bluuebunny/crossref_metadata_2025 huggingface dataset:
The effect of antidiuretic hormone on Na movement across frog skin
Authors: Cereijido M. , Rotunno Catalina A.
Published: December 2014

1. The effect of antidiuretic hormone (ADH) on the movement and distribution of Na was studied. This was done using three different approaches: (a) the measurement of Na and 22Na in slices of epithelium of skins which were exposed to Ringer of varied composition containing 22Na, (b) the measurement of the influx of Na from the outer to the inner bathing solution with 22Na added to the outside, and (c) the use of a recently introduced technique which permits the direct evaluation of the flux from the outer solution → epithelium, (JOT), i.e. the flux across the barrier which is generally regarded as the site of ADH activity.

2. ADH increased the influx from the outer to the inner bathing solution of Na (50%) not only when the concentration of Na on the outside was 115 m
M (i.e. higher than in the epithelium) but even when the concentration was 1 m
M (67%).

3. When the skin was bathed with 1m
M‐Na Ringer on the outside, ADH increased the unidirectional Na flux JOT by 56% (Rana pipiens) and 71% (Leptodactylus ocellatus). When the concentration was 115 m
M a small increase (17%) was observed in paired skins of R. pipiens. Under this condition no change was observed in L. ocellatus.

4. The amount of epithelial sodium which is labelled by 22Na added to the outside was taken to reflect the amount of Na involved in Na transport across the epithelium. Depending on whether the concentration of Na on the outside was high (115 m
M) or low (1 m
M), ADH produced an increase, or a decrease, of both the total Na content and the amount of 22Na exchanged.

5. When the concentration of Na on the outside was low, ADH increased the total influx and JOT in spite of the fact that it lowers the total Na content and does not affect the exchangeable pool of Na. This observation is inconsistent with the view that the effect of ADH is due to the fact that the increased permeability of the outer barrier allows more Na into the cell, and that the resulting increase of Na concentration in the cytoplasm accelerates the Na pumps at the inner side of the cells.

6. It is concluded that ADH speeds up Na movements at the outward facing barrier, and that this exchange which facilitates the penetration of Na into a transporting compartment produces also a gain or a loss of Na in compartments not directly involved in Na transport across the epithelium. One compartment which is not involved in Na transport might be the cytoplasm of the epithelial cells.
Primary afferent depolarization and flexion reflexes produced by radiant heat stimulation of the skin
Authors: Burke R. E. , Rudomin P. , Vyklický L. , Zajac F. E.
Published: December 2014

1. The reflex effects of pulses of intense radiant heat applied to the skin of the central plantar pad have been studied in unanaesthetized (decerebrate) spinal cats.

2. Pad heat pulses produced flexion of the ipsilateral hind limb and increased ipsilateral flexor monosynaptic reflexes, due to post‐synaptic excitation of flexor alpha motoneurones. These effects were accompanied by reduction of extensor monosynaptic reflexes and post‐synaptic inhibition of extensor motoneurones.

3. Ipsilateral (and contralateral) pad heat pulses consistently evoked negative dorsal root potentials (DRPs) as well as increased excitability of both cutaneous and group Ib muscle afferent terminals. The excitability of group Ia afferents was sometimes also increased during pad heat pulses, but to a lesser extent.

4. Pad heat pulses produced negative DRPs in preparations in which positive DRP components could be demonstrated following electrical stimulation of both skin and muscle nerves.

5. The motor and primary afferent effects of heat pulses always accompanied one another, beginning after the pad surface temperature had reached rather high levels (usually 48–55° C).

6. Negative DRPs increased excitability of cutaneous and group Ib afferents, and motoneurone activation produced by pad heat pulses was essentially unmodified when conduction in large myelinated afferents from the central plantar pad was blocked by cooling the posterior tibial nerve trunk.

7. It is concluded that adequate noxious activation of cutaneous afferents of small diameter produces primary afferent depolarization in a variety of large diameter afferent fibres, as well as post‐synaptic effects in alpha motoneurones.
The influence of wind resistance in running and walking and the mechanical efficiency of work against horizontal or vertical forces
Authors: Pugh L. G. C. E.
Published: December 2014

1. O2 intakes were determined on subjects running and walking at various constant speeds, (a) against wind of up to 18·5 m/sec (37 knots) in velocity, and (b) on gradients ranging from 2 to 8%.

2. In running and walking against wind, O2 intakes increased as the square of wind velocity.

3. In running on gradients the relation of O2 intake and lifting work was linear and independent of speed. In walking on gradients the relation was linear at work rates above 300 kg m/min, but curvilinear at lower work rates.

4. In a 65 kg athlete running at 4·45 m/sec (marathon speed) V̇O2 increased from 3·0 l./min with minimal wind to 5·0 l./min at a wind velocity of 18·5 m/sec. The corresponding values for a 75 kg subject walking at 1·25 m/sec were 0·8 l./min with minimal wind and 3·1 l./min at a wind velocity of 18·5 m/sec.

5. Direct measurements of wind pressure on shapes of similar area to one of the subjects yielded higher values than those predicted from the relation of wind velocity and lifting work at equal O2 intakes. Horizontal work against wind was more efficient than vertical work against gravity.

