bluuebunny/crossref_metadata_2025 huggingface dataset:
THE INFLUENCE OF CORAMINE ON CIRCULATORY CAROTID SINUS REFLEXES
Authors: Müller Reinhard
Published: December 2014

1. The blood‐pressure‐decreasing carotid sinus pressure reflex is weakened in urethanised rabbits under the influence of Coramine. An essential increase in the so‐called residual blood‐pressure is to be regarded as a sign of the increase in tone of the peripheral circulation.

2. Both in the urethanised rabbit and in the urethanised cat the blood‐pressure‐raising carotid occlusion reflex shows a larger rise in blood‐pressure under the effect of Coramine than before its administration. This is also to be regarded as a sign of the peripheral vascular tonic effect. This result is obtained both with intact and severed aortic nerves.

3. Coramine produces in animals whose aortic nerve has been severed a larger rise in blood‐pressure than in the intact animal.

4. The effect of Coramine on the carotid sinus itself can be excluded for the results reported. Coramine is capable only in high concentration of influencing the presso‐receptors locally.
CONSTRICTION OF RENAL VESSELS IN THE FROG (RANA ESCULENTA) AND ITS EFFECTS ON THE SYSTEMIC BLOOD‐PRESSURE
Authors: Vogt Marthe
Published: December 2014

A method is described which permits daily readings of the frog's systemic blood‐pressure to be made in light ancesthesia.

Constriction of one or of both renal portal veins was performed in frogs (Rana esculenta) in which the abdominal vein had been ligated. The constriction had no effect on the systemic blood‐pressure.

Obstruction of the aorta just above the origin of the renal arteries in Rana esculenta did not alter the frogs' blood‐pressure, neither did this operation do so in combination with constriction of the renal portal veins.

Some of these experiments were done in the Molteno Institute for Parasitology. It is a pleasure to thank Professor Keilin for the facilities he gave me.
THE HUMORAL STIMULATION OF GASTRIC SECRETION
Authors: Gregory R. A. , Ivy A. C.
Published: December 2014

Evidence has been presented that there are at least two components in the humoral stimulation of a transplant of the gastric fundus by a meal—one liberated from the gastric mucosa by the presence of secretagogues, and the other from the mucosa of the small intestine by the presence therein of food or secretagogues. The results of the experiments in which the mucosa of one or other of the pouches of the two‐pouch preparation was aniæsthetised by procaine have provided indirect evidence that the gastric component of the humoral stimulation is hormonal in nature. No such experiments have been performed in connection with the intestinal phase.

Experiments on one dog only, in which the pyloric region of the gastric mucosa was removed from the main gastric pouch of the two pouch preparation, lead to the conclusion, subject to confirmation on other animals, that the presence in the main gastric pouch of this region of the stomach is not essential for the demonstration of the humoral response of the transplant to perfusion of the main gastric pouch with a solution of secretagogues.
CLEARANCE AND CUMULATION OF ADRENALINE
Authors: Ansari M. Y.
Published: December 2014

1. Continuous infusion of adrenaline in the cat produces over a wide range of dosage a plateau response in both the nictitating membrane and blood‐pressure.

2. This indicates that enzyme saturation does not occur even with large doses [correction of conclusion of Clark and Raventos, 1939 b].

3. The rate of clearance of adrenaline decreases as the concentration is increased. The relation found is that the fraction cleared per minute varies inversely as 3(conc.).

4. The relation between dosage and response and the relation between rate of continuous infusion and height of plateau response indicate similar rates of clearance.

5. The times of half‐clearance found varied from 0·8 to 5 minutes.

I gratefully acknowledge my indebtedness to the late Professor A. J. Clark for his help and valuable suggestions throughout the course of this work. I also wish to thank Dr. J. M. Robson for going through the written matter, and Mr. N. E. Condon for the technical help.

The expenses of this research were defrayed by a grant from the Moray Fund of Edinburgh University.
SOME EFFECTS OF THYROID AND GONADOTROPHIC PREPARATIONS IN THE FOWL
Authors: Greenwood Alan W. , Blyth J. S. S.
Published: December 2014

1. Extracts of Horse, Sheep, and Pig Pituitary, Pregnant Mare's Serum and Chorionic Gonadotrophin were administered to hens prior to and during the moulting period. Dried thyroid powder was fed during the non‐productive phase.

2. Injections of P.M.S. to laying hens resulted in cessation of egg production within 5 days, and the onset of a heavy moult. The combs increased in size during treatment. Apart from a slight increase in comb size in the group receiving Pig Pituitary extract, no reaction to the other gonadotrophins could be detected at the dosage‐level employed.

3. In non‐laying hens P.M.S. had little effect; Pig Pituitary appeared to cause a temporary reactivation of the reproductive organs, but in no case did ovulation occur. The other gonadotrophins were again inactive.

