bluuebunny/crossref_metadata_2025 huggingface dataset:
Activity of single neurones in the hypothalamic feeding centres: effect of gastric distension
Authors: Anand B. K. , Pillai R. V.
Published: December 2014

1. Unit activity from neurones of hypothalamic ‘feeding’ and ‘satiety’ centres, and from adjacent hypothalmic regions, was recorded by means of steel micro‐electrodes inserted by a stereotaxic method, under Dial anaesthesia.

2. The spike frequency of these neurones was observed during inflation of the stomach with intragastrically placed balloons, and during electrical stimulation of the gastric branches of the vagus. As control measures, distension of the peritoneal cavity and stimulation of a sensory nerve were also carried out. These tests were repeated after severing the gastric vagal branches.

3. In fasted animals the frequency of spontaneous discharge was slower in the units of the satiety centre as compared with those of the feeding centre. The spike frequency of neurones in these two hypothalamic regions maintained an inverse relationship in all experimental situations.

4. Distension of the stomach and stimulation of the gastric vagal branches increased the spike frequency of satiety neurones, decreased the spike frequency of feeding neurones, and did not produce any change in spike frequency of adjacent hypothalamic neurones. A few units in the lateral mammillary region also changed their spike frequency on gastric distension. These responses were abolished after severing the gastric nerves.

5. The results suggest that distension of the stomach brings about satiation through vagal afferents activating the hypothalamic satiety mechanism.

6. The role of this in the nervous regulation of food intake is discussed.
Pulmonary vasoconstriction in asphyxia during cross‐circulation between twin foetal lambs
Authors: Campbell A. G. M. , Cockburn F. , Dawes G. S. , Milligan J. E.
Published: December 2014

1. The effect of asphyxia on pulmonary vascular resistance was measured in anaesthetized foetal lambs whose left lung was supplied with arterial blood from a twin, both still being attached to their placentas by intact umbilical cords.

2. In foetal lambs of 91‐92 days gestation asphyxia of the recipient caused no pulmonary vasoconstriction so long as its left pulmonary artery was supplied with normal blood from a twin donor. Asphyxia of the donor caused pulmonary vasoconstriction in the unasphyxiated recipient; this was therefore wholly due to a local effect of the blood passing through the lung.

3. In foetal lambs of 98‐142 days gestation asphyxia of the recipient caused a small degree of pulmonary vasoconstriction, even though the left pulmonary artery was supplied with normal blood from the twin donor. This vasoconstriction was abolished by administration of hexamethonium or by cutting the sympathetic nerves to the left lung.

4. In mature foetal lambs pulmonary arterial inflow and venous outflow were measured simultaneously. Broncho‐pulmonary blood flow was less than 5% of total pulmonary flow. Pulmonary O2 consumption was 0·75 ± 0·11 ml./100 g.min, or about 5% of total foetal O2 consumption.
The behaviour of the sodium pump in red cells in the absence of external potassium
Authors: Garrahan P. J. , Glynn I. M.
Published: December 2014

1. When red cells loaded with 24Na are incubated in balanced glucose salt solutions, the removal of external potassium reduces sodium efflux by about one third. Ouabain reduces the residual sodium efflux by about one half.

2. The ouabain‐sensitive efflux of sodium into potassium‐free solutions is accompanied by an equal ouabain‐sensitive influx of sodium.

3. If sodium in the external potassium‐free salt solution is progressively replaced with choline, both the ouabain‐sensitive sodium efflux and the ouabain‐sensitive sodium influx are reduced until, with only 5 m
M‐Na externally, both become very small.

4. At sodium concentrations intermediate between 140 m
M and 5 m
M, ouabain‐sensitive sodium influx and ouabain‐sensitive sodium efflux remain equal within the limits of experimental error. The relation between the magnitude of the ouabain‐sensitive sodium exchange and the external sodium concentration is roughly linear.

5. As the external sodium concentration is decreased beyond 5 m
M towards zero, ouabain‐sensitive sodium efflux increases again.

6. In the presence of 5 m
M‐K, the ouabain‐sensitive sodium efflux is scarcely affected by replacing most of the external sodium with choline.

7. In the presence of ouabain, sodium efflux is unaffected by external potassium and is little affected by replacing external sodium with choline.

8. The results suggest that in the absence of external potassium the ouabain‐sensitive transport mechanism catalyses a one‐for‐one exchange of sodium ions across the cell membrane. The relation between this exchange and Ussing's classical ‘exchange diffusion’ is discussed.

9. The exchange does not occur in the presence of external potassium at physiological concentrations.

10. Calculations of sodium efflux were based on the specific activities of total cell sodium: separate experiments confirmed that these were the same as the specific activities of sodium lost to sodium‐free solutions. No evidence of a slowly exchanging sodium fraction was found.
The stoicheiometry of the sodium pump
Authors: Garrahan P. J. , Glynn I. M.
Published: December 2014

1. When resealed ghosts containing adenosine triphosphate (ATP), magnesium and sodium were incubated in a medium containing potassium, ATP was hydrolysed vigorously by a ouabain‐sensitive mechanism. If the ghosts contained potassium instead of or in addition to sodium, and the external solution contained sodium but no potassium, there was little ouabain‐sensitive hydrolysis of ATP. As it is known that the ouabain‐sensitive ATPase in fragmented ghosts requires both sodium and potassium ions, these results show that the ATPase is activated by potassium externally and by sodium internally, and suggest that the ions activating the ATPase are the ions that are transported.

