bluuebunny/crossref_metadata_2025_split huggingface dataset:
The effect of sodium and calcium ions on the release of catecholamines from the adrenal medulla: sodium deprivation induces release by exocytosis in the absence of extracellular calcium
Authors: Lastowecka Anna , Trifaró J. M. 
Published: December 2014

1. Perfusing bovine adrenal glands with Na+‐free Locke solution for 15–40 min did not modify the increase in the release of catecholamines from glands stimulated by acetylcholine. However, after 80–100 min of perfusion with Na+‐free solution, the response to acetylcholine stimulation was decreased or abolished.2. Immediately after switching the perfusion medium to Na+‐free solution, there was a sharp increase (6–10 times over control values) in catecholamine output.3. Graded substitution of Na+ in the perfusion fluid enhanced the output of catecholamines. This increase in the output of amines was linearly related to the logarithm of the extracellular Na+ concentration.4. The release of catecholamines in the absence of Na+ was not reduced by the presence of atropine and hexamethonium nor by the omission of Ca2+ in the presence of EDTA or EGTA.5. Excess of Mg2+ in the perfusion fluid reduced (10 m
M‐Mg2+) or blocked (20 m
M‐Mg2+) the increase in the output of catecholamines induced by Na+ deprivation in the presence or absence of extracellular Ca2+.6. Na+ deprivation induced release of catecholamines during perfusion of the glands with depolarizing concentrations (56 m
M) of K+.7. In the presence or the absence of extracellular Ca2+, the increase in the output of catecholamines induced by Na+ deprivation was accompanied by an increase in the output of dopamine β‐hydroxylase, but not of lactate dehydrogenase. In addition, during perfusion with Ca2+ free solution, Na+ deprivation induced a parallel increase in both catecholamine and adenosine triphosphate outputs.8. The ratios of catecholamines to dopamine β‐hydroxylase and catecholamines to adenosine triphosphate determined in the perfusates collected from glands during perfusion with Na+‐free medium were similar to those measured in the soluble contents of isolated chromaffin granules. These results provided biochemical evidence in favour of exocytosis as the mechanism of secretion during Na+ deprivation.
Isometric contractions of motor units in self‐reinnervated fast and slow twitch muscles of the cat
Authors: Bagust J. , Lewis D. M. 
Published: December 2014

1. Isometric contractions of motor units have been studied in self‐reinnervated soleus and flexor digitorum longus muscles, the motor nerves of which had been transected 6 months earlier.2. The distributions of motor unit tetanic tensions in both muscles were skewed towards large values and showed greater variance than normal: there were motor units which produced more tension and others which developed less tension than in control muscles. Mean tensions of motor units are compared with those of the controls.3. The variance of times to peak of motor units in both muscles was significantly smaller than normal.4. Conduction velocities of axons were slower than normal above the point of nerve section. A number of axons did not functionally cross this point and those that did conducted slowly below the neuroma.5. Many of the correlations seen in normal muscle between axon conduction velocity, motor unit tetanic tension, twitch time to peak and ratio of twitch to tetanic tension were demonstrated in reinnervated muscle.6. We suggest that the pattern of motor unit organization in self‐reinnervated muscle can in part be due to random regrowth of axons but is largely produced by specific processes related to axon size which are not identical in fast and slow muscle.
Effect of glycylglycine and glycine on jejunal absorption rate of L‐histidine in man in vivo
Authors: Cook G. C. 
Published: December 2014

