bluuebunny/crossref_metadata_2025_split huggingface dataset:
The optical density of erythrolabe determined by retinal densitometry using the self‐screening method
Authors: King‐Smith P. E. 
Published: December 2014

1. Retinal densitometry has been used to determine the optical density of erythrolabe in foveal cones.2. A self‐screening method was used, as in Rushton's (1963b) measurements on chlorolabe.3. Psychophysical experiments have demonstrated that self‐screening in cones depends on the direction of the light in the same manner as the Stiles—Crawford efficiency. Stiles—Crawford measurements were therefore made on each subject and a method was devised to allow for the corresponding reduction in self‐screening in densitometry.4. Complications arising from coloured bleaching products, the presence of a second visual pigment and the fluorescence of visual pigments are considered.5. The mean value for optical density at 560 nm was found to be 0·40 ± 0·07
S.E. of mean for the five subjects (two deuteranopes, two deuteranomalous subjects and one normal subject).6. This result is in good agreement with Rushton's (1963b) value of 0·35 for chlorolabe using retinal densitometry.7. The densitometry results are also in reasonable accord with recent psychophysical and microspectrophotometry measurements. This provides evidence that densitometry measures all the cone pigment in an unbiased manner and not just a superficial sample.
The optical density of erythrolabe determined by a new method
Authors: King‐Smith P. E. 
Published: December 2014

1. A new method is described for the determination of optical density by retinal densitometry based on an analysis of stray light.2. The basic assumption used is that the stray light present in retinal densitometry is independent of wave‐length. The justification for this assumption is considered.3. The stray light and hence the optical density was determined by a method of successive approximations using a Linc 8 computer.4. The optical density of erythrolabe for the direction of maximum Stiles—Crawford efficiency was determined for five subjects, two deuteranopes, two deuteranomalous and one red‐rich normal subject. The mean values for three of the subjects were close to the grand mean value of 0·42, but the other two subjects had considerably higher and lower values respectively.5. The results are in satisfactory agreement with optical density values determined by the self‐screening method using retinal densitometry, and also with determinations using microspectrophotometry and psychophysics.6. The relevance of dielectric wave‐guide modes in the outer segments is considered.
Amylase secretion by the perfused cat pancreas in relation to the secretion of calcium and other electrolytes and as influenced by the extrenal ionic environment*
Authors: Argent B. E. , Case R. M. , Scratcherd T. 
Published: December 2014

1. Amylase secretion from the perfused pancreas consists of two components: a small continuous basal secretion and a stimulated secretion in response to acetylcholine or cholecystokinin‐pancreozymin. The response to small doses of either stimulant was repeatable over several hours.2. The calcium concentration of pancreatic juice, always less than that of the perfusate, was normally constant above secretory rates of 0·15 g/10 min. However, when the concentration of enzymes in the juice rose, either after stimulation or at very low secretory rates, the calcium concentration rose in parallel, suggesting that this calcium is bound to, or is a component of, pancreatic enzymes.3. Elevation of the perfusate calcium concentration resulted in a parallel increase in the calcium concentration of the pancreatic juice.4. Calcium‐free solutions initially caused a small reduction in basal and stimulated amylase secretion and, after prolonged periods of perfusion, abolished stimulated secretion and caused a reduction in electrolyte secretion. The latter was completely reversed by calcium‐rich perfusates but the effects on enzyme secretion were only partially reversible.5. Calcium‐rich perfusates had no effect on the rate of electrolyte secretion but potentiated submaximally stimulated amylase secretion.6. Barium did not substitute for calcium in supporting pancreatic secretion.7. Alterations in the extracellular concentrations of sodium, potassium and magnesium had no direct effect on amylase secretion.8. The local anaesthetic tetracaine inhibited amylase secretion at a lower concentration than that required to inhibit electrolyte secretion.9. It is concluded (a) that calcium is secreted into the pancreatic juice in two fractions, one associated with enzymes and the other with the electrolyte component of the juice; and (b) that calcium ions play an important role in the stimulus‐secretion coupling of pancreatic acinar cells, but that the effects of calcium depletion on electrolyte secretion may principally be due to alterations in the permeability of the duct system.
Electrical properties of toad sartorius muscle fibres in summer and winter
Authors: Dulhunty Angela F. , Gage Peter W. 
Published: December 2014

