bluuebunny/crossref_metadata_2025 huggingface dataset:
The effects of high concentrations of an electrolyte on the swelling of non‐metabolizing tissue slices
Authors: Davey K. J. , Skegg D. C. G.
Published: December 2014

1. Rat kidney cortical slices, with metabolism suppressed by iodoacetate, were incubated anaerobically at 26° C in hyperosmotic saline media. Changes in tissue composition with time, up to 12 hr, were studied. Despite initial shrinkage, gross swelling occurred, even in saline media of more than twice the concentration of normal extracellular fluid.

2. The composition of non‐metabolizing kidney slices incubated at 26° C in a balanced saline medium containing 7 g polyethylene glycol 6000 (PEG 6000)/100 ml. was determined at intervals up to 12 hr. The tissue water, sodium and chloride contents had reached constant levels by 6 hr. Potassium continued to leak slowly from the tissue, but there was no significant further loss between 10 and 12 hr.

3. Non‐metabolizing kidney slices were incubated in PEG medium containing additional quantities of either a non‐electrolyte (400 m‐osmole glucose/kg H2O) or an electrolyte (400 m‐osmole NaCl/kg H2O), both of which penetrated the tissue to attain approximately uniform concentrations in cells and media. Whereas the slices in the glucose medium attained the same equilibrium water content as those incubated in PEG medium alone, the final water content of slices in the medium containing additional NaCl was significantly lower. This difference might have resulted from depression of intracellular colloid osmotic pressure by the high salt concentration.
The release of a renally active substance by perfused rat hearts
Authors: Lockett Mary F. , Retallack R. W.
Published: December 2014

1. A substance (HS) which resembles the 18‐monoacetate of
D‐aldosterone (18‐MA) in its biological actions is released by perfused rat hearts, HS is assayed in terms of activity equivalent to synthetic 18‐MA.

2. Isolated rat hearts perfused with modified Krebs bicarbonate Ringer without recirculation secrete progressively less and less HS.

3. Addition of
D‐aldosterone to recirculating perfusate supplying a heart no longer secreting measurable quantities of HS causes a rapid and very marked increase in the output of HS from the heart. If radioactively labelled
D‐aldosterone is supplied the HS synthesized is radioactively labelled. No measurable amounts of HS are formed from 18‐hydroxycorticosterone.

4. Chromatographic differentiation between 18‐MA and HS, initially difficult, has been achieved.

5. The rate of secretion of HS from the hearts of adrenalectomized animals is markedly reduced: synthesis of HS is immediately resumed when these hearts are supplied with
D‐aldosterone, but at a subnormal rate.
Urine concentration during solute diuresis in potassium‐depleted rabbits. Evidence for a defect in tubular sodium transport
Authors: Barraclough M. A. , Guignard J-P. , Jones N. F.
Published: December 2014

1. The relationship between osmolal clearance (Cosm) and the reabsorption of solute‐free water by the kidney (TH2Oc) was examined during 10% mannitol and 2·3% saline diuresis in normal and potassium‐depleted rabbits.

2. In normal rabbits at osmolal clearances close to 3·0 ml./min, TH2Oc during mannitol diuresis was 0·87 ± 0·06 ml./min and during saline diuresis 1·19 ± 0·07 ml./min. The mean difference in TH2Oc of 0·32 ± 0·05 ml./min was highly significant (P < 0·001).

3. In one group of potassium‐depleted rabbits with a reduction in maximal urinary concentration, TH2Oc during both mannitol and saline diureses was reduced significantly below normal and the increment in TH2Oc normally seen during saline diuresis was abolished.

4. In a second group of potassium‐depleted rabbits maximal urinary concentration (1253 ± 88 m‐osmole/kg H2O) was not significantly different from that in normal rabbits (1272 ± 116 m‐osmole/kg H2O). In these animals, TH2Oc at osmolal clearances close to 3·0 ml./min was not significantly different during mannitol diuresis (0·83 ± 0·07 ml./min) from that in normal animals, whereas it was reduced significantly during saline diuresis (0·89 ± 0·07 ml./min, P < 0·001) and the difference in TH2Oc normally seen between mannitol and saline diuresis was abolished.

5. The inability to increase TH2Oc during saline diuresis above that achieved during mannitol appears to be the earliest manifestation of the concentrating defect associated with potassium depletion. It probably results from an impairment of sodium transport by the ascending limb of the loop of Henle. This is supported by the fact that potassium‐depleted rabbits excreted a greater percentage of the filtered load of sodium than did normal controls.
Inward spread of activation in vertebrate muscle fibres
Authors: González‐Serratos H.
Published: December 2014

1. A method for detecting the activation of individual myofibrils or groups of myofibrils within an isolated muscle fibre is described. It consists in making all the myofibrils wavy by setting the fibre in gelatine and compressing it longitudinally; active shortening of myofibrils can then be recognized by the straightening out of the waves.

2. The time course of this straightening during a twitch was found by high‐speed ciné micrography.

3. There is a delay of activation between the superficial and central myofibrils, from which the velocity of inward spread of activation can be found.

4. This velocity has a Q10 of 2, and is about 7 cm/sec at 20° C. The mechanism of the inward spread of activation is discussed.

