bluuebunny/crossref_metadata_2025_split huggingface dataset:
The release of nucleotides, 5‐hydroxytryptamine and enzymes from human blood platelets during aggregation
Authors: Mills D. C. B. , Robb I. A. , Roberts G. C. K. 
Published: December 2014

1. Adenosine diphosphate (ADP) and adrenaline caused the aggregation of human platelets suspended in plasma containing citrate anticoagulant and stirred at 37° C. The aggregation occurred in two phases and the second phase was associated with the appearance in the plasma of up to 30% of the ATP and 55% of the ADP present in the platelets. The concentration of ADP appearing in the plasma was up to 7 times the concentration added.2. Radioactivity was released by ADP and by adrenaline from platelets labelled with radioactive 5‐hydroxytryptamine; this release was closely correlated with the second phase of aggregation and with the release of nucleotides.3. Acid phosphatase, β‐glucuronidase and adenylate kinase were released to a small extent during second phase aggregation by ADP or adrenaline; thrombin and collagen particles caused significantly greater release of β‐glucuronidase than of either acid phosphatase or of adenylate kinase.4. Morphological changes indicating degranulation of the platelets were observed during the second phase of aggregation produced by adrenaline and by ADP.5. The second phase of aggregation, degranulation of platelets, and the release of nucleotides, of labelled 5‐hydroxytryptamine and of enzymes, were all inhibited by concentrations of amitriptyline which did not inhibit aggregation.
Cholinergic receptors at sympathetic preganglionic nerve terminals
Authors: Koketsu K. , Nishi S. 
Published: December 2014

1. In the paravertebral sympathetic chain of bullfrogs, some part of the preganglionic nerve located within the ganglion was depolarized transiently when acetylcholine (ACh) was directly applied to the ganglion, particularly in the presence of an anticholinesterase (anti‐ChE). The axonal part of the preganglionic nerve, on the other hand, showed no detectable depolarization following direct application of ACh (with anti‐ChEs) to the interganglionic nerve trunk.2. The ACh depolarization was markedly depressed by nicotine, and less markedly by (+)‐tubocurarine, whereas it was not affected by atropine. Nicotine, similar to ACh, transiently depolarized only the intraganglionic portion of the presynaptic fibres.3. The action potentials, recorded from the axonal as well as the terminal parts of the preganglionic nerve, showed spike potentials followed by a marked negative after‐potential. The negative after‐potential was followed by a positive after‐potential which was markedly enhanced by repetitive nerve stimulation.4. A slow negative potential followed the positive after‐potential in the repetitive responses of the terminal parts of the preganglionic nerve. The slow negative potential was enhanced by anti‐ChEs, eliminated by ACh and nicotine, and unaffected by atropine.5. The amplitude of the action potentials of the terminal parts of the preganglionic nerve, and particularly that of the negative after‐potential, was significantly depressed during the development of ACh depolarization as well as the slow negative potential, indicating that the two types of slow depolarization originated in the intraganglionic portion of the presynaptic fibres, presumably somewhere near or at the nerve terminals.6. ACh depolarization similar to that observed with bullfrog sympathetic ganglia was observed with rat superior cervical ganglia. The present experiments provide evidence that a certain part of the preganglionic nerve terminals is depolarized by the action of the transmitter released from their endings.
The effects of antral acidification on the gastric secretion stimulated by endogenous and exogenous gastrin
Authors: Magee D. F. , Nakajima S. 
Published: December 2014

