bluuebunny/crossref_metadata_2025 huggingface dataset:
Morphine hyperglycaemia
Authors: Feldberg W. , Gupta K. P.
Published: December 2014

1. To find the site where morphine acts when producing hyperglycaemia on injection into the cerebral ventricles in unanaesthetized cats, morphine sulphate was infused or injected through an implanted Collison cannula into different parts of the liquor space in an amount of 0·75 mg except on microinfusion into the posterior hypothalamus, when the amounts were 80 or 160 μg. The glucose was determined in blood samples collected from the inferior vena cava.

2. Microinfusions of morphine into the posterior hypothalamus did not produce hyperglycaemia.

3. Infusion of morphine into the liquor space at the entrance of the aqueduct or of the fourth ventricle produced hyperglycaemia. Any structures in the walls of the third ventricle as well as the peri‐aqueductal grey are thus excluded as the site of action.

4. Infusion of morphine into the subarachnoid space just above the corpora quadrigemina or below the ventral surface of the brain stem produced hyperglycaemia. With these routes the morphine does not enter any part of the ventricular cavities and the action would appear to be on structures at the ventral surface of the brain stem.

5. Injection of morphine into the cisterna magna produces hyperglycaemia when the doses are larger than those already effective on injection into the cerebral ventricles. This also suggests an action on structures at the ventral surface of the brain stem, as this surface is reached more readily from the ventricles than from the cisterna.

6. It is concluded that on injection into the cerebral ventricles, the morphine has to pass into the subarachnoid space, through the foramina of Luschka, in order to produce hyperglycaemia. It then reaches the ventral surface of the brain stem and probably acts there on structures in the upper part of the medulla oblongata.

7. Infusion of morphine into the corpora quadrigemina near the caudal end of the superior corpora can produce profound hypoglycaemia.

8. Anaesthesia depresses the morphine hyperglycaemia, but when the dose injected into the cerebral ventricles is increased four times or more, hyperglycaemia is also produced in pentobarbitone sodium anaesthesia.
Temperature regulation during fever: change of set point or change of gain? A tentative answer from a behavioural study in man
Authors: Cabanac M. , Massonnet B.
Published: December 2014

1. Four subjects were immersed in a stirred water‐bath maintained at either 30 or 40° C. The left hand was placed out of the bath in a glove receiving water at a temperature selected by the subject as most pleasurable. Experiments were conducted during the euthermic state and during either spontaneous or induced fever.

2. The results of control experiments confirm a previous observation using the same method, that preferred hand skin temperature was a linear function of internal temperature but also indicated an influence by mean skin temperature.

3. The general pattern of response during fever was identical to that when fever was absent except that the regulated steady state internal temperature was higher and the slopes of preferred temperature plotted against internal temperature were steeper.

4. The results seem to support the concept of a change in set point rather than that of a change in the gain of the thermoregulatory processes during fever.
Identification of cone mechanisms in graded responses of foveal striate cortex
Authors: Gouras Peter , Padmos Pieter
Published: December 2014

1. The earliest electrical response detectable in foveal striate cortex of anaesthetized Rhesus monkeys following light stimulation is a graded potential which is positive at the cortical surface and negative in the grey matter and has a peak latency of about 60 msec. The response is similar at both the on‐ and the off‐phase of a light stimulus.

2. The relationship of this graded potential to the depth of the recording electrode, to the latency of extracellular impulses and to post‐synaptic potentials suggests that it is generated by the depolarization of cortical cells.

3. Action spectra obtained in the presence of strong selective chromatic adaptation indicate the participation of all three cone mechanisms in this response.

4. Each cone mechanism contributes a similar potential to the response but antagonism between cone mechanisms is apparent. The proportion in which a cone mechanism contributes to the response varies from one area to another implying topographical differences in the representation of cone mechanisms in striate cortex.
New techniques for calibrating the Lloyd—Haldane apparatus
Authors: Cormack R. S. , Heath J. R.
Published: December 2014

1. A new way of measuring the graduation error in the stem of the Lloyd—Haldane burette is described, in which a fixed mass of water is made to occupy different parts of the stem. This gave the same answer as the gravimetric method, but was much easier.

2. Two independent methods of measuring the ‘meniscus error’ gave values of 0·006 and 0·008 ml. respectively. It is concluded that the bulb volume can be measured gravimetrically with the burette inverted, provided that the value so obtained is corrected by adding about 0·007 ml.

3. Alternatively, this estimation can be made with the burette the right way up, no correction then being needed. To do this the lower end of the burette must be blocked and a method of doing this without the need to fuse on a glass tap is described.

4. After calibration by the above methods analyses on fresh air for CO2 + O2 gave a mean value of 20·98%, which, in the authors’ view, is the correct value.

5. The observer error was measured and from this the theoretical maximum accuracy of gas analysis by Haldane's method was calculated. It is concluded that the calculated% should be correct to the second decimal place in about half the analyses, the rest having an error of ± 0·01%. Results approaching this were obtained.
Acetylcholine synthesis from recaptured choline by a sympathetic ganglion
Authors: Collier B. , Katz H. S.
Published: December 2014

1. The recapture and re‐use of choline formed by the hydrolysis of released acetylcholine (ACh) was studied in the superior cervical ganglion of the cat using radioactive tracer techniques. The ganglion's ACh store was labelled by perfusion, during preganglionic nerve stimulation, with Krebs solution containing [3H]choline.