5. On relaxation the waves reappear, showing that there is a spontaneous elongation of the myofibrils.
Effects of removing the external potassium on the smooth muscle of guinea‐pig taenia coli
Authors: Tomita T. , Yamamoto T.
Published: December 2014

1. Removal of the external K ions depolarized the membrane of the guinea‐pig taenia coli by about 5 mV, and increased the frequency of the spontaneous spike activity. After about 20 min in K‐free solution, the frequency gradually decreased and spontaneous activity stopped after about 60 min.

2. Readmission of K produced a transient hyperpolarization by 10–15 mV for 10–20 min, and lowered the excitability. The membrane resistance decreased during the hyperpolarization. When the external K concentration was returned to normal before the spontaneous activity had disappeared in K‐free solution, there was a complete suppression of the spontaneous electrical and mechanical activities, accompanied by hyperpolarization of the membrane. The duration of this suppression of electrical and mechanical activities depended on the exposure time to K‐free solution, the recovery being delayed by longer exposure.

3. The effects of removing external K were essentially the same in the presence of tetrodotoxin (10−7 g/ml.), of atropine (10−6 g/ml.), and also in low Cl (2–7 m
M).

4. The effects of ouabain (10−6 g/ml.) were similar to those of zero K but appeared more slowly. After treatment with ouabain, the membrane was hyperpolarized by removing the external K and there was no hyperpolarization nor suppression of the mechanical activity on readmission of external K.

5. Rb substitution for K produced little effect and addition of 5·9 m
M‐Rb after K‐removal produced a typical suppression of activity as the readmission of K. When K was replaced with an equimolar concentration of Cs, the effects were similar to those produced by K‐free solution.

6. The pattern of the response to a change in the external K concentration was different below 23° C. The spontaneous activity was suppressed by removal of K, and increased by returning the external K.

7. It is concluded that, in the taenia, the membrane potential can be modified by an electrogenic pump, the activity of which is inhibited by removing K, by ouabain, and by lowering the temperature to about 23° C. During the recovery from the exposure to K‐free solution or to ouabain, the pump activity is potentiated, causing hyperpolarization of the membrane by 10–20 mV. Rb can, Cs cannot, replace K in activating the pump at the same concentration as K.
The frequency dependent character of the membrane capacity in cardiac Purkyně fibres
Authors: Carmeliet E. , Willems J.
Published: December 2014

1. The upstroke of the action potential was used as a signal of variable frequency in order to measure the apparent membrane capacity of cardiac Purkyně fibres.

2. The upstroke in Na‐Tyrode can be regarded as a high frequency signal. Action potentials in Na‐free, Sr‐Tyrode are characterized by a very small rate of depolarization (5 V/sec) and conduction velocity (15 cm/sec) and were used as a low frequency signal.

3. On changing from Na‐ to Sr‐Tyrode the apparent membrane capacity increased by a factor of 3·77 and approached the value estimated by the square‐current technique.

4. Cable properties (space and time constants, internal core and membrane resistance) were found to be constant when changing from Na‐ to Sr‐Tyrode.

5. The significance of the frequency dependent character of the membrane capacity is discussed in relation to propagation and form of the action potential.
Control of water content of non‐metabolizing kidney slices by sodium chloride and polyethylene glycol (Peg 6000)
Authors: Robinson J. R.
Published: December 2014

1. Cortical slices from kidneys of adult rats were equilibrated for 24 and 48 hr in the refrigerator in solutions containing 5 m
M‐K, 2·5 m
M‐Ca and Mg,
M/15 phosphate buffer (pH 7·4), 5 m
M cyanide and iodoacetate with 5, 6, 7 and 8% polyethylene glycol (PEG 6000) and 77, 154, 308, 462 and 770 m
M‐NaCl.

2. There were no consistent differences in water content between slices after 24 and after 48 hr.

3. Slices contained more water when either the concentration of NaCl or that of PEG was reduced. The increase in water content induced by lowering the concentration of either was prevented by a higher concentration of the other.

4. Water content was held constant at 3·25 kg.kg−1 dry PEG‐free tissue despite a fall in [NaCl] from 770 to 77 m
M (more than 1200 m‐osmole.kg−1) by increasing PEG from 5·1 to 7·7% corresponding to an increase of the order of 15 m‐osmole.kg−1.

5. It is suggested that PEG 6000 was so much more effective than NaCl, osmole for osmole, because PEG 6000 acted as a non‐penetrating solute, whereas NaCl penetrated the slices and reduced the ‘Donnan excess’ component of the intracellular colloid osmotic pressure so that this could be balanced by a smaller concentration of PEG.
Factors affecting the quantitative response of human eccrine sweat glands to intradermal injections of acetylcholine and methacholine
Authors: Foster K. G.
Published: December 2014

1. Using a ventilated capsule in conjunction with an infra‐red water vapour analyser, and an indwelling intradermal needle, quantitative studies were made relating the magnitude of the sweat responses to the doses of acetylcholine or methacholine.

2. Acetylcholine dose—response curves were constructed, and from these curves the threshold dose was defined. The threshold was similar in all subjects (10−3 ±
S.E. 10−4 μg/0·1 ml.).