1. The area and circumference of surface fibres of sartorius muscles were measured from photomicrographs of frozen sections of whole muscles, and compared with the values obtained assuming a circular cross‐section. The latter assumption gave an over‐estimate of the mean area of 28%, but only a 2% over‐estimate of the circumference. In isolated, single fibres, the assumption gave over‐estimates of 25 and 6%, of area and circumference respectively.2. The passive electrical properties of fibres were different in summer and winter. The mean internal resistivity, membrane resistance and membrane capacitance were 147 Ω.cm, 7·6 kΩ.cm2 and 4 μF/cm2 in summer, and 194 Ω.cm, 3·9 kΩ.cm2 and 6·7 μF/cm2 in winter, in fibres of comparable diameters in situ. In single fibres in summer, the mean values were 120 Ω.cm, 8·6 kΩ.cm2 and 3·6 μF/cm2.3. In glycerol‐treated fibres the mean specific membrane capacitance was 1·0 μF/cm2 in summer and 2·0 μF/cm2 in winter. The internal resistivity and specific membrane resistance were 167 Ω.cm and 8·9 kΩ.cm2 in summer, and 232 Ω.cm and 3·9 kΩ.cm2 in winter.4. Early after‐depolarizations were recorded in glycerol‐treated fibres which had a low membrane capacitance, did not twitch and showed little ‘creep’. Electron micrographs of glycerol‐treated fibres showed disruption of the transverse tubular system and sarcoplasmic reticulum.5. After exposure of muscles to 400 m
M urea or acetamide for 1 hr, muscle fibres did not twitch and had a reduced membrane capacitance in Ringer solution.
Effects of proteolytic enzymes on function and structure of frog neuromuscular junctions
Authors: Betz W. , Sakmann B. 
Published: December 2014

1. Frog cutaneous pectoris nerve‐muscle preparations were incubated with collagenase and protease and examined with electrophysiological and electron microscopic techniques.2. The physiological properties and intracellular ultrastructural appearance of individual muscle and nerve cells were not affected by the enzyme treatment. However, neuromuscular transmission and the morphology of the nerve‐muscle junction were altered.3. Collagenase produced an irreversible loss of activity of end‐plate cholinesterase and a partial loss of stainable ‘synaptic cleft material’.4. Protease produced these changes and, in addition, the entire basement membrane was digested, which led to ‘synaptic disjunction’ of nerve terminals and muscle end‐plates.
Location of inexchangeable sodium in the nucleus and cytoplasm of oocytes of Bufo bufo exposed to sodium‐free solutions
Authors: Dick D. A. T. , Fry D. J. 
Published: December 2014

1. In oocytes exposed to Ringer solution in which Li substitutes for Na, 13–62% Na is inexchangeable with Li.2. Nuclei of oocytes isolated by dissection in salt solutions swell irrespective of the concentration or ionic components of the solution. When isolated in 4% bovine albumin solutions, swelling is negligible.3. When the nuclei of cells exposed to Li are isolated in 4% albumin solution, less than 6% of the inexchangeable Na is found in the nucleus, while 36–88% of it is found in the cytoplasmic fragments remaining after removal of the nucleus.4. When a Li‐exposed cell is crushed in a cellophane bag and dialysed against Ringer or Li‐substituted Ringer, 86–92% of the inexchangeable Na diffuses out.5. It thus appears that the inexchangeable Na is located almost entirely in the cytoplasm and hardly at all in the nucleus, and is not bound to macromolecules within the cell.
The effect of salt adaptation on the permeability and cation selectivity of the goldfish intestinal epithelium
Authors: Ellory J. C. , Nibelle Jacqueline , Smith M. W. 
Published: December 2014