1. In conscious dogs with Heidenhain fundic pouches and denervated antral pouches control dose—response curves to gastrin pentapeptide or methacholine were constructed, both when the antral pouch was empty and when it was stimulated with ACh (0·5 g/100 ml.) in citrate buffer adjusted to pH 5·5 or 1·5.2. When the antral pouches were irrigated with ACh (0·5 g/100 ml.) at pH 1·5 the acid outputs from the Heidenhain pouch in response to graded doses of gastrin pentapeptide or methacholine were significantly less at each dose level than those obtained with ACh at pH 5·5.3. The acid outputs from the Heidenhain pouch in response to either pentapeptide or methacholine with or without antral irrigation with ACh at pH 1·5 were approximately equal. Therefore the difference between the dose—response curves obtained by stimulation with ACh at pH 5·5 and those obtained by stimulation with ACh at pH 1·5 represents gastrin release rather than release of an inhibitory hormone.4. The pepsin outputs from the Heidenhain pouch during antral irrigation with ACh at pH 1·5 were significantly less than those obtained with ACh at pH 5·5 at each dose of methacholine.5. The maximal pepsin output was significantly greater in response to methacholine than to gastrin pentapeptide.6. Gastrin pentapeptide was not a significant stimulant of pepsin secretion from the Heidenhain pouch.7. The intestinal phase of parietal secretion was not inhibited by bathing the separated antrum with acid.
The effect of an exteroceptive stimulus on milk ejection in lactating rats
Authors: Deis R. P. 
Published: December 2014

1. The exteroceptive stimulus emanating from a lactating rat and the litter while suckling was used to induce milk ejection in another lactating mother 15 min before the replacement of her own litter. The effect of the external stimulus on milk ejection during one 30 min period and four 15 min periods of nursing was studied.2. After being isolated for 9 hr the litter from the mother subjected to the exteroceptive nursing stimulus (induced rat) obtained a significantly greater amount of milk during 30 min of nursing than that obtained by the litter from the control mother.3. When deaf mother rats were used the gain of milk by the litter showed no difference between the control and the induced mother. This result indicated that the effective external stimulus is an auditory one and is probably produced by the mother rat and the young while suckling.4. The administration of oxytocin (Syntocinon, Sandoz) 20 m‐u./100 g body wt., 15 min before the replacement of the litter produced a milk ejection similar to that obtained under the influence of the auditory stimulus. This would indicate that the exteroceptive stimulus probably evokes the release of oxytocin from the neurohypophysis.5. When nursing was performed in four periods of 15 min each the litter of the control mother obtained milk only in the second period of nursing while the litter of the induced mother obtained milk in all four periods of nursing and the amount of milk obtained in the whole hour was greater than that from the control rat.6. The administration of oxytocin just before the replacement of the litter every 15 min produced milk ejection only in the first two periods of suckling in the control rats but the induced rats were capable of ejecting milk during all four periods.7. The most satisfactory conclusion for the results obtained is that the
C.N.S. regulates both the release of oxytocin in response to suckling and the response of the mammary gland to oxytocin, in the lactating rat.
A direct synaptic connexion between the left and right giant cells in Aplysia
Authors: Hughes G. M. , Tauc L. 
Published: December 2014

1. In Aplysia fasciata, intrasomatic stimulation of the giant cell (RGC) of the right upper quadrant of the abdominal ganglia is followed after a constant delay by the appearance of a synaptic potential recorded in the giant cell (LGC) of the left pleural ganglion.2. The synaptic potential recorded in the LGC soma has a biphasic form (hence biphasic post‐synaptic potential or BPSP) consisting of a fast depolarizing phase of about 200‐800 μV amplitude and 0·15‐0·25 sec duration, followed by a slow hyperpolarizing phase of about 200‐800 μV amplitude and 1‐3 sec duration.3. During repetitive stimulation summation results in an over‐all hyperpolarization at low frequencies (less than 5/sec) and an over‐all depolarization for higher frequencies. Very high frequencies (25/sec) of stimulation of the RGC may elicit a spike in the LGC.4. Stimulation with two shocks showed increasing effects with shorter intervals on both the depolarizing and hyperpolarizing phase. These effects were progressive and there was no falling out of one of the two phases as might be expected if the BPSP was a composite of an inhibitory post‐synaptic potential (IPSP) and an excitatory post‐synaptic potential (EPSP).5. The effects of artificially imposed polarization of the LGC through a second micro‐electrode suggest that the BPSP results from a chemical transmission mechanism for both its depolarizing and hyperpolarizing phases but electrical transmission cannot be excluded.6. Curare has no effect on the BPSP and thus excludes a cholinergic transmission mechanism. Chloride ions injected into the LGC soma do not appear to modify the BPSP and hence it is concluded that the hyperpolarizing phase is different from IPSPs of the same cell.7. No synaptic potential is recorded in the RGC following stimulation of the LGC, except in a single preparation in which the RGC soma was situated in the right pleural ganglion. In this case the synaptic potential recorded in both giant cells following stimulation of the other, was biphasic in form.8. It is concluded that the BPSP is a unitary monosynaptic potential which is a characteristic feature of the organization of these two giant cells.
The relation of oxygen intake and velocity of walking and running, in competition walkers
Authors: Menier D. R. , Pugh L. G. C. E. 
Published: December 2014