3. Factors affecting the acetylcholine dose—response curves were studied. Optimum conditions for stimulation in all subjects occurred using a capsule of 0·63 cm diameter, injection volume of 0·1 ml. and a solution temperature of 37° C. When the skin temperature was 36° C the maximal acetylcholine response was then the same as the maximal thermal response.

4. No change in the acetylcholine dose—response curves occurred with repeated determinations at the same site on the same occasion.

5. The dose—response relationship for methacholine was similar to that for acetylcholine. The methacholine response was, however, more prolonged and so the volumes secreted were greater.
Influence of variations in hydration and in solute excretion on the effects of lysine‐vasopressin infusion on urinary and renal tissue composition in the conscious rat
Authors: Atherton J. C. , Evans Jeanne A. , Green R. , Thomas S.
Published: December 2014

1. The changes in urinary and renal tissue composition induced by continuous, intravenous infusion of lysine‐vasopressin (60 μ‐u./min. 100 g body wt. until steady‐state conditions prevailed) in normally hydrated, hydropaenic, saline‐loaded (0·9%, w/v) and mannitol‐loaded (15%, w/v) rats were determined and compared with those induced in water‐loaded rats.

2. Previous reports that the urinary responses to antidiuretic hormones vary both with hydration status and with concurrent solute excretion rate were confirmed.

3. The data show that variations in urinary responses were accompanied by differences in the papillary responses to lysine‐vasopressin.

4. The results are discussed in terms of the effects of hydration and concurrent solute excretion on factors influencing (a) medullary accumulation of water and solute, (b) osmotic water reabsorption and (c) osmotic equilibration across the collecting duct; and of the effects of lysine‐vasopressin on these factors.

5. It is concluded that the effects of hydration and solute excretion on the antidiuretic responses to lysine‐vasopressin may be interpreted by differences in (a) the medullary composition prevailing at the start and (b) any further changes in medullary composition that can be induced under the experimental circumstances.
Chromatic sensitivity and spatial organization of cat visual cortical cells: cone‐rod interaction
Authors: Hammond P.
Published: December 2014

1. Colour sensitivity and spatial organization were determined for the dominant‐eye receptive fields of thirty‐eight simple or complex cells in cat primary visual vortex. Receptive fields were all from the cortical area associated with central vision. Each cell was investigated with threshold or suprathreshold monochromatic stimuli, under scotopic, low and high mesopic adaptation.

2. The Purkinje shift, well defined for all units, was consistent with dual input from each of only two receptor mechanisms, viz. 556 nm cones and 500 nm rods. With change of adaptation level there was a systematic change in the peak sensitivity of spectral response curves to suprathreshold monochromatic stimuli, equated for quantum flux but of different wave‐length. Equally with change of adaptation, the relative shift in threshold between wave‐lengths selective for cone or rod activation was in close agreement with the change predicted from the Dartnall nomogram curves for visual pigments 556 and 507 respectively.

3. For ganglion cells with concentric fields rod input derives from a spatially larger area than cone input. Rod field centre and rod field surround are substantially larger than the corresponding centre and surround for cones (Andrews & Hammond, 1970b). For cortical cells a conclusive comparable change could only be demonstrated for one simple unit. Its receptive field consisted of a horizontal excitatory stripe with asymmetric inhibitory flanks. When light‐adapted the weaker, upper flank was functionally undetectable, indicative of purely rod input to this sideband, and the preference for upward movement was enhanced.

4. No difference in receptive field configuration, or in spatial extent of input mediated by cones or by rods, was detected for any other unit. The discrepancy between retinal and cortical findings is discussed. It is inferred that cortical fields are compounded essentially by convergent input from geniculate cell field‐centres.
Pressure waves and gradients in the canine thoracic duct
Authors: Browse N. L. , Lord R. S. A. , Taylor Alexis
Published: December 2014

1. Pressures have been measured in the thoracic duct of anaesthetized and conscious dogs to ascertain the mean pressures, the nature of the pressure waves and the pressure gradients along the duct and between it and the great veins.

2. The average mean pressure in the thoracic duct of ten anaesthetized dogs was 1·4 mm Hg. The pressure waves were secondary to respiration and the pulsations of the aorta. No waves were transmitted from the great veins.

3. Pressures in conscious dogs varied from day to day, sometimes being positive, sometimes negative. They were increased by panting and by drinking.

4. The pressure gradients along the duct were small, no more than 0·5–2·0 mm Hg along its whole length.

5. No evidence was found of spontaneous contractions of the duct.
The glycogenolytic response to stimulation of the splanchnic nerves in adrenalectomized calves, sheep, dogs, cats and pigs
Authors: Edwards A. V.
Published: December 2014

1. The effects of stimulation of the peripheral ends of one or both splanchnic nerves have been investigated in calves, sheep, dogs, cats and pigs after removal of both adrenal glands.

2. Stimulation of both splanchnic nerves produced comparable hyperglycaemic and glycogenolytic effects in sheep, dogs and cats; the mean liver glycogen concentration was reduced by between 7·0 and 10·5 mg/g, five min after stimulation was discontinued, at which time the mean plasma glucose concentration had risen by between 126 and 137 mg/100 ml.