4. Consistent symptoms of ovarian stimulation resulted from the administration of thyroid, and a number of birds resumed egg production following this treatment. Variations in the degree of response obtained appeared to be related to the media in which this hormone powder was fed.
SOME MORPHOLOGICAL FEATURES OF THE SPINAL CORD IN THE RABBIT, WITH SPECIAL REFERENCE TO THE PRODUCTION OF ARTIFACTS
Authors: Trowell O. A.
Published: December 2014

1. The occurrence of artifacts in the spinal cord of the rabbit as exposed by the usual post‐mortem methods is described. Such artifacts were not met with in the spinal cords of rat, guinea‐pig, cat, dog, goat, or monkey, exposed in the same way. The artifacts occurred principally in the upper thoracic and upper lumbar regions, and were of two varieties—

(A) Large discrete swellings on the posterior surface of the cord associated with large underlying cavities. This artifact was due to spontaneous herniation of cord substance through small accidental tears in the dura mater. The spontaneous herniation was shown to be the combined result of three morphological features of the exposed cord and meninges in the rabbit, namely

(i) The posterior part of the dura is tightly stretched (mainly longitudinally) and exerts a direct pressure on the posterior surface of the cord, the subarachnoid space in this region being obliterated.

(ii) In the upper part of the spinal cord this dural pressure is accentuated by the usual flexed attitude of the upper part of the vertebral column at post‐mortem examination.

(iii) In those two regions of the cord where the artifacts most commonly occur the cord substance is softer in consistence than elsewhere. Serial sections of the cord revealed quantitative differences in the proportions of the white matter, myelin, neuroglia, and pia mater at different levels which might account for the softer consistence in these two regions. The rabbit's cord as a whole appeared to be softer than that of other species.

(B) Multiple small radial cavities or cracks in the cord substance. These were shown to result from the exposure of the cord and to be related to the soft consistence of the cord, but their precise cause was not determined.

2. Methods are described for histological fixation of the cord without opening the vertebral canal, by which means the above artifacts can be eliminated.

3. Mention is made of the varying size of the central canal at different levels in the rabbit's cord.

4. The frequent occurrence of a few small spherical empty holes in the white matter of the rabbit's brain and spinal cord is reported. Their nature is discussed, but no conclusion is reached as to their significance.

5. The possible occurrence of similar artifacts in other species is discussed and the importance of eliminating such artifacts in all pathological investigations of acute traumatic lesions of the spinal cord is pointed out.

I have to thank the Carnegie Trust for the Universities of Scotland for a grant towards the cost of the illustrations of this paper.
THE PROTECTIVE ACTION OF THE SERUM AGAINST NATURAL HÆMOLYSIN
Authors: Lee Jui‐Shuan , Tsai Chiao
Published: December 2014

1. Rabbit serum exhibits an inhibitory behaviour towards the hæmolytic action of dog serum on rabbit cells. The protective power of rabbit serum increases after the destruction of its complement by heating.

2. Rabbit serum may hæmolyse its own cells after the latter have b een sensitized by heated dog serum.

3. Rabbit serum, either fresh or heated, is able to reduce or abolish the sensitizing action of dog serum, presumably due to the existence of a thermostable anti‐sensitizing factor in the rabbit serum.

4. It is therefore concluded that the protective action afforded by rabbit serum against the hæmolytic action of dog serum on rabbit cells may be attributed to two factors: the anti‐complementary factor, which, according to our previous investigation, is largely due to cholesterol and allied substances, and an anti‐sensitizing factor, which inhibits the sensitization of rabbit cells by dog serum, and thus prevents the rabbit serum from becoming hæmolytic to its own cells. The exact nature of the anti‐sensitizing factor is unknown.
A STUDY OF ARSINE POISONING
Authors: Levvy G. A.
Published: December 2014

1. In experiments in which the arsenic in the carcases of miceexposed to arsine was determined, the percentage of the gas inhaled which was absorbed appeared to be approximately the same (64 percent.) over a hundredfold range in gas concentration.

2. The median lethal dose of arsine for mice, in terms of the gas absorbed, increased with decreasing concentration inhaled, suggesting that arsine is rapidly detoxicated in the body. At the highest concentration studied, the median lethal dose was 0–67 mg. AsH3/kg.

3. The ventilation rate in mice appeared to be different in exposures to arsine of different durations. From this, peculiarities in the median lethal exposure curve may be explained.

4. The arsenic in tissues from rabbits killed immediately after short exposures to arsine was determined. Although the tissues were freed from blood before hæmolysis commenced, some organs, in particular the liver, contained considerable amounts of arsenic. It is suggested that this arsenic reached the tissues as arsine, unchanged by reaction with the erythrocytes.

5. Intraperitoneal injection of 17 mg./kg. of ethane‐1:2‐dithiol doubled the duration of the exposure to 0·50 mg. AsH3 per litre required for 50 per cent. mortality in mice. The median lethal dose of the dithiol alone was about 55 mg./kg. It was effective several hours after exposure to arsine.

6. Factors in gas chamber design of importance in carrying out toxicity determinations were studied, and a new type of chamber which permitted accurately controlled exposures of short duration was constructed.

7. It is concluded that the high toxicity of arsine in the higher concentration range may in part be due to the action on vital organs of unchanged gas, reaching them in physical solution in the blood plasma.

The author wishes to express his thanks to the late Professor A. J. Clark and to Professor G. F. Marrian for encouragement in carrying out this work, to Professor J. H. Gaddum for suggestions regarding the interpretation of certain of the results, to the late George Abbot and to Charles Bell for technical assistance, and to N. E. Condon for the construction of gas chambers. Permission from the Director General of Scientific Research (Defence), Ministry of Supply, to publish these results is gratefully acknowledged.
SPONTANEOUS INTRACORPUSCULAR INACTIVATION AND REACTIVATION OF HÆMOGLOBIN
Authors: Fegler G.
Published: December 2014

1. The intracorpuscular inactivation of hæmoglobin (presumably methæmoglobin formation) occurred in the suspensions of the horse r.b.c. (pH 7·4–7·3) when these were exposed to gas mixtures of air + CO2, oxygen + CO2, and N2 + CO2 for different periods of time (2–15 minutes). Also inactivation occurred in the r.b.c. suspensions in buffer solutions of pH 7·2–7·1 when exposed to air or nitrogen.