1. The short‐term uptake of Na by the goldfish mucosa was compared using both inulin and choline as markers of extracellular space. The results were virtually identical, the distribution of both choline and inulin increasing rapidly to measure a space at 1 min which then remained nearly constant during a following 4 min incubation.2. Using inulin as space marker, the uptake of various alkali metal cations was determined from a 1 min contact with the mucosa. The relative rates of uptake were Tl > K > Rb > Cs > Na > Li, with a low selectivity ratio, the range of permeabilities being no greater than 5.3. The selectivity sequence was the same in both salt and fresh‐water adapted fish. Of the alkali metal cations tested, only Na showed a significantly decreased uptake on adaptation to salt.4. Isolated intestinal preparations from salt‐adapted fish showed a reduced short‐circuit current compared with fish adapted to fresh water, the values being 12·3 ± 1·2 and 35·7 ± 1·5 μA cm−2 respectively. In both cases the short‐circuit current was equivalent to the net transport of Na measured isotopically.5. In Krebs—Henseleit medium, the measured tissue resistance was approximately 100 Ω cm−2 for both salt and fresh‐water adapted fish.6. It is concluded that regulation of cation transport in goldfish intestinal epithelium is specific for Na and mediated primarily through cellular rather than extracellular pathways.
The ionic dependence of the strength and spontaneous relaxation of the potassium contracture induced in the heart of the frog Rana pipiens
Authors: Chapman R. A. 
Published: December 2014

1. The tension generated by isolated frog atrial trabecules, during exposure to solutions containing a high potassium concentration, is not maintained but spontaneously relaxes. The final part of this relaxation can be fitted by a single exponential function.2. The recovery of the tension generating mechanisms following the spontaneous relaxation of a potassium contracture depends on the preceding membrane potential and the time since the last contracture.3. The rate of the exponential phase of the spontaneous relaxation is independent of the [K]o and hence the membrane potential, the [Ca]o; and when the [Ca]o/[Na]o2 ratio is maintained it is also independent of the [Na]o. This relaxation is not influenced by atropine or pronethalol.4. When sodium is totally excluded from the bathing medium the rate of relaxation of a later potassium contracture is much increased. It is argued that this change is due to a fall in the intracellular sodium concentration.5. The consequences of these results are discussed, and the hypothesis that is favoured would require that contraction is induced by a transient release of calcium into the sarcoplasm, probably triggered by a potential dependent, and probably also transient, influx of calcium through the cell membrane. Relaxation is supposed to occur when this activator‐calcium is then removed by an intracellular relaxing system that resembles the sarcoplasmic reticulum of other muscles. What this intracellular structure might be, is also discussed.
An inhibition of post‐ganglionic motor transmission in the mammalian vas deferens by D‐lysergic acid diethylamide
Authors: Ambache N. , Dunk Linda P. , Verney J. , Zar M. Aboo 
Published: December 2014

1. Under certain conditions
D‐lysergic acid diethylamide (LSD), 10−9‐10−6 g/ml., exerted an immediate, prolonged and slowly reversible inhibitory effect upon the post‐ganglionic motor transmission in desheathed guinea‐pig vas deferens preparations.2. The most critical factor influencing this action of LSD appeared to be the train length. With short trains of less than 4 or 5 pulses the twitch inhibition produced by LSD was often total. With longer trains (5–20 pulses), the degree of inhibition declined with increase in train length. These results suggest the existence of two components in the motor response to post‐ganglionic stimulation, distinguished by their susceptibility to LSD.3. The inhibition of the LSD‐susceptible component was related to the dose of LSD in the range 10−9‐10−6 g/ml., reaching a maximum at 0·5‐1 × 10−6 g/ml. The response remnants elicited by trains of more than 5 pulses under these conditions could not be reduced further by a ten‐ to twenty‐fold increase in LSD concentration to 10−5 g/ml. and were in fact slightly potentiated.4. The inhibition of post‐ganglionic motor transmission by LSD was not explicable on the basis of an α‐adrenoceptor blockade because it was not associated with any reduction in motor responses to noradrenaline.5. The use of propranolol excluded mediation of the LSD‐inhibition by β‐adrenoceptors.6. The LSD effect was not due to a non‐specific smooth muscle depression because it was not associated with any reduction in motor responses to acetylcholine, ATP or bradykinin.7. The inhibitory effect of LSD on post‐ganglionic transmission resembled that of noradrenaline in that it was antagonized by phentolamine; another α‐adrenoceptor blocking agent, phenoxybenzamine, was less effective than phentolamine in this respect.8. The LSD‐inhibition was obtained in preparations taken from reserpinized guinea‐pigs.9. The inhibition of motor transmission in the vas deferens by LSD was confirmed in rats, Meriones shawii and rabbits.10. The inhibition of post‐ganglionic transmission by LSD was unrelated to its ability to antagonize 5‐hydroxytryptamine (5‐HT), to which the longitudinal muscle of the guinea‐pig vas deferens is insensitive. The more potent 5‐HT antagonists, methysergide and BOL 148 were either virtually inactive or considerably weaker than LSD.
The effects of changes in arterial plasma calcium concentration on submandibular secretory potentials
Authors: Creed Kate E. , McDonald I. R. 
Published: December 2014