1. Using a double‐lumen tube jejunal perfusion system in vivo, the effects of glycylglycine and glycine on the jejunal transfer rate of
L‐histidine have been studied in a 30 cm jejunal segment, in six Zambian African men. Data on the effect of
L‐histidine on glycylglycine transfer rate have also been obtained. The solutions perfused in each subject contained (A)
L‐histidine (100 m‐mole l.−1), (B)
L‐histidine (100 m‐mole l.−1) and glycylglycine (50 m‐mole l.−1), (C) glycylglycine (50 m‐mole l.−1), and (D)
L‐histidine (100 m‐mole l.−1) and glycine (100 m‐mole l.−1).2. Whereas the presence of glycine in the perfusing fluid significantly impaired the absorption rate of
L‐histidine (P < 0·01), glycylglycine had no significant effect. The presence of
L‐histidine in the perfusing fluid had no significant effect on the rate of glycylglycine absorption. When compared with results for glycine absorption rate in twelve Zambian African subjects in another study, the presence of
L‐histidine produced a significant impairment in the rate of glycine absorption (P < 0·001).3. The results demonstrate a mutual inhibition between the rates of
L‐histidine and glycine absorption. The lack of a similar inhibition between
L‐histidine and glycylglycine is consistent with the concept of independent transfer mechanisms for amino acids and dipeptides in the human jejunum.
The formation of synapses in mammalian sympathetic ganglia reinnervated with preganglionic or somatic nerves
Authors: McLachlan Elspeth M. 
Published: December 2014

1. A study has been made of the formation of synapses in the superior cervical ganglion of the guinea‐pig, during reinnervation either with axons of the cervical sympathetic trunk, or with somatic axons of the nerve to the sternohyoid muscle.2. No significant changes in either the geometry or electrical parameters of sympathetic motorneurones were detected following denervation for periods of 3–6 weeks, or after reinnervation with either preganglionic or somatic axons.3. The post‐ganglionic action potential reappeared about 4 weeks after preganglionic trunk section (eighteen of eighteen ganglia); its amplitude increased progressively and was almost normal by more than 10 weeks after nerve section. A very small response was detected from thirteen of eighteen ganglia after periods longer than 8 weeks after cross‐reinnervation with somatic axons.4. Regenerated preganglionic or somatic nerve terminals were demonstrated around the ganglion cells using ZIO impregnation and electron‐microscopy; the structure of these terminals was unchanged following regeneration into the ganglia, although many more synapses were formed by preganglionic terminals than by somatic terminals.5. The facilitation of evoked synaptic potentials which occurs during repetitive stimulation of preganglionic axons was retained following their regeneration, whereas most synapses formed on ganglion cells by regenerating somatic axons showed facilitation of transmitter release during trains of stimuli, rather than the normal depression.6. These observations suggest that the structure and electrical properties of adult mammalian autonomic motorneurones are not under neural control, but that these neurones do show some selectivity in the type of nerve which they will permit to form synapses on them.
The density and photosensitivity of human rhodopsin in the living retina
Authors: Alpern M. , Pugh E. N. 
Published: December 2014

1. The visual pigment in a 5° circular patch of the living human retina 18° temporal from the fovea was studied with the Rushton retinal densitometer. The measuring light (570 nm) was selected to obviate artifacts from colour photoproducts.2. The action spectrum of a 10% bleach agrees well with the action spectrum at absolute threshold for the same patch of retina. The quantized C.I.E. scotopic spectral sensitivity curve is a good description of both spectra. Therefore, the visual pigment studied must be human rhodopsin.3. Its density has been estimated in five different ways. The results are in reasonable agreement. The optical density of human rhodopsin in vivo is about 0·35 (common logarithmic units) at its γmax.4. The photosensitivity of human rhodopsin in vivo was determined by studying its rate of bleaching in response to steps of monochromatic light exposed to the dark adapted eye, by measuring the amount bleached in the steady state by monochromatic lights as well as the amount bleached by 10 sec flashes of white light.5. The results obtained by the different methods are in good agreement with each other and with previous estimates made by others using white light.6. The photosensitivity of human rhodopsin in vivo [εγmax = 62,000 to 120,000 l./cm mole] is much higher than expected from in vitro measurements.
The projection of the posterior knee joint nerve to the cerebellar cortex
Authors: Belcari Paola , Carli G. , Strata P. 
Published: December 2014

1. In decerebrate cats, electrical stimulation of the posterior knee joint nerve evokes in the depth of the cerebellar cortex field potentials which have been identified as due to both mossy and climbing fibre inputs.2. The potentials evoked through the mossy fibres have a latency of 15–17 msec and are more widespread. Those evoked through the climbing fibres have a latency of 26–33 msec and are more restricted.3. Stimulation of the larger fibres originating from the Golgi receptors gives only a very restricted projection. When the fibres originating from the Ruffini receptors are also activated, the effect on the cerebellar cortex is more widespread.4. The results have been confirmed by recording unitary activity.
Fluorescent staining of acetylcholine receptors in vertebrate skeletal muscle
Authors: Anderson M. J. , Cohen M. W. 
Published: December 2014

