bluuebunny/crossref_metadata_2025 huggingface dataset:
Chronic intraocular pressure elevation impairs autoregulatory capacity in streptozotocin‐induced diabetic rat retina
Authors: Wong Vickie H. , Armitage James A , He Zheng , Hui Flora , Vingrys Algis J. , Bui Bang V.
Published: December 2014

Purpose

To assess ocular blood flow responses to acuteIOPstress following 4 weeks of chronicIOPelevation in streptozotocin (STZ)‐induced diabetic and control rats. We hypothesise that chronicIOPelevation for 4 weeks will further impair blood flow regulation inSTZ‐induced diabetic rats eyes.

Methods

Two weeks following citrate buffer orSTZ‐injections chronicIOPelevation was induced in Long Evans rats via fortnightly intracameral injections of microspheres (15 μm) suspended in 5% polyethylene glycol.IOPwas monitored daily. Electroretinography (ERG, −6.79–2.07 log cd s m−2) was undertaken at Week 4 to compare photoreceptor (RmPIII),ON‐bipolar cell (Vmax) and ganglion cell dominantERG[scotopic threshold response (STR)] components. 4 weeks post‐chronicIOPinduction, ocular blood flow (laser Doppler flowmetry) was measured in response to acuteIOPchallenge (10–100 mmHg, in 5 mmHg steps, each 3 min).

Results

Four weeks of chronicIOP(mean ± S.E.M., citrate: 24.0 ± 0.3 to 30.7 ± 1.3 andSTZ‐diabetes: 24.2 ± 0.2 to 31.1 ± 1.2 mmHg) was associated with reduced photoreceptor amplitude in both groups (−25.3 ± 2.2% and −17.2 ± 3.0%, respectively).STZ‐diabetic eyes showed reduced photoreceptor sensitivity (citrate: 0.5 ± 1.8%,STZ‐diabetic: −8.1 ± 2.4%). ParadoxicallyON‐bipolar cell sensitivity was increased, particularly in citrate control eyes (citrate: 166.8 ± 25.9%,STZ‐diabetic: 64.8 ± 18.7%). The ganglion cell dominantSTRwas not significantly reduced inSTZ‐diabetic rats. Using acuteIOPelevation to probe autoregulation, we show thatSTZ‐diabetes impaired autoregulation compared with citrate control animals. The combination ofSTZ‐diabetes and chronicIOPelevation further impaired autoregulation.

Conclusions

STZ‐diabetes and chronicIOPelevation appear to be additive risk factors for impairment of ocular blood flow autoregulation.
Implications of Channel Structure and Operational Mode Upon a Manufacturer's Durability Choice
Authors: Bhaskaran Sreekumar R. , Gilbert Stephen M.
Published: December 2014

Motivated by the observation that durability ratings of automobile manufacturers are not necessarily linked to the proportion of leasing but tend to decrease with the density of their dealer networks, we explore the interactions between channel structure (direct interaction with consumers vs. through an intermediary(ies)) and mode of operations (leasing vs. selling) and their implications for a manufacturer's willingness to invest in making her product more durable. Using a manufacturer who leases her product directly to consumers as a point of reference, we find that an isolated change in either the channel structure (selling through an intermediary), or the operational mode (leasing to selling) can decrease the manufacturer's willingness to provide durability. However, if combined, these two changes together may strengthen the manufacturer's willingness to invest in durability. Specifically, the traditional result that a manufacturer who leases provides more durability than one who sells, can be reversed in a decentralized channel.
Sexual Assault, Overweight, and Suicide Attempts in U.S. Adolescents
Authors: Anderson Laura M. , Hayden Brittany M. , Tomasula Jessica L.
Published: December 2014

Associations between overweight, sexual assault history, and suicide attempts were examined among 31,540 adolescents from the combined 2009 and 2011 nationally representative Youth Risk Behavior Surveys samples. These variables have not previously been studied concurrently. It was hypothesized that overweight and sexual assault, together, would interact and result in increased suicide attempts. Findings across analyses included (a) no significant associations between sexual assault and overweight in females or males (p = .65 and p = .90, respectively), (b) statistically significant associations between female (but not male) overweight status and suicide attempts (p = .001), (c) a strong association between sexual assault and suicide risk in males (p < .001) and females (p < .001), and (d) an elevated risk for suicide in overweight males with co‐occurring sexual assault, with over 33% of males with such histories attempting suicide. Preliminary findings have powerful implications for research and secondary prevention.
The release of 5‐hydroxytryptamine from the rat stomach in vitro
Authors: Bennett A. , Bucknell Anne , Dean A. C. B.
Published: December 2014

1. 5‐HT was released into the lumen of the intact isolated rat stomach and into the bath fluid surrounding a preparation of the body and antrum stretched mechanically.

2. Release of 5‐HT increased when the pressure inside the intact stomach was raised or when the body/antrum preparation was stretched.

3. This increased release was not prevented by hexamethonium, atropine, hyoscine or procaine, and was probably due to distortion of cells containing 5‐HT.

4. During periods of peristalsis induced by transmural stimulation the pharmacological activity of the fluid in the stomach was usually increased owing to a greater release of 5‐HT and also to the release of an unidentified substance.

5. In reserpine‐treated rats, 5‐HT was released into the stomach but transmural stimulation did not produce true peristalsis and only rhythmic contractions occurred.