2. Preganglionic stimulation (5 Hz for 20 min) of ganglia containing [3H]ACh released similar amounts of radioactivity when perfusion was with neostigmine—choline—Krebs or with hemicholinium—Krebs. This indicated that neostigmine does not increase transmitter release.

3. The amount of radioactivity collected from stimulated ganglia during perfusion with choline—Krebs was 39% of the amount of radioactivity collected during perfusion with medium containing neostigmine or hemi‐cholinium. This difference in release was almost (85%) accounted for at the end of the experiment by extra radioactive ACh in the ganglia perfused with choline—Krebs. It is concluded that during preganglionic nerve stimulation approximately 50–60% of endogenously produced choline is recaptured for ACh synthesis; thus, during activity preganglionic nerve terminals appear selectively to accumulate choline.

4. However, chronically decentralized ganglia accumulated as much choline as did acutely decentralized ganglia, and this was interpreted as indicating that at rest preganglionic nerve terminals do not selectively accumulate choline.

5. Increased exogenous choline concentration increased the amount of radioactivity collected during nerve stimulation in the absence, but not the presence, of an anticholinesterase agent. The spontaneous efflux of radioactivity was little affected by changes in external choline levels. It is concluded that exogenous choline and choline made available from released transmitter compete for uptake into nerve terminals.
Inhibition of thermoregulatory non‐shivering thermo‐genesis by trauma in cold‐acclimated rats
Authors: Stoner H. B.
Published: December 2014

1. Heat production and blood flow in the interscapular brown adipose tissue of 3° C acclimated rats have been measured by the heated thermo‐couple technique.

2. When the environmental temperature (Ta) was reduced from 30 to 3° C heat production by the brown adipose tissue began to increase at the lower limit of the thermoneutral zone and then increased linearly.

3. Blood flow also increased when Ta was reduced but was not so well correlated with Ta. There was however a good positive correlation between blood flow and heat production.

4. During the first hour after a 4 hr period of bilateral hind‐limb ischaemia in a 20° C environment the percentage of rats not producing heat in the interscapular brown adipose tissue increased and the tissue blood flow fell.

5. By varying the Ta of the injured rat it was found that the Ta at which heat transfer from the interscapular brown adipose tissue commenced was significantly lower than in the controls although the slope of the regression lines relating heat production and Ta was unaltered.

6. Blood flow also increased in the injured rat when Ta was lowered but the increase in the tissue blood flow per unit increase in heat production was less than in the controls.

7. In a 5° C environment heat production in the interscapular brown adipose tissue of the injured rat was further increased by the
S. C. injection of
L‐isoprenaline or
L‐noradrenaline.

8. It is concluded that the central control of thermoregulatory non‐shivering thermogenesis is inhibited after injury in the rat.
The carotid sinus baroreceptor reflex in the pregnant rabbit
Authors: Humphreys P. W. , Joels N.
Published: December 2014

1. The reflex responses to baroreceptor stimulation have been compared in eight pregnant and eight non‐pregnant anaesthetized female rabbits.

2. The vascularly isolated, innervated carotid sinus was exposed for 30 sec to a series of non‐pulsatile pressures ranging from 30 to 230 mmHg. The contralateral sinus nerve and both aortic nerves were cut. Systemic arterial pressure and heart rate were measured at each sinus pressure.

3. The range of arterial pressure change which could be evoked from the isolated innervated sinus was less in the pregnant than in the non‐pregnant rabbits. Mean changes were 98 and 61 mmHg respectively. On the other hand changes in heart rate were similar in the two groups (45 and 43 beats/min respectively).

4. The smaller blood pressure response in the pregnant animals resulted from a lesser rise in systemic arterial pressure at low levels of sinus pressure. At high sinus pressures the blood pressure fell to a similar level in both groups of animals.

5. Pressure on the great vessels by the gravid uterus was not a factor since there was no consistent difference between the responses obtained with the rabbit lying on its back or on its side.

6. Mechanisms which might be responsible for the difference found are discussed.
The projection of the vestibular nerve to the cerebral cortex in the cat
Authors: Mills K. R. , Taylor A.
Published: December 2014

1. The cerebral cortex in the cat has been examined for responses to contra‐lateral vestibular nerve shocks and to natural stimuli.

2. Stimulation of the nerve produces short latency (3·5 msec) surface positive responses in very restricted areas. Within these areas, unitary discharges occur during the equivalent negative phase below the surface.

3. It has not been possible to evoke unitary activity in these areas by natural stimulation during light anaesthesia with pentobarbitone, chloralose or urethane.

4. The distribution and properties of the shock evoked responses have been studied with special attention to the problem of stimulus spread. They are shown to be overlapped by somato‐sensory and auditory projections, but to be distinguishable from them. Evidence is presented that previously reported longer latency responses were probably due to stimulus spread.