2. The reactivation (reduction of methæmoglobin) succeeds the inactivation if the exposure to N2 + CO2 or N2 lasts longer than several minutes. The phenomenon may be expressed by a U‐shaped curve showing the phases of inactivation, equilibrium, and reactivation.

3. The extent of reactivation depends on the degree of deoxygenation, while the intracellular decrease in pH is a main factor of the inactivation.

4. Temperatures in the region of 38°C. favour the inactivation as well as the reactivation.

5. Attempts were made to imitate in vitro the changing conditions to which the blood is exposed in the vascular bed by subjecting the suspensions to suitable changes of gas phase.

6. The results obtained were discussed in relation to in vivo conditions.
THE ACTION OF CARBON DIOXIDE ON ISOLATED PERFUSED DOG LUNGS
Authors: Duke Helen N.
Published: December 2014

1. Isolated dog lungs under negative or positive pressure ventilation have been perfused with blood through the pulmonary artery at constant volume inflow. The response of the pulmonary vessels to various concentrations of CO2 in the ventilating gas has been observed.

2. The capacity of the pulmonary blood‐vessels is markedly diminished by increasing the concentration of CO2 inhaled from the small percentage present in atmospheric air to 5 or 10 per cent., and the pulmonary arterial pressure frequently shows a 5 to 20 per cent. increase.

3. The lung blood‐volume shows an inverse relationship to the CO2 content of the arterial blood.

4. The effect of adrenaline on the pulmonary vessels is not altered during ventilation of the lungs with 5 per cent. CO2 in air.

5. The response to CO2 is not inhibited by ergotoxine or by atropine.

6. The possible site of action of CO2 is discussed.
THE PROTEIN‐SPARING EFFECT OF CARBOHYDRATE IN NORMAL AND BURNED RATS
Authors: Lathe G. H. , Peters R. A.
Published: December 2014

1. Studies of the nitrogen excretion of tube‐fed rats have been made under different dietary conditions, and following a standard burn.

2. Substitution of carbohydrate for the fat of a 25 per cent. fat diet, without changing the caloric intake, results in a reduced nitrogen excretion.

3. In unburned animals a sucrose supplement given with the meals substantially reduces the nitrogen excretion on a non‐fat diet during a 3‐day period, following which it rises toward its previous level.

4. The data obtained upon the effect of sucrose supplements after burning, when examined statistically, did not permit of a decision either way.

5. The significance of these findings is discussed.
THE RENAL CLEARANCE OF CHORIONIC GONADOTROPHIN IN NORMAL AND PATHOLOGICAL PREGNANCY
Authors: Loraine J. A.
Published: December 2014

1. Estimates of the renal clearance of C. G. have been made in 12 normally pregnant women, 7 pregnant diabetics, 29 cases of pre‐eclamptic toxæmia, 9 cases of essential hypertension in pregnancy, and 5 cases of essential hypertension with superimposed toxæmia. In all estimations the prostatic weight method of assay was used.

2. In all types of cases the mean clearance of C. G. was found to be less than 1·00 ml./min. Such a low figure is typical of protein clearance.

3. In normal and diabetic pregnancy, constant figures for clearance were obtained in the three trimesters of pregnancy.

4. The mean clearances in severe cases of pre‐eclamptic toxæmia and in pregnant diabetics were found to be significantly lower than those in normal pregnancy.

5. In all groups of cases the concentration in the urine was on the average, very nearly exactly equal to the concentration in the serum.
THE INFLUENCE OF THYROIDECTOMY ON POST‐BURN N LOSS IN RATS
Authors: Gribble M. De G. , Peters R. A. , Wakelin R. W.
Published: December 2014

The loss of N following thermal burns in rats is largely abolished after thyroidectomy.
THE RELATION OF PULMONARY ARTERIAL PRESSURE VARIATIONS TO THE ACTIVITY OF AFFERENT PULMONARY VASCULAR FIBRES
Authors: Pearce J. W. , Whitteridge D.
Published: December 2014

1. A method of recording pulmonary arterial pressure in animals with closed chests and spontaneous respiration is described.

2. The activity of pulmonary vascular fibres is shown to bear a direct relationship to the pulmonary arterial pulse pressure. Some evidence is put forward for the belief that the receptors of these fibres are situated on the arterial side of the pulmonary vascular bed.
COMPARISON OF SOME OF THE ACTIONS OF ADRENALINE AND NORADRENALINE ON THE KIDNEY
Authors: Pickford M. , Watt J. A.
Published: December 2014

1. Observations were made on conscious dogs of the effect on water excretion during diuresis of both single injections and infusions of adrenaline and noradrenaline. The renal clearances of creatinine and diodone were also measured.

2. Adrenaline, before and after atropinization, decreased the rate of urine flow, the renal plasma flow and the glomerular filtration rate. Before atropine the heart was slowed, but after atropine it was accelerated.

3. Noradrenaline before atropine decreased the rate of urine flow, the renal plasma flow and the pulse rate, but increased the glomerular filtration rate. After atropine the urine flow and pulse rate decreased as before, but both renal plasma flow and glomerular filtration rate increased.

