scholarly journals EXPERIMENTS ON THE RELATION OF THE INHIBITORY TO THE ACCELERATOR NERVES OF THE HEART

1897 ◽  
Vol 2 (2) ◽  
pp. 151-179 ◽  
Author(s):  
Reid Hunt
Keyword(s):  
Mode Of Action ◽  
Inhibitory Effect ◽  
Relative Strength ◽  
The Other ◽  
Maximal Stimulation ◽  
The One ◽  
Considerable Period ◽  
Minimal Stimulation ◽  
Ventricular Beat ◽  
Stimulation Of

The experiments described in Part IV of this paper show that in whatever manner the problem of the relation of the vagus to the accelerators is approached, whether the accelerators are stimulated during a stimulation of the vagus, or the vagus during a stimulation of the accelerators, or both are stimulated simultaneously, either for a short or for a longer period, the result is the same, viz., the effect upon the rate of the heart is determined entirely by the relative strength of the stimuli applied to the two nerves. If the stimuli are of approximately the same strength, as judged by the effect of stimulating the nerves separately, the rate of the heart is but slightly affected; if the stimulus applied to the vagus is the stronger, the heart is slowed; if it is weaker, the heart is accelerated. In all cases the result of stimulating the two nerves simultaneously is approximately the algebraic sum of the results of stimulating them separately; sometimes the inhibitory effect slightly predominates, but not more frequently than does the accelerator effect. Moreover, the two nerves may be stimulated simultaneously for a considerable period of time without either completely overcoming the effect of the other. Thus as far as their effect upon the rate of the ventricular beat is concerned, the vagus and accelerator nerves seem to be purely antagonistic; the statement that a minimal stimulation of the one can completely overcome a maximal stimulation of the other is undoubtedly incorrect, and the hypotheses as to the mode of action of these nerves upon the heart, based upon this statement, lose their chief support.

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.

scholarly journals The integration of plant behaviour V—Growth substance and traumatic curvature of the root

1935 ◽  
Vol 117 (803) ◽  
pp. 92-119 ◽  
Keyword(s):  
Positive Curvature ◽  
Inhibitory Effect ◽  
Growth Substance ◽  
The Other ◽  
Root Tip ◽  
Lower Side ◽  
Mode Of Operation ◽  
The One ◽  
Lateral Wound ◽  
Plant Behaviour

The manner of response of the root to injury is well known. A lateral wound made within 1 mm or 2 mm of the extreme tip gives rise to a negative curvature: the root curves away from the wound. A similar injury made elsewhere in the growing region evokes a positive curvature; the root curves towards the wound. The curvatures are manifestly growth curvatures. Like those induced by gravity, traumatic curvatures are the consequence of unequal growth of opposite sides of the region of elongation. In the one case they are undoubtedly brought about by the stimulus of gravity; and in the other they are supposed also to owe their origin to a stimulus, a wound stimulus. But, whereas something at all events is known of the way in which the stimulus of gravity acts on the root, the mode of operation of the wound stimulus—if stimulus there be— remains obscure. The Went-Cholodny hypothesis of geotropism which is supported by Cholodny’s experiments (1924, 1926), those of the authors in collaboration with R. Snow (1931), of Boysen-Jensen (1933, a, b ), and others (Snow, 1932), attributes to growth substance contained in the root an essential part in geotropic curvature. It holds that growth substance which inhibits the growth of the root is a normal secretion of the root tip. Produced continuously by the tip, it passes upwards by straight paths and reaches all parts of the region of elongation. Although in the passage through the elongating region the concentration falls off progressively, the dis­tribution of growth substance at any given level is uniform and therefore, the inhibitory effect being equal on all sides, the unstimulated root continues to follow a straight downward path. When, however, the root is exposed to the stimulus of gravity the uniformity of distribution of growth substance is disturbed; more is found to occur on the lower than on the upper side of the tip and the inequality of distribution is held to be due to a passage downward from the one side to the other. Since the lower side of the tip now contains more, and since growth substance travels from tip to elongating region by straight paths, the lower side of the elongating region comes also to contain more than the upper side; the upper side grows faster than the lower and the root curves downward.