5. Reasons are discussed for the extreme sensitivity of the vestibulocortical pathway to anaesthesia.
Discharge of type B atrial receptors during changes in vascular volume and depression of atrial contractility*
Authors: Gilmore Joseph P. , Zucker Irving H.
Published: December 2014

1. Single unit recordings from type B atrial receptors were obtained from slips of the left cervical vagus nerve during acute increases and decreases in atrial pressure produced by infusion of isotonic saline and withdrawal of blood.

2. Atrial receptor discharge reached a peak frequency at the peak of the ‘v’ wave of the atrial pulse, a time when the rate of change of atrial pressure was zero.

3. The receptor discharge exhibited hysteresis when increases in atrial pressure were compared to decreases in atrial pressure during circulatory volume expansion and haemorrhage, respectively. This hysteresis was not due to a change in atrial compliance.

4. The hysteresis was still observed when the pulse pressure of the ‘v’ wave was plotted against receptor discharge.

5. Type B atrial receptors did not show adaptation after 15 min of a sustained increase in left atrial pressure.

6. Acute depression of atrial contractility with propranolol increased resting fibre discharge as a result of the associated increase in atrial pressure.
Renal response of the new‐born dog to a saline load: the role of intrarenal blood flow distribution
Authors: Kleinman Leonard I. , Reuter John H.
Published: December 2014

1. The renal response to an intravenous saline load was studied in thirty new‐born mongrel dogs aged 1–30 days and in seven adult dogs.

2. After the infusion of isotonic saline at a rate of 2·0 ml. min−1 kg−1 for 15 min and then at a rate of 0·5 ml. min−1 kg−1 for an additional 105 min, the puppies excreted a significantly smaller fraction of the infused sodium than did the adults (P < 0·01).

3. Both puppies and adults increased their glomerular filtration rates after the saline load. However, adults excreted a larger fraction of their filtered sodium than did the puppies (P < 0·01).

4. There was no correlation between age and the ability to respond to a saline load during the first month of life.

5. Intrarenal blood flow distribution was measured by the radioactive microsphere technique. After saline infusion in the puppy there was an increase in outer cortical blood flow but inner cortical blood flow remained relatively constant. The result was a decrease in the ratio of inner to outer cortical blood flow (IC/OC ratio). In contrast the IC/OC ratio tended to increase in the adult dog after saline expansion.

6. There was no correlation between the magnitude of change of sodium excretion and the change of intrarenal blood flow distribution in the puppy.

7. These results confirm that the natriuretic response of the new‐born dog kidney is less efficient than that of the adult dog. This is due primarily to the failure of the puppy kidney to decrease fractional sodium reabsorption. Although the new‐born dog alters intrarenal blood flow distribution in response to saline loading this alteration does not appear to play a significant role in sodium excretion.
The effect of fasting on hexose transfer in rat intestine
Authors: Sanford P. A. , Smyth D. H.
Published: December 2014

1. A technique has been developed whereby accurately defined segments of rat intestine can be isolated in vivo, and this technique was used to study the influence of fasting on hexose transport.

2. In the distal ileum the transport of glucose and galactose was stimulated by fasting. The effect was specific as neither amino acid transport nor the permeability of the luminal membrane of the absorbing epithelium was altered by fasting. The increased hexose transport was accompanied by a reduced accumulation of hexose in the gut wall. In the proximal jejunum hexose transport was not stimulated by fasting.

3. The results of in vitro experiments show the relative importance of hexose metabolism in providing energy for transport in different regions of the small intestine in both fed and fasted animals. In conditions where hexose metabolism was reduced, e.g. by fluoride, the proximal jejunum behaved more like the distal ileum and a stimulation of hexose transport in response to fasting was demonstrable in vivo.

4. Motility studies showed that phenol red introduced into the stomach reached the ileum sooner, achieved a higher concentration and remained there for a longer period of time in the fasted animal.

5. The changes in carbohydrate metabolism, hexose transport capacity and gastrointestinal motility are discussed in relation to adaptations of the rat to fasting.
The effect of vasopressin upon the vasculature of the isolated perfused rat kidney
Authors: Cross R. B. , Trace J. W. , Vattuone J. R.
Published: December 2014

The timed uptake of 131I‐labelled human serum albumin was used as an index of regional perfusion in the isolated rat kidney.

1. Arginine vasopressin in doses of 1, 5 and 10 μu./ml. of perfusate decreased papillary perfusion. Total renal perfusion was decreased only by the 5 μu. dose.

2. Ornithine‐8‐vasopressin in doses of 5 and 10 μu./ml. of perfusate decreased papillary perfusion. Total renal perfusion was decreased only by the 10 μu. dose.

3. When the relative viscosity of the perfusate was increased to a value of 2·0 from the control value of 1·7, both papillary perfusion and total renal perfusion were reduced.

4. Arginine vasopressin further reduced papillary flow in kidneys perfused with high viscosity artificial plasma.
The effects of infusions of synthetic adrenocorticotrophin in the conscious calf
Authors: Edwards A. V. , Hardy R. N. , Malinowska Krystyna W.
Published: December 2014

1. A technique is described by which the whole of the effluent blood from the right adrenal gland can be collected as required from conscious, unrestrained calves. The technique may be used to measure adrenal blood flow gravimetrically and to compute the output of adrenal hormones under various conditions in the normal calf.