3. In five 3‐5 week‐old calves which were tested under identical conditions the mean liver glycogen concentration was reduced by 13·3 ± 1·9 mg/g and the plasma glucose concentration raised by 216 ± 1·9 mg/100 ml., 5 min after stimulation was terminated.

4. In pigs, stimulation of both splanchnic nerves invariably produced a rise in the plasma glucose concentration, even when the concentration of glycogen in the liver was less than 5 mg/g before stimulation. The response was, nevertheless, considerably smaller in these animals than in any of the other species investigated.

5. Splanchnic nerve stimulation also caused a rise in mean aortic blood pressure and blood haematocrit during the period of stimulation; changes of approximately the same order of magnitude were encountered in all five species.

6. Dogs were found to resemble calves in that the hyperglycaemic response to stimulation of a single splanchnic nerve did not differ significantly from that obtained when both were stimulated simultaneously; furthermore, either nerve was found to be equally effective.

7. In cats the change in plasma glucose concentration in response to stimulation of a single splanchnic nerve was always less than that which occurred in response to bilateral stimulation although comparable changes in blood haematocrit occurred in both groups of animals.

8. It is concluded that stimulation of the splanchnic nerves causes break‐down of glycogen in the livers of various unrelated species of adult animals but that the magnitude of the hyperglycaemic response in the young calf provides further evidence of the importance of the sympathetic system in the control of metabolism in the young animal.
Presynaptic depolarization of myelinated afferent fibres evoked by stimulation of cutaneous C fibres
Authors: Jänig W. , Zimmermann M.
Published: December 2014

1. The origin of the dorsal root potential observed following a volley in cutaneous unmyelinated or C fibres (C‐DRP) has been investigated by several assays.

2. Measurements of the spatial decrement of the C‐DRP along the dorsal roots indicate that mainly the thick myelinated primary afferent fibres contribute to this C‐DRP.

3. The spatial configuration of the intraspinal potential field during the course of the C‐DRP is similar to that of the field correlated to the A‐DRP, i.e. the DRP evoked by a volley in the A fibres of the same cutaneous nerve. It is concluded therefrom that both A‐ and C‐DRPs signal presynaptic depolarizations of afferent fibres in the same regions of the dorsal horn.

4. Intrafibre recordings reveal that C input produces primary afferent depolarization (C‐PAD) mainly in cutaneous and articular afferents, but not in muscle Group Ia afferents.

5. These findings and direct measurements of the interactions between A‐ and C‐DRPs indicate that the pathways involved in A‐ and C‐PAD exhibit convergence.

6. C‐DRPs were also recorded from contralateral rootlets.

7. Some functional aspects of the PAD produced by an afferent volley in C fibres are discussed.
Effects of changing the ionic environment on passive and active membrane properties of pregnant rat uterus
Authors: Abe Y.
Published: December 2014

1. In pregnant rat myometrium electrotonic potentials, produced by externally applied current, were recorded intracellularly.

2. The space constant, λ, was 1·8 mm, the time constant, τm, 120 msec. The values obtained on the 7th day and on the 20th day of pregnancy were the same.

3. The magnitude of the electrotonic potential and the time constant of the membrane were increased in the absence of potassium from the external solution and decreased by excess potassium.

4. The magnitude of the electrotonic potential and the time constant of the membrane were increased by the replacement of chloride with C6H5SO3μ or SO42‐, and decreased with NO3μ or Iμ replacement.

5. When the sodium chloride was replaced with sucrose (16·7 m
M sodium remaining in the buffers) the spontaneous spikes deteriorated and activity stopped within 30 min. However, for periods up to 4 hr, a spike of larger amplitude and faster rate of rise than in normal solution could be evoked when a depolarizing current was applied.

6. When the external calcium concentration was raised (5 and 10 m
M) the amplitude and the rate of rise of the evoked spike were increased. They were decreased by reducing calcium. In zero calcium spontaneous activity stopped within 15 min.

7. The effects of calcium deficiency were much less marked and slower in onset when, simultaneously, the sodium concentration was reduced to 16·7 m
M.

8. When calcium was replaced with strontium (2·5 m
M), the membrane was depolarized and the duration of the spontaneous and evoked action potential was prolonged, mainly due to a slowed rate of repolarization. When the concentration of strontium was raised to 7·5 or 12·5 m
M the membrane was hyperpolarized, the duration of the action potential became short and the amplitude of the spike was increased.

9. Addition of barium or the replacement of calcium with barium caused depolarization and oscillatory membrane activity. However, a spike could be evoked by applying conditioning hyperpolarization.

10. Manganese abolished the spontaneous and evoked spike. Tetrodotoxin had no effect.

11. The results show that rat uterus has cable‐like properties. The action potential may be due to calcium entry, while sodium, by influencing the membrane potential in competition with calcium, may be involved in the spontaneous spike generation and the spread of excitation.
Oxytocin and ADH secretion in relation to electrical activity in antidromically identified supraoptic and paraventricular units
Authors: Dyball R. E. J.
Published: December 2014

1. Electrical recordings were made from antidromically identified supraoptic and paraventricular units during intracarotid injections of hypertonic and isotonic sodium chloride solutions in rats.