1. α‐Bungarotoxin was labelled with fluorescent dyes and used as a stain for visualizing the distribution of acetylcholine receptors in vertebrate skeletal muscle fibres.2. Dye‐toxin conjugates had the same pharmacological properties as native toxin, but their potencies were lower.3. Fluorescent staining was examined in teased muscle fibres. The stain was found to be confined to the neuromuscular junction and associated with the subsynaptic membrane.4. Staining intensity was reduced by curare and even more so by carbachol, but not by atropine or neostigmine. Pre‐treatment of muscles with unlabelled α‐bungarotoxin entirely prevented staining.5. The staining at amphibian neuromuscular junctions was characterized by a pattern of intense transverse bands occurring at intervals of approximately 0·5‐1 μm, with fluorescence of lower intensity between them. Fluorescent staining was not detected on adjacent, extrasynaptic, muscle membrane. In side views the staining appeared as a fine line with small protuberances occurring at the same intervals as the intense bands seen face‐on. These results indicate that acetylcholine receptors are associated with the entire subsynaptic membrane, including the membrane of the junctional folds and that their density changes abruptly at the border between synaptic and extrasynaptic muscle membrane.
The velocity of lymph flow in the canine thoracic duct
Authors: Browse N. L. , Rutt D. R. , Sizeland D. , Taylor Alexis 
Published: December 2014

1. The velocity and pattern of movement of lymph in the thoracic duct of anaesthetized and conscious dogs has been studied by observing the movement of droplets of ultrafluid lipiodol in the duct.2. The velocity of flow when anaesthetized varied from 0·1–2·0 cm/sec, to 5·0 cm/sec when conscious.3. The pattern of flow was affected by respiration and the cardiac cycle. Most movement occurred at the end of inspiration.4. The duct of five autopsy preparations was perfused with saline to assess the volume and velocity of flow produced by the level of pressure gradients previously observed in the duct. These studies show that the small gradients (2–5 mmHg) observed during life are more than sufficient to produce the normal volume and velocity of flow measured. The mean resistance of the duct was 0·5 mmHg/ml. min.
γ‐Aminobutyric acid and inhibition in the septal nuclei of the rat
Authors: McLennan H. , Miller J. J. 
Published: December 2014

1. The electrophoretic application of γ‐aminobutyrate (GABA) and glycine to septal neurones inhibited their discharge, but the currents required to cause equivalent degrees of inhibition were always smaller for GABA than for glycine.2. The actions of GABA but not those of glycine were antagonized by bicuculline and not by strychnine and vice versa.3. The recurrent collateral inhibition of lateral septal neurones and the direct inhibition of medial cells evoked by stimulation of the fimbria were blocked by bicuculline but not by strychnine.4. The bursting patterns of discharge of laterally situated medial septal neurones was disrupted by bicuculline, but required a longer application of the drug than was needed to block the direct fimbrial inhibition. It is suggested that this disruption is due to diffusion of the drug to affect the inhibitory interneurones of the lateral septum.5. It is concluded that the inhibitory processes in the septum involve GABA as the synaptic transmitter.
Changes of of extracellular potassium concentration induced by neuronal activity in the spinal cord of the cat
Authors: Kříž N. , Syková Eva , Ujec E. , Vyklický L. 
Published: December 2014

