bluuebunny/crossref_metadata_2025_split huggingface dataset:
Relationship between cortisone and muscle work in determining muscle size
Authors: Goldberg A. L. , Goodman H. M. 
Published: December 2014

1. Large doses of cortisone caused marked atrophy of the plantaris muscle and other pale muscles of hind limbs of hypophysectomized rats, but hormone treatment had little effect on the size of the red soleus muscle.2. Denervation increased the sensitivity of the soleus and plantaris to the catabolic effects of cortisone.3. Increased work induced by tenotomy of the synergistic gastrocnemius made the plantaris muscle less sensitive to cortisone‐induced atrophy.4. Since the catabolic effects of cortisone are more pronounced in the less active muscles, it is suggested that in mobilizing body protein for gluconeogenesis the hormone spares those muscles physiologically most active.5. The rapidity with which muscles lose weight in response to cortisone indicates that the hormone must decrease protein half‐lives as well as decrease protein synthesis.
An analysis of possible nervous mechanisms involved in the peristaltic reflex
Authors: Kottegoda S. R. 
Published: December 2014

1. The effects of drugs on peristalsis and on the contractions of the two muscle coats of the isolated guinea‐pig ileum in response to co‐axial electrical stimulation have been studied.2. Co‐axial stimulation (0·1 msec pulses) never produces simultaneous contraction of both muscle coats. When one muscle contracts, the other either relaxes or remains quiescent.3. The circular muscle contraction has two components. The first is reflex in origin and is brought about either by distension of the gut with increasing intraluminal filling or by the contraction of the longitudinal muscle in response to electrical stimulation at low frequency (1/sec), provided this raises the intraluminal pressure to the threshold for eliciting the circular muscle contraction. As the circular muscle contracts, the longitudinal muscle relaxes although stimulation continues. If the circular muscle contraction is prevented by reducing the intraluminal filling, or by adding a ganglion‐blocking drug, the longitudinal muscle remains contracted until withdrawal of the stimulus.4. In the presence of hyoscine, the reflex contraction of the circular muscle is unimpaired but, since the longitudinal muscle contraction is abolished, a higher intraluminal pressure is required to elicit the reflex.5. The second component of the circular muscle contraction appears in response to electrical stimulation at high frequency (3‐10/sec), upon withdrawal of electrical stimulation. This delay indicates the simultaneous stimulation of a dominant inhibitory innervation.6. The excitatory nerves to the circular muscle require a higher frequency of stimulation than those to the longitudinal muscle, which respond to single shocks.7. Cholinergic blocking agents (hyoscine, morphine, hemicholinium and botulinum toxin) antagonize the responses of the longitudinal muscle to co‐axial stimulation without affecting those of the circular muscle, thus suggesting that the excitatory fibres to the circular muscle are not cholinergic. Prostaglandins (E1 and E2) selectively antagonize the circular muscle contractions evoked by co‐axial stimulation. Tetrodotoxin blocks both longitudinal and circular muscle responses.8. Dimethylphenylpiperazinium (DMPP) and 5‐hydroxytryptamine (5‐HT) stimulate ganglia but have no direct action on the smooth muscle of guinea‐pig ileum.9. During a maintained contraction of the longitudinal muscle in the presence of high concentrations of acetylcholine (2·5 × 10−7 to 10−6 g/ml.) a contraction of the circular muscle accompanied by a relaxation of the longitudinal muscle is elicited by distension of the gut, and by co‐axial stimulation. Similar reciprocal responses are produced by 5‐HT or by DMPP and they are finally blocked by DMPP.10. These results are consistent with the hypothesis that in the myenteric plexus there exists an arrangement of nerves which ensures that the two muscle coats of the intestine do not contract simultaneously but are activated reciprocally so that when one muscle layer contracts the other relaxes or is prevented from contracting.
The effect of CO2 on ventilation and breath‐holding during exercise and while breathing through an added resistance
Authors: Clark T. J. H. , Godfrey S. 
Published: December 2014