6. Peristalsis was seldom reduced by methysergide, and it is concluded that 5‐HT is not essential for gastric peristalsis in the rat.
Further studies of the mechanism of passive sensitization
Authors: Mongar J. L. , Winne D.
Published: December 2014

1. The mechanism of passive sensitization of chopped guinea‐pig lung when incubated with rabbit antiserum alone and in the presence of non‐antibody γ‐globulin has been investigated.

2. The effect of concentrations of antibody on the fraction of receptors occupied by molecules attached at one, two or three points has been calculated assuming mass action relations. If a single attachment is sufficient for sensitization the predicted log concentration—effect curve is S‐shaped; if two or more attachments are needed the curve is bell‐shaped. The effect of inhibiting non‐antibody γ‐globulin on the shape and position of the curves has also been calculated.

3. The effect of incubating with a wide range of concentrations of antibody on the subsequent histamine release with antigen has been determined. Bell‐shaped curves were obtained. Their shape and position were altered by inhibiting non‐antibody in a manner predicted by the two‐point attachment hypothesis.

4. The first affinity constants for antibody and non‐antibody γ‐globulin have been calculated from the experimental concentration—effect curves. They are similar and have a value of about 107 l./mole. Approximate values for the second affinity constants and for the fraction of receptors effectively occupied at maximum sensitization have also been estimated.
A study of the increased sensitivity of denervated and re‐innervated muscle to depolarizing drugs
Authors: Maclagan Jennifer , Vrbová Gerta
Published: December 2014

1. The response of re‐innervated muscles to depolarizing blocking drugs was studied.

2. During the early stages of re‐innervation the ‘new’ neuromuscular junctions are more sensitive to decamethonium and suxamethonium. The recovery from the block and the repolarization of the end‐plate are markedly slowed.

3. This increased sensitivity does not appear to be characteristic of all newly formed neuromuscular junctions. It was found that in new‐born kittens the muscles are very insensitive to neuromuscular blocking drugs.

4. It is concluded that the increased sensitivity of re‐innervated muscles to depolarizing blocking drugs and the slow repolarization are due to a persistence of changes which developed during denervation.
Activity of neurones in the paraventricular nucleus of the hypothalamus and its control
Authors: Brooks C. McC. , Ishikawa T. , Koizumi Kiyomi , Lu H-H.
Published: December 2014

1. Activity of the paraventricular nucleus neurones was recorded by micro‐electrodes during resting conditions and while various osmotic, chemical, direct and indirect neural stimuli were applied. This activity was correlated with evidence of oxytocin release by recording milk ejection responses.

2. Seventy‐four per cent of all paraventricular nucleus neurones were osmosensitive in that firing was augmented following close arterial injection of hypertonic solutions (1 ml. 1
M‐NaCl in 10‐15 sec). A very few neurones showed decreased activity and in twenty‐two per cent no change at all occurred following injection. Evidence indicated that the observed depressions of cellular firing rate were due to other than osmotic stimulation.

3. In post‐partum cats an osmotically‐induced neurone discharge increase was accompanied by a milk ejection response equivalent to that produced by 2‐3 m‐u. of oxytocin.

4. Paraventricular neurones were also sensitive to acetylcholine. Intracarotid injections of 40‐80 μg of acetylcholine greatly increased discharge rates and caused a very definite milk ejection response.

5. Stimulation of the nipples by gentle suction, but not by electrical shock, and distension of the uterus in post‐partum cats increased unit discharge in the paraventricular nucleus and evoked a milk ejection response.

6. Neurones of the paraventricular nucleus, unlike those of the supraoptic nucleus, did not appear to be specifically responsive to electrical stimulation of skin and muscle afferent or of central nervous structures. Such stimuli did cause slight augmentations or depressions in firing rates of cells within and adjacent to the paraventricular nuclei, but many neurones were unaffected. Stimuli such as those applied appeared to have a general central effect involving paraventricular as well as many other neurones.

7. Direct electrical excitation of the pituitary stalk produced a milk ejection response in post‐partum cats. Electrical pulses applied to the paraventricular nuclei were less effective for reasons discussed.
Action of choline on frog sartorius muscle
Authors: Ochs S.
Published: December 2014

1. External and micro‐electrode measurements were made of fibre membrane potentials taken at intervals along the length of frog sartorius muscle fibres before and after adding choline. In ‘cold‐treated’ Rana pipiens which had been kept at 1‐3° C for at least 5 days, 10−3 w/v choline caused a long‐lasting depolarization of approximately 3 hr. Depolarization occurred first at the end‐plate region and spread more slowly to the end‐plate free region. The potential became equalized along the muscles during recovery.

2. R. pipiens kept at room temperature showed a faster repolarization in the choline solution, within approximately 1 hr. R. temporaria showed a similar recovery time in muscles from ‘cold‐treated’ animals. In R. temporaria kept at room temperature the duration was shorter, approximately 20‐30 min. The apparently generalized depolarization of the muscle seen in ‘cold‐treated’ R. pipiens appears to be due to the spreading effect of a long‐maintained depolarization at the end‐plates. A similar far‐spread of depolarization was seen following crush of fibres.