1. Changes of extracellular K+ concentration, [K]e, arising in the spinal cord of the cat in response to an afferent stimulation were studied by means of K+‐specific micro‐electrodes.2. In the most active areas of the spinal cord a single volley in a large afferent input like the common peroneal nerve or the posterior tibial nerve produced a transient increase in [K]e of 0·05–0·1 m
M, which reached its peak in 0·2–0·3 sec and it declined in about 3 sec.3. Much higher increases in [K]e were found during repetitive stimulation of an afferent input. The highest increase (by 3 m
M) was at 100 Hz, but even at 1 Hz a significant increase of 0·25 m
M was observed. Equilibration of accumulated K+ was slow with a time constant of about 6 sec, which is much longer than could be expected for the same process in free solution.4. A characteristic distribution of increased [K]e was found in the spinal cord in response to 100 Hz afferent stimulation. The highest increase of 3 m
M was found in and around the intermediate nucleus, but at depths between 0·9–1·8 mm the [K]e increase exceeded 1 m
M.5. In the ventral horns afferent stimulation (100 Hz) increased [K]e by 0·25 m
M, while the same stimulation of the ventral root resulted in a [K]e increase of less than 0·05 m
M.6. The consequences of Ke+ accumulation after neuronal discharge are discussed in respect to its possible role in the depolarization of primary afferent terminals.
A nervous mechanism for descending inhibition in guinea‐pig small intestine
Authors: Hirst G. D. S. , McKirdy H. C. 
Published: December 2014

1. Intracellular recordings were made from neurones in the myenteric plexus of guinea‐pig small intestine under conditions in which these neurones received synaptic input from an adjacent segment of intestine.2. Most long synaptic pathways in the myenteric plexus were found to lead in an anal direction.3. Such pathways could be excited by either distension or transmural electrical stimulation of the intestinal segment.4. Similar stimuli evoked inhibitory junction potentials in the circular muscle layer but only on the anal side of the stimulated region of intestine.5. The results are discussed in relation to the concept of descending inhibition (Bayliss & Starling, 1899).
The regulation of cellular volume in liver slices
Authors: Macknight A. D. C. , Pilgrim Jennifer P. , Robinson Bridget A. 
Published: December 2014

1. Rat, rabbit and guinea‐pig liver slices were incubated in media at 37° C to study effects of ouabain and of metabolic inhibition on tissue composition.2. Slices initially incubated in oxygenated balanced medium did not swell when exposed to either balanced media or potassium‐free media containing ouabain in concentrations ranging from 0·1 to 10 m
M though they lost potassium and gained a comparable amount of sodium.3. Without prior incubation in oxygenated medium slices initially swelled when incubated with ouabain but then maintained their new volume.4. Slices whose metabolism was inhibited by incubation with nitrogen and 1 or 10 m
M iodoacetamide lost as much potassium as slices exposed to 10 m
M ouabain but became swollen with the uptake of sodium, chloride and water.5. The results show that liver cells, like renal cortical cells, possess a metabolically dependent, ouabain‐insensitive, potassium‐independent mechanism concerned in the regulation of cellular volume.
The cyclic motility of the omasum and its control in sheep
Authors: Bueno L. , Ruckebusch Y. 
Published: December 2014

1. The mechanical activity of different parts of the omasum was recorded by means of small balloons and/or strain‐gauges in conscious sheep. These events were related to the electrical activity of the omasal body, the omasal groove and the leaves and to the changes in diameter of the reticulo‐omasal orifice. Humoral, behavioural and nervous influences were examined.2. Two patterns of contraction of the omasum were found. One, confined to the oral and middle thirds of the organ, originated at the omasal groove and proceeded to the right and then the left surfaces of the body and ceased at the onset of reticular contraction. The other was limited to the aboral third of the organ near the abomasum; in this part the contractions were prolonged regardless of the reticular contraction and some gave rise to a reversed propagation over the organ. The characteristic cyclic motility of the omasum was slightly reduced in sheep fasted for 48 hr and in those fed on pelleted food, and it persisted after vagotomy.3. The reticulo‐omasal orifice always dilated strongly during the second phase of reticular contraction. It also dilated noticeably during the extra‐contraction associated with regurgitation. In each case alternating opening and closing movements at a frequency of 5–7/min followed. Contractions of the omasal leaves, which were independent of those of the omasal body, occurred at a rate of approximately 2–3/min. They passed from the free border to the base and travelled in an aboral direction. After local application of fatty acids the frequency of their contractions increased to approximately the same rate as that of the orifice.4. It is concluded that the motility of the omasum in sheep involves a wave of contraction starting at a point on the omasal groove just posterior to the reticulo‐omasal orifice and passing slowly over the omasal body. With the exception of the occasional reversed contractions this pattern is closely associated with rumino‐reticular cycles even though the omasal contractions and the movements of the leaves are partially independent of vagal innervation.
Effects of rapid cooling on the electrical properties of the smooth muscle of the guinea‐pig urinary bladder
Authors: Kurihara S. , Kuriyama H. , Magaribuchi T. 
Published: December 2014