6. The energy cost of overcoming air resistance in track running may be 7·5% of the total energy cost at middle distance speed and 13% at sprint speed. Running 1 m behind another runner virtually eliminated air resistance and reduced V̇O2 by 6·5% at middle distance speed.
Influence of lysine‐vasopressin dosage on the time course of changes in renal tissue and urinary composition in the conscious rat
Authors: Atherton J. C. , Green R. , Thomas S.
Published: December 2014

1. The changes in urinary and renal tissue composition induced by continuous, intravenous infusion of lysine‐vasopressin (2·5, 5, 15 and 60 μ‐u./min. 100 g body wt.) for up to 4½ hr in water‐loaded, conscious rats were determined.

2. Both the magnitude of, and the time required to attain, maximal and stable responses, in respect to both urinary and tissue composition, varied with the dose.

3. The dose‐dependent changes in medullary composition were compounded of graded decreases in water content and graded increases in solute (mainly Na and urea) content.

4. The relative contribution of the changes in water, Na and urea contents varied with time and with dose. Significant increases in papillary urea content occurred with all doses. The range of change in urea content was wider than that for any other solute.

5. At low doses, the changes in urinary flow and osmolality were ascribable, almost entirely, to large decreases in free‐water clearance, with minor changes in medullary composition; at higher doses, the increases in urinary osmolality were accompanied by steep increases in medullary solute concentrations.

6. A variable, dose‐dependent, transient natriuresis occurred during the phase of increasing medullary Na concentration; the peak natriuresis preceded the times of maximal osmolal and Na concentrations in the papilla and urine.

7. The differences in osmolal, urea and Na concentrations between papilla and urine also changed with time.

8. Both the transitional and steady‐state changes induced by lysine‐vasopressin are discussed in terms of intrarenal mechanisms. It is concluded that the data are most reasonably interpreted on the basis that several hormone‐sensitive loci exist in the kidneys, each with individual dose—response and kinetic characteristics.
Intracellular concentrations of sodium, potassium and chloride in the salt‐gland of the domestic goose and their relation to the secretory mechanism
Authors: Peaker M.
Published: December 2014

1. The composition of the nasal salt‐glands of geese was found to be Na 57 ± 3·5 (
S.E.), K 52·3 ± 3·9 and Cl 78·3 ± 11·0 m‐equiv/kg fresh tissue. During secretion, the Na content was significantly raised to 72·4 ± 3·4 m‐equiv/kg.

2. Salt‐gland slices incubated in Krebs—Henseleit bicarbonate medium plus glucose (6 m
M), in the presence of [14C]sucrose as an extracellular marker had the following composition, Na 85·3 ± 3·1, K 37·1 ± 3·1 and Cl 74·3 ± 3·6 m‐equiv/kg. The calculated intracellular concentrations were for Na 61·5 ± 2·1, K 105·3 ± 8·7 and Cl 37·8 ± 5·0 m‐equiv/l. intracellular water.

3. Ouabain (10−4
M) significantly decreased the tissue and cell K concentration and significantly increased the Na concentration.

4. Acetylcholine (10−6
M) and eserine (10−4
M) in the incubation medium had no effect on intracellular composition.

5. Raising the Na concentration of the medium to 172 m‐equiv/l. and the Cl to 156 m‐equiv/l. in two experiments had no effect on the calculated intracellular composition.

6. These results do not support reports that the cells have a very high Na concentration (about 350 m‐equiv/l. intracellular water). They are compatible with the hypothesis that the hypertonic secretion is formed across the luminal membrane of the secretory cell by an active Na+ pump and there are no data to suggest that Na+ is concentrated across the basal membrane by a ouabain‐insensitive process.

7. The data are discussed in relation to permeability studies and to electrical potential measurements within the gland by other workers.
Platelet aggregation and strenuous exercise
Authors: Poller L. , Priest Celia M. , Thomson Jean M.
Published: December 2014

1. Platelet aggregation in the Chandler's tube has been found to be increased in a group of normal male and female volunteers who undertook strenuous physical exercise. This coincided with acceleration of the ‘intrinsic’ blood clotting system and a rise in fibrinogen. The rise in fibrinogen occurred despite increased fibrinolysis.

2. The study confirms the sensitivity of the platelet aggregation system to changes in the ‘intrinsic’ clotting mechanism. Acceleration of this system in this study resulted from a physiological cause and produced accelerated aggregation in the coagulation‐affected phase.
The effect of ACTH on calcium distribution in the perfused cat adrenal gland
Authors: Jaanus Siret D. , Rubin R. P.
Published: December 2014

1. Experiments were carried out to study the effects of adrenocorticotrophin (ACTH) on calcium distribution in the isolated cat adrenal gland perfused with Locke solution.

2. The addition of ACTH to Locke solution caused a small, but significant, increase in the radiocalcium (45Ca) space and content of the adrenal cortex.

3. The average 45Ca washout curve obtained after exposure to ACTH was significantly displaced above the average washout curve for the control glands during the first 20 min of washout. During the time that the two curves were significantly different, maximum corticosteroid secretion was attained.

4. The rate of 45Ca efflux was slowed after ACTH was added to the perfusion medium.

5. The total calcium content of the cortex was not altered by ACTH.

6. Perfusion with calcium‐free Locke caused a rapid decrease in the calcium content of the cortex to about 20% of the control value. Dinitrophenol was required to deplete completely the cortical calcium content during perfusion with the calcium‐deprived medium.