4. It is concluded that neither adrenaline nor noradrenaline has a direct action on kidney activity, but affects it by altering the conditions of the systemic circulation.
THE OXIDATION OF OXYHÆMOGLOBINS FROM DIFFERENT ANIMAL SPECIES
Authors: Eggleton Philip , Fegler George
Published: December 2014

1. Hæmoglobin solutions derived from horse, ox, and dog blood were treated with graded amounts of (a) ferricyanide and (b) iodine, and the resulting methæmoglobin formation measured spectrophoto‐metrically.

2. It was found that when oxyhæmoglobin solutions are partially oxidized with iodine at pH 5·8 a considerable proportion of iodine oxidizes some part of the molecule other than the hæm.

3. When the iodine added is enough to produce 50 per cent. oxidation of the hæm, the globin has reduced 2 equivalents (horse), 4·5 equivalents (ox), and 6·5 equivalents (dog) of iodine respectively.
THE EFFECT OF INSULIN ON THE SECRETION OF GASTRIC JUICE IN THE GOAT
Authors: Hill K. J.
Published: December 2014

1. In goats provided with innervated pouches of the abomasum, the intramuscular injection of insulin was followed by a depression of volume‐rate and of the free and total acidity of the secretion.

2. No relation was observed between the degree of hypoglycæmia and the depression of gastric secretion, or between the degree of hypoglycæmia produced by a given dose of insulin and the previous duration of fasting.
On the sodium and potassium currents of a human neuroblastoma cell line.
Authors: Ginsborg B L , Martin R J , Patmore L
Published: December 2014

1. The patch‐clamp method was applied to the study of ionic currents activated by depolarization of undifferentiated IMR‐32 human neuroblastoma cells. Whole‐cell sodium and potassium currents and single potassium ion channel currents from cell‐attached patches were investigated. 2. Cells had a mean resting potential of ‐38 mV and mean input resistance of 1.6 G omega. Single action potentials were evoked under current clamp during the injection of depolarizing currents. 3. A voltage‐dependent inward sodium current was observed which reversed at +44 mV. A Boltzmann fit to the activation curve gave a half‐maximal activation voltage of ‐41.6 mV and a 'slope' of 3.9 mV. The steady‐state inactivation curve had a half‐maximal inactivation voltage of ‐81 mV and a 'slope' of 9.7 mV. 4. The time‐dependent activation and inactivation of the current displayed classical Hodgkin‐Huxley kinetics. Values for the time constants tau m and tau h of 0.16 and 0.63 ms were calculated for a voltage jump from ‐80 to ‐10 mV; tau m and tau h decreased as the step potential was changed from ‐30 to +20 mV. 5. Outward currents were activated in bathing solutions substantially free of anions and could thus be attributed to potassium ions. The tail current reversed in direction on repolarization to ‐60 mV when the potassium concentration in the bathing solution was increased from 6 to 30 mM. When the bathing solution contained 145 mM‐potassium, and the patch pipette, 95 mM, a depolarization to ‐10 mV from a holding potential of ‐60 mV evoked an inward current. 6. Outward currents were examined by using voltage pulses which depolarized the cell to ‐20 mV, or more positive values, from a holding potential of ‐80 mV and by pulses which depolarized the cell to 0 mV, or to positive values, from a holding potential of ‐30 mV. A Boltzmann fit of typical activation data gave a half‐maximal activation voltage of 17 mV and a 'slope' of 14 mV. 7. The time course of the rising phase of the current was described by a function of the form A(1‐exp[‐(t‐delta t)/tau]), where delta t varied between 1 and 4 ms and tau varied between 4 and 27 ms, decreasing with increasing depolarization. There was no evidence for a fast transient component. 8. The amplitude of outward currents was reduced by extracellular calcium ions, cobalt ions, tetraethylammonium and 4‐aminopyridine.(ABSTRACT TRUNCATED AT 400 WORDS)
Electrophysiological properties of neurones in the region of the paraventricular nucleus in slices of rat hypothalamus.
Authors: Tasker J G , Dudek F E
Published: December 2014

1. Neurones in the region of the hypothalamic paraventricular nucleus (PVN) of the rat were studied with intracellular recording in the coronal slice preparation. Three types of hypothalamic neurones were distinguished according to their membrane properties and anatomical positions. Lucifer Yellow or ethidium bromide was injected intracellularly to determine the morphology of some recorded cells. 2. The most distinctive electrophysiological characteristic was the low‐threshold depolarizing potentials which were totally absent in type I neurones, present but variable in type II neurones and very conspicuous in type III neurones. Type II neurones generally showed relatively small low‐threshold depolarizations (26.5 +/‐ 2.2 mV) which generated at most one to two action potentials. Type III neurones, on the other hand, generated large low‐threshold potentials (40.3 +/‐ 2.8 mV) which gave rise to bursts of three to six fast action potentials. Deinactivation of the low‐threshold conductance in both type II and type III neurones was voltage‐ and time‐dependent. Low‐threshold potentials persisted in TTX (1‐3 microM) but were blocked by solutions containing low Ca2+ (0.2 mM) and Cd2+ (0.5 mM), suggesting they were Ca(2+)‐dependent. 3. Type I neurones had a significantly shorter membrane time constant (14.5 +/‐ 1.7 ms) than those of type II (21.6 +/‐ 1.7 ms) and type III neurones (33.8 +/‐ 4.4 ms). Input resistance and resting membrane potential did not differ significantly among the cell groups. 4. Current‐voltage (I‐V) relations were significantly different among the three cell types. Type I neurones had linear I‐V relations to ‐120 mV, while type III neurones all showed marked anomalous rectification. I‐V relations among type II neurones were more heterogeneous, although most (75%) had linear I‐V curves to about ‐90 to ‐100 mV, inward rectification appearing at more negative potentials. 5. Type I neurones generated fast action potentials of relatively large amplitude (64.2 +/‐ 1.1 mV, threshold to peak) and long duration (1.1 +/‐ 0.1 ms, measured at half‐amplitude); the longer duration was due to a shoulder on the falling phase of the spike. Type II neurones had large spikes (66.5 +/‐ 1.6 mV) of shorter duration (0.9 +/‐ 0.1 ms) with no shoulder. Type III neurones had relatively small spikes (56.1 +/‐ 2.2 mV) of short duration (0.8 +/‐ 0.1 ms) with no shoulder. 6. The three cell populations showed different patterns of repetitive firing in response to depolarizing current pulses. Type I neurones often generated spike trains with a delayed onset and little spike‐frequency adaptation.(ABSTRACT TRUNCATED AT 400 WORDS)
Post‐inhibitory excitation and inhibition in layer V pyramidal neurones from cat sensorimotor cortex.
Authors: Spain W J , Schwindt P C , Crill W E
Published: December 2014