2. The blood concentrations of vasopressin and oxytocin were estimated by bio‐assay before and at different intervals after similar injections.

3. Although a significant change in the action potential activity of the supraoptic nucleus was associated with hormone release, the results were not entirely consistent with a simple relationship between action potential activity and hormone secretion. Firstly, although some units were excited by the stimulus a substantial number were inhibited. Secondly, the blood concentration of the hormones, particularly ADH, remained elevated for longer than might have been expected if additional hormone had ceased to be secreted as soon as firing rates had returned to control values.

4. There were substantial differences between the initial blood concentrations of vasopressin and oxytocin but the firing rates of units in the supraoptic and paraventricular nuclei appeared to be the same.

5. Although significantly less paraventricular than supraoptic units were affected by hypertonic injections the blood concentration of oxytocin was increased by a factor of 8 whereas that of vasopressin was increased by a factor of 2·7.
Variations in mucosal water and sodium transfer associated with the rat oestrous cycle
Authors: Crocker Ann D.
Published: December 2014

1. Mucosal water and sodium transfer were measured in everted sacs of rat jejunum.

2. Mucosal water transfer was higher at pro‐oestrus and oestrus than at metoestrus and dioestrus.

3. Injection of 10 μg aldosterone
I.P. 28 hr before the experiment produced a stimulation of mucosal water and sodium transfer in sacs prepared from rats at dioestrus but not in sacs from rats at oestrus.

4. A significant increase in mucosal water and sodium transfer was observed when sacs from dioestrous rats were incubated with angiotensin at a concentration of 10−9 g/ml. No effect was obtained in sacs from oestrous rats.

5. Treatment of adrenalectomized‐ovariectomized rats with oestradiol caused a stimulation of mucosal water transfer 28 hr after injection.

6. It is suggested that the actions of ovarian steroids on water and electrolyte metabolism might be due to increased activity of both the adrenal cortex and the renin‐angiotensin system.
The effect on drinking of peptide precursors and of shorter chain peptide fragments of angiotensin II injected into the rat's diencephalon
Authors: Fitzsimons J. T.
Published: December 2014

1. Recently it has been shown that injection of angiotensin II into the anterior diencephalon causes the rat to drink water. In the present experiments the dipsogenic action of a number of other substances including substances related to angiotensin was tested.

2. Injection of 0·001 Goldblatt u. renin into the angiotensin‐sensitive region causes the water‐replete rat to drink. Drinking is slower in onset and continues for longer than after injection of angiotensin II.

3. Synthetic tetradecapeptide renin substrate and angiotensin I were as effective as angiotensin II at causing water‐replete rats to drink.

4. β‐aspartic acid1‐valine5‐angiotensin II was also fully effective; but the
D‐arginine substituted octapeptide was much less effective.

5. The (2–8) heptapeptide retained about 50% of the dipsogenic activity of the octapeptide, whereas the absence of phenylalanine at the other end of the peptide chain in the (1–7) heptapeptide results in an inactive compound.

6. The (3–8) hexapeptide and the (4–8) pentapeptide, both of which have phenylalanine at the end of the chain, and the (1–4) and (5–8) tetrapeptide fragments of angiotensin II showed only a slight action on intake of water.

7. Kallikrein, bradykinin, adenosine‐3′5‐cyclic phosphate, vasopressin and oxytocin caused no drinking when injected into the angiotensin‐sensitive region.

8. It is concluded that the requirements for the dipsogenic activity of angiotensin are the same as those for its other biological actions with the qualification that the precursor peptides are also active, presumably because they give rise to angiotensin II locally.
The control by internal calcium of membrane permeability to sodium and potassium
Authors: Romero P. J. , Whittam R.
Published: December 2014

1. A study has been made of the relationship between the concentration of internal calcium and the permeability of human red cell membranes to sodium and potassium.

2. Fresh red cells contain very little calcium, but after being depleted of ATP by ageing they took up calcium from Ringer solution. The entry was unaffected by external sodium and potassium but was markedly pH dependent. When supplied with energy, calcium‐loaded cells actively extruded calcium by a saturable process which was also unaffected by the distribution of sodium and potassium across the membranes. The activity of the calcium pump was sufficient to maintain the low internal concentration found under physiological conditions.

3. Raising internal calcium in metabolically poor cells caused a loss of cell potassium which was greater than the concomitant sodium gain. These changes were reversed when ATP was supplied. External calcium had no effect. The increase in permeability to sodium and potassium was enhanced by the simultaneous addition of fluoride, and, even more so, of iodoacetate. These inhibitors had no effect on membrane permeability unless calcium was also present. Inosine potentiated the action of fluoride and iodoacetate in causing potassium loss, by allowing more calcium to enter the cells.

4. The results suggest that the permeability of human red cell membranes to sodium and potassium is regulated by internal calcium, which in turn is controlled by a calcium pump that utilizes ATP.
Efferent and afferent impulse activity recorded from few‐fibre preparations of otherwise intact sinus and aortic nerves
Authors: Neil E. , O'Regan R. G.
Published: December 2014

1. In anaesthetized cats, the efferent discharge recorded from slips of otherwise intact sinus nerves was sparse in eupnoeic conditions but increased markedly during systemic hypoxia or asphyxia or following the injection of cyanide or acetaldehyde into the circulation of the ipsilateral carotid body.