1. The concentration of Ca in the arterial blood plasma perfusing submandibular glands of anaesthetized cats and possums (Trichosurus vulpecula) was altered by constant‐rate close arterial injection of isotonic CaCl2 or EDTA solutions.2. There were no significant changes in the resting potentials of surface acinar cells in either species when the arterial plasma Ca concentration was altered over the range 0–30 m
M.3. Secretory potentials in response to parasympathetic stimuli and close arterial injection of ACh were reduced and finally abolished during EDTA injection, but temporarily restored by injection of CaCl2.4. Secretory potentials in response to 1 Hz parasympathetic stimuli in the cat were enhanced by increasing the gland arterial Ca concentration up to 5 m
M; but responses to 10 Hz stimuli or close arterial ACh injection were not affected. There was no such enhancement of secretory potentials in the possum.5. Increase in the gland arterial plasma Ca concentration above 5 m
M caused reduction in the amplitudes of the secretory potentials to all stimuli in both species, until they were abolished at 7–10 m
M in the possum and 15–20 m
M in the cat.6. In both species, increase in the gland arterial plasma Ca concentration caused increase in the gland blood flow and enhancement of the vasodilator effects of parasympathetic stimuli and ACh injection. EDTA injection was sometimes associated with a vasoconstrictor response to parasympathetic stimuli.7. It is concluded that the secretory potentials, but not the resting potentials, of submandibular secretory cells require the presence of Ca in the interstitial fluid. It is suggested that Ca affects both the release of transmitter and at higher concentration the mechanism by which it activates the secretory cells.
Release of transmitters into the perfused third cerebral ventricle of the cat
Authors: Ashkenazi Ruth , Holman R. B. , Vogt Marthe 
Published: December 2014

1. The third cerebral ventricle of cats treated with nialamide and anaesthetized with chloralose was perfused, and the effluent was tested for 5‐hydroxytryptamine (5‐HT) and also for acetylcholine (ACh) when the perfusion fluid contained neostigmine.2. Under ‘resting’ conditions a 25 min sample of effluent contained from < 1 to 6 ng 5‐HT; the release remained steady during many hours of perfusion. It was necessary to watch out for traces of blood which might contribute to the 5‐HT content and which were only visible after centrifugation.3. A number of regions in the ventral mid‐brain and hind‐brain were stimulated, including the two most anterior nuclei of the raphe, nucleus linearis rostralis and intermedius. Release of 5‐HT (rarely more than 2 ng) was only obtained on stimulation of these two nuclei, whereas ACh was released by stimulating many points, such as the reticular formation or the decussation of the superior cerebellar peduncles, but not the two raphe nuclei.4. Low frequencies of stimulation were more effective at releasing 5‐HT, and high frequencies at releasing ACh.5. Since the amount of 5‐HT released on stimulation was rarely more than 2 ng, a powerful re‐uptake process was suspected and confirmed by the use of chlorimipramine. Intravenous, intraperitoneal and intraventricular use of this drug temporarily increased the basal release to values ranging from 20 to 50 ng in 25 min samples, and about trebled the release on stimulation of either of the linear nuclei.6. Intravenous administration of chlorimipramine (10 mg/kg) caused the disappearance of electrical responses evoked in the brain stem by afferent sensory stimuli.
Studies on the site of termination of static and dynamic fusimotor fibres within muscle spindles of the tenuissimus muscle of the cat
Authors: Brown M. C. , Butler R. G. 
Published: December 2014

1. The site of termination of static and dynamic fusimotor fibres has been mapped by finding which intrafusal muscle fibres have been depleted of glycogen as a result of tetanic stimulation of single γ fibres. Long periods of stimulation coupled with occlusion of the blood supply were necessary to cause glycogen depletion.2. In cat tenuissimus muscle, dynamic γ motor fibres always activated bag intrafusal muscle fibres, and occasionally chain fibres. Static γ fibres always activated chain fibres and frequently activated bag fibres as well.3. It is argued that these results can be fitted into the hypothesis of the mechanism of internal functioning of the spindle originally proposed by Jansen & Matthews (1962). It is also pointed out that the results raise problems concerning the mechanism of development of the spindle motor innervation.
Effects of anions and cations on the resting membrane potential of internally perfused barnacle muscle fibres
Authors: Lakshminarayanaiah N. , Rojas E. 
Published: December 2014