1. The effect of conditioning pre‐pulses on repetitive firing evoked by intracellular current injection was studied in layer V pyramidal neurones in a brain slice preparation of cat sensorimotor cortex. Most cells displayed spike frequency adaptation (monotonic decline of firing rate to a tonic value) for several hundred milliseconds when depolarized from resting potential, but the cells differed in their response when pre‐pulses to other potentials were employed. In one group of cells, the initial firing rate increased as the pre‐pulse potential was made more negative (post‐hyperpolarization excitation). Adaptation was abolished by depolarizing prepulses. In a second group, the initial firing rate decreased as the pre‐pulse potential was made more negative (post‐hyperpolarization inhibition). Hyperpolarizing pre‐pulses caused the initial firing to fall below and accelerate to the tonic rate over a period of several seconds. A third group displayed a mixture of these two responses: the first three to seven interspike intervals became progressively shorter and subsequent intervals became progressively longer as the conditioning pre‐pulse was made more negative (post‐hyperpolarization mixed response). 2. Cells were filled with horseradish peroxidase or biocytin after the effect of pre‐pulses was determined. All cells whose firing patterns were altered by pre‐pulses were large layer V pyramidal neurones. Cells showing post‐hyperpolarization excitation or a mixed response had tap root dendrites, fewer spines on the apical dendrite and larger soma diameters than cells showing post‐hyperpolarization inhibition. 3. Other electrophysiological parameters varied systematically with the response to conditioning pre‐pulses. Both the mean action potential duration and the input resistance of cells showing post‐hyperpolarization excitation were about half the values measured in cells showing post‐hyperpolarization inhibition. Values were intermediate in cells showing a post‐hyperpolarization mixed response. The after‐hyperpolarization following a single evoked action potential was 20% briefer in cells showing post‐hyperpolarization excitation compared to those showing inhibition. 4. Membrane current measured during voltage clamp suggested that two ionic mechanisms accounted for the three response patterns. Post‐hyperpolarization excitation was caused by deactivation of the inward rectifier current (Ih). Selective reduction of Ih with extracellular caesium diminished post‐hyperpolarization excitation, whereas blockade of calcium influx had no effect. Post‐hyperpolarization inhibition was caused by enhanced activation of a slowly inactivating potassium current. Selective reduction of this current with 4‐aminopyridine diminished the post‐hyperpolarization inhibition. 5. Chord conductances underlying both Ih and the slow‐transient potassium current were measured and divided by leakage conductance to control for differences in cell size.(ABSTRACT TRUNCATED AT 400 WORDS)
Sensory integration in the spino‐olivocerebellar pathways of the anaesthetized cat.
Authors: Lidierth M
Published: December 2014

1. The responses evoked by peripheral nerve stimulation in the c1 and c3 zones of the cerebellar cortex have been examined in barbiturate‐anaesthetized cats. The responses evoked via the spino‐olivocerebellar pathways (SOCPs), which terminate in the cortex as climbing fibres, were recorded as positive multiunit field potentials from the cerebellar surface of lobule V. 2. Low‐strength conditioning stimulation of the superficial radial, ulnar or median nerve frequently modified the climbing fibre‐mediated responses evoked by a subsequent test stimulus to one of the other nerves. In most cases this modification involved a depression of the evoked response. The depression was not dependent on the conditioning stimulus evoking climbing fibre‐mediated responses in the cortex. 3. The depression of the evoked responses increased as the conditioning stimulus intensity was raised within the range of 1.1‐1.5 x threshold (1.1‐1.5T). 4. Topical application of bicuculline to the surface of the dorsal column nuclei reduced the depression evoked by conditioning stimulation and it is therefore concluded that GABAergic inhibition in the cuneate nucleus contributes to the depression. 5. The inhibition is discussed in relation to its possible contribution to movement‐related regulation of the excitability of SOCPs which occurs during locomotion in awake cats.
The voltage responses of hair cells in the basal turn of the guinea‐pig cochlea.
Authors: Russell I J , Kössl M
Published: December 2014