3. Length‐constants of muscle fibres determined with pulses were found to be within the normal range in muscles from ‘cold‐treated’ R. pipiens and slightly reduced after adding choline.
Membrane capacity of the cardiac Purkinje fibre
Authors: Fozzard H. A.
Published: December 2014

1. The basis for the relatively high membrane capacitance of the cardiac Purkinje fibre has been investigated.

2. The capacitance measured by analysis of the cable response to a current step (square wave) was compared in the same fibres to the capacitance calculated from the foot of the propagated action potential. The square wave value for capacitance was 12·8 ± 1·3 μF/cm2 and that from the foot of the action potential, 2·4 ± 0·5 μF/cm2.

3. The capacitative filling at the beginning of a voltage clamp in short Purkinje fibres was measured. The current‐time course deviated from that predicted by a model membrane containing resistance and capacitance in parallel.

4. The results obtained by both methods are consistent with two components to the membrane capacitance, with part in parallel with the membrane resistance (2·4 μF/cm2) and part (7 μF/cm2) in series with a resistor (300 Ω cm2).

5. The value of the series resistor could be increased by decreasing the conductivity of the extracellular fluid.

6. The possible anatomical basis for these findings is discussed.

7. Implications of this model on the shape of the Purkinje fibre action potential and on the electrical triggering of contraction are considered.
The excitatory synaptic action of climbing fibres on the Purkinje cells of the cerebellum
Authors: Eccles J. C. , Llinás R. , Sasaki K.
Published: December 2014

1. A single climbing fibre makes an extraordinarily extensive synaptic contact with the dendrites of a Purkinje cell. Investigation of this synaptic mechanism in the cerebellum of the cat has been based on the discovery by Szentagothai & Rajkovits (1959) that the climbing fibres have their cells of origin in the contralateral inferior olive.

2. Stimulation in the accessory olive selectively excites fibres that have a powerful synaptic excitatory action on Purkinje cells in the contralateral vermis, evoking a repetitive spike discharge of 5‐7 msec duration. Almost invariably this response had an all‐or‐nothing character. In every respect it corresponds with the synaptic action that is to be expected from climbing fibres.

3. Intracellular recording from Purkinje cells reveals that this climbing fibre stimulation evokes a large unitary depolarization with an initial spike and later partial spike responses superimposed on a sustained depolarization.

4. Typical climbing fibre responses can be excited, but in a much less selective manner, by stimulation of the olive‐cerebellar pathway in the region of the fastigial nucleus, there being often a preceding antidromic spike potential of the Purkinje cell under observation.

5. Impaled Purkinje cells rapidly deteriorate with loss of all spike discharge, the climbing fibre response being then reduced to an excitatory post‐synaptic potential. This potential shows that stimulation of the inferior olive may evoke two or more discharges at about 2 msec intervals in the same climbing fibre. The complexity of neuronal connexions in the inferior olive is also indicated by the considerable latency range in responses.

6. A further complication is that, with stimulation in the region of the fastigial nucleus, the initial direct climbing fibre response is often followed by a reflex discharge, presumably from the inferior olive, which resembles the responses produced by inferior olive stimulation in being often repetitive.

7. Typical climbing fibre responses have been evoked by peripheral nerve stimulation and frequently occur spontaneously.

8. An account is given of the way in which the responses evoked by climbing fibres in the individual Purkinje cells can account for the potential fields that an inferior olive stimulus evokes on the surface and through the depth of the cerebellar cortex.

9. By the application of currents through the recording intracellular electrode it has been possible to effect large changes in the excitatory post‐synaptic potential produced by a climbing fibre, it being diminished and even reversed with depolarizing currents and greatly increased by hyperpolarizing currents.
Comparison of the reflex responses elicited by stimulation of the separately perfused carotid and aortic body chemoreceptors in the dog
Authors: Daly M. de Burgh , Ungar A.
Published: December 2014

1. In dogs under chloralose and urethane anaesthesia, the carotid and aortic bodies were isolated from the circulation and separately perfused with blood, the composition of which could be controlled at will. The remainder of the systemic circulation was perfused at constant blood flow, thereby enabling the reflex vascular responses to be determined. The systemic venous blood was oxygenated in the isolated perfused lungs of a second dog and the PO2 and PCO2 of the systemic arterial blood was maintained constant.

2. Using hypoxic hypercapnic blood to stimulate the arterial chemoreceptors, carotid body excitation in spontaneously breathing animals caused an increase in respiratory minute volume approximately seven times larger than that evoked by stimulation of the aortic bodies. Whereas the hyperpnoea of carotid body origin is due to an increase in rate and depth of breathing, that from the aortic bodies is due predominantly to an increase in respiratory frequency.

3. Stimulation of the carotid bodies in spontaneously breathing animals caused small variable changes in systemic vascular resistance, whereas stimulation of the aortic bodies invariably increased the vascular resistance.

4. When pulmonary ventilation was maintained constant, the vascular response to stimulation of the carotid bodies was considerably modified in that constriction invariably occurred; that from the aortic bodies, however, was little affected. There was now no significant difference in the size of responses from the two groups of chemoreceptors. These constrictor responses represent the primary vascular effects.

5. A similar modification of the carotid body vascular response occurred in the spontaneously breathing animal after denervation of the lungs, and is due to abolition of a lung‐inflation vasodilator reflex.

6. The size of the primary vasoconstrictor responses from the carotid and aortic bodies is reduced by lowering the arterial blood PCO2.