2. Resealed ghosts containing ATP, magnesium and sodium were incubated in sodium‐free media containing potassium, with and without ouabain, and the rate of loss of sodium and rate of hydrolysis of ATP were measured. The hydrolysis of 1 molecule of ATP by the ouabain‐sensitive mechanism was accompanied by the ouabain‐sensitive loss of about 3 sodium ions.

3. 24Na and 42K were used to measure sodium efflux and potassium influx in identical batches of fresh red cells under the same conditions and at the same time. Each flux was measured in the presence and absence of ouabain. The ratio (ouabain‐sensitive sodium efflux)/(ouabain‐sensitive potassium influx) was significantly greater than 1 (1·20 ± 0·01 and 1·35 ± 0·01 in two experiments). If a small fraction of the potassium influx represented a ouabain‐sensitive potassium: potassium exchange, the ratio of the numbers of ions moved in the sodium: potassium exchange catalysed by the pump must have been even further from unity.

4. Resealed ghosts containing [γ‐32P]ATP, magnesium, 24Na and orthophosphate were incubated in balanced salt solutions with and without potassium and with and without ouabain. A comparison of sodium efflux, estimated from 24Na loss, with ATP hydrolysis, estimated from the formation of [32P]orthophosphate, showed that the sodium:sodium exchange in a potassium‐free medium was accompanied by little or no ouabain‐sensitive hydrolysis of ATP.

5. Experiments on intact red cells loaded with 24Na showed that both sodium:sodium exchange in a potassium‐free medium, and sodium:potassium exchange in a medium containing potassium, were partially inhibited by oligomycin (1‐10 μg/ml.). Inhibition of the sodium:potassium exchange was not affected by raising the external potassium concentration.
Nature of thalamo‐cortical relations during spontaneous barbiturate spindle activity
Authors: Andersen P. , Andersson S. A. , Lømo T.
Published: December 2014

1. The relation between thalamic and cortical spontaneous spindles was investigated in cats anaesthetized with barbiturates.

2. Simultaneous recordings with multiple electrodes in the thalamus and cortex revealed a high correlation between thalamic and cortical spindle activity, both with regard to the occurrence of the spindles as well as to their individual waves, provided a critical location of the electrodes was secured. The results indicate a point‐to‐point relation between a group of thalamic cells and a small cortical area to which these cells project. In the spontaneous rhythm, the cortical columns are probably individually controlled by a thalamic rhythmic entity. This point‐to‐point relation was found in all the major sensory projection systems and in one thalamic ‘association’ nucleus and its corresponding ‘association’ cortex.

3. Cortical barbiturate spindles appeared either as local spindles in a restricted cortical area or as compound spindles in several areas. Spindles recorded from electrodes separated by 2 mm or more were clearly different with regard to intraspindle wave frequency, duration, and the time of start and stop of the spindle. These differences increased with increasing distance between the electrodes, and were most pronounced when the corticograms of the two hemispheres were compared.

4. Spontaneous spindle activity interfered with orthodromic transmission through n. ventralis posterolateralis (VPL) and medial geniculate nucleus (MG), judged by depression of the thalamic and cortical responses to peripheral nerve volleys or clicks. Such inhibition required the afferent volley to be delivered at a particular time of the spontaneous oscillations. Further, orthodromic volleys reset the rhythmic spindle waves in the appropriate thalamic and cortical areas.

5. These findings lead to a new concept of the thalamic pace‐maker function. During barbiturate anaesthesia, small assemblages of thalamic neurones seem to have the ability to generate independent rhythmic discharges, and thereby control the rhythm of the particular cortical column to which this thalamic group projects.

6. During barbiturate anaesthesia, many facultative pace‐makers seem to be present in the thalamus. The total number may be as large as 25,000‐35,000. Usually, many of these rhythmic thalamic units beat in synchrony or near synchrony.
The effect of vagal stimulation on plasma insulin and glucose levels in the baboon*
Authors: Daniel P. M. , Henderson J. R.
Published: December 2014

1. The concentration of insulin in the blood of fifteen fasting baboons, anaesthetized with pentobarbitone sodium, was measured by a specific radio‐immunoassay method.

2. The mean resting concentration of insulin was: inferior vena cava (IVC) 22 μu./ml. and splenic vein (after splenectomy) 140 μu./ml.

3. Subdiaphragmatic stimulation of the cut right vagal trunk (at 10 impulses/sec, duration 1·5 msec, for 10 min) produced a mean increase of 50% over resting levels in IVC insulin concentration and an increase in splenic vein insulin of 30% over resting levels.

4. The mean resting level of blood glucose in splenic vein blood was 89·4mg%, that in IVC blood was 79·4mg%. The difference is significant (P < 0·005).

5. Vagal stimulation did not alter these glucose levels, so that insulin release following vagal stimulation is not secondary to hyperglycaemia.

6. The increased insulin secretion following vagal stimulation might be expected to produce hypoglycaemia. Its failure to do so is discussed.
Micro‐iontophoretic studies on neurones in the cuneate nucleus
Authors: Galindo A. , Krnjević K. , Schwartz Susan
Published: December 2014

1. Cuneate cells in anaesthetized cats were strongly excited by
L‐glutamate, and somewhat less by
D‐glutamate; cells which receive afferents from hair receptors were particularly sensitive.

2. Glutamate could be used to demonstrate post‐synaptic inhibitory inputs from the dorsal column, the medial lemniscus and the frontal cortex.