1. The oxygen intake of four Olympic walkers was measured while walking and running at varying velocities on a treadmill at an altitude of 1800 m.2. The relation between O2 intake and running at speeds between 8 km/hr and 21 km/hr was linear. The relation for walking at speeds up to 8 km/hr followed an upward concave curve. These findings were similar to results obtained at sea level by other investigators.3. For walking at speeds between 8 km/hr and 14·5 km/hr the relation of O2 intake and velocity was a straight line having a slope twice that of running.4. Maximum O2 intake in walking averaged 60·0 ml./kg/min (range 55·8‐64·1 ml./kg/min) compared with 57·4 ml./kg/min (range 55·2‐60·2 ml./kg/min) in running. An international class long distance runner serving as a control reached a maximum O2 intake of 70 ml./kg/min.
Effect of a saline environment on sodium transport by the toad colon
Authors: Ferreira H. G. , Smith M. W. 
Published: December 2014

1. Colons isolated from saline‐adapted or aldosterone‐injected toads maintained transmural potential differences with the serosal side positive to the mucosa. The short‐circuit currents of colons taken from aldosterone‐injected toads could be expressed quantitatively by the net flux of sodium measured isotopically. This did not apply to saline‐adapted colons where the net sodium flux was from serosa to mucosa.2. The short‐circuit currents of colons taken from aldosterone‐injected animals increased as the sodium concentration was raised from 10 to 50 m
M, then decreased as the sodium concentration was further increased to 115 m
M. Adaptation to saline changed this relationship, the short‐circuit current becoming directly dependent on the sodium concentration.3. Faecal sodium was higher than serum sodium in saline‐adapted toads. There was little or no change in the level of serum sodium or potassium. The urine of saline‐adapted toads also contained high concentrations of sodium.4. The total and ouabain‐sensitive ATPase activities of mucosal scrapings taken from saline‐adapted colons were about half those found in the aldosterone‐injected animal. Ten per cent of the total ATPase activity could be inhibited by ouabain.5. Microsomal fractions of mucosal scrapings taken from saline‐adapted toads contained 4 times less Na+ + K+‐activated ATPase than did corresponding fractions from aldosterone‐injected animals. High concentrations of sodium inhibited the microsomal ATPase activity irrespective of the previous conditions of adaptation.6. Regulation of sodium movements across the toad colon appears to be a complex process with the mucosal cells changing their properties so that they either absorb or secrete sodium ions depending on the physiological state of the animal.
The effect of serum on the uptake of thyroid hormones by the perfused rat heart
Authors: Hillier A. P. 
Published: December 2014

1. The effect of serum on the uptake of radioactive
L‐thyroxine and
L‐3,5,3′‐tri‐iodothyronine has been studied in the perfused rat heart.2. With thyroxine binding protein (rat serum) in the perfusion fluid the uptake of both hormones is much reduced.3. This inhibitory effect of serum on hormone uptake is greater with thyroxine than with tri‐iodothyronine.4. Serum in the perfusion fluid accelerates the release of accumulated thyroid hormone from the rat heart.5. High concentrations of thyroxine increased the thyroxine space of hearts perfused by solutions containing serum.
Some aspects of adenosine triphosphate synthesis from adenine and adenosine in human red blood cells
Authors: Whittam R. , Wiley J. S. 
Published: December 2014

1. The synthesis of ATP has been studied in human erythrocytes. Fresh cells showed no net synthesis of ATP when incubated with adenine or adenosine, although labelled adenine was incorporated into ATP in small amounts.2. Cold‐stored cells (3‐6 weeks old) became progressively depleted of adenine nucleotides but incubation with adenosine or adenine plus inosine restored the ATP concentration to normal within 4 hr. Incorporation of labelled adenine or adenosine into the ATP of incubated stored cells corresponded to net ATP synthesis by these cells.3. Synthesis of ATP from adenosine plus adenine together was 75% derived from adenine and only 25% from adenosine, indicating that nucleotide synthesis from adenine inhibits the simultaneous synthesis of nucleotide from adenosine.
Identification of cone mechanisms in monkey ganglion cells
Authors: Gouras Peter 
Published: December 2014