7. The results are consistent with the suggestion that a translocation of calcium occurs during stimulation of the cortex by ACTH. The source of the calcium ions needed to support the secretory response to ACTH is probably not the extracellular fluid; but ACTH may shift calcium from a rapidly exchanging to a more slowly exchanging cellular pool.
Effect of ouabain and metabolic inhibitors on the Na and K movements of nucleotide contents of L cells
Authors: Lamb J. F. , MacKinnon M. G. A.
Published: December 2014

1. The general characteristics and Na and K movements of L cells (derived from mouse epithelium) have been measured. Both cells grown in suspension (LS cells) and as a monolayer (L cells) were used.

2. The volume of L cells was 1·2 × 10−9 cm3 and of LS cells 3·5 × 10−9 cm3; of this 82% was water.

3. Electron micrographs showed the presence of numerous protrusions (filopodia) from both forms of the cell. These had the effect of increasing the surface area of the cell by 2‐4 times over smooth cells of the same volume. On changing from the flattened to the spherical shape during trypsinization, the filopodia altered to maintain a constant V/A ratio.

4. These cells contain K, about 170 m‐mole/l. intracellular water and Na, 9 m‐mole/l. intracellular water (L cells only) at 20° C. The K fluxes are 1·9 p‐mole/cm2 sec for LS cells and 0·8 p‐mole/cm2 sec for L cells and the Na fluxes are 1·8 p‐mole/cm2 sec for L cells (expressed as per total cell surface (including filopodia)). If expressed as p‐mole/cell per sec then L and LS cells have the same K flux.

5. 10−4
M ouabain reduces the K influx to half, indicating an insensitivity to the glycosides common to the species. In the prolonged presence of ouabain the cells come into a new steady state with a [K]1, of 140 and a [Na]1 of 20–30 m‐mole/l. intracellular water, but a constant [Na + K]1.

6. Both DNP (10−3
M) and IAA (10−4
M) are required for maximum inhibition of K uptake, as both aerobic and anaerobic metabolic pathways may be used to drive the pump.

7. K removal decreases the Na efflux, and Na removal (eventually) decreases the K influx providing evidence for Na/K coupling.

8. The cells contain 7·5 m‐mole/litre intracellular water of ATP, a level some 15 times that of ADP.

9. The Na pump in these cells is very similar to that found in other tissues in that (a) it requires K to work, (b) it is blocked by ouabain and metabolic inhibitors and (c) it transports three molecules of Na for each two molecules of K.
Effects of graded pulsatile pressure on the reflex vasomotor responses elicited by changes of mean pressure in the perfused carotid sinus‐aortic arch regions of the dog
Authors: James Jennifer E. Angell , Daly M. de Burgh
Published: December 2014

1. In the anaesthetized dog, the carotid sinuses and aortic arch were isolated from the circulation and separately perfused with blood by a method which enabled the mean pressure, pulse pressure and pulse frequency to be varied independently in each vasosensory area. The systemic circulation was perfused at constant blood flow by means of a pump and the systemic venous blood was oxygenated by an extracorporeal isolated pump‐perfused donor lung preparation.

2. We have confirmed our previous observations that under steadystate conditions the vasomotor responses elicited reflexly by changes in mean carotid sinus pressure are modified by alterations in carotid sinus pulse pressure, whereas those evoked by changes of mean aortic arch pressure are only weakly affected by modifications of aortic pulse pressure.

3. When the carotid sinus and aortic arch regions are perfused in combination at constant pulse frequency (110 c/min), the relationship between mean carotid sinus‐aortic arch pressure and systemic arterial perfusion pressure is dependent on the size of the pulse pressure.

4. Increasing the pulse pressure alters the curve relating the mean carotid sinus‐aortic arch pressure to systemic arterial perfusion pressure in such a way that the perfusion pressure is lower at a given carotid sinus‐aortic arch pressure within the range 80–150 mm Hg. The larger the pulse pressure, up to about 60 mm Hg, the greater the fall in systemic arterial perfusion pressure. Above a mean carotid sinus‐aortic arch pressure of about 150 mm Hg, alterations of pulse pressure have little effect.

5. There is a family of curves representing the relation between mean carotid sinus‐aortic arch pressure and systemic vascular resistance, depending on the pulse pressure.
The effect of environmental conditions on the growth and function of brown adipose tissue
Authors: Hardman M. J. , Hull D.
Published: December 2014

1. Rabbits were reared from birth under one of two contrasting conditions. They were either well‐fed and kept in a cool environment, or kept warm but fed on alternate days only. When they were a week old their metabolic responses to cold or the net exchanges of glucose, free fatty acid and glycerol by their brown adipose tissue in vivo before and during noradrenaline infusions were measured.

2. The cold‐reared rabbits grew normally, the under‐fed rabbits were undersized; in both groups the brown adipose tissue wet weights were less than those normally found at birth. In cold‐reared rabbits this was due largely to the low fat content, in the under‐fed rabbits it was not.

3. The rabbits' rates of oxygen consumption at a thermoneutral temperature and in response to cold was greater in the cold‐reared rabbits.

4. The increase in temperature over brown adipose tissue and the increase in blood flow in response to noradrenaline infusion was also greater in the cold‐reared rabbits.

5. Although the brown adipose tissue of cold‐reared rabbits contained 30% fat it did not release fatty acids 24 hr after a feed. In contrast the brown adipose tissue of the under‐fed rabbits released fatty acids at a high rate.