3. Many cuneate cells were also strongly excited by adenosinetriphosphate (ATP); this was probably due to the chelating action of ATP, as citric acid was also quite effective.

4. γ‐Aminobutyric acid (GABA) readily blocked all forms of spontaneous and evoked activity, except antidromic invasion of cuneothalamic neurones; cells which receive proprioceptive afferents were particularly sensitive to GABA. Glycine had a comparable effect.

5. Acetylcholine (ACh), catecholamines, histamine, 5‐hydroxytryptamine (5‐HT) and an extract containing substance P mostly had only weak depressant actions. Cholinergic and mono‐aminergic mechanisms are probably not very significant in the cuneate.

6. These results are consistent with the possibility that glutamate and GABA (or glycine), or some closely related compounds, are the main excitatory and inhibitory transmitters in the cuneate nucleus.

7. If ATP is released from afferent nerve endings, it could also play a significant role in excitation.
A study of synaptic transmission in the absence of nerve impulses
Authors: Katz B. , Miledi R.
Published: December 2014

1. The axo‐axonic giant synapse in the stellate ganglion of the squid has been used to study synaptic transmission.

2. When nerve impulses have been eliminated with tetrodotoxin, synaptic transfer of potential changes can still be obtained by applying brief depolarizing pulses to the presynaptic terminal.

3. Suitably matched pulses are as effective as the normal presynaptic spike in evoking post‐synaptic potentials. The synaptic delay and the time course of the post‐synaptic potential are very similar to that in the normal preparation.

4. The synaptic transfer (input/output) characteristic has been studied under different experimental conditions. With brief (1‐2 msec) current pulses, post‐synaptic response becomes detectable when the presynaptic depolarization exceeds about 30 mV. The post‐synaptic potential increases about tenfold with 10 mV increments of presynaptic depolarization.

5. Calcium increases, magnesium reduces the slope of the synaptic transfer curve. The influences on this curve of (i) duration of the pulse, (ii) preceding level of membrane potential, (iii) position of recording electrode, (iv) rate of repetitive stimulation are described.

6. After loading the synaptic terminal with tetraethylammonium ions, large inside‐positive potentials can be produced in the terminal and maintained for many milliseconds.

7. By raising the internal potential to a sufficiently high level, synaptic transfer becomes suppressed during the pulse, and the post‐synaptic response is delayed until the end of the pulse.

8. This observation is in accord with a prediction of the ‘calcium hypothesis’, viz. that inward movement of a positively charged Ca compound, or of the calcium ion itself, constitutes one of the essential links in the ‘electro‐secretory’ coupling process of the axon terminal.
The dependence of slow inward current in Purkinje fibres on the extracellular calcium‐concentration
Authors: Reuter H.
Published: December 2014

1. In sodium‐free solution electrical constants of short Purkinje fibres were similar to those in Tyrode solution. Alterations in the extracellular calcium concentration ([Ca]o = 0; 1·8; 7·2 m
M) had no appreciable effect on these constants, unless the fibres were soaked in calcium‐free solution for more than 40 min.

2. In sodium‐free solution without calcium there was constant or increasing outward current in response to sudden depolarizations (voltage‐clamp technique) over the whole voltage range ‐85 to +40 mV. In calcium‐containing solution initial outward current was followed by a slow change in current towards zero which was sometimes large enough to produce a net inward current. This current had a threshold in the voltage range ‐60 to ‐40 mV. It was not affected by alterations in the extracellular chloride or magnesium concentrations. The dependence on [Ca]o suggests that the slow inward current is carried by calcium ions.

3. Negative slopes in the steady‐state current—voltage relations were obtained in fibres soaked in calcium‐containing solutions but were never observed in calcium‐free solution.

4. The calcium equilibrium potential (ECa) was estimated to be about 150 mV, inside positive.

5. In Tyrode solution the slow inward current was smaller than in sodium‐free solution and its threshold was shifted to about ‐20 to ‐10 mV. It was dependent on [Ca]o as in sodium‐free solution. It was increased by adrenaline and not affected by tetrodotoxin.

6. It is concluded that calcium ions carry an appreciable membrane current in the inward direction when the membrane of the Purkinje fibre is depolarized. This calcium current may be involved in excitation—contraction coupling.
Peripheral modification of sensory nerve responses after cross‐regeneration
Authors: Robbins N.
Published: December 2014

1. Chemical responses of skin and tongue, recorded in vivo from intact and self‐regenerated cutaneous or lingual nerves, were compared to responses from cutaneous nerves cross‐united with distal stumps of lingual nerves. Cross‐innervated tongue grafts were also studied.

2. In contrast to normal tongue—nerve preparations, skin preparations usually showed responses to chemical stimulation with longer latency, higher threshold, and less variation of temporal pattern with diverse stimuli. These characteristics were similar when the nerve, having been cut, had regenerated.

3. On chemical stimulation of the tongue, cutaneous nerves cross‐innervating the tongue often yielded records which were ‘gustatory’ by all criteria. Some responses with low threshold and short latency were also obtained from dorsal cutaneous nerves innervating tongue grafts.

4. Thus, cutaneous nerves can serve the same role as gustatory nerves. The functional characteristics of these sensory neurones are not predetermined and must depend on the environment of the nerve endings.
The renal accumulation of urate and p‐aminohippurate in the rabbit
Authors: Møller Jesper V.
Published: December 2014

1. During intravenous infusion of urate and p‐aminohippurate (PAH), the concentration of these two substances in cortex tissue of rabbit kidney exceeded the corresponding plasma concentration.