1. Blue, green, and red sensitive cone mechanisms have been studied in two types of on‐centre ganglion cells in the Rhesus monkey's retina.2. One type of cell receives signals from both green and red sensitive cone mechanisms, both of which excite in the centre and inhibit in the periphery of the cell's receptive field. These cells discharge transiently to maintained stimuli of any wave‐length and are called phasic.3. The second type of cell receives excitatory signals from only one cone mechanism, either blue, green or red sensitive, in the centre, and inhibition from another cone mechanism in the periphery of its receptive field. These cells discharge continuously to maintained stimuli of appropriate wave‐length and are called tonic.4. Tonic cells outnumber phasic cells although both are found adjacent to one another throughout the retina. Phasic cells are relatively more common toward the periphery and tonic cells relatively more common toward the fovea.
Reconstruction of the repolarization process in cardiac Purkinje fibres based on voltage clamp measurements of membrane current
Authors: Noble D. , Tsien R. W. 
Published: December 2014

1. The results of the voltage clamp experiments described in a preceding paper (Noble & Tsien, 1969) have been used to reconstruct the repolarization process in Purkinje fibres.2. The results show that, at the beginning of the plateau, the instantaneous current—voltage relation has a region of net inward current which, in the absence of additional outward current, would prevent repolarization.3. The activation of the outward current, ix1, overcomes this region of inward current within about 300 msec. This first phase of the plateau is limited mainly by the speed of activation of ix1 and, during this time, there exists a threshold for all‐or‐nothing repolarization. The calculated time course of this threshold corresponds well with that recorded experimentally in uniformly polarized preparations.4. Once the net inward current has been abolished, the rate of repolarization is mainly limited by the membrane capacity, although ix1 continues to activate until about 500 msec. The outward current, ix1, begins to deactivate during the rapid terminal phase of repolarization, but it is not fully deactivated at the end of the action potential. A second action potential initiated at this time would therefore be shorter than the first.5. The effect of the initial outward current transient, recently identified as largely chloride current (Dudel Peper, Rüdel & Trautwein, 1967 a), has been calculated. The result is a notch at the beginning of the plateau similar to that often recorded experimentally. The action potential duration is not greatly influenced by this current component.6. The role of outward currents other than ix1 in repolarization is discussed. It is concluded that the outward current component primarily responsible for terminating the action potential may vary and depends on the action potential duration. In Purkinje fibres with action potentials of normal duration, ix1 is the main time‐dependent outward current involved.
Action of cocaine and chronic sympathetic denervation on vagal escape
Authors: Campos H. A. , Urquilla P. R. 
Published: December 2014

1. The effect of cocaine has been studied on vagal escape and on the tachycardia due to vagal stimulation in the atropinized dog. All the dogs were submitted to acute cervical section of the spinal cord and acute or chronic sympathetic denervation.2. Cocaine, 5 mg/kg or 40 μg/kg/min,
I.V., induces a significant enhancement of the ventricular escape. The effects of a continuous infusion of cocaine are more reproducible than those of a single injection of the drug.3. Cocaine, 40 μg/kg/min,
I.V., potentiates the tachycardia due to vagal stimulation in the atropinized dog.4. Chronic thoracic sympathectomy markedly retards the recovery of the ventricular rate from the inhibitory action of the vagus. Under this condition, the infusion of cocaine does not significantly enhance the ventricular escape.5. These findings suggest that an adrenergic mechanism located at the sympathetic nerves supplying the heart is substantially involved in the phenomenon of vagal escape.
The effect of sodium and calcium on the action potential of the smooth muscle of the guinea‐pig taenia coli
Authors: Brading Alison , Bülbring Edith , Tomita T. 
Published: December 2014