2. When the sinus nerve was cut distal to the efferent slip the responses to cyanide or acetaldehyde were abolished. The sparse ‘resting’ activity which remained was increased following the intravenous injection of adrenaline. Following distal section, the impulse traffic of the efferent slip did increase during systemic hypoxia but the response was much feebler than when the nerve was otherwise intact.

3. The impulse activity of most efferent slips, peeled off from the otherwise intact sinus nerve, was abolished when the glossopharyngeal nerve was cut central to its junction with the same sinus nerve, indicating that the activity was probably recorded from genuine efferent units. The discharge of some ‘efferent’ preparations was still present, however, following such section and showed an increase to local injections of cyanide. This activity was probably recorded from looping or branching chemoreceptor afferents.

4. The discharge of efferent slips of the cut aortic nerve was increased following the intravenous injection of adrenaline and during systemic hypoxia. These responses were not present when the vagus nerve was cut central to the nodose ganglion.

5. In eupnoea, chemoreceptor afferent activity recorded from slips of the sinus or aortic nerves is much the same whether these nerves be otherwise intact or whether they be cut. During systemic hypoxia, chemoreceptor afferent discharge was less when it was recorded from the otherwise intact nerves than when these nerve trunks were cut.

6. The cell bodies of sinus nerve efferent fibres are synaptically excited by chemoreceptor afferents coursing in the same nerve trunk. The increase of efferent impulse activity aroused by this means depresses chemoreceptor afferent discharge.
The dependence of the contractile force generated by frog auricular trabeculae upon the external calcium concentration
Authors: Chapman R. A. , Tunstall J.
Published: December 2014

1. A method is described by which the solutions bathing single auricular trabeculae, isolated from the heart of the frog, can be rapidly altered while the tension generated and the membrane potential can be measured simultaneously.

2. Changes of the [Ca]o result in changes of the twitch strength similar to that reported for frog ventricle.

3. At [Ca]o of less than 1 m
M, the isometric contracture tension generated during application of K‐rich solutions, and the maximum rate of tension development, are proportional to [Ca]o3.

4. This relationship is not the consequence of (a) the hypertonicity of the K‐rich solutions, (b) the dependence of the membrane potential on [Ca]o, or (c) the facilitation due to a twitch response at the initiation of the contracture.

5. Reduction of the [Na]o increases the strength of the high‐K contractures according to the ratio of [Ca]o/[Na]o2; Na ions in the bathing medium are shown to competitively inhibit the potentiating action of Ca ions on the force generated during contractures.

6. An equation is derived which assumes that three Ca compounds act co‐operatively at some stage in the process of excitation—contraction coupling.

7. Two hypotheses are discussed. The first proposes that the sarcoplasmic [Ca] established during depolarization of the muscle membrane depends upon [Ca]o3, and tension generated by the contractile elements on a first order reaction with ionic Ca. The second suggests that if the sarcoplasm [Ca] established during excitation is proportional to [Ca]o, then three Ca ions are required to activate the contractile response at the unit level.
The storage of endogenous noradrenaline in sympathetic nerve terminals
Authors: Bisby M. A. , Fillenz Marianne
Published: December 2014

1. The subcellular distribution of noradrenaline in sympathetic nerve terminals of rat vas deferens and cat spleen has been studied by cell fractionation methods combined with fluorescence and electronmicroscopic histochemical methods for noradrenaline.

2. Pinched‐off axon varicosities (synaptosomes) were isolated and identified by fluorescence and electronmicroscopy in the mitochondrial pellet.

3. The proportion of large to small dense‐cored vesicles in electronmicrographs of sympathetic nerve terminals varies in different organs. In rat vas deferens 4% and in cat spleen 20% are large vesicles.

4. Density gradients of rat vas deferens have a single low density peak of noradrenaline at 0·6
M sucrose, whereas those of cat spleen have an additional peak of noradrenaline at 1·1
M sucrose.

5. Small dense‐cored vesicles were identified electronmicroscopically in the low density fractions and large dense‐cored vesicles in the high density fractions from density gradients.

6. We conclude that both small and large dense‐cored vesicles store noradrenaline.
The mechanism of excitation by acetylcholine in the cerebral cortex
Authors: Krnjević K. , Pumain R. , Renaud L.
Published: December 2014

1. The muscarinic depolarizing action of ACh on cortical neurones is associated with an increase in membrane resistance (mean ΔV/ΔR = 3·16 mV/MΩ).

2. ACh also promotes repetitive firing by slowing repolarization after spikes.

3. The depolarizing effect has a mean reversal level of −86·7 mV (with mean resting potential −56 mV).

4. It is concluded that as a muscarinic excitatory agent, ACh probably acts by reducing the resting K+ conductance of cortical neurones, and also the delayed K+ current of the action potential.