The effects of low temperature (36–10° C) on the electrical properties of smooth muscle cells of the urinary bladder were investigated with microelectrodes and the double sucrose gap method.1. Lowering the temperature from 36 to 20 and to 10° C, depolarized the membrane from −37 to −33 and to −25 mV respectively. Spontaneous and propagated spike activity ceased completely at below 20° C but evoked spikes were occasionally observed at 10° C. A sustained contracture was evoked below 25° C.2. At both normal and low temperatures, the tissue had cable‐like properties. The length constant was reduced from 1·82 mm (36° C) to 1·54 mm (20° C) and to 1·04 mm (10° C). On the other hand, the time constant of the membrane calculated from the cable equations was prolonged by lowering the temperature from 157 msec (36° C) to 257 msec (20° C) and to 508 msec (10° C). The effective resistance of the membrane was increased to 1·8 times at 20° C and to 2·9 times the control value at 10° C.3. From the changes in various parameters of the membrane at low temperature, an increase in the longitudinal resistance of the tissue was postulated.4. The possible mechanisms of action of low temperature on the electrical properties of the smooth muscle of the urinary bladder were discussed in relation to those of the taenia coli and stomach, especially on the effects of low temperature on the sequestered Ca in the cell.
Light and X‐ray diffraction studies on chick skeletal muscle under controlled physiological conditions
Authors: Matsubara Ichiro 
Published: December 2014

1. The sarcomere length (s) of ehick slow and fast muscles (anterior and posterior latissimus dorsi (ant. lat. dorsi and post. lat. dorsi)) was measured by the method of light diffraction. In resting ant. lat. dorsi, s changed from 1·76 to 2·30 μm during stretch from minimum to maximum muscle lengths in situ, and in resting post. lat. dorsi from 2·18 to 2·63 μm.2. Resting tension started to rise in ant. lat. dorsi when s exceeded 1·7–1·8 μm, but in post. lat. dorsi not until s exceeded 2·6–2·7 μm.3. X‐ray diffraction patterns showed that ant. lat. dorsi contains collagen filaments; collagen reflexions were not seen in patterns obtained from post. lat. dorsi with the same exposure time.4. The relation between active tension and sarcomere length was similar for ant. and post. lat. dorsi. The maximum active tension was observed when s = 2·05–2·15 μm in ant. lat. dorsi, and when s = 2·10–2·25 μm in post. lat. dorsi.5. X‐ray diffraction patterns from both muscles showed that the periodic structures of the thick and thin filaments are similar to those in frog and rabbit skeletal muscles.6. The volume of the myofilament lattice in resting ant. lat. dorsi was 3·06 (± 0·14) × 109 Å3, in resting post. lat. dorsi 2·98 (± 0·09) × 109 Å3. These values are close to that of frog skeletal muscle. The lattice volume remained constant in ant. lat. dorsi and post. lat. dorsi over the range of sarcomere lengths found in situ.7. The equatorial diffraction patterns from the ant. lat. dorsi in rigor (glycerol extracted) were different from that of the resting muscle, and suggested that a large number of cross‐bridges were attached to the thin filaments during rigor. During potassium contracture, however, the diffraction pattern remained similar to that from the resting ant. lat. dorsi.
The autonomic innervation of the nasal blood vessels of the cat
Authors: Eccles R. , Wilson H. 
Published: December 2014

1. A study has been made in the anaesthetized cat of the stimulation parameters required to separate the vasodilator and vasoconstrictor responses evoked in the nose by stimulating the cut peripheral end of the Vidian nerve.2. The extent of the vasodilation and vasoconstriction was found to be dependent on the stimulation frequency, but whereas vasodilation reached a maximum at 25 Hz, vasoconstriction occurred at lower frequencies and was maximum between 10 and 15 Hz.3. Atropine, in a dose much greater than that which inhibits nasal secretion, did not abolish the vasodilator responses evoked by Vidian nerve stimulation. This suggests that the Vidian nerve may convey atropine resistant fibres to the nasal vasculature.