2. In a group of seven calves mean cortisol output from the right adrenal gland was found to vary between 20 and 40 ng.kg−1 min−1 and corticosterone between 6 and 18 ng.kg−1 min−1 during a 2 hr period, 24 hr after surgery.

3. Intravenous infusions of synthetic adrenocorticotrophin (5 ng.kg−1 min−1) produced a significant increase in the output of both cortisol and corticosterone within 5 min. The output of both hormones rose to maximal values within 10–20 min and mean values of approximately 300 ng.kg−1 min−1 (cortisol) and 120 ng.kg−1 min−1 (corticosterone) were maintained thereafter for the duration of the infusion (120 min). The output of both steroids fell to values comparable with those observed initially within 45–60 min after the infusion was discontinued.

4. These changes in glucocorticoid output in response to adrenocorticotrophin produced a significant rise in the concentration of both cortisol and corticosterone in peripheral plasma. It is noteworthy that the rise in the mean corticosterone concentration in the peripheral plasma was substantially less than that which might be expected from relating the rise in mean plasma cortisol concentration to cortisol output.

5. The results of control experiments have eliminated the possibility that the sampling procedure might itself increase steroid output or peripheral plasma concentration. Comparison of results from calves of widely disparate ages (8–38 days) provided no evidence that either the resting output of cortisol or corticosterone or the response to adrenocorticotrophin changes with age within the range examined.

6. Infusion of adrenocorticotrophin (5 ng.kg−1 min−1) also stimulated an abrupt rise in adrenal blood flow; mean resting flow (210 ± 23 μl.kg−1) increased by approximately 30% within 5 min and attained peak values (355–365 μl.kg−1 min−1) between 10 and 30 min. Thereafter, adrenal blood flow steadily decreased and then fell rapidly to within the resting range when the infusion was terminated. No significant changes in heart rate or aortic blood pressure occurred during these infusions.

7. The results are discussed in relation to those obtained in other species and under differing conditions by other workers.
Non‐transmitting neuromuscular junctions during an early stage of end‐plate reinnervation
Authors: Dennis M. J. , Miledi R.
Published: December 2014

1. Electrophysiological studies were made on regenerating motor end‐plates in frog cutaneous pectoris muscle after crushing the motor nerve.

2. The pattern of degenerative and regenerative changes is similar to that already described for the frog sartorius, although it occurs more quickly in the cutaneous pectoris. Resumption of synaptic transmission first occurs after 9 days, in muscle fibres closest to the nerve crush. During the subsequent 12 days synaptic contact is progressively re‐established across the muscle.

3. During the period of regeneration muscle fibres can be found which have been reinnervated, but which do not produce an end‐plate potential in response to stimulation of the nerve trunk. This is referred to as the ‘non‐transmitting’ stage of regeneration.

4. Increases in extracellular potassium, addition of lanthanum to the bath and focal extracellular stimulation all indicate that the axon terminals at non‐transmitting junctions do have a releasable supply of neurotransmitter. Focal stimulation occasionally sets up active responses in these nerve terminals.

5. It is concluded that this ‘non‐transmitting’ stage results from failure of action potential propagation in the regenerating neurone proximal to the end‐plate region.
Characteristics of transmitter release at regenerating frog neuromuscular junctions
Authors: Dennis M. J. , Miledi R.
Published: December 2014

1. A study was made of the onset of transmission and the characteristics of transmitter release from regenerating nerve terminals in frog muscle fibres.

2. Soon after transmission had been restored, some junctions were found which responded to nerve stimulation with only subthreshold end‐plate potentials.

3. The evoked transmitter release had a non‐linear dependence on the external calcium concentration, like that seen at normal junctions.

4. The synaptic delay was only slightly longer than normal, and the amplitudes of single quantum potentials evoked by nerve stimulation seemed to have a normal distribution.

5. The mean amplitude of the spontaneous miniature end‐plate potentials was often substantially smaller than the mean amplitude of the evoked quantal potentials at a given end‐plate. Some of these small spontaneous potentials were due to transmitter release from the axon terminal. Possible explanations for this discrepancy in size of spontaneous and evoked potentials are discussed. Two to three weeks after reinnervation began, the amplitude of the spontaneous miniature end‐plate potentials returned to normal.
The transamination of glutamate and aspartate during absorption in vitro by small intestine of chicken, guinea‐pig and rat
Authors: Parsons D. S. , Volman‐Mitchell Hetty
Published: December 2014

1. Procedures are described for direct measurement of the extent and rate of transamination of glutamate and aspartate over periods of up to 90 min, during absorption in vitro by the small intestine of chicken, guinea‐pig, and rat.

2. During absorption of dicarboxylic amino acids by rat small intestinal segments circulated through the lumen in vitro, alanine contributed up to 85% of the amino acids appearing in the fluid secreted at the serosal surface. In guinea‐pig and chicken intestine, the proportion of alanine in the secreted amino acids did not exceed 60%.

