manipulation and the thalamic nuclei could not be distinctly outlined. SEP monitoring using the semimicroelectrode significantly improved the precision of target localization, which allowed minimizing of the volume of the therapeutic lesion without losing surgical effectiveness, while avoiding complications associated with increased penetration of the coagulating electrode. It is suggested that recording serial thalamic SEPs with the semimicroelectrode is a practical method to refine stereotactic targets in the thalamus.

scholarly journals The interaction between two trains of impulses converging on the same motoneurone

1929 ◽  
Vol 105 (738) ◽  
pp. 363-371 ◽  
Keyword(s):  
Mechanical Effect ◽  
The Other ◽  
Muscle Fibres ◽  
Flexor Muscle ◽  
Afferent Pathways ◽  
Afferent Nerves ◽  
Maximal Stimulation ◽  
The Common ◽  
The Relationship ◽  
Stimulation Of

It was shown in an earlier paper (7) that if maximal stimulation of either of two different afferent nerves can reflexly excite fractions of a given flexor muscle, there are generally, within the aggregate of neurones which innervate that muscle, motoneurones which can be caused to discharge by either afferent (i. e., motoneurones common to both fractions). The relationship which two such afferents bear to a common motoneurone was shown, by the isometric method of recording contraction, to be such that the activation of one afferent, at a speed sufficient to cause a maximal motor tetanus when trans­mitted to the muscle fibres, caused exclusion of any added mechanical effect when the other afferent was excited concurrently. This default in mechanical effect was called “occlusion.” Occlusion may conceivably be due to total exclusion of the effect of one afferent pathway on the common motoneurone by the activity of the other; but facilitation of the effect of one path by the activation of the other when the stimuli were minimal suggests that, in some circumstances at least, the effect of each could augment and summate with th at of the other at the place of convergence of two afferent pathways. Further investigation, using the action currents of the muscle as indication of the nerve impulses discharged by the motoneurone units, has now given some information regarding the effect of impulses arriving at the locus of convergence by one afferent path when the unit common to both is already discharging in response to impulses arriving by the other afferent path. Our method has been to excite both afferent nerves in overlapping sequence by series of break shocks at a rapid rate and to examine the action currents of the resulting reflex for evidence of the appearance of the rhythm of the second series in the discharge caused by the first when the two series are both reaching the motoneurone.

Neural Patterns Associated with Ventilatory Movements in Dragonfly Larvae

1970 ◽  
Vol 52 (1) ◽  
pp. 167-175
Author(s):  
P. J. MILL
Keyword(s):  
Control System ◽  
Motor Activity ◽  
Action Potentials ◽  
Motor Units ◽  
The Other ◽  
Ventilatory Control ◽  
Expiratory Phase ◽  
Segmental Nerve ◽  
Ventral Muscle ◽  
Stimulation Of

1. Rhythmic bursts of motor activity associated with the expiratory phase of ventilation have been recorded from the second lateral segmental nerves of posterior abdominal ganglia in Aeshna and Anax larvae. 2. In Aeshna the rhythmic expiratory bursts contain one, or sometimes two, motor units; whereas in Anax there are almost invariably three units. In both animals only one unit is associated with action potentials in the respiratory dorso-ventral muscle. 3. Motor activity synchronized with the expiratory bursts in the second nerves has been recorded from the other lateral nerves and from the last unpaired nerve. In addition the fifth lateral nerves carry inspiratory bursts. 4. It has been confirmed that stimulation of a first segmental nerve can re-set the ventilatory rhythm by initiating an expiratory burst in the second nerves. The original frequency is immediately resumed on cessation of stimulation. 5. The nature of the ventilatory control system in dragonfly larvae is discussed in relation to other rhythmic systems in the arthropods.

Effects of intravenous anesthetic agents on left ventricular function in dogs

1977 ◽  
Vol 232 (1) ◽  
pp. H44-H48
Author(s):  
L. D. Horwitz
Keyword(s):  
Left Ventricular Pressure ◽  
Cardiovascular Effects ◽  
Sympathetic Nerves ◽  
Left Ventricular ◽  
Intravenous Anesthetic ◽  
First Derivative ◽  
Anesthetic Agents ◽  
Thiopental Sodium ◽  
Stimulation Of ◽  
Mean Heart Rate

The cardiovascular effects of ketamine hydrochloride and thiopental sodium were studied in 11 dogs. During anesthesia, mean heart rate rose to 185 beats/min with ketamine and 147 beats/min with thiopental. Cardiac output was increased with ketamine but unchanged by thiopental. The maximum first derivative of the left ventricular pressure (dP/dt max) fell by 14% with thiopental but did not change significantly with ketamine. Propranolol resulted in attenuation of the tachycardia and a fall of 10% in dP/dt max with ketamine but had little effect on the response to thiopental. Phentolamine had no consistent effects on either drug. With pentolinium both drugs decreased dP/dt max. Intracoronary injection of ketamine decreased dP/dt max. Adrenalectomy had little effect on the responses to either anesthetic. The results lead to the conclusion that both ketamine and thiopental have myocardial depressant effects, but, whereas thiopental does not alter sympathetic tone, the depressive effects of ketamine are obscured by stimulation of cardiac sympathetic nerves.

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