2. Following the administration of 2,4‐dinitrophenol, fumarate, succinate, probenecid, and salicylate, accumulation of urate in kidney cortex and renal net secretion of urate were abolished. The accumulation and secretion of PAH were only partially inhibited after infusion of these compounds.

3. The renal accumulation of urate was reduced in relation to the inhibition of urate excretion during infusion of various amounts of PAH.

4. The combined data indicate a correlation between renal accumulation and excretion of urate and PAH. It appears likely that accumulation of urate and PAH in vivo is due to tubular secretion of these two substances, although in the case of urate a small contribution from tubular reabsorption of urate cannot be excluded.
Distribution of peripheral blood flow in primary tissue hypoxia induced by inhalation of carbon monoxide
Authors: Chalmers J. P. , Korner P. I. , White S. W.
Published: December 2014

1. The effects of primary tissue hypoxia induced by the inhalation of small concentrations of carbon monoxide in air on the distribution of blood flow in the portal, renal, muscle and skin beds have been studied in normal unanaesthetized rabbits, in animals without functioning autonomic effectors (‘de‐efferented’ rabbits) and in animals with section of the carotid sinus and aortic nerves (‘de‐afferented’ rabbits).

2. The pattern of blood flow distribution during CO hypoxia was similar in ‘de‐efferented’ and ‘de‐afferented’ animals, suggesting that the effects in the latter were determined by local mechanisms. The susceptibility of the various beds to the local dilator effects of CO hypoxia was markedly different, the greatest dilator effects being observed in the portal bed, followed by skin, kidney, and muscle. The pattern is somewhat different from that observed in arterial hypoxia.

3. In this type of hypoxia the arterial baroreceptors are probably the main afferent source of reflex activity. In normal animals reflex constrictor effects affect the portal and renal beds most, ‘moderating’ the local dilator effects of hypoxia in these beds. In muscle there is vasodilatation, probably the result of adrenaline secretion, but the response in skin is largely determined by the local effects of hypoxia. The total orthosympathetic activity evoked in this type of hypoxia appears to be less than in severe arterial hypoxia.
Effects of haemorrhage on the distribution of the peripheral blood flow in the rabbit
Authors: Chalmers J. P. , Korner P. I. , White S. W.
Published: December 2014

1. The effects of bleeding unanaesthetized rabbits by 26% of their blood volume on the blood flow in the portal, renal, muscle and skin beds were investigated in normal animals, in animals without functioning autonomic effectors, and in animals with section of the carotid sinus and aortic nerves.

2. In animals without functioning autonomic effectors there was progressive vasodilatation during the 4 hr following haemorrhage, which differed markedly in the different regional beds studied. The dilatation was greatest in the portal bed, followed by kidney and skin, but there was no significant change in the vascular resistance in muscle.

3. In normal animals with intact reflexes the vascular resistance either increases or remains at control values, suggesting that reflex constrictor effects oppose locally acting dilator mechanisms. During the 4 hr following haemorrhage reflex vasoconstrictor effects were greatest in kidney, followed by muscle, portal bed and skin.

4. In animals with section of the carotid sinus and aortic nerves reflex constrictor effects were absent in the portal, muscle and skin beds, but significant vasoconstriction was still evident in the renal bed, though of smaller magnitude than in normal animals. The results suggest that the arterial baroreceptors are a major source of reflex activity following haemorrhage, but that other reflexogenic zones contribute to the renal effects in normal animals.
The effects of alteration of CO2 and pH on intestinal blood flow in the cat
Authors: McGinn F. P. , Mendel D. , Perry P. M.
Published: December 2014

1. The effect of alteration of arterial blood pH on intestinal blood flow in the cat has been determined under conditions of constant perfusion pressure.

2. Arterial blood pH was altered over the range 7·12‐7·70 by infusion of acid and alkali. When end‐tidal CO2 was held constant, there was no change in intestinal blood flow.

3. When arterial blood pH was altered over the range 7·19‐7·55 by the administration of CO2 at constant respiratory volume and rate, flow increased with increasing CO2.

4. The intestinal vascular bed was less responsive to noradrenaline at pH 7·2 than at pH 7·6. The change in sensitivity was evident when end‐tidal CO2 was controlled and depended therefore on a change in hydrogenion concentration.

5. The dilator effect of CO2 did not depend upon alteration of sensitivity to noradrenaline since it was seen after adrenergic blockade.
Distribution of chylomicrons and albumin in dog kidney
Authors: Pinter G. G.
Published: December 2014

1. Under specified experimental conditions the distribution space of labelled chylomicrons in the kidney was 13·8 ± 0·9 ml./100 g. tissue. The assumption is supported that this provides a measure for the quantity of intravascular plasma constituents.

2. Values for red blood cells and albumin distribution spaces were 5·2 ± 0·6 and 20·2 ± 1·0 ml./100 g tissue, respectively, in the whole kidney. The ratio of tissue haematocrit over simultaneous arterial haematocrit averaged 0·56. The extravascular albumin fraction amounted to about 31·0% of the total albumin in the whole kidney.

3. A statistically significant correlation was demonstrated between osmotic urine/plasma (U/P) ratios (within the approximate limits of 0·6‐1·8) and quantities of extravascular albumin in the medulla.
Force:velocity properties of kitten muscles
Authors: Close R. , Hoh J. F. Y.
Published: December 2014

1. The characteristics of isometric contractions and force:velocity properties of the extensor digitorum longus (EDL) and soleus (SOL) muscles of neonatal kittens were determined in situ.