7. The results indicate that there is a fundamental difference in the functions of the carotid and aortic bodies. They exert a quantitatively similar primary control of the ‘vasomotor centre’ which is in striking contrast to the relatively more powerful influence on respiration by the carotid bodies. In the spontaneously breathing animal, however, the primary vasoconstrictor response from the carotid bodies is offset to a varying degree by the lung‐inflation vasodilator reflex initiated by the concomitant hyperpnoea. This is not evident with the aortic bodies because of the relatively weaker respiratory response they evoke.
The oxygen consumption of the placenta and foetal membranes in the sheep
Authors: Campbell A. G. M. , Dawes G. S. , Fishman A. P. , Hyman A. I. , James G. B.
Published: December 2014

1. In anaesthetized sheep near term the O2 uptake of the foetus from the placenta was reduced to zero either by replacing the foetus with a mechanical pump, or by ventilation of the foetus after delivery or in utero. When umbilical arterial and venous PO2 were made equal, they were much less than maternal arterial PO2.

2. This difference in PO2 was attributed to O2 consumption both within the placental cotyledons and the extra‐cotyledonary foetal membranes.

3. The foetal membranes and cord in the sheep are supplied by branches of umbilical blood vessels and constitute an oxygen‐consuming by‐pass on the foetal side of the placenta.

4. The O2 consumption of individual placental cotyledons was measured in vivo.

5. The combined O2 consumption of the whole placenta and foetal membranes in vivo was a considerable fraction of foetal O2 consumption.

6. The consequences of these observations are discussed in relation to O2 transfer across the placenta.
The distribution of calcium—47 in the rat
Authors: Anderson J. , Tomlinson R. W. S.
Published: December 2014

1. Plasma specific activities were measured at various times after the intravenous injection of calcium‐47 in four different age groups of rats.

2. The data may be represented as two power functions. The change in power function occurs at a set time which is significantly different in three of the age groups.

3. Various bones, muscle and skin all show different uptakes of the calcium‐47 and the change in the power function of the plasma data probably represents an equilibrium of the soft tissue calcium.
The increased extensibility of pregnant myometrium
Authors: Schofield Brenda M.
Published: December 2014

1. Experiments were carried out on isolated strips of uterine muscle to determine the extensibility of the myometrium at different stages of pregnancy and post‐partum.

2. Results showed that the extensibility increases significantly after mating and remains fairly constant from days 7 to 27 of pregnancy. Thereafter there is a further significant increase in extensibility which lasts until delivery. During the first 24 hr post‐partum the extensibility decreases rapidly.

3. In unilateral pregnancy there appeared to be no difference in extensibility between the two horns.

4. The extensibility found in the myometrium of oestrous females could be reproduced in ovariectomized rabbits treated with oestrogen. When progesterone was injected in addition to oestrogen, the extensibility was significantly increased but not to the same extent as in mid‐pregnancy.

5. The extra increase in extensibility found at the end of pregnancy was not reproduced in ovariectomized rabbits after long‐term injections of oestrogen and progesterone followed by additional relaxin or diminished progesterone therapy or relaxin and diminished progesterone therapy.

6. It is suggested that the changes in extensibility of the myometrium associated with pregnancy are hormone‐based, that the main hormone is progesterone and that perhaps equivalent changes can only be reproduced in the ovariectomized rabbit by critical doses of oestrogen and progesterone.
Potentiometric measurement of membrane action potentials in frog muscle fibres
Authors: Frankenhaeuser B. , Lindley B. D. , Smith R. S.
Published: December 2014

1. A potentiometric method for recording membrane action potentials from small segments of isolated skeletal muscle fibres has been described.

2. The value of the method in muscle physiology has been appraised by recording from fast and slow skeletal muscle fibres of the frog under a variety of conditions.

3. Artifacts associated with this method have been described and their sources investigated.
Observations on the histamine forming capacity of mouse tissues and of its potentiation after adrenaline
Authors: Pearlman D. S. , Waton N. G.
Published: December 2014

1. The histamine forming capacity (h.f.c.) was determined in minced or homogenized skin, lung, skeletal muscle or stomach of mice weighing 18‐20 g using radioactive 14C histidine as substrate and determining the radioactive 14C histamine formed by conversion to its dibenzenesulphonyl derivative.

2. The optimal pH for the formation of histamine was 7·0‐7·5 for lung and skin, 6·5‐7·5 for skeletal muscle. For stomach a more acid pH was optimal and depended on substrate concentration.

3. The formation of histamine increased with an increase of the substrate histidine.

4. The formation of histamine was not affected by the presence in the incubation mixture of chlorpromazine, pyridoxal‐5‐phosphate, non‐radioactive histamine or benzene. The addition of aminoguanidine slightly increased the formation in skin, lung and skeletal muscle but not in stomach. The formation was unchanged when incubation was in an atmosphere of nitrogen instead of air.

5. H.f.c. for stomach of normally fed mice varied 170‐fold. For stomachs of mice unfed for 16 hr, h.f.c. was much lower and it varied only sevenfold.

6. Injection of adrenaline into mice increased h.f.c. of the skin, lung and skeletal muscle. With skin tissue a linear log. dose log. response relation was demonstrated. The injection of adrenaline caused however either no or only a slight increase in the h.f.c. of stomach tissue.