scholarly journals Time-dependence of biological activity induced by covalent insulin-receptor complexes in rat adipocytes

1985 ◽  
Vol 232 (1) ◽  
pp. 49-53 ◽  
Author(s):  
A Schüttler ◽  
C Diaconescu ◽  
D J Saunders ◽  
D Brandenburg
Keyword(s):  
Insulin Receptor ◽  
Inhibitory Effect ◽  
Receptor Complex ◽  
Half Time ◽  
Simple Method ◽  
Receptor Complexes ◽  
Maximal Stimulation ◽  
Monocomponent Insulin ◽  
Specific Receptors ◽  
Stimulation Of

Lipogenesis in isolated adipocyte preparations is stimulated when photosensitive insulin derivatives are attached covalently to specific receptors. This response was compared quantitatively with that to reversibly associated insulin, and it was shown that both covalent and reversible insulin-receptor complexes behave very similarly. The extent of stimulation of lipogenesis was studied as a function of time. Cells were incubated in buffer for various times before addition to vials containing 0 (basal) or 10 ng of monocomponent insulin/ml (maximal) and [U-3H]glucose. After 60 min, the toluene-soluble [3H]lipids were measured. The maximal stimulation induced by reversibly bound insulin was virtually constant over a period of 4 h. In contrast, adipocytes to which N alpha B2-(2-nitro-4-azidophenylacetyl)-des-PheB1-insulin had been covalently attached at the start of the experiment showed a loss of stimulation with time when incubated at 37 degrees C. This loss was decreased in the presence of lysosomotropic agents such as chloroquine at concentrations (approx. 200 microM) that had very little or no effect on the basal and maximal lipogenesis rates. A simple method was used to transform the measured rate of loss of stimulation into a rate of loss of effective units. A half-time of 80 min was calculated for the effective covalent insulin-receptor units in adipocytes at 37 degrees C at pH 7.4. This is very close to values reported by others for the internalization of covalent complexes in these cells, suggesting that this may be the causative event for the deactivation of the insulin-receptor unit. The inhibitory effect of chloroquine on the deactivation may indicate that the insulin-receptor complex can function even after internalization.

scholarly journals VII. Experimental researches in electricity.-Twenty-third Series

1850 ◽  
Vol 140 ◽  
pp. 171-188 ◽  
Keyword(s):  
Magnetic Field ◽  
Mode Of Action ◽  
Royal Society ◽  
The Other ◽  
Experimental Proof ◽  
Philosophical Paper ◽  
Iron Nickel ◽  
The One ◽  
Experimental Researches ◽  
The Magnetic Field

Four years ago I suggested that all the phenomena presented by diamagnetic bodies, when subjected to the forces in the magnetic field, might be accounted for by assuming that they then possessed a polarity the same in kind as, but the reverse in direction of, that acquired by iron, nickel and ordinary magnetic bodies under the same circumstances (2429. 2430.). This view was received so favourably by Plücker, Reich and others, and above all by W. Weber, that I had great hopes it would be confirmed; and though certain experiments of my own (2497.) did not increase that hope, still my desire and expectation were in that direction. Whether bismuth, copper, phosphorus, &c., when in the magnetic field, are polar or not, is however an exceedingly important question; and very essential and great differences, in the mode of action of these bodies under the one view or the other, must be conceived to exist. I found that in every endeavour to proceed by induction of experiment from that which is known in this department of science to the unknown, so much uncertainty, hesitation and discomfort arose from the unsettled state of my mind on this point, that I determined, if possible, to arrive at some experimental proof either one way or the other. This was the more needful, because of the conclusion in the affirmative to which Weber had come in his very philosophical paper; and so important do I think it for the progress of science, that, in those imperfectly developed regions of knowledge, which form its boundaries, our conclusions and deductions should not go far beyond, or at all events not aside from the results of experiment (except as suppositions), that I do not hesitate to lay my present labours, though they arrive at a negative result, before the Royal Society.