6. It was concluded that both prolonged cold exposure and undernutrition influenced the function and development of brown adipose tissue during the first week of life. Cold exposure increases the thermogenic capacity of the tissue, undernutrition reduces it. The net release of fatty acids from brown adipose tissue, is, in part, dependent on the tissues' own intracellular requirements.
The distribution of chloride ions in the smooth muscle cells of the guinea‐pig's taenia coli
Authors: Casteels R.
Published: December 2014

1. The intracellular Cl concentration of taenia coli cells, determined by an analytical procedure and by an extrapolation procedure, has a value between 60 and 73 m‐mole/l. cell water.

2. This concentration is too high to be explained by a passive distribution. The discrepancy could be due to a binding of Cl in the intracellular or extracellular compartment or to an active uptake of Cl by the cells.

3. Determination of the activity coefficient for Cl in homogenates of smooth muscle did not support the hypothesis of binding of Cl ions.

4. The efflux of 36Cl from taenia coli cells was not affected by foreign anions. After 1 hr exposure to a Cl‐free solution, the tissues contained less than 1 m‐mole of Cl/kg wet wt., even if Cl had been replaced by a slowly penetrating anion. Because the intracellular cation concentration remained constant, it has to be assumed that new anionic groups can be formed in the cells.

5. The intracellular Cl concentration decreases during exposure to ouabain or to K‐free solution. The uptake seems therefore to be linked to the uptake of K through the Na pump.

6. Exposure to K‐free solution increases the K permeability of the membrane. Under the same experimental conditions the Cl permeability of the membrane increases as long as K is leaking out of the cells.

7. The anions in the external solution exert an important influence on the K permeability of the membrane. NO3 and I cause a small increase of the permeability and large anions such as benzenesulphonate, propionate or pyroglutamate cause a pronounced decrease of this permeability.
The origin of lipoprotein in the intestinal and hepatic lymph of unsuckled new‐born calves
Authors: Lascelles A. K. , Wadsworth J. C.
Published: December 2014

1. Experiments have been conducted to determine the origin and character of the lipid in thoracic duct lymph of new‐born, unsuckled calves. This involved the collection and analysis of intestinal and hepatic lymph from two bile‐fistulated and seven non‐fistulated animals.

2. The output of total esterified fatty acid in intestinal and hepatic lymph in the unfed calf after recovery from the anaesthetic was about 0·6 and 0·025 g/hr, respectively.

3. Three lipoprotein fractions were obtained by ultracentrifugation of intestinal lymph samples. These appeared to correspond to very low‐ (d < 1·005), low‐ (1·2 > d < 1·005) and high‐ (d = 1·20) density lipoprotein of human serum. These lipoproteins contained approximately 40%, 50% and 10% respectively of the total lipid.

4. Very low‐density lipoprotein was not found in blood serum or hepatic lymph and it was evident that very low‐density lipoprotein and most of the low‐density lipoprotein in intestinal lymph were derived from sources other than the capillary filtrate.

5. The output of total esterified fatty acid in intestinal lymph fell steadily during the course of an 11–16 hr period of bile deprivation to values 55% of those in comparable calves without bile fistulae. This was accompanied by a virtual disappearance of very low‐density lipoprotein and a decrease in low‐density lipoprotein of approximately 50%. These effects could not be attributed to starvation.

6. There was a general resemblance in fatty‐acid composition between biliary lipid and the triglyceride of the lipoproteins, the predominant fatty acids being 16:0 and 18:1. The presence of appreciable levels of odd carbon number and branched‐chain fatty acids were consistent with the transfer of significant amounts of free fatty acid from maternal blood to the foetus.

7. It is concluded that most of the lipid in thoracic‐duct lymph of unfed, new‐born calves is derived from the intestines and that the fatty acids of the very low‐density lipoprotein in intestinal lymph arise from the absorption of biliary phospholipid.
The influence of hepatic portal circulation on urine flow
Authors: Liang C. C.
Published: December 2014

1. A study of the effect of changes in the hepatic portal venous pressure (HPVP) on the rate of urine flow in dogs has been made. Normally this pressure varies between 3·7 and 14·9 cm H2O. It can be raised or lowered by varying the method of manipulation of the visceral organs.

2. When the HPVP was raised within 15 cm H2O above the premanipulation level it caused an increase in urine flow to 2‐3 times the normal levels within 2‐5 sec. If the HPVP was raised to more than 15 cm H2O above the pre‐manipulation levels it resulted in a period of antidiuresis. The urine flow returned rapidly to normal level immediately after the pressure was released.

3. The kidney volume increased when an induced diuresis occurred and decreased when an antidiuresis occurred.

4. The urine chloride concentration decreased during diuresis, but total chloride excretion increased. Total chloride excretion was reduced when an antidiuresis occurred.

5. Topical application of local anaesthetics at the hilus of the kidney and on the renal nervous plexus abolished the response. This and other evidence indicate that this effect on urine flow is a result of nervous reflex activity, probably involving the sympathetic but not the vagus.

6. The receptive area lies in the mesentery between the mesenteric capillaries and the main portal vein.
The effect of angiotensin on cation transport by rat kidney cortex slices
Authors: Munday K. A. , Parsons B. J. , Poat Judith A.
Published: December 2014

1. A study has been made of the effect of angiotensin (10−12 g/ml.) on active and passive transport of sodium, potassium and water between rat kidney cortex slices and the incubation medium.