7. The effect of adrenaline on h.f.c. in skin, lung and skeletal muscle was not abolished by α‐ or β‐adrenergic blocking agents either injected separately or together before the injection of adrenaline.
Micro‐electrophoretic studies of neurones in the cat hippocampus
Authors: Biscoe T. J. , Straughan D. W.
Published: December 2014

1. Drugs have been applied micro‐electrophoretically to units in the hippocampal cortex of the anaesthetized cat, and their effects on cell firing were recorded simultaneously.

2.
L‐Glutamate rapidly and powerfully excited hippocampal units, an effect which was quickly reversed on stopping the expelling current. The local application of
L‐glutamate also excited a fast seizure discharge at 15‐50/sec. Both these effects of
L‐glutamate were strongly depressed by fimbrial stimulation.

3. γ‐Aminobutyric acid had a strong depressant action on all the units on which it was tested; the time course of this effect was rapid.

4. ACh excited half the units to which it was applied. Characteristically this excitation developed slowly over many seconds and persisted after stopping the expelling current. Most cholinoceptive units were found to be concentrated in the superficial layer of the cortex corresponding to the hippocampal pyramidal cells and their main dendritic processes.

5. Atropine selectively blocked the excitation of cholinoceptive units by ACh, but not the excitation by
L‐glutamate. No cholinoceptive units were blocked by dihydro‐β‐erythroidine, though several were selectively blocked by dimethyl (+)‐tubocurarine.

6. The most usual effect seen with 5‐HT was depression, though several units were found to be excited. Some of the units tested with 3‐hydroxytyramine (dopamine) or noradrenaline were found to be depressed.
The separation of cone mechanisms in dark adaptation
Authors: Du Croz J. J. , Rushton W. A. H.
Published: December 2014

1. In dark adaptation the threshold is raised as though the bleaching of visual pigment generated an equivalent background. Now Stiles has shown that real coloured backgrounds act selectively upon the various colour mechanisms, so we ask: ‘Do equivalent backgrounds from coloured bleachings also act selectively?’

2. When dark adaptation was plotted using a blue test flash (Fig. 1b) following bleaching by orange light a kinked curve was obtained. The upper branch was shown to have the same dark adapted threshold as Stiles blue (π1) mechanism and the lower branch as his green (π4) mechanism. The π4 dark adaptation curve alone (unkinked) was obtained using a white instead of an orange bleach.

3. Dark adaptation curves were obtained in which the test flash was presented upon various steady backgrounds. In conditions where only π4 was involved (Fig. 3) the experimental results fitted the curves calculated on the assumption that the equivalent background of bleaching simply adds to the real background in raising the threshold—a condition already established for rods.

4. In conditions where π4 and π1 were both present (blue test, yellow‐green background and white bleach) kinked dark adaptation curves were obtained (Fig. 2) where the upper branch (π4) coincided with those of Fig. 3 and the lower were due to π1.

5. The blue mechanism recovers in dark adaptation at about the same rate as red and green, or slightly slower.

6. Dark adaptation curves with red (π5) and green (π4) limbs can be obtained after a deep red bleach (Fig. 4) using a red test flash and a green background. The red and the green limbs were also plotted alone in their entirety by slightly changing the conditions.

7. We are led to the idea of three colour mechanisms that adapt as independently one of another after bleaching as they do with backgrounds.

8. Though this simple independence accounts for the wide and conspicuous range of adaptive phenomena, we have encountered some special conditions (not here described) that seem to imply a measure of interaction between the different colour mechanisms.
The continuous estimation of angiotensin formed in the circulation of the dog
Authors: Regoli D. , Vane J. R.
Published: December 2014

1. The use of the rat colon as a blood‐bathed organ is described for detecting changes in angiotensin concentration in the circulating blood of dogs.

2. Partial occlusion of the aorta by a balloon inflated above the renal arteries leads to a contraction of the blood‐bathed rat colon.

3. From the experimental evidence, it is concluded that this contraction is due to an increased concentration of circulating angiotensin, brought about by the liberation of renin from the kidneys.

4. The characteristics of renin release have been studied. It occurs within seconds of reducing the blood pressure to the kidneys and is proportional to the degree of reduction of blood pressure.

5. With a prolonged reduction of renal blood pressure the concentration of angiotensin increases over the first 10‐12 min and then reaches a stable level.

6. After a small haemorrhage angiotensin often appears in the circulation without a concomitant release of catechol amines.

7. Greater haemorrhages induce the secretion of catechol amines as well as of renin. The catechol amine secretion is inhibited by ganglion block, but the renin secretion is not.

8. It is concluded that the secretion of renin by the kidneys in response to a fall of renal blood pressure is a physiological response, probably of importance in homoeostasis.
Mineral composition and rates of flow of effluent from the distal ileum of liquid‐fed calves
Authors: Smith R. H.
Published: December 2014

1. Liquid‐fed calves (aged 1½‐4 months) examined more than five weeks after inserting a re‐entrant fistula into the distal ileum, of normal sodium and potassium status and without abnormal gut infection, showed mean emergence rates from the ileum for sodium, potassium and water of 2·3 m‐mole/hr, 0·38 m‐mole/hr and 21 g/hr respectively after 16 hr fasting.