1. Ventilation was measured while subjects were made to rebreathe from a bag containing CO2 and O2 in order to expose them to a steadily rising CO2 tension (PCO2). The object of the experiments was to determine the effect of a variety of stimuli upon the increase in ventilation and fall in breath‐holding time which occurs in response to the rising PCO2.2. Steady‐state exercise at 200 kg.m/min resulted in a small fall in the slope of the ventilation—CO2 response curve (SV) and a small, though not statistically significant, fall in the PCO2 at which ventilation would be zero by extrapolation (BV). There was a marked fall in the slope of the breath‐holding—CO2 response curve (SBH) and an increase in the PCO2 at which breath‐holding time became zero by extrapolation (BBH).3. These results have been interpreted with the aid of a model of the control of breath‐holding and it is suggested that there is no change in CO2 sensitivity on exercise, either during rebreathing or breath‐holding.4. An increase in the resistance to breathing caused a marked reduction in SV and BV, but no change in the breath‐holding—CO2 response curve. These findings suggest that the flattening of the ventilation—CO2 response curve is mechanical in origin and acute airway obstruction produces no change in CO2 sensitivity.5. On the basis of these results, we suggest that more information about CO2 sensitivity can be obtained by a combination of ventilation and breath‐holding—CO2 response curves.
Visual area of the lateral suprasylvian gyrus (Clare—Bishop area) of the cat
Authors: Hubel David H. , Wiesel Torsten N. 
Published: December 2014

On anatomical and physiological grounds a zone of cat cortex deep in the medial bank of the suprasylvian sulcus (the Clare—Bishop area) is known to receive strong visual projections both from the lateral geniculate body and area 17. We have mapped receptive fields of single cells in this area in eight cats.Active responses to visual stimuli were found over most of the medial bank of the suprasylvian sulcus extending to the depths and over to the lowest part of the lateral bank. The area is clearly topographically arranged. The first responsive cells, recorded over the lateral convexity and 2‐3 mm down the medial bank, had receptive fields in the far periphery of the contralateral visual fields. The receptive fields tended to be large, but showed considerable variation in size and scatter in their positions. As the electrode advanced down the bank, fields of successively recorded cells gradually tended to move inwards, so that in the depths of the sulcus the inner borders of many of the fields reached the vertical mid line. Here the fields were smaller, though they still varied very much in size.Receptive fields were larger than in 17, 18, or 19, but otherwise were not obviously different from the complex and lower‐order hypercomplex fields in those areas. No simple fields, or concentric fields of the retino‐geniculate type, were seen. Cells with common receptive‐field orientation were grouped together, but whether or not the grouping occurs in columns was not established.Most cells were driven independently by the two eyes. Fields in the two eyes seemed to be identical in organization. Cells dominated by the contralateral eye were much more common than ipsilaterally dominated ones, but when cells with parafoveal and peripheral fields were considered separately, the asymmetry was seen to apply mainly to cells with peripheral fields.
Comparison of the effects of water deprivation and sodium chloride imbibition on the hormone content of the neurohypophysis of the rat
Authors: Jones C. W. , Pickering B. T. 
Published: December 2014

1. Vasopressin and oxytocin have been measured in the neurohypophysis of rats which had either been given a 2% (w/v) NaCl solution to drink or been deprived of drinking water for up to 5 days.2. There was a progressive decrease in the vasopressin content of the glands in both groups; the rates of depletion were not significantly different.3. Oxytocin also decreased progressively in both groups but the glands from the ‘saline‐treated’ rats contained less hormone than those from the ‘water‐deprived’ animals.4. The differences in gland content of oxytocin could not be correlated with differences between the plasma osmolalities or sodium concentrations of the two groups.
Tetrodotoxin‐resistant electric activity in presynaptic terminals
Authors: Katz B. , Miledi R. 
Published: December 2014