1. Spontaneous spike activity and action potentials evoked by external field stimulation were recorded, intracellularly and with the double sucrose gap method, from the smooth muscle of guinea‐pig taenia coli.2. Replacement of external NaCl with sucrose (leaving 10 m
M‐Na in the buffer) caused hyperpolarization and stopped spontaneous activity within 10 min. Spikes could, however, be evoked for 2‐3 hr. The amplitude, the overshoot and rate of rise of the spike were increased.3. In 10 m
M‐[Na]o the intracellular Na concentration was reduced from 35 to 24 m
M, shifting the Na‐equilibrium potential from +34 to ‐22 mV.4. Excess Ca (12·5 m
M) caused hyperpolarization and increased membrane conductance. The amplitude and the rate of rise of the spike were increased, the threshold was raised and the latency of the spike evoked by threshold stimulation became shorter.5. The effect of reducing the external Ca concentration depended on the Na concentration present, being greater with higher external [Na]o. When the membrane was depolarized and spikes deteriorated in low Ca (0·2‐0·5 m
M) reduction of Na to 10 m
M caused repolarization and recovery of the action potential.6. Mn (0·5‐1·0 m
M) blocked spontaneous spike discharge after 20 min. Higher concentrations (more than 2·0 m
M) were required to block the evoked action potential.7. The results indicate that the smooth muscle spike in taenia is due to Ca‐entry and that Na influences spike activity indirectly by competing with Ca in controlling the membrane potential.
The re‐distribution of cytochrome oxidase, noradrenaline and adenosine triphosphate in adrenergic nerves constricted at two points
Authors: Banks P. , Mangnall D. , Mayor D. 
Published: December 2014

1. The experiments correlate certain changes in the ultrastructure of cat hypogastric nerves constricted at two points with the distribution of a mitochondrial enzyme (cytochrome oxidase), noradrenaline (stored in some of the vesicles with an electron dense core, i.e. granular vesicles) and adenosine triphosphate (ATP) (present in noradrenaline storage granules, mitochondria and the soluble fraction of the axon).2. Noradrenaline (NA) and granular vesicles accumulated proximal but not distal to both constrictions. The total amount of NA and the concentration of granular vesicles above the first constriction was greater than that present in a similar piece of normal nerve, indicating that the cell body was continuing to produce the transmitter despite injury to its axon. The granular vesicles proximal to the first constriction were found in swollen or distorted axons and in new axonal outgrowths. It was concluded that the movement of NA in these constricted nerves was only centrifugal in direction.3. Mitochondria and cytochrome oxidase accumulated on both sides of the two constrictions, indicating a bi‐directional movement of mitochondria in the damaged axons. The possibility that some of the increase in the cytochrome oxidase could be related to an increase in the number of mitochondria in cells other than neurones is considered.4. The adenosine triphosphate content increased on both sides of the two constrictions. This increase developed more slowly and was less marked than that of the other two substances.5. It was concluded that (a) there was a close correlation between the behaviour of noradrenaline and granular vesicles and between cytochrome oxidase and mitochondria, (b) the dense cored vesicles and the mitochondria moved independently of one another and at different rates after constriction of non‐myelinated axons, (c) while some of the changes may be attributed to an obstruction to the free movement of axoplasm others may be due to an active reaction to axonal injury, and (d) localized intraaxonal synthesis of noradrenaline and cytochrome oxidase did not occur between the two constrictions.
Sodium ions and the secretion of catecholamines
Authors: Banks P. , Biggins Rosemary , Bishop R. , Christian B. , Currie N. 
Published: December 2014

1. Perfusion of bovine adrenal glands with a potassium‐free Tyrode solution results in an increased spontaneous release of catecholamines and an increased response to stimulation with carbamylcholine.2. Perfusion with a Tyrode solution containing 70 m
M‐KCl causes a marked secretion of catecholamines and a subsequent inhibition of secretion in response to stimulation with carbamylcholine.3. Perfusion with sodium‐free media abolishes or severely reduces the secretory response of the gland to carbamylcholine and to 70 m
M‐KCl although the basal secretion shows an initial rise.4. Perfusion with sodium‐deficient media permits some retention of the secretory response.5. A possible role for intracellular sodium ions in the secretion of catecholamines is discussed.