2. Angiotensin has no effect on the passive uptake of sodium and loss of potassium by slices incubated under conditions which inhibit active transport.

3. Active sodium extrusion by slices incubated under aerobic conditions is stimulated, whereas active potassium uptake is inhibited by angiotensin.

4. Sodium pump activity is stimulated by angiotensin in the presence of ouabain or in the absence of potassium in the incubation medium, conditions which block the sodium for potassium exchange pump.

5. There is a 2 min latent period following the application of angiotensin before a response is observed.

6. These findings are discussed in relation to the mechanism of action of angiotensin on kidney sodium and fluid transport processes.
The propagation of transient potentials in some linear cable structures
Authors: Jack J. J. B. , Redman S. J.
Published: December 2014

1. Analytical solutions have been given for the time course of voltage transients occurring in one‐dimensional cable structures, with linear uniform membrane properties.

2. These solutions show how the time course of the voltage transients generated at different distances are affected by variations in the time course of current injection (at one point on the cable) and by alterations in the length of the cable, with either sealed or open end terminations. These effects are illustrated with computed results.

3. Simple measurements from the time course of a membrane potential displacement, occurring in a one‐dimensional cable structure following a brief current injection across the membrane, are used to evaluate the parameters which describe the cable model. These parameters are the membrane time constant, the electrotonic length of the cable, the cable end termination, and in the case of a post‐synaptic potential, the distance between the electrode and the active synapse.
Coronary blood flow, oxygen delivery rate and cardiac performance
Authors: Bacaner Marvin B. , Lioy Franco , Visscher Maurice B.
Published: December 2014

1. Studies have been made on the isolated blood‐perfused heart of dogs in which isometric tension development at various settings of resting tension (RT) was measured at various levels of O2 delivery rates controlled by altering (a) coronary blood flow (CBF), (b) O2 capacity or (c) O2 saturation of the perfusate. Measurements were also made of O2 consumption and vascular perfusion resistance.

2. The capacity of the left ventricle to develop tension at any given setting of resting tension was found to be directly correlated with changes in O2 delivery rate using any of the above three methods of altering the latter.

3. The slopes of the curves relating resting tension to developed tension are positively correlated with total O2 delivery to the heart.

4. The O2‐dependent metabolic effect upon tension production was found to be slow in development, in contrast to the Frank—Starling effect, which reached full development in the first heart beat after a change in resting length and tension.

5. The O2 consumption of the isometrically contracting heart is strongly correlated with the O2 delivery rate at all particular values of resting tension and related developed tension.

6. The metabolic state of the myocardium as determined by the rate of O2 delivery within physiological ranges is (a) a direct major determinant of the tension‐producing capacity of the heart muscle and (b) determines the magnitude of adaptation via the Frank—Starling mechanism.
Plasma oxytocin concentration and paraventricular neurone activity in rats with diencephalic islands and intact brains
Authors: Dyball R. E. J. , Dyer R. G.
Published: December 2014

1. Plasma oxytocin concentrations and the discharge rates of identified paraventricular neurones were compared in intact animals and diencephalic island preparations.

2. Substantial amounts of oxytocin (88–322 μu./ml.) were found in the plasma of intact rats but in no case was it detected in the plasma of island preparations. The discharge rate of paraventricular units was also significantly reduced in these preparations.

3. The results are consistent with the hypothesis that an increase in the discharge rate of paraventricular neurones is associated with oxytocin release from the neurohypophysis.

4. The discharge rates of identified paraventricular units were not affected by intravenous injections of oxytocin either in intact animals or island preparations.
Movement of choline acetyltransferase in axons disconnected from their cell bodies
Authors: Ekström J. , Emmelin N.
Published: December 2014

1. Phrenic nerves of rats were cut out and divided into two parts of equal length, one proximal and one distal. The activity of choline acetyltransferase of the two pieces was estimated. Four groups of rats were studied: (1) normal rats, and rats in which 3 days earlier, (2) the right nerve had been cut in the uppermost part of the thorax, (3) a ligature had been tied round the right nerve just above the diaphragm, and (4) these two procedures had been combined.

2. In normal rats the activity of the enzyme was about the same in proximal and distal pieces. Ligation of the nerve caused an increase of the activity, of about 50%, in the distal but not in the proximal segment.

3. After section of the nerve the activity below the section was 18% of normal in the proximal, and 9% in the distal piece.

4. When the nerve was both cut and tied the activity decreased to the same level in both pieces, and this was about the level of the proximal piece after mere section of the nerve.

5. It is concluded that choline acetyltransferase can move for some time along the axons to the nerve terminals even when the connexion with the soma has been interrupted.
Competitive interaction of β‐guanidino propionic acid and γ‐aminobutyric acid on the muscle fibre of the crayfish
Authors: Feltz Anne
Published: December 2014

1. The interaction of β‐guanidino propionic acid and γ‐aminobutyric acid has been investigated on the crayfish muscle by measurement of the membrane conductance.

2. The increase in membrane conductance produced by GABA is depressed by β‐guanidino propionic acid. This antagonist acts in a competitive way as shown by the shift of log dose—response curves and by the results of tests for competitive interaction (method of Schild (1947); Lineweaver and Burk's plot).