2. The mean contraction time is 51 msec for EDL and 70 msec for SOL and the half‐relaxation time is 51 msec for EDL and 109 msec for SOL.

3. The average maximum isometric tetanic tension per unit cross‐sectional area of muscle is 1·27 kg/cm2 for EDL and 1·17 kg/cm2 for SOL.

4. The average twitch:tetanus ratio is 0·28 for EDL and 0·119 for SOL; the low value for SOL was found for both indirect and direct stimulation.

5. The average maximum speed of shortening of a sarcomere is 22·8 μ/sec for EDL and 12·7 μ/sec for SOL.

6. These properties of neonatal muscles are compared with those of adult cat muscles and discussed in connexion with differentiation of mammalian muscles into fast and slow types.
Excitation of Mytilus smooth muscle
Authors: Twarog Betty M.
Published: December 2014

1. Membrane potentials and tension were recorded during nerve stimulation and direct stimulation of smooth muscle cells of the anterior byssus retractor muscle of Mytilus edulis L.

2. The resting potential averaged 65 mV (range 55‐72 mV).

3. Junction potentials reached 25 mV and decayed to one half maximum amplitude in 500 msec. Spatial summation and facilitation of junction potentials were observed.

4. Action potentials, 50 msec in duration and up to 50 mV in amplitude were fired at a membrane potential of 35‐40 mV. No overshoot was observed.

5. Contraction in response to neural stimulation was associated with spike discharge. Measurement of tension and depolarization in muscle bundles at high K+ indicated that tension is only produced at membrane potentials similar to those achieved by spike discharge.

6. Blocking of junction potentials, spike discharge and contraction by methantheline, an acetylcholine antagonist, supports the hypothesis that the muscle is excited by cholinergic nerves. However, evidence of a presynaptic action of methantheline complicates this argument.
The action of 5‐hydroxytryptamine on Mytilus smooth muscle
Authors: Hidaka T. , Osa T. , Twarog Betty M.
Published: December 2014

1. In the nerve—muscle preparation, where catch was characteristically minimal, 5‐hydroxytryptamine (5‐HT) had no effect on resting membrane potential, junction potentials, spikes or contraction.

2. In muscle bundles, where catch was prominent, 5‐HT did not change membrane potentials, but prolonged junction potentials and lowered the threshold for spike discharge and contraction.

3. In muscle bundles, exposed to high concentrations of 5‐HT, depolarization evoked repetitive spikes, while in low 5‐HT, spikes were seldom fired even with much greater depolarization.

4. In muscle bundles, the effective membrane resistance, Reff., decreased from 45‐60 to 23‐35 MΩ as 5‐HT concentration was increased.

5. It is suggested that 5‐HT may facilitate spike discharge by lowering the internal free Ca2+ concentration.
Pulmonary lymph flow and the uptake of liquid from the lungs of the lamb at the start of breathing
Authors: Humphreys P. W. , Normand I. C. S. , Reynolds E. O. R. , Strang L. B.
Published: December 2014

1. Lymph from the lungs of lambs and sheep was found to enter both the right lymph duct and the thoracic duct. Right lymph duct flow was collected by constructing a venous sac, the venous tributaries of which were ligated but which the right lymph duct entered; thoracic duct flow was collected by cannulating the duct. Lymph from sites other than the lungs was excluded from the collections.

2. Measurements were made of the surface tension characteristics of lung extracts and of the liquid present in foetal lungs. These values were used together with gestational age and crown‐rump length to designate the foetal lambs into mature and immature groups.

3. Lymph flow from the lungs averaged 0·99 ml./kg body wt./hr in immature foetal lambs, and 1·81 ml./kg/hr in mature foetal lambs before the start of ventilation. Lymph flow from the lungs of spontaneously delivered new‐born lambs (mean age 51 hr) averaged 0·86 ml./kg/hr. In adult ewes right lymph duct flow averaged 0·11 ml./kg/hr and total lung lymph flow was estimated indirectly to be 0·33 ml./kg/hr. Calculated rates of protein flow in lung lymph (flow × protein concentration) were greater in foetal lambs than in adult sheep.

4. Total thoracic duct flow averaged 2·48 ml./kg/hr in immature foetal lambs, 5·30 ml./kg/hr in mature foetal lambs, 3·65 ml./kg/hr in new‐born lambs, and 2·92 ml./kg/hr in adult ewes.

5. At the start of ventilation there was an increase in lymph flow from the lungs, which at 15‐30 min reached a mean of 6·4 ml./kg/hr in mature lambs and 2·6 ml./kg/hr in immature lambs. At the same time the protein concentration of lymph decreased but the calculated protein flow increased.

6. The lungs of foetal lambs weighed more than the lungs of spontaneously delivered new‐born lambs, and the difference could be accounted for by liquid which could be aspirated through the trachea of the foetal lamb. On ventilation of the lungs for 2 hr, without first allowing the escape of any lung liquid, lung weight measurements indicated that about 66% of the lung liquid had been taken up in mature lambs and about 50% in immature lambs.

