bluuebunny/crossref_metadata_2025_split huggingface dataset:
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.