scholarly journals The influence of homodromous and heterodromous electric currents on transmission of excitation in plant and animal

1915 ◽  
Vol 88 (607) ◽  
pp. 483-507 ◽  
Keyword(s):  
Electric Current ◽  
The Other ◽  
Muscle Preparation ◽  
Mimosa Pudica ◽  
Electric Currents ◽  
Joint Effects ◽  
Conducting Tissue ◽  
The One ◽  
Conduction Of Excitation ◽  
Stimulation Of

I have in a previous paper described investigation on the conduction of excitation in Mimosa pudica . It was there shown that the various characteristics of the propagation of excitation in the conducting tissue of the plant are in every way similar to those in the animal nerve. Hence it appeared probable that any newly found phenomenon in the one case was likely to lead to the discovery of a similar phenomenon in the other. A problem of great interest which has attracted my attention my attention for several years is the question whether, in a conducting tissue, excitation travels better with or against the direction of an electric current. The experimental difficulties presented in the prosecution of this enquiry are very numerous, the results being complicated by the joint effects of the direction of current on conductivity and of the poles on excitability. As regards the latter, the changes of excitability in the animal nerve under electrotonus have been demonstrated by the well-known experiments of pflüger. In a nerve-and-muscle preparation, the presence of a pole P is shown to induce a variation of excitability of a neighbouring point S. When P is kathode, the excitability of the point S, near it, is enhanced; stimulation of S, previously ineffective, now becomes effective, and the resulting excitation is transmitted to M, causing response of the muscle. Conversely, the application of anode at P causes a depression of excitability of S. Stimulus previously effective now becomes ineffective. In this manner the transmission of excitation may be indirectly modified by the polar variation of excitability of the stimulated point (fig. 1 a ).

scholarly journals The Anti-Bactericidal Action of the Bile Salts

1911 ◽  
Vol 11 (3) ◽  
pp. 373-380 ◽  
Author(s):  
S. Lyle Cummins
Keyword(s):  
Gall Bladder ◽  
Typhoid Fever ◽  
Mode Of Action ◽  
Bile Salts ◽  
Culture Media ◽  
The Other ◽  
Bactericidal Action ◽  
Gall Stones ◽  
The One

Bile and the bile salts are substances of great importance in connection with typhoid fever. On the one hand, they are extensively used in differential media for the isolation of B. typhosus from the excreta, and in media designed to cultivate the bacillus from the blood; while on the other, the survival of the organism in the gall bladder and its association with gall stones and cholicystitis indicate that bile may play an important rôle in the etiology of the disease. It would appear therefore that a study of the mode of action of bile in culture media for the isolation of B. typhosus might, apart from its bearing on bacteriological technique, incidentally throw light on the far more important question of typhoid fever and the production of typhoid carriers.

The Significance of Dopamine for the Mode of Action of Neuroleptics and the Pathogenesis of Schizophrenia

1977 ◽  
Vol 130 (5) ◽  
pp. 463-474 ◽  
Author(s):  
H. M. van Praag
Keyword(s):  
Side Effects ◽  
Clinical Research ◽  
Mode Of Action ◽  
Chemical Structure ◽  
Animal Experiments ◽  
The Other ◽  
Therapeutic Effects ◽  
Supporting Evidence ◽  
Pathogenetic Mechanism ◽  
The One