1. Intracellularly recorded voltage responses to tones and to current injection were measured from inner (IHC) and outer (OHC) hair cells in the basal turn of the guinea‐pig cochlea. 2. The voltage responses of IHCs to tones are increased by negative current and decreased by positive current. For any given current strength, the decrease in the receptor potential amplitude caused by positive current is less than the increase caused by negative current. This was attributed to the voltage‐dependent rectification of the membrane conductance. 3. Estimates of the reversal potential of the receptor current were based on extrapolation of the slopes of the current‐voltage relations for potentials more negative than ‐60 mV. The estimated reversal potentials were close to the measured endolymphatic potential. 4. Negative current increased the IHC membrane time constant and increased the transducer driving voltage. When receptor potentials to low‐frequency tones were adjusted for constant driving voltage and for the membrane time constant, the positive DC component of the receptor potential was decreased relative to the AC component by current injection but the DC component in response to high‐frequency tones near the best frequency of the IHC (16 kHz) was unchanged by negative current. 5. When compensated for constant driving voltage and low‐pass filtering due to the basolateral membrane conductance, the proportion of the transducer conductance open in IHCs at rest is increased by negative current. 6. Negative current injection reduced the positive DC components of OHC voltage responses to low‐frequency tones and may make them negative. In some cases negative current injection decreased the amplitude of the OHC receptor potential while positive current injection enhanced it. From these observations it is proposed that negative current injection shifts the operating point of the OHC transducer functions towards a positive, saturating region of the relationship and positive current decreases the proportion of the transducer conductance which is open at rest.
Effect of muscle mass on the pressor response in man during isometric contractions.
Authors: Williams C A
Published: December 2014

1. Changes in blood pressure and heart rate were measured in six healthy male subjects during voluntary isometric contractions of the forearm and quadriceps muscles. Arterial pressure was measured directly via a catheter inserted into the radial artery of the non‐contracting arm. Each subject exerted two types of contractions: (a) sustained contractions at 70% of the maximum voluntary contraction (MVC) until fatigue occurred and (b) sustained contractions starting at maximum tension (100% MVC), held for a total duration of 1 min. 2. During fatiguing contractions at 70% MVC, there was a progressive increase in blood pressure, reaching a peak level at fatigue. The same level of mean arterial pressure was achieved during contractions of the same relative tension, regardless of the muscle mass. The same trend was observed for the changes in heart rate. 3. During contractions which started with the maximum tension, where tension fell continuously during the 60 s of maximal effort, mean arterial pressure rapidly increased to high levels within a few seconds, and then increased further by 20‐30 mmHg during the sustained maximal effort. There was no difference in the initial rapid increases in mean arterial pressure, nor in the final mean arterial pressures reached between contractions of the forearm or quadriceps muscles. There were no differences in the heart rates achieved during these contractions either. 4. There was no significant difference between the mean arterial pressures observed at fatigue of a 70% MVC contraction or at the end of the 60 s maximum effort during handgrip contractions, or during contractions with the quadriceps muscles. 5. These results support the view that muscle mass is not a determinant of the magnitude of the cardiovascular reflexes during fatiguing isometric contractions in man.
Role of peptidoleukotrienes in capsaicin‐sensitive sensory fibre‐mediated responses in guinea‐pig airways.
Authors: Ellis J L , Undem B J
Published: December 2014

1. The right bronchus with the right vagus nerve remaining intact was isolated from the guinea‐pig. Stimulating the end of the right vagus nerve distal to the bronchus resulted in a biphasic contractile response with a rapid first phase and a second phase which persisted after the cessation of stimulation. The first phase was selectively sensitive to atropine, while the second phase was non‐cholinergic, but abolished by pre‐treatment with the sensory C fibre toxin, capsaicin. This biphasic contraction was mimicked by electrical field stimulation of the bronchus and strips of the distal aspect of the trachea. 2. The capsaicin‐sensitive second phase produced by either vagus nerve stimulation or electrical field stimulation, was inhibited by greater than 50% by the selective peptidoleukotriene receptor antagonist SKF 104353, whereas the inactive stereoisomer of SKF 104353, SKF 104373, was without effect. SKF 104353 did not inhibit the cholinergic first phase, nerve conduction along the vagus nerve, or contractions to exogenously added substance P and neurokinin A. 3. The inhibitory effect of SKF 104353 on second‐phase contractions was mimicked by two structurally unrelated selective peptidoleukotriene receptor antagonists, WY 48252 and ICI 198615, and by the 5'‐lipoxygenase inhibitor REV 5901. 4. Exogenously added leukotriene D4 (1 nM) potentiated the second‐phase contractions in the trachea and this effect was reversed by 0.1 microM‐SKF 104353. Leukotriene D4 did not affect responses to exogenously added substance P or neurokinin A. 5. Stimulation of the right vagus nerve produced plasma extravasation in the trachea and in the main bronchi of atropine‐ and propranolol‐pre‐treated guinea‐pigs. This was inhibited by about 50% by SKF 104353 (10 mg/kg, I.V.), whereas SKF 104373 (10 mg/kg, I.V.) was without effect. 6. It is suggested that endogenous peptidoleukotrienes make a significant contribution to the airway smooth muscle and vascular effects of capsaicin‐sensitive nerve stimulation in the guinea‐pig.
In mice, the muscle weakness due to age is absent during stretching.
Authors: Phillips S K , Bruce S A , Woledge R C
Published: December 2014