1. The electric properties of the giant synapse in the stellate ganglion of the squid have been further investigated.2. During tetrodotoxin (TTX) paralysis, a local response can be elicited from the terminal parts of the presynaptic axons after intracellular injection of tetraethyl ammonium ions (TEA).3. The response is characterized by an action potential of variable size and duration, whose fall is often preceded by a prolonged plateau. The response, especially the duration of the plateau, is subject to ‘fatigue’ during repetitive stimulation.4. The TTX‐resistant form of activity is localized in the region of the synaptic contacts, and shows a marked electrotonic decrement even within less than 1 mm from the synapse. It is found only on the afferent, not on the efferent, side of the synapse.5. During the plateau of the response, the membrane resistance is greatly reduced below its resting value.6. The response depends on presence of external calcium and increases in size and duration with the calcium concentration. Strontium and barium substitute effectively for calcium. Manganese and, to a lesser extent, magnesium, counteract calcium and reduce the response. The response also declines, and ultimately disappears, if sodium is withdrawn for long periods.7. The relation of the local TTX‐resistant response to the influx of calcium ions and to the release of the synaptic transmitter is discussed.
Mechanism of stimulation of type J pulmonary receptors
Authors: Paintal A. S. 
Published: December 2014

1. The responses of type J pulmonary receptors (identified according to existing criteria) were studied in anaesthetized cats by recording impulses in individual vagal afferent fibres whose conduction velocity ranged from 0·8 to 7 m/sec.2. Measurements of actual latencies between insufflation of halothane or ether into the lungs and the excitation of the endings, and the latencies before and after circulatory arrest have established that the endings are located in the interstitial tissues close to the pulmonary capillaries. Mainly for this reason, the term juxta‐pulmonary capillary receptors (i.e. type J receptors) has been applied to these endings in preference to the term K deflation receptors used hitherto.3. The endings were stimulated by pulmonary congestion produced by occlusion of the aorta or left a—v junction for short periods. They were markedly stimulated during pulmonary congestion following injection of alloxan (150 mg/kg) or the addition of chlorine to the inspired air. This excitation was associated with a marked rise in pulmonary artery pressure and the occurrence of pulmonary oedema. However, the actual onset of excitation occurred some time after the rise in pressure and it was in fact more closely related to fall in pulmonary compliance. The frequency of discharge averaged over about 10–20 sec (in order to take the periods of relative inactivity into account) was 7·5 impulses/sec in 10 fibres (range 0·6–19 impulses/sec;
S.D. 6·3). This is intense stimulation of the endings and the congestion so produced is therefore regarded as a severe stimulus for the endings.4. The pattern of excitation was variable. In some fibres the activity consisted of periodic bursts of impulses which seemed to be set off during the deflation phase of artificial respiration, sometimes during the inflation phase. This periodic activity was not due to contraction of smooth muscle as the endings are not stimulated following injection of histamine (into the right ventricle) which is known to stimulate smooth muscles in the alveolar ducts and respiratory bronchioles.5. It is postulated that the actual stimulus for the endings is a rise in interstitial pressure or volume produced by a rise in pulmonary capillary pressure. Evidence has been gathered to show that the latter rises during muscular exercise; this rise must stimulate the endings. It was therefore postulated that stimulation of the endings should cause reflex inhibition of limb muscles (for terminating exercise).
The partition of uterine blood flow in the pregnant rabbit
Authors: Duncan Sheila L. B. 
Published: December 2014

1. In pregnant rabbits near term, cardiac output and its distribution were measured by injection of isotope‐labelled microspheres into the left ventricle. Hypoxaemia (mean Pa,O2 35 mm Hg) caused a reduction in placental and renal flows, while myometrial flow was unchanged and coronary and cerebral blood flows increased.2. In the lateral (ovarian) end of the uterine horn foetal and placental weight and absolute maternal placental blood flow were greater than in intermediate or medial positions. Placental flow (per 100 g placental tissue) was most in the most lateral placenta and decreased in the intermediate positions, especially when there were many placentas in the same horn.3. Abortions and runts (more than 2
S.D. below the mean weight for their age) occurred most often in the medial end of the uterine horn, while oversize foetuses (more than 2
S.D. above the mean weight) usually occupied the most lateral position.4. Ovarian blood flow (460 ml./100 g. min) was relatively large (e.g. compared with renal flow, 275 ml./100 g.min).
Afferent connexions to Group I activated cells in the main cuneate nucleus of the cat
Authors: Rosén Ingmar 
Published: December 2014