5. These results are discussed in relation to the possible role of ACh in cortical function.
The imprecision arising from the application of the Henderson—Hasselbalch relationship to the blood of anaesthetized dogs
Authors: Linden R. J. , Norman J.
Published: December 2014

1. Arterial blood samples were obtained from anaesthetized dogs in which either a respiratory alkalaemia, a respiratory acidaemia or a non‐respiratory acidaemia was produced and from animals in which no deliberate changes in acid—base balance were produced. The samples were analysed for pH, carbon dioxide tension and concentration, oxygen tension and concentration and haematocrit. From these determinations the plasma carbon dioxide concentration, the plasma bicarbonate ion concentration and pK′ were calculated.

2. The value of pK′ lay within the range 5·86–6·27. The temperatures of the animals studied were between 36·75 and 39·25° C but there was no significant relationship between pK′ and temperature.

3. The values of pK′ increased with an alkalaemia and decreased with an acidaemia.

4. In addition to the variation of pK′ with pH there was a considerable residual scatter of pK′ values at any one pH value.

5. It was concluded that in these experimental conditions the use of the Henderson—Hasselbalch equation in a form not dealing with activities was unacceptable and could lead to much larger errors than has hitherto been thought.
Comparison of aortic and carotid baroreflexes in the dog
Authors: Donald David E. , Edis Anthony J.
Published: December 2014

1. Experiments with vascularly isolated, blood‐perfused aortic arch and carotid sinus preparations in sixteen dogs have provided evidence which suggests that, in the reflex regulation of normal arterial blood pressure, the aortic and carotid baroreflexes are not equivalent.

2. Two different techniques were used. In one, a steel cannula was inserted into the ascending aorta and arch and fixed in position by ligatures about the aorta. The blood‐filled space (aortic jacket) thus created could be distended with known pressures; the cardiac output passed through the cannula into the descending aorta. In the other, an extracorporeal circulation utilizing an isolated heart—lung preparation was used to separately perfuse the carotid sinuses, aortic arch, and systemic circulation of a test dog.

3. Independent open‐loop analysis of the aortic and carotid baroreflexes in each dog indicated that they were essentially similar in their over‐all modus operandi but that there were quantitative differences between them which would suggest a predominant role for the carotid sinus reflex in the control of normal blood pressure.

4. The carotid sinus Blutdruck‐charakteristik curve was symmetrical about the range of normal blood pressure for the dog while the aortic arch curve was displaced to the right.

5. The carotid sinus system had the greater gain (with reference to limb vascular resistance) and exhibited a greater maximal capacity to alter vascular resistance reflexly.

6. When the carotid and aortic systems were activated simultaneously by distension, the reflex depressor responses were summed, essentially by a process of simple addition. A carotid‐induced pressor response obscured a simultaneous aortic‐induced depressor response of equal magnitude.

7. In five dogs studied, the functional reflexogenic area of the aortic arch did not extend distally beyond the origin of the left subclavian artery.
Growth and reproduction of mice cross‐fostered between parents reared at different temperatures
Authors: Barnett S. A. , Neil Alexandra C.
Published: December 2014

1. Litters of mice, Mus musculus, of the highly inbred strain A2G/Tb, were reduced to four at birth and cross‐fostered within and between three classes: (i) bred at 21° C (controls); (ii) the first generation reared at −3° C (‘new stock’); (iii) the seventeenth to twenty‐third generations reared at −3° C (‘old stock’). There were therefore nine classes of fostered mice.

2. There was a higher death rate in the nest and after wearing among mice of new‐stock parentage, regardless of foster‐parentage.

3. Litters reared at 21° C were heavier at 3 weeks than those reared at −3° C, regardless of parentage; the effect of temperature was also evident in body weights at 16 weeks. There was compensatory growth between 3 and 16 weeks, shown by lower variance in body weight, within classes, at 16 weeks.

4. Members of fostered litters were mated, and their reproductive performance recorded to the age of 28 weeks.

5. More young were born and weaned per pair at 21° C than at −3° C, regardless of true parentage. In contrast, nestling mortality depended principally on true parentage; there were fewer deaths among the young of mice whose true parents were old stock, regardless of foster‐parentage; this effect was especially evident for losses of whole litters.

6. Mean body weights of the nine classes of fostered females were positively correlated with mean numbers of young born to them, and with the mean weights of their young at 3 weeks; but there was no such correlation with death rates among their young.

7. Young of some of the fostered mice were also mated. The effect of old‐stock ancestry on nestling mortality was not evident in this further generation. Some mice were studied after transfer between temperatures without fostering. Their breeding performance confirmed that old‐stock mice did not retain their superiority after two generations at 21° C.

8. General conclusions are: (i) differences of growth between classes of fostered mice reflected the temperature in which the mice were reared, whereas mortality among fostered mice was influenced by the conditions they had experienced in utero; (ii) the production of young by the fostered mice was influenced by environmental temperature, while the death rates among these young in the nest reflected the conditions experienced in utero by their parents.
Interaction between colour and spatial coded processes converging to retinal ganglion cells in goldfish
Authors: Spekreijse H. , van den Berg T. J. T. P.
Published: December 2014

1. Extracellular recordings were made from ganglion cell units in the isolated goldfish retina. The discharge patterns of these units are spatial and colour coded.

2. Even for weak stimuli these ganglion cell responses are highly distorted. To a first approximation a rectifying element can account for the observed distortion.

3. A method is introduced to determine whether the interaction between the spatial and colour‐coded processes occurs preceding or after the rectifying stage.