1. Single barnacle muscle fibres from Megabalanus psittacus (Darwin) were internally perfused with a number of K salt solutions (200 m
M) which were made isotonic to the barnacle saline with sucrose.2. 200 m
M‐K acetate solution, in general, was found to be more effective than other solutions of K salts in generating and maintaining stable resting membrane potential of −56·0 ± 0·7 mV (all potentials are referred to the external solutions as ground). The various K salts, on the basis of the magnitude of the resting potential they generated in the muscle fibres, followed the sequence, acetate > isethionate > aspartate > glutamate > fluoride > monohydrogen phosphate > succinate > citrate > sulphate > oxalate > iodobenzoate > ferrocyanide > chlorate > nitrate > chloride > thiocyanate > iodide > bromide > cyanide.3. The resting potential in muscle fibres perfused with solutions of acetate, aspartate and glutamate increased linearly with the logarithm of the K concentration (slope = 30·4 mV for K acetate and 27·4 for K aspartate and glutamate) when the ionic strength of the solutions was progressively increased from 50 to 650 m
M. On the other hand, similar increase of ionic strength beyond 200 m
M of solutions of K isethionate, fluoride, monohydrogen phosphate, succinate and citrate depolarized the muscle fibres.4. Perfusion of acetate solutions of other alkali metal ions gave low values for the resting potential and followed the sequence K > Na > Rb > Li > Cs. Also NH4 and Tris ions gave low values for the resting potential which underwent oscillations associated with the twitching of the fibre and occasionally became positive in value (action potential).5. Addition of tetraethyl ammonium chloride (TEA‐Cl), 20–100 m
M, to K acetate solutions (200 m
M) depolarized the fibre membrane and the consequent reduction of resting potential varied linearly with the logarithm of TEA concentration.6. Replacement of chloride ion by acetate or isethionate in the external solution did not change significantly the resting potential although the values were consistently lower by about 2 mV.7. Complete elimination of K in the external solution and reduction of its ionic strength using sucrose depolarized the muscle fibres by about 27 mV when Na was changed from 475 to 1 m
M. Under these conditions, external solutions completely in acetate form gave resting potentials which were more positive than those observed in completely chloride solutions by 6–8 mV.8. Replacement of Na by Li, Tris, choline, tetramethyl or tetraethyl ammonium ion in the external solution made the values of the resting potential more positive (depolarization). Similarly increasing the concentration of K (or Cs or Rb in place of K) by correspondingly decreasing the concentration of Na in the outside solution depolarized the fibres and the resting potential became zero at a concentration of 280 m
M (or 308 or 1500 m
M for Rb or Cs, respectively) on extrapolation.
Pancreatic enzyme response to secretin and cholecystokinin‐pancreozymin in the rat
Authors: Fölsch U. R. , Wormsley K. G. 
Published: December 2014

1. The report describes a new technique for collecting pancreatic juice in anaesthetized rats. The technique, which involves perfusion of the duodenum, is particularly suitable for analysing the characteristics of pancreatic enzyme secretion. To ensure stable secretory conditions, the rats were kept at 30° C.2. Different combinations of secretin and cholecystokinin‐pancreozymin have been given by continuous intravenous infusion and the patterns of secretion of amylase and trypsin have been defined.3. Maximal secretion of the pancreatic enzymes was observed with 60 IU/kg.hr CCK‐PZ (amylase) or 120 CU/kg.hr (trypsin) combined with 0·5 CU/kg.hr (secretin).4. Pancreatic enzyme secretion in response to submaximal stimulation with CCK‐PZ was potentiated by secretin.5. Supramaximal stimulation with CCK‐PZ resulted in significantly less secretion of pancreatic enzymes than in response to maximal stimulation.6. The pancreatic secretion of enzymes was poorly sustained during constant‐rate stimulation with intravenous hormones, at all dose rates.7. The significance and possible mechanisms of the biphasic pattern of enzyme secretion in response to increasing doses of stimulant hormones and the fall‐off in enzyme secretion during constant‐rate stimulation are discussed.