3. For the different species studied, a relationship was found between the extent to which the dicarboxylic amino acids were transaminated to alanine and the total amount of GPT found in other studies to be present in the intestinal mucosa. In both rat and guinea‐pig small intestine, the proportion of alanine in the total amino acids appearing at the serosal surface was similar in the jejunum and ileum. The rate of appearance of alanine in serosal fluid was greater in the ileum than in the jejunum of the rat.

4. Reasons are given for supposing that for all the species studied there is a limit to the capacity of the small intestinal mucosa to subject free dicarboxylic amino acids to transamination. It is concluded, however, that it is unlikely that this capacity will be exceeded under in vivo conditions.
The effects of cortisone acetate on stomach evacuation and the absorption of 125I‐labelled globulins in young rats
Authors: Morris B. , Morris R.
Published: December 2014

1. After short exposure (3–5 hr) to
I.P. cortisone acetate (5 mg), the reduced transmission of labelled globulin to the circulation in 14‐day‐old rats is due to the slow release of the oral dose from the stomach. The ability of the small intestine to absorb and transmit globulin to the circulation is comparable in control and experimental animals.

2. About 26 hr after cortisone acetate treatment (5 mg), the greatly reduced absorption of labelled globulin from oral doses administered to rats aged 15 days is due to the combined effects of the slower release of the dose from the stomach and to changes which have occurred in the small intestine.

3. About 50 hr after the administration of 5 mg cortisone acetate the effect on the rate of stomach evacuation is minimal in rats aged 16 days. When labelled globulin is introduced directly into the duodenum of these animals virtually no absorption occurs.

4. The results obtained from the experiments in which labelled globulin was injected into the duodenum support the contention that the proximal half of the small intestine is an important site for macromolecular transport.
Storage and release of acetylcholine in a sympathetic ganglion
Authors: Birks R. I. , Fitch S. J. G.
Published: December 2014

1. The hypotheses of preferential release of newly synthesized acetylcholine (ACh) and two compartment storage of transmitter in the cat superior cervical ganglion have been re‐examined by testing, first, the assumption that ganglionic ACh stores do not alter during a 20 min rest following 60 min preganglionic nerve stimulation at 20/s, and secondly, the implication that the rate of ACh release should be high near the onset of activity and decline to a lower rate with time irrespective of the frequency of stimulation.

2. The ganglionic ACh stores were found to increase by 38 ± 8% within 20 min following 60 min preganglionic nerve stimulation at 20/s, and this extra ACh was releasable.

3. The rate of ACh release from ganglia perfused with cat plasma and stimulated at 4/s increased over the first 5 min of stimulation to reach a 27% higher rate that was maintained.

4. Correction of the original data to allow for the post‐activation increase in ACh stores suggests that newly synthesized ACh equilibrates with most of the preformed stores. The time course of ACh release at 4/s does not support the two compartment model as currently formulated.

5. These findings resolve in part a conflict between the physiological data and a recent hypothesis for ACh storage based on ganglion morphology.
Comparison of the effects of stimulation of the sympathetic vasomotor nerves and the adrenal medullary catecholamines on the hind limb blood vessels of the rabbit
Authors: Powis D. A.
Published: December 2014

1. The responses to sympathetic nerve stimulation and to the adrenal medullary hormones have been studied in the hind limb vascular beds of the anaesthetized rabbit.

2. Simultaneous measurements of femoral arterial blood pressure and of femoral venous blood flow indicate that stimulation of the sympathetic nerves decreases the calculated vascular conductance in both the intact and skinned hind limbs. Evidence is presented to show that these changes are due to vasoconstriction.

3. The vasoconstriction in both skin and muscle vascular beds reaches a maximum at frequencies of stimulation around 15 Hz. No vasodilatation is obtained at any frequency of stimulation.

4. The rabbit adrenal gland secretes only adrenaline during splanchnic nerve stimulation at frequencies between 3 and 60 Hz. The amounts liberated from both glands over this frequency range are 25–500 ng.kg body wt.−1 min−1.

5. Intravenous infusions of adrenaline in concentrations similar to those liberated by the adrenal glands during splanchnic nerve stimulation, and of noradrenaline, cause only vasoconstrictor responses in skin and muscle.

6. Simultaneous stimulation of the sympathetic nerves to the hind limb and infusion of adrenaline in quantities that could be liberated by splanchnic nerve stimulation at equivalent frequencies shows that the vasoconstrictor effects exerted by the individual components are additive, though the effects produced by the direct sympathetic nerve supply overshadow those produced by the catecholamine.

7. The results are discussed in the context of the possible vascular role of the adrenal medullary hormones in the rabbit.
Responses of rostral hypothalamic neurones to peripheral temperature and to amines
Authors: Jell Ralph M.
Published: December 2014

1. Five‐barrelled micropipettes have been used to record extracellularly the activity of neurones in the rostro‐medial hypothalamus of methoxyflurane‐anaesthetized cats, and to apply acetylcholine (ACh), noradrenaline (NA) and 5‐hydroxytryptamine (5‐HT) by micro‐iontophoresis to the vicinity of each neurone encountered. Peripheral thermal stimulation was achieved by blowing warm (42° C) and cold (4° C) air in the face of the animal, and thermoresponsiveness was compared with amine responsiveness.