1. Extracellular recordings were made from a total of 240 group I activated cells in the main cuneate nucleus. Cuneothalamic relay neurones (128) were identified by antidromic stimulation of the medial lemniscus in the ventrobasal thalamic complex.2. A majority of the relay neurones were activated by afferents in only one of six dissected forelimb nerves innervating muscle groups at various joints. Even among afferents from adjacent synergistic muscles, convergence to individual neurones was infrequent.3. Some of the relay neurones received excitation from group II muscle afferents in the same nerve that provided group I excitation. Excitation from group II muscle afferents in other nerves was uncommon. Some neurones were weakly excited by cutaneous volleys.4. Inhibition of group I relay cells was produced from cutaneous afferents and group II muscle afferents. Weak inhibition was sometimes observed from group I afferents. The relay cells were also inhibited by stimulation of the cerebral cortex with a focus around the lateral end of the cruciate sulcus. A good correspondence was found between the inhibition and the depolarization of group I afferent terminals in the cuneate nucleus.5. A majority of the group I activated cells not antidromically activated from the ventrobasal complex (‘non‐relay cells’) were excited by cortical stimulation. Excitation from cutaneous afferents and group II muscle afferents was frequently found among these cells.6. The group I activated cells were found almost exclusively in the ventral part of the nucleus.7. The pattern of convergence found in eleven group I activated cells in the dorsal horn of the spinal cord from C 2 to C 4 is described.
Excitation of Group I activated thalamocortical relay neurones in the cat
Authors: Rosén Ingmar 
Published: December 2014

1. Extracellular recordings have been made from 134 group I activated neurones in the ventrobasal thalamic complex. One hundred of the neurones were identified as thalamocortical relay neurones by antidromic activation from the projection areas for group I afferents.2. The discharge evoked by group I volleys showed characteristic fluctuations in latency and number of spikes. The mechanisms underlying these phenomena are discussed.3. Half of the relay neurones were activated from afferents in only one of six dissected forelimb nerves innervating muscle groups at the various forelimb joints. Two‐thirds of the relay neurones were activated from at least two adjacent synergistic muscles.4. The pattern of group I convergence in the thalamic neurones is compared with that at the cuneate and cortical levels of the group I pathway to the cerebral cortex. It is suggested that integration of information from synergistic muscles occurs at the thalamic level and that integration of information from muscle groups of more unrelated function occurs at the cortical level.5. A few of the thalamocortical cells (15%) were activated by group II muscle afferents, often in the same nerve as that which provided group I excitation. Weakly linked excitation from cutaneous afferents was observed in 39% of the neurones.6. Stimulation of the group I projection area in the first sensorimotor cortex at moderately high stimulus frequencies produced a trans‐synaptic excitation in most of the group I activated cells.
The role of energy metabolism in calcium‐evoked secretion from the adrenal medulla
Authors: Rubin R. P. 
Published: December 2014

1. Experiments were carried out on cat adrenal glands perfused with Locke solution to study the effects of inhibition of metabolism on calcium‐evoked catecholamine release.2. In the presence of sodium cyanide (CN, 0·2 m
M), a low concentration of glucose (1 m
M) prevented the gradual decline in the secretory response to sequential exposures to calcium. Furthermore, when the secretory response was almost completely blocked by perfusing with a glucose‐deprived solution containing CN, restoration of secretion was correlated with the glucose concentration in the perfusion medium.3. In the presence of CN, 2‐deoxyglucose blocked both the protective effect and the restorative effect of glucose. The deoxyglucose inhibition of the glucose‐dependent restoration of secretion was antagonized by a higher concentration of glucose.4. Restoration of calcium‐evoked secretion was also observed after the washout of CN. The extent of this restoration was not at all related to the glucose concentration and was not affected by various inhibitors of carbohydrate metabolism, including deoxyglucose.5. Analysis of adrenal glands which had been perfused first with a glucose‐free solution containing CN and subsequently with the normal medium indicated that no discernible synthesis of catecholamines had taken place during the experimental procedures.6. The data provide further evidence that the action of calcium to trigger medullary secretion requires the presence of metabolic energy and support the hypothesis that an interaction between calcium and high‐energy nucleotides is a step in the sequence of events leading to the extrusion of catecholamines from the chromaffin cell.
Temperature dependence of a sodium—potassium permeability ratio of a molluscan neurone
Authors: Gorman A. L. F. , Marmor M. F. 
Published: December 2014