7. It was concluded that the rate at which lymph is formed in the lungs is greater per kilogram body weight in foetal than in new‐born lambs and greater in them than in ewes. The increase in lymph flow at the start of ventilation could account for the removal of about 40% of the liquid present in the lungs of the mature foetus and about 25% of the liquid in the lungs of the immature foetus.
Tension development by isolated muscle spindles of the cat
Authors: Diete-Spiff K.
Published: December 2014

1. Tension developed by mammalian intrafusal muscle fibres stimulated directly with single or repetitive electrical pulses has been determined in sixteen isolated lumbrical muscle spindles of the cat's foot.

2. On microscopic observation, contraction to single shocks was observed in ten preparations. In three of these preparations twitch‐like records were obtained.

3. In the preparations that ‘twitched’, the tetanic fusion frequency was 10 pulses/sec at 20° C.

4. In the ‘twitching’ intrafusal fibres the magnitude of contraction increased with increase of stimulus strength.

5. In one of these spindles, only ‘slow’ contractions were obtained at low stimulus strengths when it was stimulated repetitively at 100 pulses/sec. With increase in stimulus strength, such ‘slow’ contractions gave twitch‐like responses towards the end of a period of repetitive stimulation.

6. Tension changes were recorded from all preparations stimulated repetitively. With supramaximal stimuli, the usual frequency of stimulation at which intrafusal tension was recorded was 10 pulses/sec at 20° C. The magnitude of contraction increased progressively with increase in stimulus frequency.

7. Larger intrafusal tensions and faster time courses of contraction were obtained when the electrodes were astride the capsular region than when they were over the inferior extracapsular region.
An electrophysiological study of some reticulo‐ruminal and abomasal reflexes in sheep
Authors: Iggo A. , Leek B. F.
Published: December 2014

1. In halothane‐anaesthetized sheep in which reticulo‐ruminal (gastric) contractions were present, nervous discharges have been recorded electrophysiologically in sixty‐four single efferent gastric units (grouped in seven types) dissected from the mid‐cervical region of the left vagus. An examination was made of the reflex effects on the efferent discharges of the procedures given in paragraphs 2‐5.

2. Under isotonic recording conditions the total discharge was reduced but the peak frequency of most types of unit was enhanced compared with the discharge recorded under control isometric conditions.

3. Abolition of reticular contractions by the use of preganglionic and post‐ganglionic blocking agents resulted in an efferent discharge pattern similar to that recorded under isotonic conditions.

4. Sudden deflation or inflation of the reticulum at the start of a reticular contraction had an effect that depended on the initial volume of the reticulum. It could be either excitatory and/or inhibitory.

5. Acidification of the abomasal contents reflexly enhanced the discharge in three of ten efferent gastric vagal units. An abomasal pH less than 1·0 appears to be less important in providing an excitatory drive to the ‘gastric centres’ in halothane‐anaesthetized sheep than in decerebrate sheep.

6. It is estimated that the total reflex time is > 1·3 sec for reticulo‐reticular reflexes and > 2·1 sec for reticulo‐ruminal reflexes. The central reflex time is > 370 msec.

7. It is concluded that a tonic afferent input from ‘in series’ reticular tension receptors during the quiescent period of the primary (reticulo‐ruminal) cycle provides a reflex drive to the ‘gastric centres’ and largely determines the rate and amplitude of the reticular and ruminal contractions.

8. The enhanced afferent input, during a reticular contraction under isometric recording conditions, modifies the size, form and duration of the later phases in the contraction sequence of the reticulum and rumen. The reflex effects are predominantly excitatory at low and moderate levels of reticular tension and inhibitory at high levels.
The effect of distending a pouch of the left atrium on the heart rate
Authors: Ledsome J. R. , Linden R. J.
Published: December 2014

1. A pouch has been prepared consisting of a part of the wall of the left atrium together with the left pulmonary vein—atrial junctions.

2. An increase of perfusion pressure in the pouch caused a reflex increase in heart rate.

3. The afferent path of the reflex was in the vagus nerves and the efferent path was in the sympathetic nerves.

4. The receptors most likely to be stimulated by an increase in pressure in the pouch are those receptors situated in the subendocardium of the pulmonary vein—left atrial junctions.
Motor unit types of cat triceps surae muscle
Authors: Burke Robert E.
Published: December 2014

1. Motor units, defined as including a motoneurone (cell body, dendrites and axon) plus the muscle unit innervated, have been examined in the triceps surae motor pool of pentobarbital anaesthetized cats.

2. The technique of intracellular stimulation and recording which was used permitted measurement of the axonal conduction velocity, post‐spike hyperpolarization duration and input resistance of individual motoneurones, and the correlation of these properties with the characteristics of the twitch and tetanus responses of the muscle unit innervated by the cell elicited by direct intracellular stimulation.

3. On the basis of muscle unit speed of contraction, motor units were divided into two groups: (a) fast twitch, or F, type with twitch time to peak (TwTp) less than or equal to 30 msec, and (b) slow twitch, or S, type with TwTp of 40 msec or greater. The twitch tensions (TwTen) produced by type F units were significantly larger (median value = 18 g) than the tensions generated by type S units (TwTen median value = 1·6 g). Type F muscle units had much higher tetanus fusion frequencies (median = 85 pulses/sec) than the S type (median 25 pulses/sec), and tended to have smaller tetanus to twitch tension ratios (Tet/Tw) (median = 2·6) than type S units (median = 5·4).

4. The gastrocnemius heads contained a mixture of F and S types of muscle units, the proportions found being about 3 to 1 respectively. Units encountered in the soleus muscle were uniformly of type S. The characteristics of gastrocnemius and soleus type S motor units were not identical but appeared to represent quantitative differences in units of the same qualitative type.

