摘要:

Summary.A gastric secretory factor predominantly localized in the pyloric region is present in mucosal extracts from cats, dogs, and pigs.The active agent is not histamine.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1943.tb02832.x

出版商:Blackwell Publishing Ltd    

年代:1943

数据来源: WILEY

摘要:

Summary.Histamine does not stimulate the peptic glands of the cat's gastric mucosa.Histamine does not inhibit the peptic secretion evoked by electrical stimulation of the vagi.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1943.tb02833.x

出版商:Blackwell Publishing Ltd    

年代:1943

数据来源: WILEY

摘要:

Summary.The gastric‐secretory excitant from the pyloric mucosa shows the following chemical porperties:—It is soluble in water. The solubility varies with the pH.It is insoluble in ether, acetone, benzene, and absolute and 80% ethyl alcohol.It is stable in weak acid and alkaline solutions. It resists heating in N/10 HCl at 100° C. but is destroyed when heated in N/10 NaOH to this temperature.It is inactivated by pepsin, trypsin (duodenal juice), and ultraviolet light.It dialyses through cellophane.It is precipitated by trichloracetic acid, metaphosphoric acid, NaCl, and ace

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1943.tb02834.x

出版商:Blackwell Publishing Ltd    

年代:1943

数据来源: WILEY

摘要:

Summary.The mechanical reaction of the isolated cross striated muscle fibre and the time course of the structural changes are investigated by means of microcinematographing the changes in length occuring in the anisotropic and isotropic substance, and recording the mechanical tension simultaneously. A's part in the height of compartment (A/A + I) varies continuously between 64 per cent at rest, and 56 per cent at the apex of contraction. The apex of the single contraction is reached 50 ms after the last resting point, and after a further 50 ms A/A + I returns to the resting value. The change of A/A + I occurs more quickly immediately after rest than during the remainder of the time course. There is a striking conformity between the decrease and increase in the change of A/A + I in spite of the essential difference in the simultaneously registered course of tension.The time course of the change in A/A + I during contraction and the size of the change in the range of stretch investigated (length 100–145), is independent of the stretch‐and amounts to about 100 ms.In spite of the fact that A/A + I reaches its resting value after 100 ms an essential mechanical tension is still found. This difference may be explained by assuming a different time course of the contraction and relaxation process in A and I.In accordance with previous investigations, no “all or none” reaction is found in the directly stimulated (curarised) fibre.The change of A/A + I propagates over the fibre without decrement. In experiments comparing local stimulation of the one end of the fibre with stimulation of the entire fibre, the same tension and gradation is found with both methods of stimulation. Locally released contractions are therefore propagated over the fibre without decrement. The intensity of the propagated wave of contraction is thus graded with the strength of stimulation, and proceeds over the fibre without decrement. Thus in muscle, in contradistinction to nerve, we have a combination of propagation and gradation.Simultaneous recording of the change in cross striation and tension at varying strength of stimulation shows that there is no measurable grading in A/A + I at equilibrium length and moderate degrees of stretch, whereas the mechanical tension varies in the ratio 1:3. To explain this apparent constancy in A/A + I at different degrees of contraction, one must either assume a very complicated mutual compensation between the changes in stiffness and equilibrium length in the A and I substance, or reckon with an “all or none” reaction of the minute structure elements. The latter possibility is a more simple explanation of the experimental observations. According to whether the contraction is weak or strong, a larger or smaller amount of resting submicroscopic elements shunts the contracting units.A quantitative examination of this assumption shows that a grading of contraction cannot induce measurable changes in A/A + I as long as the resting tension is relatively small. Only with a high degree of stretch (length 170), can a measurable gradation be expected in A/A + I The theory is confirmed by experiments. On the basis of the molecule equivalent previously described, and the present observations, a structural interpretation of the contraction mechanism is attempted.The authors are indebted to Dr. H. King, National Institute for Medical Research, Hampstead, for his kindness in supplying us with purified curarinechlorid, and to Mr. E. Kaiser, Engineer, for valuable advice concerning the treatment and interpretation of the material.The present work has been supported by grants from theMichaelsen Foundation, and theNordish Insulin

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1943.tb02835.x

出版商:Blackwell Publishing Ltd    

年代:1943

数据来源: WILEY

摘要:

Summary.The efferent “reflex” output in the dorsal root L 6 in response to afferent discharges from L 7 (the so‐called dorsal root reflex) has been studied in decerebrate cats with the aid of electrical stimuli of variable form. Special attention has been paid to the effect of temperature.Prolonged afferent discharges, set up by constant currents, cause prolonged dorsal root reflexes. Increased duration of the afferent discharge is accompanied by an inhibitory block, far more pronounced at normal temperature than at low temperature of the spinal cord.Intermittent afferent stimuli, set up by brief iterated shocks, elicit intermittent dorsal root “reflex” discharges which successively diminish in size. This depression increases with stimulus frequency and for any frequency is far more pronounced at normal temperature than at low temperature of the spinal cord.Afferent discharges set up by linearly rising currents of steep gradient, elicit well marked “reflex” discharges. But slowly rising currents, which still give well marked impulses in the input root, fail to cause the reflex response. For this to occur the linearly rising stimuli must be increased in strength so as to cause prolonged repetitive discharges. The necessary increase in current strength is greater at high than at low temperature of th