4. With various stimulus patterns such as checkerboards, bars, annuli, etc., not only the location of the interaction point but also the mode of operation underlying the colour and spatial interactions has been studied.

5. The presented data indicate that for the common phasic ganglion cells in the goldfish retina spatial and colour interaction occurs preceding the rectifying stage. Moreover an algebraic mode of operation governs this interaction.

6. The charm of the presented method lies in the fact that no assumptions need to be made about the dynamics of the various retinal transformations converging to the ganglion cells. Neither is a description required for the non‐linear (rectifying) element in order to answer the question of the location and the mode of operation of the colour and spatial interaction mechanism.
The discharge of sweat in Welsh Mountain sheep
Authors: Johnson K. G.
Published: December 2014

1. Experiments were done on Welsh Mountain sheep to determine whether the sheep can be caused to discharge sweat continuously.

2. On administration of sequences of four to eighteen
I.V. injections of adrenaline or noradrenaline (200 μg), sheep responded to the first 4‐5 injections with decreasing amounts of sweat discharge. Thereafter, the responses were fairly constant at about 10% of the first discharge. Occasionally one injection within a series elicited no sweat discharge but on other isolated occasions large discharges of sweat were induced. The blood pressure response to repeated
I.V. injections of adrenaline remained constant.

3. Inhalation of amyl nitrite or rebreathing of expired air during
I.V. adrenaline injections had little effect on the pattern of intermittent sweat discharges and did not induce a continuous outflow of fluid from the sweat glands.

4. Continuous infusions of adrenaline and of carbachol did not cause a change in the rate of continuous water vapour loss from the skin but possibly increased the frequency of intermittent sweat discharges.

5. Electrical stimulation of the cervical sympathetic nerve for short (0·5–2 min) or long (20–30 min) periods caused only transient (3–6 min) increases in water vapour loss from the cheek skin.

6. None of these experiments indicated that the sweat glands of the sheep can be induced to discharge fluid continuously.
Spino‐spinal mechanisms in the chloralose anaesthetized cat
Authors: Abrahams V. C.
Published: December 2014

1. In chloralose anaesthetized cats the events in the lumbosacral cord that follow stimulation of a forepaw or neck nerve have been examined.

2. Four events take place in the lumbosacral cord after forepaw or neck muscle nerve stimulation. These are: (1) a brief period of generalized enhanced motoneurone excitability, (2) a prolonged and as yet unexplained enhancement of monosynaptic reflexes, (3) a period of presynaptic inhibition in muscle and skin afferent fibres, and (4) a prolonged inhibition of spino‐bulbo‐spinal reflexes.

3. A variable and sometimes selective reduction of one or another descending effects follows the placing of small lesions in the anterior portion of the suprasylvian gyrus.
Amino acid metabolism in the isolated perfused rat liver
Authors: Kerly Margaret , Spruyt Joy E. L.
Published: December 2014

1. Rat livers have been perfused with homologous blood and the distribution of 15N from labelled amino acids added to the perfusate studied.

2. Each of the amino acids added, aspartate, alanine, glycine, and glutamate (unlabelled) were rapidly removed from the perfusate. Glutamate was formed from added aspartate (but not from added alanine or glycine) by transamination in the perfusate plasma; the perfusate concentration of no other amino acid was affected by addition of any of the acids investigated.

3. Urea output was increased by addition of aspartate, increase in output after addition of alanine or glycine was not significant.

4. After addition of labelled aspartate, alanine or glycine an increase in isotope ratio was detected in urea, ammonia, glutamine, aspartate and alanine in the perfusate and, in some experiments, in the liver. After addition of alanine an increase was also detected in lysine, tyrosine, phenylalanine, methionine, proline, tryptophan and threonine+serine (analysed together).
Binocular interaction fields of single units in the cat striate cortex
Authors: Bishop P. O. , Henry G. H. , Smith C. J.
Published: December 2014

1. Based on average response histograms to an optimal stimulus, binocular interaction field plots were obtained from twenty‐five simple neurones in the striate cortex of the cat. Each binocularly activated cell has two interaction fields, one for each eye. The binocular interaction field for one eye plots the changes in the amplitude of the response from the other eye as the two receptive fields of the binocularly activated cell are moved across one another, first into and then out of alignment in the plane of the optimal stimulus (tangent screen).

2. The binocular interaction field provides an important clue to the nature of the spatial organization of the excitatory and inhibitory regions of the monocular receptive field. The commonest type of receptive field organization has regions of inhibition (inhibitory side bands) to either side of the discharge centre in the direction at right angles to the optimal stimulus orientation. As well as inhibition, there are subliminal excitatory effects.

3. Binocular interaction fields differ with the various cell types, i.e. cells that are discharged only from the one eye, cells binocularly discharged with very weak or absent monocular responses and cells showing binocularly opposite direction selectivity.

4. Marked facilitation to an optimal stimulus occurs when the two receptive fields of a binocularly activated neurone are in accurate alignment. Facilitation switches to depression for very small degrees of receptive field misalignment in a direction at right angles to the optimal stimulus orientation. These observations are of importance in relation to mechanisms for binocular single vision and depth discrimination.