5. Motoneurones innervating type F muscle units had faster axonal conduction velocities, shorter post‐spike hyperpolarizations and lower input resistances than those supplying type S units. However, no combination of motoneurone properties alone was sufficient to separate unambiguously types F and S motor units.
Periodic eye tracking in the monkey
Authors: Fuchs A. F.
Published: December 2014

1. Eye movements were measured in monkeys trained for visual tracking.

2. In response to periodic square wave target movements, monkeys do not show a significant reduction in the latency of saccadic movements.

3. Under similar conditions, human beings subconsciously reduce their latency and after several cycles are in step with the target.

4. In response to sinusoidal targets, monkeys show a latency or phase lag which increases monotonically with frequency starting at 0·3 c/s. Human beings can remain in phase with the target at frequencies up to 1·0 c/s.

5. Hence, monkeys do not exhibit the human predictive tracking response.
The effect of adrenaline on the adenosine otriphosphate and creatine phosphate content of intestinal smooth muscle
Authors: Bueding E. , Bülbring Edith , Gercken G. , Hawkins J. T. , Kuriyama H.
Published: December 2014

1. The smooth muscle of guinea‐pig taenia coli was used to investigate the relation between metabolic and physiological effects of adrenaline. Electrical and mechanical activity was recorded with the sucrose gap technique and, in parallel experiments, the concentration of energy‐rich phosphate compounds, adenosinetriphosphate and creatine phosphate, (ATP and CP) in the tissue was determined.

2. Adrenaline (in concentrations from 2 × 10−9 g/ml. to 5 × 10−8 g/ml.) increased the tissue content of energy‐rich phosphate compounds. This effect was coincident with the physiological, inhibitory effect on electrical and mechanical activity.

3. After anaerobic exposure of the tissue to substrate‐free medium, the biochemical and the physiological effects of adrenaline were both abolished; both recovered after readmission of oxygen and/or substrate.

4. In muscles depleted of glycogen in substrate‐free medium, either by anoxia or by high temperature, adrenaline produced its stabilizing effect on the cell membrane and the increase in ATP and CP content when β‐hydroxybutyrate was the substrate, i.e. in the complete absence of carbohydrate from the medium and from the tissue.

5. When adrenaline was applied simultaneously with the readmission of substrate, the ATP and CP content of pieces treated with adrenaline was greater than of control pieces, though the tension of both was zero. This indicates that the effect was not secondary to the muscle relaxation but was the result of increased ATP synthesis.

6. The physiological and biochemical effects of adrenaline were both abolished by the same concentration of imidazole (0·05
M).

7. Low concentrations of ATP (1 × 106‐5 × 10−6
M)—like adrenaline—inhibited electrical and mechanical activity of the taenia. This effect was also abolished by imidazole.
The effect of haemorrhage on hepatic artery and portal vein flows in the anaesthetized cat
Authors: Greenway C. V. , Lawson Anne E. , Stark R. D.
Published: December 2014

1. In cats anaesthetized with pentobarbitone, the hepatic artery and portal vein flows and pressures were recorded simultaneously.

2. Removal of blood from the animal did not cause a decrease in the hepatic artery flow unless the arterial pressure fell below 80 mm Hg. In contrast, the portal vein flow fell markedly.

3. After restoration of the blood, the hepatic artery flow increased to above the pre‐haemorrhage level, while portal vein flow returned only partly towards the control level.

4. It is concluded that haemorrhage causes a vasodilation in the hepatic artery vascular bed and a vasoconstriction in the vascular beds drained by the portal vein. By this means, the oxygen supply to the liver is maintained as far as possible.
Membrane currents at large positive internal potentials in single myelinated nerve fibres of rana pipiens
Authors: Moore L. E.
Published: December 2014

1. A voltage clamp for single myelinated nerve fibres was developed from commercially available operational amplifiers.

2. Under voltage clamp conditions steady‐state currents were measured. The currents reached a maximum value at about E = + 100 mV. Currents for greater potentials decreased.

3. The preceding polarization markedly affected the magnitude of the delayed current at high cathodal potentials; however, the currents continued to reach maximum values.

4. As predicted by the constant field theory, currents at high cathodal polarizations were essentially independent of the external potassium concentration. Also, these currents were independent of the external calcium concentration.

5. Two pulse voltage clamp experiments showed that instantaneous outward currents did not reach a limiting value. The limiting steady‐state current was reached with an exponential time constant of about 1 msec.
Effects of adrenaline on human blood platelets
Authors: Mills D. C. B. , Roberts G. C. K.
Published: December 2014

1. Adrenaline at concentrations too low to cause aggregation of human platelets potentiates the aggregation by adenosine diphosphate. Noradrenaline has the same effect but is less active than adrenaline; isopropylnoradrenaline is inactive or inhibitory.

2. The potentiation of adenosine diphosphate by catecholamines is blocked by the adrenergic α‐receptor antagonists phentolamine and dihydroergotamine but not by 2‐halogenoethylamines or by adrenergic β‐receptor antagonists.

3. Both the first and second phases of adenosine diphosphate aggregation are potentiated by catecholamines but the second phase more than the first.

4. The release from the platelets of adenine nucleotides which is associated with the second phase of aggregation is also increased by adrenaline.
The stoicheiometry of sodium ion movement from frog muscle
Authors: Harris E. J.
Published: December 2014

1. Further measurements of the consumption of high energy phosphate during the active extrusion of sodium ions from frog muscle were made in the presence of iodoacetate or dinitrofluorobenzene.