2. One hundred and twenty‐two neurones were obtained from ten cats. Eleven (9%) were warm‐responsive and sixteen (13%) were cold‐responsive. The rest did not respond to facial warming or cooling.

3. No consistent relationship was observed between amine responses and responsiveness to facial temperature. Warm‐responsive neurones were mainly depressed or unaffected by amines. Cool‐responsive neurones were excited, depressed or unaffected by amines with the exception that no 5‐HT excitations were seen. Thermoresponsive neurones were more likely to be amine depressed than non‐thermoresponsive neurones.

4. Six thermoresponsive neurones responded to peripheral temperature and to amines in a way which fitted the amine model of Myers (1971). Fifteen thermoresponsive neurones fitted the model of Bligh, Cottle & Maskrey (1971), according to the same criteria.

5. The results lend little support to the amine model, as predicted from amine micro‐injection and release studies in primates, but support more strongly the model of Bligh et al. (1971) which is based on intraventricular injections of amines in sheep, goats and rabbits. On the basis of the latter model, functional identification was possible in 63% of the thermoresponsive rostral hypothalamic neurones tested.
The effects of load and force on tremor at the normal human elbow joint
Authors: Joyce G. C. , Rack Peter M. H.
Published: December 2014

1. Spontaneous flexion‐extension tremor of the elbow was recorded in normal human subjects while they exerted a flexing force against different loads.

2. Increases in the flexing force up to ½ or ¾ of the subject's maximum were accompanied by increases in the amplitude of the tremor. A further increase to very large forces was associated with a decrease in tremor.

3. When the subject flexed against a spring, the frequency of the tremor was related to the properties of the spring; with increasingly stiff springs the tremor frequency increased up to about 12 Hz. With the stiffest springs, however, the tremor became irregular and very small in amplitude.

4. Weights added to the limb at the wrist reduced the frequency of tremor.

5. By using appropriate combinations of spring and mass, the principal tremor frequency could be adjusted between 2 and 12 Hz, higher in some subjects. Within this range the frequency2 was approximately proportional to the spring stiffness/mass, just as it is in a spring‐mass system, though the forearm provided some of this mass, and some of the spring‐like resistance was in the flexor muscles.

6. When by suitable loading the tremor frequency was brought between 8 and 12 Hz, and the subject forcibly flexed his elbow, the tremor became regular and large in amplitude. This was a form of limited instability in the stretch reflex which arose because a powerful reflex response to extension of the elbow acted back on the flexor muscles after a delay.

7. When the limb was so loaded that its natural frequency was outside this 8–12 Hz range, it behaved as a filter, and in response to any disturbing noise it oscillated mainly at frequencies close to the natural frequencies of either the mechanical system or the stretch reflex.

8. This filtering function of the limb with its stretch reflex probably plays an important part in the control of normal movement and tremor.

9. The large flexing forces that were here associated with vigorous tremor normally occur when a limb supports a large mass. Such a mass would give the mechanical system within the limb a low natural frequency; inconveniently large oscillations in the 8–12 Hz range would therefore seldom occur.
Dependence of intestinal glucose absorption on sodium, studied with a new arterial infusion technique
Authors: Fisher R. B. , Gardner M. L. G.
Published: December 2014

1. A new preparation of isolated rat jejunum plus ileum (ca. 100 cm) is described in which a saline infusate is pumped into the superior mesenteric artery, the superior mesenteric vein having been ligated.

2. The arterial infusate washes out the tissue spaces: the lumen is perfused in a single pass with a segmented flow as by Fisher & Gardner (1974).

3. At an arterial infusion rate of 3 ml./min, steady states are set up in the tissue fluid within 10–15 min: the compositions of the fluids bathing both sides of the mucosa can therefore be controlled.

4. The rate of glucose absorption from the lumen falls only gradually when the luminal sodium is replaced by choline abruptly while the tissue fluid sodium is maintained at 144 m‐equiv/l. by arterial infusion.

5. The rate of glucose absorption from the lumen is unaffected by replacement of sodium in the arterial infusate by choline.

6. Ouabain (10−4 M) in an arterial infusate containing sodium 144 m‐equiv/l. causes inhibition of glucose and water absorption from the lumen. There is no effect of ouabain when the arterial infusate contains sodium, 0 or 72 m‐equiv/l.

7. Arterial ouabain does not reverse the effects of depletion of luminal sodium. Simultaneous removal of luminal sodium and application of arterial ouabain causes faster inhibition of glucose absorption than does either treatment alone.

8. Glucose absorption is more likely to depend on rate of efflux of sodium from mucosal cell to tissue fluid than on a sodium gradient at the brush border or on intracellular sodium concentration.
Sodium—calcium sites in smooth muscle and their accessibility to lanthanum
Authors: Burton Josiane , Godfraind T.
Published: December 2014

1. The Na, K, Ca, and Mg contents were determined in longitudinal smooth muscles of the guinea‐pig ileum incubated in various physiological solutions with or without ouabain or in a solution containing LaCl3 10 m
M instead of CaCl2.

2. The Na and K contents were dependent upon the K concentration of the physiological solution. A decrease in [K]o below 6 m‐mole/l. increased tissue Na.