2. Sodium and potassium emergence rates changed little when the residues from a milk or glucose‐solution feed arrived at the distal ileum. When magnesium chloride was added to a glucose‐solution feed an increase sometimes occurred but only in association with decreased small‐intestine transit time.

3. Widely differing sodium and potassium intakes had no appreciable direct effect on their emergence rates. Continued feeding of a diet deficient in either ion, however, altered the calf's metabolism and led to appropriate changes in the sodium/potassium ratio of ileal effluent. These changes were not simulated by injecting adrenal cortex hormones. The ratio also decreased when ileal effluent was allowed to discharge for several weeks without being returned to the colon. It was abnormally high in samples obtained less than five weeks after inserting cannulae.

4. An increase in sodium and potassium emergence rates, which often occurred spontaneously at about 3 months of age, appeared to be due to infection and was usually prevented by giving aureomycin orally.

5. Water emergence rate reflected changes in the emergence rates of osmotically effective constituents and isotonicity was maintained. In effluent after fasting, the cations involved were mainly sodium and potassium, and [Na] + [K] was approximately constant (mean 132 m‐mole/l.). In effluent following feeds of milk or glucose, magnesium chloride solution, [Na] + [K] was depressed and [Na] + [K] + 1·5 [Mg] was approximately constant (mean 139 m‐mole/l.). Magnesium behaved as it were mainly ionic. Calcium had no apparent osmotic effect and was probably insoluble.

6. Bicarbonate was the major anion in ileal effluent after a milk feed with smaller amounts of chloride, phosphate and some other unknown anion(s).
The surface area of the intestinal mucosa in the lactating rat
Authors: Boyne R. , Fell B. F. , Robb I.
Published: December 2014

1. The mucosal and serosal surface dimensions of the rat duodenum, jejunum and ileum were obtained by measurement of photographs of histological sections. The surface areas were calculated from these data.

2. Measurements were made on the intestines from virgin rats and from rats on the sixteenth day of lactation. The mucosal area/unit length of serosa was appreciably increased in all parts of the intestine during lactation. The mucosal area/serosal area (MA/SA) ratio was also markedly increased, but to a lesser extent distally, where an important component of the intestinal hypertrophy was dilatation of the intestine.
Pharmacological properties of cholinoceptive neurones in the medulla and pons of the cat
Authors: Bradley P. B. , Dhawan B. N. , Wolstencroft J. H.
Published: December 2014

1. Iontophoretic application of acetylcholine to neurones in the medulla and pons of the unanaesthetized decerebrate cat excited 35·5% and inhibited 22%. This was not a representative sample of lower brain stem neurones, since most penetrations were made medially. Some cholinoceptive neurones were in the medial reticular formation.

2. The time course of the response to different doses has been described.

3. Nicotine and nicotinic agents 1,1‐dimethyl‐4‐phenylpiperazinium iodide (DMPP) and choline phenyl ether (TM1) excited neurones excited by acetylcholine but, with one exception, did not inhibit neurones inhibited by acetylcholine.

4. Muscarinic agents mimicked both the excitatory and inhibitory responses to acetylcholine. (±)‐muscarine and bethanechol (β‐methylcholine carbamate) had a prolonged and powerful inhibitory action.

5. Oxotremorine [1‐(2‐oxopyrrolidino)‐4‐pyrrolidino‐butyne‐2] had a long‐lasting excitatory action on neurones excited by acetylcholine.

6. Eserine and neostigmine potentiated the action of acetylcholine but in addition they had a strong excitatory effect on many brain stem neurones, independently of the action of acetylcholine.

7. Excitatory and inhibitory responses to acetylcholine could be antagonized by gallamine, hexamethonium and atropine. Dihydro‐β‐erythroidine (DHβE) antagonized only excitatory responses. (+)‐Tubocurarine was a weak antagonist.

8. It is concluded that the excitatory responses have both nicotinic and muscarinic properties but the inhibitory responses are only muscarinic. Since the pharmacology of these two types of response is different, it is concluded that the inhibitory action is not due to an indirect effect from excitation of a neighbouring inhibitory neurone.
Exchange of structurally bound phosphate in muscular activity
Authors: Cheesman D. F. , Hilton Elizabeth
Published: December 2014

1. When rectus abdominis and sartorius muscles of the frog are incubated with 32P‐orthophosphate and subsequently minced, extracted with carbonate‐bicarbonate buffer and water, and converted to acetone powders, considerable radioactivity remains associated with the solid material.

2. Muscles labelled with 32P and subjected to contracture at room temperature with KCl or ACh yield acetone powders which, in comparison with those of uncontracted control muscles, show a significantly decreased radioactivity. There is no evidence for a corresponding decrease in the total phosphate content.

3. Relaxation of a contracted muscle restores the 32P content of its acetone powder at least to the level for a resting, control muscle.

4. When two recti are incubated with 5 × 10−4
M‐DNP after labelling with 32P, subsequent depolarization of one muscle with KCl usually results in an increase in the activity of the bound phosphate fraction, with little or no contracture in addition to that already caused by the DNP.