1. The temperature dependence of the membrane potential of a molluscan giant neurone was examined under conditions which block the electrogenic activity of the Na—K exchange pump.2. When the Na pump was blocked by ouabain or the removal of external K, the membrane potential depolarized as temperature was increased.3. This depolarization was prevented by the replacement of external Na with impermeant cations, but was greater when Na was replaced with Li.4. All observed effects of ouabain were attributable to inhibition of the Na pump. The depolarization in response to ouabain at warmer temperatures was completely reversible, and the rate of both onset and reversibility of the ouabain effect was dependent upon temperature.5. Using a modified form of the constant field equation, the internal K concentration and the Na—K permeability ratio, PNa/PK, were calculated from the experimental data.6. PNa/PK was found to increase from 0·028 at 4° C to 0·068 at 18° C. It is suggested that this increase is due primarily to a change in PNa.
Spinal sympathetic reflexes initiated by coronary receptors
Authors: Brown A. M. , Malliani A. 
Published: December 2014

1. The main left coronary artery of vagotomized spinal cats was perfused at different flows and pressures. The changes in pressure were limited to the coronary bed.2. Increased coronary flow which increased coronary arterial pressure provoked a reflex increase in sympathetic discharge in the white ramus of the third thoracic spinal nerve and the inferior cardiac nerve. Reflex reductions in activity were not observed.3. Occlusion of the coronary sinus and myocardial ischaemia, due to cessation of pump inflow, evoked similar reflex increases of sympathetic activity. The effect of myocardial ischaemia was apparent before systemic arterial blood pressure fell or left ventricular end‐diastolic pressure rose.4. Increased coronary arterial pressure, myocardial ischaemia and coronary sinus occlusion could activate the same preganglionic neurone.5. The afferent limb of the excitatory coronary‐sympathetic reflex was in the cardiac sympathetic nerves, mainly on the left. Afferent nerve fibres running in these nerves and in the third left thoracic sympathetic ramus communicans were excited by increased coronary arterial pressure, myocardial ischaemia, and occlusion of the coronary sinus. Inhibition was not observed. Many of the receptors were further localized by direct probing over the coronary vessels and adjacent myocardium.6. Some receptors were excited by increased coronary arterial pressure alone, others by coronary sinus occlusion, and still others by myocardial ischaemia. In addition, some receptors were excited by all three stimuli.
The effects of changes of extramural, ‘intrathoracic’, pressure on aortic arch baroreceptors
Authors: James Jennifer E. Angell 
Published: December 2014

1. The isolated aortic arch was perfused by a method enabling the mean pressure, pulse pressure and pulse frequency to be varied independently. The preparation was also subjected to phasic and non‐phasic changes of extramural pressure.2. The aortic arch baroreceptor impulse activity in single or few‐fibre preparations was increased by raising the intra‐aortic pressure and by applying a negative extramural pressure at constant intra‐aortic pressure.3. Curves relating impulse frequency and negative extramural pressure were similar to those relating impulse frequency to intra‐aortic pressure. The effective stimulus to the aortic arch baroreceptors is the transmural pressure resulting from the algebraic difference of the intra‐aortic and extramural pressures.4. Rhythmical alterations in extramural pressure caused phasic changes in baroreceptor impulse activity. As the pressure became more negative, the impulse frequency increased and other baroreceptors were recruited.5. During pulsatile perfusion of the aortic arch the maximum impulse activity occurred when the negative phase of extramural pressure coincided with the systolic phase of the perfusion pressure.6. These findings are discussed in relation to the effects of changes of intrathoracic pressure on aortic baroreceptor activity in vivo