3. A rise in [Na]i was followed by an increase of total cell Ca preceding a secondary decrease of total Ca, as well as by an increased 45Ca content occurring even when total Ca was decreased.

4. Muscles washed in the lanthanum solution contained less Ca and Na than those incubated in the physiological solution. The Mg content was not significantly modified in the presence of La.

5. In the La solution, the 45Ca diffusion space was not different from the [14C]inulin diffusion space, indicating that there was no Ca entry within the cell nor Ca binding at superficial sites. 45Ca content of preloaded muscles decreased; this decrease was blocked after 30 min washout in the La solution: this arrest lasted a further 45 min.

6. The cell Ca fraction displaced by increased [Na]i originated from a Ca compartment which was not blocked by La.
Relationship between blood pressure alterations and bursts of panting in the conscious dog: a comparison of the effects of exercise and heat exposure
Authors: Dampney R. A. L. , Hales J. R. S.
Published: December 2014

1. Continuous recordings of the arterial blood pressure and intrathoracic pressure of conscious dogs have been taken, in each animal, under two different conditions: (a) during mild exercise on a treadmill in a thermoneutral environment (19–22° C Tdb, 13·5–17·5° C Twb); (b) at rest in conditions of mild heat stress (35–40° C Tdb, 20–26° C Twb), and of severe heat stress (35–40° C Tdb, 30–34° C Twb).

2. Under all conditions, panting occurred, but there were differences in its pattern. During exercise, panting usually occurred in short regular bursts of about 10 sec duration, whereas during both mild and severe heat stress it occurred in bursts of irregular but usually longer duration. At comparable rectal temperatures, the intensity of panting (as measured by the amplitude of intrathoracic pressure variations) was markedly greater during exercise than during heat stress; the frequency, however, was lower.

3. During exercise, the bursts of panting were associated with striking oscillations in mean blood pressure, whereas during mild and severe heat stress they were associated with much smaller changes in mean blood pressure. In addition, cross‐correlation analysis revealed that blood pressure changes were far more strongly correlated with bursts of panting during exercise than during mild or severe heat stress.

4. In view of the present and previous results, it is suggested that both the bursts of panting and the associated cardiovascular changes during exercise are stimulated primarily by metabolic rather than thermoregulatory factors. During heat stress, bursts of panting are solely thermally induced, and are therefore not associated with similar cardiovascular alterations.
Intracellular sodium and potassium concentrations in oocytes of Bufo bufo at the beginning of maturation
Authors: Dick D. A. T. , Ho‐Yen D. O.
Published: December 2014

1. During the first phase of maturation in oocytes of Bufo bufo, after the growth phase but before ovulation, intracellular Na rises to 120 m‐mole/l. cell water while K falls to 15 m‐mole/l. cell water.

2. At the same time, the ouabain‐insensitive Na efflux and total Na influx both increase while the ouabain‐sensitive Na efflux is unchanged.
Ornithine decarboxylase activity, nucleic acids and cell turnover in the livers of pregnant rats
Authors: Campbell Rosa M. , Fell B. F. , Mackie W. S.
Published: December 2014

1. Comparisons were made between the livers of pregnant and non‐pregnant rats, all of which were fed on a ration of 20 g food per day.

2. In the second half of pregnancy there were marked increases in the weight of the liver and in its total content of protein, RNA and DNA. RNA concentration increased from the 15th day of gestation.

3. Between the 12th and 18th day of pregnancy liver weight, total RNA, totla DNA and mean liver cell nuclear volume increased in parallel at approximately the same rate of 6–10% per day.

4. Ornithine decarboxylase activity was enhanced in pregnancy by the 5th day of gestation and rose to peak activity at the 18th day.

5. The mitotic index of hepatic parenchymal cells was elevated in the first and last stages of pregnancy. The later peak in mitosis was associated with a rapid fall in mean nuclear volume.

6. There was histological evidence of cell turnover in the liver of pregnant rats; enlargement of the liver was associated with both hyperplasia and cell deletion.
Methionine accumulation in villi isolated from maturing rat intestine
Authors: Fondacaro Joseph D. , Nathan Paul , Wright Walter E.
Published: December 2014

1. This study compares the absorption rates of methionine in 15‐day‐old rats (preweaned) and 30‐day‐old rats (post‐weaned), and the effect of varying initial substrate concentration on the absorption rate of methionine in tissue removed from specific sites in the small intestine.

2. The experiments utilize a new in vitro method, the villus technique, permitting evaluation of the mucosal (villus) absorptive cells separated from the relatively non‐transporting muscle and connective tissue components (non‐villus tissue).

3. When the villus technique was used in a comparative age study of absorption by jejunal and duodenal tissue, it was found that at initial methionine concentrations below 1·0 m
M, no difference in the transport rate between preweaned and post‐weaned animals was observed.

4. However, in preweaned animals, methionine transport is faster in the ileum than in the jejunum or duodenum.

5. With initial methionine concentration greater than 1·0 m
M, duodenal and jejunal villi from preweaned animals transport methionine better than villi from older animals.

6. At these higher methionine concentrations there is a slightly better transport by ileal villi from 30‐day‐old rats than in the younger group.