3. Perfusion of GABA was shown to induce a receptor desensitization. As a consequence, the slope of the dose—response curve plotted in Hill's co‐ordinates increases when care is taken to minimize this phenomenon. The significance of this slope for establishing the real number of GABA molecules binding with the GABA receptor is discussed.
On the nature of the oscillations of the membrane potential (slow waves) produced by acetylcholine or carbachol in intestinal smooth muscle
Authors: Bolton T. B.
Published: December 2014

1. Intracellular recording was made with glass micro‐electrodes from cells of the longitudinal muscle of the guinea‐pig ileum in isotonic and in hypertonic solution.

2. In isotonic solution spontaneous bursts of electrical activity occurred; these consisted of a slow potential component which carried a burst of spike action potentials. Acetylcholine increased the size (and the frequency) of the slow potential component. This had the effect of first reducing and then abolishing the spike potentials; continuous slow wave activity was thus produced. Slow waves were about 1 sec in duration and up to 50 mV in size in isotonic solution.

3. In hypertonic solution the membrane potential was stable. There were no spontaneous spikes and no slow potentials. However, spikes, but not slow potentials, were elicited by depolarizing current. Carbachol (or acetylcholine) reduced the membrane potential and initiated spikes and oscillations of the membrane potential (slow waves). Slow waves were 2‐5 sec in duration and 10–40 mV in size in hypertonic solution.

4. The response to carbachol in hypertonic solution was unaffected by surgical denervation of the tissue, by tetrodotoxin, or by ganglion blocking agents, indicating that muscarinic stimulants produced their effects by acting directly on the smooth muscle cell.

5. In hypertonic solution slow waves occurred only in the presence of a muscarinic stimulant and could not be elicited with depolarizing current (unless carbachol was present) nor by increasing the external potassium concentration.

6. In hypertonic solution slow waves were abolished by hyperpolarizing the membrane and their rate of rise was proportional to the level of the membrane potential from which they arose. The membrane resistance was reduced at the peak of the slow wave. Slow waves were rapidly abolished by sodium‐deficient solutions but spikes were not.

7. It is suggested that slow waves represent an inward current through a slow, sodium‐sensitive and voltage‐dependent ion channel, and that acetylcholine or carbachol increase, while hypertonic solution decreases, the current carried by this channel.
Metabolic rate and thermal insulation in albino and hairless mice
Authors: Mount L. E.
Published: December 2014

1. Rates of oxygen consumption of albino and hairless mice were measured in a metabolism chamber during periods of approximately 5 or 24 hr. Rectal temperature was measured before and after each period. The chamber temperatures used were 22, 30 and 32° C for both albino and hairless, and in addition 34 and 36° C for the hairless mice.

2. The mean age and body weight of the albino mice were 102 days and 34·6 g; the corresponding values for the hairless mice were 87 days and 32·8 g.

3. The mean minimum rates of oxygen consumption (ml./kg.min) were 31·0 for the albino and 38·8 for the hairless mouse; the corresponding estimated critical temperatures were in the ranges 30–32° C for the albino mouse and 32–34° C for the hairless mouse.

4. The mean values for core‐ambient thermal insulation (° C.m2.hr/kcal) were 0·418 and 0·328 for the albino mouse, and 0·275 and 0·221 for the hairless mouse, at 22 and 30° C respectively in each case.
The effect of type D botulinum toxin on frog neuromuscular junctions
Authors: Harris A. J. , Miledi R.
Published: December 2014

1. Botulinum toxin type D blocks neuromuscular transmission in frogs. Motor nerve impulses continue to invade the nerve terminals but cease to evoke the phasic release of transmitter normally associated with them.

2. Sensory receptors in the muscle continue to generate impulses even after 4 days of continuous exposure to botulinum toxin.

3. Contrary to expectations, spontaneous miniature end‐plate potentials did not disappear completely after botulinum intoxication; they still occurred, although with reduced frequency, in most end‐plates. These miniature potentials had a skew amplitude distribution instead of the bell‐shaped distribution of normal end‐plates.

4. The electron‐microscopic appearance of botulinum‐poisoned end‐plates was not obviously altered.

5. Even though after botulinum nerve impulses fail to release transmitter, tetanic nerve stimulation causes an increase in the frequency of miniature end‐plate potentials. Many of the unit potentials which appear during the tetanic period are of an amplitude which is larger than that of spontaneous potentials, indicating that a different class of unit is being released preferentially. Some implications of this finding are briefly discussed.
Chemical change and energy output during muscular contraction
Authors: Gilbert Claude , Kretzschmar K. M. , Wilkie D. R. , Woledge R. C.
Published: December 2014

1. The production of heat and (internal) work and the changes in the amount of phosphocreatine (PCr), ATP, inorganic phosphate (Pi) and sometimes lactate have been measured from moment to moment during and after tetanic isometric contractions of isolated frog muscles at 0° C.

2. Heat production was measured by thermopiles and a novel apparatus was employed for freezing the muscles rapidly at a chosen instant so as to halt the chemical processes before analysis.

3. Using unpoisoned muscles in oxygen, it was shown that neither oxidative recovery processes nor glycolytic ones led to appreciable restitution of PCr or ATP during 15 sec of contraction. However, clear signs of recovery processes could be seen within a minute. In our preparations artificial ‘ageing’ by storage at low temperature did not interfere with the capacity for glycolysis.

4. Our clearest result was that the break‐down of PCr was not nearly large enough to account for the rapid heat production during the first few sec of contraction. By the end of a 15 sec tetanus as much as 10 mcal/g remained unaccounted for.