1. The contractile force was compared in isolated soleus muscles from young (2.5‐8 months old) and aged (28‐31 months old) mice. Force was measured at 25 degrees C during isometric tetanic contractions during isovelocity stretching and shortening contractions. 2. The normalized isometric force was lower by 13.3% in muscles from aged mice. Muscles from young and aged mice produced 0.951 +/‐ 0.031 N mg‐1 (n = 12) and 0.824 +/‐ 0.048 N mg‐1 (n = 9) respectively. The relaxation time, from 90 to 10% of the tetanic force, of muscles from aged mice was 102.1 +/‐ 3.7 ms (n = 6), which was longer than that for muscles from young mice, 84.4 +/‐ 3.8 ms (n = 6) (means +/‐ S.E.M.). 3. The force during shortening was also reduced in muscles from aged animals by the same proportion as the isometric force. Therefore the force during shortening relative to the isometric force was the same in muscles from young and aged mice. 4. During rapid stretching soleus muscles from aged mice produced a similar force to those from young mice. Therefore stretch can remove the weakness in muscles of aged mice. 5. These changes in muscles from aged mice are similar to those produced when inorganic phosphate (Pi) levels are raised, in skinned rabbit psoas fibres, or during fatigue or with low intracellular pH (pHi), in frog muscle. It is possible therefore that the force loss due to ageing may be due to a higher Pi level or a lower pHi.
Energy metabolism in human slow and fast twitch fibres during prolonged cycle exercise.
Authors: Ball‐Burnett M , Green H J , Houston M E
Published: December 2014

1. The effects of prolonged exercise on energy metabolism in type I and type II muscle fibres in the vastus lateralis muscle were investigated in six male subjects (20.0 +/‐ 0.5 years, mean +/‐ S.E.M.) who performed one‐legged cycling at 61% of maximum O2 consumption (VO2,max; determined with one leg) until fatigue or for a maximum of 2 h. 2. Analysis of pools of freeze‐dried fibres obtained by needle biopsy and separated into specific types by the myofibrillar ATPase histochemical procedure indicated higher (P less than 0.05) lactate concentrations in type II fibres compared to type I fibres at 15 min (43.9 +/‐ 9.7 and 51.2 +/‐ 9.8 mmol (kg dry wt)‐1) and at 60 min (18.2 +/‐ 4.7 and 25.9 +/‐ 6.5 mmol (kg dry wt)‐1). No differences existed in lactate concentration between fibre types for pre‐exercise (10.0 +/‐ 1.6 and 13.3 +/‐ 2.8 mmol (kg dry wt)‐1) or post‐exercise. 3. Glycogen degradation was most pronounced in type I fibres. By the end of exercise, glycogen concentration was 82.4 +/‐ 45 mmol glucosyl units (kg dry wt)‐1 in type I fibres and 175 +/‐ 62 mmol glucosyl units (kg dry wt)‐1 in type II fibres. 4. No significant changes in ATP and creatine phosphate (CrP) were found in either fibre type with exercise. 5. It is concluded that, at least for lactate and glycogen, fibre‐specific differences are evident in prolonged submaximal exercise. The cause of the difference probably relates both to the unique energy metabolic characteristics of each fibre type and to the manner in which they are utilized during the exercise. 6. The failure to find a reduction in ATP concentration in either fibre type during prolonged exercise in the face of a progressive increase in the number of fibres showing little or no glycogen concentration suggests that protective mechanisms exist that prevent an energy crisis. The nature of these protective mechanisms remains to be elucidated.
Effects of sulphydryl modification on skinned rat skeletal muscle fibres using 5,5'‐dithiobis(2‐nitrobenzoic acid).
Authors: Wilson G J , dos Remedios C G , Stephenson D G , Williams D A
Published: December 2014

1. The sulphydryl groups of skinned skeletal muscle fibres have been reacted with 5,5'‐dithiobis(2‐nitrobenzoic acid) (DTNB) in order to determine whether the effects of modifications to the contractile proteins are reflected in changes in the physiological properties of the contractile apparatus and Ca(2+)‐regulatory system. 2. Results obtained from fast‐twitch and slow‐twitch rat fibres which were treated with DTNB (10 mM, pH 8.6, 5 degrees C) for various periods of time under relaxing conditions showed that a major effect of the modification was to reduce the level of maximally Ca(2+)‐activated force and fibre stiffness. Force and fibre stiffness were found to decline in proportion. Treatment with DTNB under these conditions did not cause a rise in force or fibre stiffness in relaxed fibres of either type. 3. The effects induced by DTNB under relaxing conditions were substantially reversed by exposure to the reducing agent dithiothreitol (DTT) (10 mM, pH 7.1, 23 degrees C). Force abolished by 30‐35 s treatment with DTNB recovered after subsequent DTT treatment to 67 +/‐ 3% (mean +/‐ S.E.M., n = 4) in fast‐twitch fibres and to 91 +/‐ 2% (n = 7) in slow‐twitch fibres. These results were significantly different (t test, P less than 0.001) indicating that the level of force recovery depended upon the fibre type. 4. DTNB was found to affect not only the maximal Ca(2+)‐activated force, but also the force‐pCa (pCa = ‐log10[Ca2+]) relationships of the fibres in a complex, fibre‐type specific way. DTT treatment partially reversed these DTNB effects. 5. The skinned fibre preparations reacted differently with DTNB under rigor conditions than under relaxing conditions, indicating that rigor modifies the reactivity of the functional sulphydryl groups to the thiol‐targeted agents. 6. When superprecipitation assays (an in vitro analogue of fibre contraction) were carried out with recombined myofibrillar proteins which had been previously reacted with DTNB it was found that modification of myosin, but not modification of thin filament proteins, led to changes in the superprecipitation reaction. 7. Both the skinned fibre results and the superprecipitation results indicate that the effects of DTNB upon the fibre characteristics are primarily due to modifications of the sulphydryl groups of myosin. Therefore, these results show that myosin is not only involved in determining the ability of the contractile apparatus to develop force but also in determining the Ca(2+)‐regulatory characteristics of the muscle fibre.
Comparative nasal effects of bradykinin, kallidin and [Des‐Arg9]‐bradykinin in atopic rhinitic and normal volunteers.
Authors: Rajakulasingam K , Polosa R , Holgate S T , Howarth P H
Published: December 2014