2. In the presence of iodoacetate the consumption of ATP for phosphorylation of hexose is appreciable and so a deduction is made from the total ATP consumption during the ion movement.

3. In the presence of dinitrofluorobenzene the deamination of adenosine monophosphate makes the changes in adenosine triphosphate and diphosphate unequal so that both substances have to be measured.

4. The present results point to the active movement of between 2·5 and 3 sodium ions per high energy phosphate bond split.
Cation loading of red blood cells
Authors: Garrahan P. J. , Rega A. F.
Published: December 2014

1. p‐Chloromercuribenzenesulphonate induces an increase in the permeability of red cell membranes to monovalent cations. Under suitable conditions the increase in permeability is large enough to allow cell cation concentration to approach equilibrium with that in the suspending media in 24 hr at 5° C.

2. The effect of the mercurial on permeability is fully reversed by cysteine.

3. These effects provide the basis for a simple procedure for preparing red blood cells of almost any desired sodium or potassium content.

4. If hypertonic media are used, cells can be obtained with normal volume but in osmotic equilibrium with the hypertonic solutions.
Physical and chemical reactions of phosphates in red cell membranes in relation to active transport
Authors: Blake A. , Leader D. P. , Whittam R.
Published: December 2014

1. A study has been made of the chemical reactions associated with the active transport of sodium and potassium in human red cells, with special reference to the action of oligomycin and the labelling of cell membranes by radioactive ATP.

2. Oligomycin had the same effects as ouabain on the various aspects of active transport in red cells. It inhibited sodium and potassium transport, the transport ATPase, and the lactate production that is controlled by the sodium pump.

3. When cell membranes were incubated with radioactive ATP they became labelled. The labelling, however, was unrelated to the activity of the transport ATPase. Incubation of membranes and intact cells showed that the labelling was a result of physical adsorption of inorganic phosphate to the membranes.

4. The results show that if there is a phosphate intermediate in the reaction of the transport ATPase in human red cell membranes, then it is present in amounts too small to be detectable by the methods that have been successfully used with organs such as brain and kidney.
Cross‐innervated mammalian skeletal muscle: histochemical, physiological and biochemical observations
Authors: Dubowitz Victor
Published: December 2014

1. Cross‐innervation of the slow soleus and fast flexor hallucis longus or flexor digitorum longus muscles has been performed in new‐born kittens and rabbits and in adult cats.

2. The effects on the histochemical and structural properties of the muscle have been studied and compared with the changes in the contractile properties.

3. Cross‐innervation has produced a dramatic change in histochemical pattern in the fast muscles, with the development of areas of muscle fibres indistinguishable from normal soleus muscle. The converse change from the histochemical pattern of slow soleus to that of fast muscle has also occurred, but has been less consistent.

4. It is concluded that the neural influence determining the contractile properties of fast and slow muscle also has a profound controlling influence on the structure and metabolic activity of the muscle fibres.

5. No significant changes could be demonstrated biochemically in the ATPase activities of the fast and slow muscles following cross‐innervation.
Effects of physalaemin on some exocrine secretions of dogs and rats
Authors: Bertaccini G. , de Caro G. , Impicciatore M.
Published: December 2014

1. Physalaemin, an endecapeptide recently found in the skin of the South American amphibian Physalaemus fuscumaculatus, possesses, besides a marked hypotensive action and a powerful sialogogic activity, also a stimulant activity on other exocrine secretions.

2. Exocrine structures which were more potently stimulated by the peptide were lacrimal glands and exocrine pancreas. In the anaesthetized dog the threshold lacrimatory dose was 0·05‐0·3 μg/kg; in the rat the threshold dose was 2·5‐5 μg/kg. The minimum active dose on exocrine pancreas of the dog was 0·05‐0·5 μg/kg.

3. Physalaemin did not influence the gastric acid secretion of the dog at the maximum tolerated dose (40 μg/kg). Gastric acid secretion of the rat was stimulated very little if at all.

4. In the dog the peptide caused some changes in the bile flow which were connected more with contracture of the gall‐bladder than with a true secretory stimulant activity. In the rat the peptide was completely ineffective.

5. The results obtained after administration of sympatholytic and parasympatholytic agents suggest that the action of the peptide is at least partly independent from the autonomic nervous system.
A comparison of the nerve impulses of mammalian non‐medullated nerve fibres with those of the smallest diameter medullated fibres
Authors: Paintal A. S.
Published: December 2014

1. Filaments were dissected from the aortic nerve of cats and impulses recorded monophasically in vivo.

2. The temporal characteristics of impulses of non‐medullated fibres were compared with those of medullated fibres with conduction velocities between 4·5 and 12 m/sec. There were no obvious qualitative differences between the two types of fibres and they appeared to belong to a homogeneous sample.

3. In non‐medullated fibres the rise time, fall time and absolute refractory period varied inversely with conduction velocity, the relation being similar to that in the medullated fibres. There was practically no difference between the temporal characteristics of the fastest non‐medullated fibres and those of the slowest medullated fibres, a result which might throw light on the question why fibres below 1 μ in diameter are not medullated.

4. The mean blocking temperature of sixteen non‐medullated fibres was 4·3° C, a value that was significantly different from the mean blocking temperature of sixteen medullated fibres (6·5° C).