5. It is concluded that the bound phosphate fraction undergoes exchange during activation, shortening and relaxation of muscle, and may represent a source of energy for muscular activity.
The activity of post‐ganglionic sympathetic nerves to the uterus of the rabbit
Authors: Bower E. A.
Published: December 2014

1. The spontaneous activity recorded from the central ends of the uterine nerves of the rabbit is described. The discharges resembled those reported from other post‐ganglionic sympathetic nerves; the individual units appeared to discharge remarkably regularly at frequencies between 4/sec and 1 per 3 sec.

2. The resting discharge in late pregnant rabbits was usually more intense than in non‐pregnant rabbits; otherwise no clear relation existed between variations in the discharges and in the sexual state.

3. The discharge was reduced by stimulation of the central end of the depressor nerve and increased by asphyxia.

4. Stimulation of either the preganglionic or the post‐ganglionic nerve by a single shock evoked a long after‐discharge in the post‐ganglionic nerve. It is shown that this after‐discharge is a property of some of the post‐ganglionic neurones supplying the rabbit's uterus which does not depend on the integrity of the preganglionic nerves or of the spinal cord, or on transmission through the ganglia, and that it is not a general property of the sympathetic post‐ganglionic neurones of the rabbit.

5. Repetitive stimulation of the preganglionic nerve at low frequencies augmented the after‐discharge in some cases and depressed it in others; stimulation at high frequencies invariably depressed the after‐discharge. Repetitive stimulation of the post‐ganglionic nerve at low or high frequencies depressed the after‐discharge.

6. If the normal preganglionic activity was interrupted abruptly by an anode block, the post‐ganglionic discharge also stopped abruptly.

7. A ganglion‐stimulating action of hexamethonium is described.

8. Adrenaline inhibited the post‐ganglionic neurones with no sign of excitation. This effect was antagonized by Rogitine without affecting the resting discharge, the action of the depressor nerve or the after‐discharge in any way.
The effect of (+)‐tubocurarine chloride and of acute hypertension on electrocortical activity of the cat
Authors: Amassian V. E. , Weiner H.
Published: December 2014

1. The effects of
I.V. injection of tubocurarine (3 mg/kg) and of acute hypotension upon electrocortical activity of cats under sodium pentobarbitone were analysed. Technical artifacts associated with changes in brain volume were minimized.

2. Initially, the superficial cortical response was reduced by tubocurarine either insignificantly or by 34% or less. Cats bled before injection of tubocurarine showed initially a similar reduction but, occasionally, a severe delayed reduction was found. Any fall in the superficial cortical response started during the secondary rise in
B.P., many seconds after the
B.P. had reached its lowest initial level. By contrast, spontaneous electrocortical activity was reduced approximately when the peak initial fall of
B.P. occurred and it started to recover during the secondary rise in
B.P. Reduction of the superficial cortical response could still be elicited after spindling had been suppressed by deep barbiturate anaesthesia. The initial thalamocortical afferent component in somatosensory area I, which was evoked by dorsal column stimulation, was less reduced by injection of tubocurarine than were the post‐synaptic positive—negative components.

3. The depressant effects of injected tubocurarine upon the superficial cortical response and spindle activity were approximated by rapid arterial bleeding.

4. The superficial cortical response was reduced following virtual arrest of the cerebral circulation by acute exsanguination or by acute oil embolization. Such reduction most likely does not depend on systemic transport of inhibitory substances to the brain.

5. After injection of tubocurarine the rate of outflow from the superior sagittal sinus was variably reduced during the initial fall in
B.P., and often showed a variable, secondary increase. A net deficit in cerebral blood flow was usually present during the period of 80 sec after injection.

6. The variability in the effects of injected tubocurarine upon electrocortical activity is attributed to the variability of the net deficit in cerebral blood flow.
Pharmacology of cortical inhibition
Authors: Krnjević K. , Randić Mirjana , Straughan D. W.
Published: December 2014

1. We have studied the effects of various pharmacological agents on the cortical inhibitory process described in the previous two papers (Krnjević, Randić & Straughan, 1966a, b); the drugs were mostly administered directly by iontophoresis from micropipettes and by systemic injection (
I.V.).

2. Strychnine given by iontophoresis or by the application of a strong solution to the cortical surface potentiated excitatory effects, but very large iontophoretic doses also depressed neuronal firing. Subconvulsive and even convulsive systemic doses had little or no effect at the cortical level. There was no evidence, with any method of application, that strychnine directly interferes with the inhibitory process.

3. Tetanus toxin, obtained from two different sources and injected into the cortex 12‐48 hr previously, also failed to block cortical inhibition selectively. As with strychnine, there was some evidence of increased responses to excitatory inputs.

4. Other convulsant drugs which failed to block cortical inhibition included picrotoxin, pentamethylene tetrazole, thiosemicarbazide, longchain ω‐amino acids and morphine.

5. The inhibition was not obviously affected by cholinomimetic agents or by antagonists of ACh.

6. α‐ and β‐antagonists of adrenergic transmission were also ineffective.

7. Cortical inhibition was fully developed in the presence of several general anaesthetics, including ether, Dial, pentobarbitone, Mg and chloralose. A temporary reduction in inhibition which is sometimes observed after systemic doses of pentobarbitone, is probably secondary to a fall in blood pressure.

8. Several central excitants such as amphetamine, caffeine and lobeline also failed to show any specific antagonistic action on cortical inhibition.

9. In view of the possibility that GABA is the chemical agent mediating cortical inhibition, an attempt was made to find a selective antagonist of its depressant action on cortical neurones. None of the agents listed above, nor any other of the substances tested, were able to block this action.