5. The source of this heat is not clear. At no time is there any sign of net break‐down of ATP; indeed there appears to be a slight increase of ATP in the stimulated muscle.

6. Break‐down of PCr continues both during relaxation and during the minute following, while the muscle is at rest. Thus during contraction there is heat production without PCr break‐down, while subsequently there is PCr break‐down without heat production.
Nucleotide requirements for sodium‐sodium exchange catalysed by the sodium pump in human red cells
Authors: Glynn I. M. , Hoffman J. F.
Published: December 2014

1. Resealed red cell ghosts containing a variety of nucleoside triphosphates, or a mixture of tri‐ and diphosphates, were allowed to lose 24Na into a 10 m
M‐K medium or a K‐free high‐Na medium in the presence and absence of ouabain.

2. Only ATP supported a ouabain‐sensitive Na:K exchange in the 10 m
M‐K medium, or a ouabain‐sensitive Na:Na exchange in the K‐free medium.

3. Because of ATPase and adenylate kinase activity, it is difficult to control the levels of ATP and ADP inside resealed red cell ghosts. Some control was achieved by incorporating into the ghosts an ATP regenerating system consisting of creatine phosphate and creatine kinase.

4. Measurements of 24Na efflux from ghosts prepared in this way showed that ADP is required for the ouabain‐sensitive exchange of Na that occurs in K‐free high‐Na media, but not for the normal exchange of Na for K that occurs in K‐containing media.

5. The significance of these findings is discussed.
Angiotensin II‐like activity in circulating arterial blood in immature and adult rabbits
Authors: Pipkin Fiona Broughton , Mott Joan C. , Roberton N. R. C.
Published: December 2014

1. Angiotensin II‐like activity was estimated from the contraction of the rat ascending colon superfused with arterial blood in an extracorporeal circuit. The colon was calibrated by infusion of synthetic angiotensin II amide (Hypertensin, CIBA Ltd).

2. Resting levels of angiotensin II‐like activity were obtained by comparison of the length of a rat colon preparation superfused alternately with blood from an intact and from a nephrectomized rabbit.

3. The resting levels of angiotensin II‐like activity reached a maximum value of about 1·6 ng/ml. at 10–14 days of age, and thereafter declined to the adult value of 0·23 ng/ml. Rabbits of less than 100 g body weight had resting levels in the same range as adults.

4. Removal of 25% of the calculated blood volume induced five times greater increments in arterial angiotensin II‐like activity in immature than in adult rabbits (1·68 ± 0·26
S.E. of mean ng/ml. compared with 0·34 ± 0·08
S.E. of mean ng/ml.).

5. No evidence was obtained that the high levels of angiotensin II‐like activity encountered in immature rabbits were attributable to a slower rate of inactivation of angiotensin by tissues.

6. The pronounced activity of the renin‐angiotensin system demonstrated by these experiments in immature rabbits especially during haemorrhage is consistent with the suggestion that this system is of particular importance in cardiovascular control in early life.
The effects of temperature and ions on the current—voltage relation and electrical characteristics of a molluscan neurone
Authors: Marmor Michael F.
Published: December 2014

1. Current—voltage relations were generated in the Anisodoris giant neurone (G cell) by either current pulses or slow biphasic current ramps.

2. Inward‐going rectification occurred during hyperpolarization at warm temperatures (10–15° C), but not at cold temperatures (0–5° C) or in the absence of external K.

3. Replacing external K with Rb eliminated inward‐going rectification in the warm, but produced it in the cold. The removal of external Na, Cl or Ca had no effect upon inward‐going rectification.

4. At cold temperatures the I—V relation was linear when generated by current pulses, but was non‐linear in accordance with the constant field hypothesis when generated by current ramps.

5. A high conductance state developed when the membrane was hyperpolarized beyond a critical potential (approximately — 130 mV in the cold, and — 110 mV in the warm) which was dependent upon external Ca, but not upon K, Na or Cl.

6. Hysteresis was observed in the ramp‐generated I—V relation whenever the cell was polarized into the high conductance state.

7. Rectification and the high conductance state appear to involve different mechanisms within the membrane. However, both are dependent upon absolute membrane potential and not the resting potential.

8. The axonal‐somatic conductance ratio for the G cell was calculated to be between 2 and 10.

9. The membrane time constant (200–100 msec) and specific resistance (0·1–1·5 × 106 Ω cm2) varied with temperature, membrane potential, and external ions in a manner that correlated with changes in the shape of the I—V relation. In addition, the resistance was dependent upon external Ca.

10. The K permeability (PK), measured during inhibition of inwardgoing rectification, was independent of temperature and membrane potential. However, PNa increased with warming.

11. The specific capacitance was calculated to be 0·5–1·0 μF/cm2. The capacitance increased slightly with warming, but was independent of membrane potential and unaffected by reductions in external K or Na.
On the direct and crossed components of reflex responses to unilateral stimulation of the carotid body chemoreceptors in the dog
Authors: McQueen D. S. , Ungar A.
Published: December 2014

1. In dogs under chloralose‐urethane anaesthesia the chemoreceptors of the two carotid bodies were separately stimulated.

2. The distribution of three primary reflex responses to carotid body stimulation was studied: parasympathetic bradycardia, sympathetic vasoconstriction, and increase in somatic phrenic nerve activity.