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1943.tb02836.x

出版商:Blackwell Publishing Ltd    

年代:1943

数据来源: WILEY

摘要:

Summary.The pulmonary ventilation and the oxygen intake during light to moderate work on the bicycle ergometer were determined under normal conditions and in experiments in which the circulation to the lower extremities was interrupted by means of pneumatic cuffs. The experiments showed, that although the oxygen intake could by this procedure be diminished by 20–50 pCt., the ventilation remained almost unchanged.From these experiments it is concluded, that the increase in the excitability of the respiratory centre towards CO2, which occurs during work cannot be ascribed to substances produced in the working muscles, but must be of nervous origi

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1943.tb02837.x

出版商:Blackwell Publishing Ltd    

年代:1943

数据来源: WILEY

摘要:

Summary.In experiments with voluntary and electrically induced work on a normal subject and on a patient (tabes dorsalis) in whom all the ordinary kinesthetic sensations were completely extinguished, the pulmonary ventilation increased during both kinds of work in the normal way i.e. corresponding to the oxygen consumption, in spite of the fact, that the cortical innervation during the electrically induced work was substituted by the apparatus for electrical stimulation.Prom these experiments it is concluded, that the nervous impulses which increase the excitability of the respiratory centre, thus causing the rise in the ventilation during work, are not of cortical origin, but most probably must be brought about reflexly from the working muscles.The experiments with the patient suffering from tabes dorsalis show further, that the reflex impulses must be carried to the centre through nerve paths outside the posterior fascicles, which are known to be destroyed in this disease.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1943.tb02838.x

出版商:Blackwell Publishing Ltd    

年代:1943

数据来源: WILEY

摘要:

Summary.On two subjects it is shown, that hyperventilation, caused by CO2‐breathing, has an increasing effect on the cardiac output if the subject lies horizontally, none, however, if the subject is tilted to an upright (60°) position. It is concluded, that the effect of CO2‐breathing on the cardiac output must be due to the mechanical forces of hyperventilation and not to a chemical action of the CO2on the circulation, as otherwise the difference of the effect in the two positions is unexplained.By increasing the inspiratory or exspiratory resistance artificially the negativity of the intra‐pleural pressure could be increased, respectively decreased. It was found that this had very slight and irregular effects on the cardiac output, and it is concluded, that the augmented negativity of the intra‐pleural pressure during hyperventilation cannot be the cause of the increased cardiac output.It is discussed how the deep respirations of the hyperventilation might influence the cardiac output, and the conclusion is put forward tentatively, that this is possible if one assumes that the enlarged respiratory movements cause a pressing‐out of blood from the intra‐pulmonary (or, and from the abdominal) vessels, when these are “filled” with blood (as in the horizontal position), not, however, when they are “empty” (as in the tilted position). The conclusion is supported by experiments, in which part of the blood was

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1943.tb02839.x

出版商:Blackwell Publishing Ltd    

年代:1943

数据来源: WILEY

摘要:

Summary.In electrically induced convulsions in the rabbit, initial cardiac inhibition and bradycardia occurs. This can be prevented by atropine and is attributed to vagus stimulation. The rise in arterial blood pressure starts in the later part of the tonic or on the onset of the clonic phase.Curare also prevents the cardiac inhibition, and the blood pressure rises at the beginning of the tonic phase. It is believed that the vagus stimulation is caused by a rise in intra‐cerebral pressure, induced by the rise of the intra‐abdominal and intrathoracic’ pressures during the convulsion, this action being prevented by curarisation.As the rise of blood pressure occurs even in curarized animals, it is not caused by the muscle convulsions.The disturbances of circulation in rabbits induced by electro‐shock differ in various respects from those found during electro‐shock convulsio

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1943.tb02840.x

出版商:Blackwell Publishing Ltd    

年代:1943

数据来源: WILEY

摘要:

Summary.The renal excretion of fructose is studied in dogs under different conditions. It is shown that the fructose is reabsorbed in the kidneys to some degree. The reabsorption is not influenced by alterations of the glucose concentration in the filtrate or by a considerable increase in the urine flow produced by the infusion of sulphate. On the other hand the excretion of fructose depends upon the concentration in the blood, a greater part of the filtered fructose being excreted at a higher plasma concentration.It is concluded, that a part of the filtered fructose is actively reabsorbed in the proximal part of the tubules by a process, the faculty of which to convey the fructose is not influenced by the amount of glucose which is simultaneously to be reabsorbed.

ISSN:0001-6772    

DOI:10.1111/j.1748-1716.1943.tb02841.x

出版商:Blackwell Publishing Ltd    

年代:1943

数据来源: WILEY