10. It was concluded that cortical inhibition differs from spinal inhibition in its pharmacological properties; and that our observations are consistent with the possibility that GABA is the cortical inhibitory transmitter.
Composition of the secretion from the eccrine sweat glands of the cat's foot pad
Authors: Foster K. G.
Published: December 2014

1. The sweat composition from the cat's foot pad was examined at various rates of secretion. Sodium pentobarbitone or chloralose anaesthesia were used.

2. Cat's pad sweat contains lactate, glucose is almost absent, and the sodium and chloride concentrations increased with increasing sweat rate. In these respects the secretion resembles human eccrine sweat.

3. The sodium, chloride, and potassium concentrations are much higher than in human sweat; also the potassium level decreased with increasing rate. Consequently, whereas human sweat is hypotonic with respect to the plasma, cat's pad sweat is slightly hypertonic with respect to the plasma even at low rates of secretion. In contrast to human sweat glands, which produce a slightly acidic secretion containing ammonia, cat's pad sweat glands produce an alkaline secretion containing bicarbonate. Also in contrast to human sweat, lactate levels decreased with increasing sweat rate.
The action of ouabain on the smooth muscle cells of the guinea‐pig's taenia coli
Authors: Casteels R.
Published: December 2014

1. The action of 10−6 g/ml. of ouabain on the membrane potential, membrane activity, tension development and the ion content of the smooth muscle of the guinea‐pig's taenia coli has been investigated.

2. This ouabain concentration produced a depolarization of the membrane, accompanied by an initial increase of the spike frequency and later a depolarization block. Removal of the ouabain produced a sudden and pronounced hyperpolarization leading to a block of spike discharge.

3. Reduction of the external sodium concentration, or an increase of the external calcium concentration, or exposure to 10−7 g/ml. adrenaline repolarized the cell membrane in the presence of ouabain.

4. Ouabain decreased the tension development of the taenia coli.

5. Ouabain decreased the intracellular potassium and chloride and increased the intracellular sodium concentration. However, the corresponding changes of the equilibrium potentials were not sufficient to explain the changes of the membrane potential.

6. A possible explanation for the action of ouabain is presented suggesting that the drug may decrease the calcium binding properties of the cell membrane.
The variation in isometric tension with sarcomere length in vertebrate muscle fibres
Authors: Gordon A. M. , Huxley A. F. , Julian F. J.
Published: December 2014

1. The variation of isometric tetanus tension with sarcomere length in single fibres from frog striated muscle has been re‐investigated with special precautions to ensure uniformity of sarcomere length within the part of the fibre being studied.

2. In most respects the results of Ramsey & Street (1940) were confirmed, but (a) the peak of the curve was found to consist of a plateau between sarcomere lengths of 2·05 and 2·2 μ, (b) the decline of tension above this plateau is steeper than found by Ramsey & Street, and (c) the decline of tension below the plateau becomes suddenly steeper at a sarcomere length of about 1·67 μ.

3. Many features of this length—tension relation are simply explained on the sliding‐filament theory.

4. It is concluded that, in the plateau and at greater lengths, the tension on each thin filament is made up of equal contributions from each bridge which it overlaps on adjacent thick filaments.

5. Internal resistance to shortening is negligible in this range but becomes progressively more important with shortening below the plateau.
The central release of acetylcholine during stimulation of the visual pathway
Authors: Collier B. , Mitchell J. F.
Published: December 2014

1. In rabbits anaesthetized with Dial ACh has been collected from the surface of the cerebral cortex during stimulation of the visual pathways.

2. The spontaneous release of ACh from the visual and non‐visual areas of the cortex was found to be similar.

3. Stimulation of the retinae by diffuse light produced a large increase in ACh release from the primary visual receiving areas (4·3 times the spontaneous release) and a smaller increase (1·9 times the spontaneous release) from other parts of the cortex.

4. Direct unilateral electrical stimulation of the lateral geniculate body evoked a large increase in ACh release (3·4 times the spontaneous release) from the ipsilateral visual cortex and a smaller increase (1·7 times the spontaneous release) from the contralateral visual area and other regions of the cerebral cortex. The evoked increase from the contralateral cortex was not mediated by transcallosal pathways.

5. The increase in ACh release evoked from the visual cortex by stimulation of the ipsilateral lateral geniculate body was dependent on the frequency of stimulation. The evoked release was smallest at low stimulus frequencies and increased to a maximum at 20 stimuli/sec.

The evoked ACh release from other areas of the cortex was independent of the frequency at which the lateral geniculate body was stimulated.

6. The possible central nervous pathways associated with the spontaneous release of ACh and the release evoked by stimulation of the eyes by light and by direct stimulation of the lateral geniculate body are discussed.

7. It is concluded that two ascending cholinergic systems may be involved; the non‐specific reticulo‐cortical pathways responsible for the e.e.g arousal response, and the more specific thalamo‐cortical pathways associated with augmenting and repetitive after‐discharge responses. The first system is thought to be concerned with the small but widespread increase in ACh release from the cortex following stimulation of the visual pathway while the second system could give rise to the larger increases evoked from the primary receiving areas of cortex. The spontaneous release of ACh from the surface of the brain may be the result of contributions from both systems.