SummaryAnimal experiments have demonstrated the likelihood that all known neuroleptics inhibit transmission in central CA-ergic systems, regardless of their chemical structure and via different mechanisms. For clinical psychiatry this fact prompts a number of questions: (1) is this phenomenon also to be found in human individuals; (2) if so, is it of importance for the clinical (side) effects of neuroleptics; (3) do patients with (schizophrenic) psychoses show signs of central CA-ergic hyperactivity ? This article presents a survey of clinical research focused on these questions which, for the sake of brevity, is confined to DA metabolism. The available data indicate the plausibility of a correlation between inhibition of DA-ergic transmission on the one hand, and on the other hand the therapeutic effects of neuroleptics and the occurrence of hypokinetic-rigid symptoms. The hypothesis that DA-ergic hyperactivity is an important pathogenetic mechanism in schizophrenic psychoses can be based only on indirect arguments; direct studies of the DA metabolism have so far failed to reveal supporting evidence. The possible causes of this failure are discussed.

scholarly journals ON THE RELATION OF DIRECT CURRENTS TO CONDENSER DISCHARGES AS STIMULI

1935 ◽  
Vol 18 (5) ◽  
pp. 755-766 ◽  
Author(s):  
H. A. Blair
Keyword(s):  
Differential Equation ◽  
Electrical Stimulation ◽  
The Other ◽  
The One ◽  
Stimulation Of

Data on the electrical stimulation of sciatic-gastrocnemius preparations of the frog by both direct currents and condenser discharges at the same time are discussed in relation to the validity of the differential equation See PDF for Equation where p is the local excitatory process, V the stimulating current or voltage, and K and k are constants. It is concluded that the constant k is the same whether it is derived from the data of the one stimulus or the other when the same fibres are being stimulated.

scholarly journals Exposed Pedagogy: Architecture as (a) Medium (of communication)

2021 ◽  
Author(s):  
◽  
Michael Smith
Keyword(s):  
Public Discourse ◽  
The Other ◽  
Social Implications ◽  
The Public ◽  
The Social ◽  
The One ◽  
Stimulation Of ◽  
Three Components

<p>Architecture schools are often isolated from the profession and the public they serve both pedagogically and physically, and often this is justified. Schools are not typically very public. However, schools could play a much greater role in the stimulation of a public discourse around architecture. The intent of this thesis is to examine how architecture can stimulate that discussion and ultimately how architecture could frame that discourse. The thesis proposes that an architecture school can and should be a vehicle for public discourse by way of framing that discourse on the one hand and overtly stimulating it on the other. Specifically, an architecture school has the capacity to contribute to public discourse through the visual affects of form making and the social implications of that same form. The research is divided into three components that chronicle an argument from contextualisation, through investigation to application.</p>

scholarly journals II. On the rhythm of the heart of the frog, and on the nature of the action of the vagus nerve

1882 ◽  
Vol 33 (216-219) ◽  
pp. 199-203
Keyword(s):  
Vagus Nerve ◽  
The Body ◽  
The Other ◽  
Micrometer Screw ◽  
Lower Lever ◽  
The One ◽  
Stimulation Of

The method of investigation employed by the author is as follows:— The heart with the vagus nerve intact having been removed from the body together with a portion of the oesophagus, a thread is tied to the very apex of the ventricle and another to the loose flap which is dis­closed at the junction of the two auricles when the two aortic trunks are cut away. The piece of the oesophagus removed with the heart is held firmly in a suitable holder and the heart suspended between two horizontal levers by means of the two threads which are attached to the auricles and ventricle. Between the two levers a clamp is placed, the edges of which can be approximated to any degree by means of a fine micrometer screw j the two limbs of this clamp are placed one on each side of the suspended heart, and by means of the micrometer screw, the tissue between the two edges can be simply held firm or compressed to any extent required. In this way, with the clamp in the auriculo-ven­tricular groove, the beats of both auricles and ventricle are registered simultaneously and separately; the contractions of the auricles pull the upper lever downwards, those of the ventricle the lower lever upwards. Similarly by varying the position of the clamp the con­tractions of any two adjacent portions of the heart can be studied, as for example, sinus and 'auricles, base and apex of the ventricle, &c.; heat, cold, and poisons can be applied to the tissue on the one side of the clamp and not on the other; and under all these various condi­tions the effects of stimulation of the vagus can be observed.

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