3. The reflex bradycardia evoked by either carotid body was mediated by both vagus nerves, but when either vagus was blocked a greater response could be obtained from the contralateral than from the ipsilateral carotid body.

4. The reflex vasoconstriction evoked by either carotid body was seen in both hind limbs, with no predominance in either limb.

5. The reflex increase in phrenic nerve activity evoked by either carotid body was seen in both phrenic nerves, with no predominance in either nerve.
Permeability of lung capillaries and alveoli to non‐electrolytes in the foetal lamb. With an Appendix
Authors: Normand I. C. S. , Olver R. E. , Reynolds E. O. R. , Strang L. B. , Welch Keasley
Published: December 2014

1. Two sets of experiments were performed on intact foetal lambs exteriorized at Caesarean section; in one set radioactively labelled test substances (inulin, sucrose, mannitol, erythritol, urea) were injected
I.V. either singly or in pairs and then followed in plasma, lung lymph and alveolar liquid; in the other set labelled test substances (inulin, sucrose, mannitol, erythritol,
D‐serine,
L‐serine,
D‐α‐alanine, urea, water, thiourea, N‐ethylthiourea) were introduced singly, in pairs, or sequentially into alveolar liquid and their concentration followed in alveolar liquid and plasma.

2. Inulin was found to cross lung capillary walls but not alveolar walls. Measurements of its concentration following injection into alveolar liquid were used to determine the volume of foetal alveolar liquid (mean = 30 ml./kg) and its rate of formation (mean = 0·036 ml./min.kg). The volume of the lung interstitial space was determined from previous experiments in which [125I]PVP had been injected
I.V. then measured after 2 hr in lung tissue and lung lymph (mean = 10·4% foetal lung weight after withdrawal of liquid; ≈ 20% wet lung tissue weight).

3. Transfer constants (min−1) for lung capillaries (KC) and alveoli (K0) were obtained from the experimental results by compartmental analysis. Permeability constants (PC and PO, cm/sec) were derived from them using estimates for capillary and alveolar areas. For lipid insoluble molecules PC and PO both increased with decreasing molecular radius, the effect being much greater for PO than PC. PO was also shown to increase with lipid solubility of the test molecule even though molecular size increased with lipid solubility in the series tested (urea, thiourea, N‐ethylthiourea).

4. Analysis of the results for the lipid insoluble substances in terms of pore theory gave a value of pore radius for lung capillaries of 150 Å and for alveolar walls of 5·5 Å. The smallness of the pores in alveolar walls is thought to prevent proteins and other plasma solutes from penetrating alveoli, and to determine the forces which operate in the osmotic flow of water across alveolar walls.
Kininogenase of the guinea‐pig's coagulating gland and the release of bradykinin
Authors: Moriwaki C. , Schachter M.
Published: December 2014

A kininogenase (CGK) in the coagulating gland of the guinea‐pig was partially purified, characterized and separated from a kininase also present in the gland. This kininogenase is not inhibited by the usual kininogenase and protease inhibitors. Our results indicate that it is identical with the esterolytic enzyme in the gland which hydrolyses the synthetic ester TAME.

The kinin released by CGK from dog's crude pseudoglobulin was purified more than 1500 times and identified as bradykinin by chromatography on paper, on carboxymethyl‐cellulose columns, and on silica gel.
Observations on the control of stepping and hopping movements in man
Authors: Jones G. Melvill , Watt D. G. D.
Published: December 2014

1. The presence of a form of stretch reflex, previously described in the arm by other authors, has been confirmed in the gastrocnemius muscle of the human leg. The electromyographic (e.m.g.) manifestation of this reflex occurred 120 msec (
S.E. of mean = 3·5 msec) following a sharply applied, and maintained, dorsiflexing force to the foot. This form of response is referred to in this article as the Functional Stretch Reflex (FSR).

2. To determine the contribution of the FSR to the control of normal leg movement, the e.m.g. activity in the above muscle was monitored during single downward steps of 12·7, 25·4 and 38·1 cm and during repetitive, rhythmic, hopping movements on one foot.

3. It was found that e.m.g. activity associated with steps to the ground began 141 msec (
S.E. of mean = 8·5 msec) before contact with the ground and ended 131 msec (
S.E. of mean = 7·6 msec) after contact, when the e.m.g. usually became temporarily inactive.

4. It is inferred from these results that the muscular deceleration associated with landing was brought about by the release of a pre‐programmed pattern of neuromuscular activity which was inaccessible to reflex activity resulting from the mechanical event of landing, rather than by a stretch reflex.

5. It was found that subjects chose their preferred frequency of hopping with great accuracy and consistency. The mean value obtained was 2·06 Hz (
S.E. of mean = 0·02 Hz).

6. At the preferred frequency, e.m.g. activity began 84 msec (
S.E. of mean = 9·6 msec) before and terminated 263 msec (
S.E. of mean = 10 msec) after contact with the ground.

7. It is inferred that in rhythmical hopping and perhaps also in running, each landing is effected, as in single steps, by a predetermined pattern of neuromuscular activity. However, when hopping at the preferred frequency, the take‐off phase of muscular activity is timed to make maximal use of the FSR, i.e. between 120 and 260 msec after initial contact.

8. The results emphasize the importance of pre‐programming complex muscular contractions suitable for opposing sudden passive stretching forces, and of initiating them prior to the onset of these forces.