1. The structure‐activity relationship of kinins within the nose has been investigated in atopic rhinitic (n = 7) and non‐rhinitic (n = 7) subjects. On 4 separate days, each separated by a week, subjects randomly underwent nasal challenge with incremental doses of either the B1 agonist [Des‐Arg9]‐bradykinin, the B2 agonists kallidin or bradykinin, or vehicle placebo in a double‐blind comparative study. The nasal response was monitored objectively by measurement of nasal airways resistance (NAR) by active posterior rhinomanometry and subjectively by symptom reporting of nasal blockage, rhinorrhoea, nasal itch and nasal pain. 2. The B2 agonists kallidin and bradykinin both induced a dose‐dependent increase in NAR (P less than 0.001) and were associated with symptomatic reporting of nasal blockage (P less than 0.05), rhinorrhoea (P less than 0.01) and nasal discomfort (P less than 0.05) compared to placebo. In contrast the effects of the B1 agonist [Des‐Arg9]‐bradykinin on NAR and symptom reporting were indistinguishable from placebo. No difference could be identified in the nasal response to kallidin and bradykinin between rhinitic and non‐rhinitic subjects and there was no evidence of B1 receptor upregulation in the disease state. For the whole group the provocative dose of agonist inducing a 50% increase in NAR (PD50) was 1.77 x 10(‐4) mol for bradykinin and 2.86 x 10(‐4) mol for kallidin (P greater than 0.05). 3. These findings identify that the nasal effects of kinins are mediated through B2 receptors and the advent of B2 receptor antagonists will permit a further evaluation of the role of kinins in rhinitis.
The influence of contralateral primary afferents on Ia inhibitory interneurones in humans.
Authors: Delwaide P J , Pepin J L
Published: December 2014

1. Contralateral influences on short latency reciprocal inhibition between wrist extensor and flexor muscles were investigated in twenty‐two healthy volunteers. Reciprocal inhibition, probably mediated through the Ia inhibitory interneurone, was measured by conditioning the flexor carpi radialis (FCR) H reflex by weak stimulation of the ipsilateral radial nerve. Maximum reciprocal inhibition occurring at a precise delay between conditioning and conditioned stimulations was taken as the test level of inhibition. 2. Contralateral median or radial nerves were stimulated at short intervals before the onset of reciprocal inhibition. The latter was increased by 8.6% after median nerve stimulation and decreased by 16.5% after radial nerve stimulation. 3. The contribution of sensory fibres in the two nerves to contralateral effects was investigated by stimulating purely sensory branches of the nerves. No clear modification of the contralateral reciprocal inhibition was observed. The effects produced by mixed nerve stimulation are thus likely to have been mediated by Ia fibres. 4. In three hemiplegic patients where reciprocal inhibition was reduced unilaterally, stimulation on the spastic side produced contralateral effects similar to those observed in normal subjects. This result indicates that contralateral effects are not mediated through the Ia inhibitory interneurone ipsilateral to the conditioning stimulus. 5. Since contralateral effects occur after short delays (2 ms, median nerve; 3 ms, radial nerve), we suggest a functional scheme in which the excitability of Ia inhibitory interneurones is modified by contralateral primary afferents via the interneurones activated by group I fibres, probably Ia fibres. The short delays indicate that the interneurone transmitting primary afferent influences to the contralateral side is probably excitatory.
Electrical responses of coronary artery smooth muscle associated with the cardiac muscle action potential in the monkey.
Authors: Mekata F
Published: December 2014

1. In cardiac strips of the monkey ventricle which included a section of coronary artery (cardiac preparation), a depolarizing response, which appeared to be an excitatory junction potential (EJP), and a hyperpolarizing response were observed from the coronary artery smooth muscles when an action potential was generated in cardiac muscle by the application of electrical stimulation to the cardiac muscle alone. 2. In an isolated preparation of the coronary artery dissected from the ventricle (arterial preparation), similar responses, an EJP and a hyperpolarizing response, could be evoked by electrical stimulation. 3. In the cardiac preparation, the threshold of electrical stimulation for generation of the cardiac action potential and for production of an electrical response in the vascular smooth muscle were the same. 4. The EJP and the hyperpolarizing responses of the smooth muscle of the coronary artery ceased or were weakened by elimination of the adventitial connective tissues and endothelium, respectively, in both the cardiac preparation and the coronary artery preparation. 5. These results indicate that the action potential of cardiac muscle generated by electrical stimulation activates the nerves and the vascular endothelium, which, in turn, produce an EJP and a hyperpolarizing response of the coronary artery smooth muscle, respectively.