7. With increasing initial concentration of methionine, physiological changes are shown to occur during maturation because transport rates into villi of mature duodenal and jejunal tissues are slower than into similar tissue from preweaned rats.

8. The underlying physiological changes responsible for the transport rate differences are not known.

9. The results reported indicate that following maturation, the absorbing mucosal cells from the duodenum, jejunum and ileum have an equal capacity for methionine accumulation.

10. The apparent localization of the major amino acid transport to the ileum as reported by others may be an artifact reflecting the inclusion of an undetermined amount of non‐absorbing muscle mass in the calculation of intestinal transport.
The effect of glycine‐conjugated bile acids on net transport and potential difference across isolated rat jejunum and ileum
Authors: Wingate D. L.
Published: December 2014

1. Five m
M glycodeoxycholate and glycochenodeoxycholate inhibit net fluid transport across isolated rat jejunum and ileum; 5 m
M glycocholate does not affect jejunal segments, but arrests fluid transport across ileal segments.

2. Inhibition of fluid transport is accompanied by some diminution of mucosal glucose uptake, but translocation of glucose to the serosal surface of jejunal segments persists in the presence of dihydroxy conjugated bile acids.

3. Inhibition of fluid transport is accompanied by a marked fall in the glucose‐stimulated transmural electropotential difference, within 5 min of mucosal exposure to the bile acids.

4. The lactate concentration gradient normally maintained across isolated intestine is abolished when fluid transport is inhibited by conjugated bile acids, even though lactate formation is not greatly reduced.

5. These results suggest that inhibition of intestinal fluid transport is reproducible in vitro, and that the inhibition is not associated with increased permeability of the mucosa, but may be associated with altered permeability of the mucosal pole of the enterocyte.

6. Although in vitro and in vivo effects of dihydroxy bile acids on fluid transport are similar, the assumption that the mode of action is likewise similar is not justified on present evidence.
Alterations in histamine metabolism of rat gastric mucosa following vagotomy
Authors: Lundell L. , Rosengren Elsa , Svensson S. E.
Published: December 2014

1. In female rats subjected to truncal vagotomy with pyloroplasty, pyloroplasty alone or sham operation, the behaviour of gastric mucosal histamine was investigated combining in vivo and in vitro methods.

2. Following truncal vagotomy with pyloroplasty mucosal histamine formation, determined in vitro, increased about fivefold and histamine content was significantly elevated. The heightened histamine formation was reflected in increased excretion of histamine in the urine.

3. On pentagastrin infusion, mucosal histamine formation increased about twofold following vagotomy with pyloroplasty and sevenfold in the sham‐operated controls. Histamine content concomitantly fell in both groups to about the same level. These alterations were paralleled by increased excretion of histamine in the urine.

4. Kinetic studies in which [14C]histidine was injected and the resulting urinary [14C]histamine determined, indicated that during the first hour of pentagastrin infusion newly formed histamine was more slowly mobilized following vagotomy with pyloroplasty than in the controls.

5. In rats subjected to a pyloroplasty alone, the increase in urinary histamine on pentagastrin infusion was significantly larger than in the sham‐operated controls. Kinetic studies indicated that this was due to a larger mobilization of preformed histamine.

6. The changes in mucosal histamine metabolism are discussed in relation to the pattern of acid secretion following the actual surgical procedures.
Inward spread of activation in frog muscle fibres investigated by means of high‐speed microcinematography
Authors: Sugi H.
Published: December 2014

1. Single fast muscle fibres of the frog were locally activated by applying current pulses to a pipette whose tip was in contact with the fibre surface, and the resulting local contractions were recorded with a high‐speed ciné‐camera at 1000–3000 frames/sec.

2. In some but not all of the fibres examined, a moderate membrane depolarization of 20–30 mV initiated a phasic type of local contraction, which showed a definite threshold and relaxed spontaneously while the depolarization still continued.

3. The phasic contraction was sometimes followed by a smaller steady contraction, which lasted as long as the depolarization went on and was regarded to be indentical with the graded type of local contraction.

4. With pipettes of 20–40 μm diameter, the phasic contraction was first initiated at the depolarized fibre surface, and spread to some extent inwards with a velocity of 0·7–2 cm/sec at 18–26° C. The velocity of inward spread of contraction had a Q10 of about 2·3.

5. With larger pipettes of more than 50–60 μm diameter, the phasic response was first initiated at the inner part definitely distant from the fibre surface, and the extent of contraction was greater at this part than at the superficial part during the course of the response. Furthermore, with depolarizations of nearly the threshold value, the steady contraction following the phasic one was seen only at the inner part, suggesting the reversal of the gradient of depolarization along the T tubules.

6. The phasic contraction spread inwards or transversely with a considerable decrement. The response spreading across the whole diameter of the fibre could be observed only in some cases.

7. The phasic response was not always sensitive to tetrodotoxin or to the removal of external sodium ions.

8. These results not only give information about the nature of the regenerative mechanism within the T system, but also suggest that the organization of the T tubule network is such that the electrotonic depolarization becomes maximum at the T tubules located distant from the fibre surface when a sufficiently large area of surface membrane is depolarized.