bluuebunny/crossref_metadata_2025 huggingface dataset:
The response of motor neurones to intramuscular injection of botulinum toxin
Authors: Watson W. E.
Published: December 2014

1. The dry mass and nucleic acid content of both nerve cell bodies and their nucleoli were measured by interference microscopy and ultra‐violet absorption microspectrography respectively: succinoxidase and acetylcholine hydrolase activities were also determined. Autoradiography was used to follow synthesis of deoxyribonucleic acid (DNA) by glial cells, and to follow nucleic acid and protein metabolism in muscle fibres.

2. After injection of botulinum toxin the synthesis of ribosomal RNA by the neurone followed closely the pattern found after axotomy.

3. After injection of toxin neuronal dry mass increased before the rate of ribosomal RNA synthesis was raised. This early increase, which was not due to increased protein synthesis, probably represents a ‘damming back’ of proteins within the nerve cell body.

4. After injection of toxin no local accumulation of microglial cells synthesizing DNA was found around the affected neurones: it is suggested that this reflects the intact system for intra‐axonal transport under these conditions.

5. The affected muscles show increased nucleic acid and protein synthesis.

6. It is suggested that the results obtained indicate that membrane expansion or synthesis which occurs both in muscle and in neurone under these circumstances is the factor responsible for inducing directly or indirectly the changes found in nucleic acid metabolism after injection of botulinum toxin and after axotomy.
Oxygen uptake and cardiac performance in the sheep
Authors: Brockway J. M. , McEwan E. H.
Published: December 2014

1. In four ewes no relationship was found between heart rate and oxygen consumption in response to cold stimulus; such a correlation was found in one wether sheep.

2. Direct Fick studies of cardiac output showed a significant correlation between heart output and oxygen uptake in two ewes and one wether. The relationship between stroke volume and heart rate was poor in the case of the ewes.

3. It is suggested that the 6‐month training period which the ewes had received, before the estimates were made of heart rate and oxygen consumption, was insufficient to allay emotional disturbance affecting the relationship between these parameters.
Changes in the flow and composition of the urine induced by the 18 monoacetate of D‐aldosterone, in cats
Authors: Lockett Mary F.
Published: December 2014

1. Isolated hearts release a steroid‐like substance into the blood stream when venous return is decreased. This substance very closely resembles the 18 monoacetate of
D‐aldosterone (18 MA) in physicochemical and biological properties.

2. Hence the changes in the flow and composition of the urine caused by infusions of the 18 MA have been examined in cats.

3. The threshold effect of both 18 MA and of antidiuretic hormone (ADH) may be antidiuretic, but higher concentrations of both substances usually produce diuresis in cats under chloralose anaesthesia.

4. Both ADH and 18 MA are antidiuretic in decerebrate cats.

5. In decerebrate cats and in cats under chloralose anaesthesia the renal actions of 18 MA, 0·003–0·02 μg/kg.min are abolished by hypophysectomy: responses to ADH remain unchanged.

6. 18 MA, 0·012 μg/kg.min causes the appearance of thioglycollate labile antidiuretic activity in blood taken from the terminal descending portion of the left lateral sinus.

7. 18 MA, 0·05–0·15 μg/kg.min causes diuresis followed by antidiuresis in cats under chloralose anaesthesia. Hypophysectomy abolishes the diuretic phase of the response and uncovers the short latency of the antidiuretic. The antidiuresis is accompanied by reduction in the concentration of urinary Na and a fall in the ratio Na/K of the urine.
Preserved vagal visceromotor function following destruction of the dorsal motor nucleus
Authors: Kerr Frederick W. L.
Published: December 2014

1. The dorsal motor nucleus of the vagus was destroyed in cats and after survival periods greater than 10 days, the response of the heart, bronchioles, oesophagus and duodenum to electrical stimulation of the cervical vagi was investigated. The responses obtained from the vagus ipsilateral to the destroyed dorsal motor nucleus were compared to those obtained from the contralateral vagus and with normal controls. No significant differences were demonstrable.

2. The responses obtained from stimulation of the cervical vagus following chronic intracranial rhizotomy of the IXth, Xth and XIth nerves were also examined. Visceromotor responses were abolished in three experiments and atypical responses were obtained in two experiments.

3. It is concluded that the dorsal motor nucleus does not supply the vagal fibres which produce contraction of the smooth muscle of the bronchioles, oesophagus and duodenum, and that it is not the source of the cardio‐inhibitory fibres

4. A simple method of destroying a longitudinal column of neurones is described.
Hormone‐induced modifications of free tyrosine in the rat thyroid gland
Authors: Hodge James V. , Melmon Kenneth L. , Sjoerdsma Albert
Published: December 2014

The concentrations of free tyrosine in liver, muscle, kidney and thyroid gland were determined in separate groups of rats maintained on a low iodine diet and treated with intraperitoneal injections of thyroxine (T 4), thyrotrophin (TSH) and TSH plus propylthiouracil (PTU). Groups of hypophysectomized rats also were given T 4. Significant changes in tissue tyrosine were generally confined to the thyroid gland. Animals treated with T 4 showed a decrease of mean thyroid tyrosine from 113·3 ± 17·9 (
S.D.) μg/g wet weight of gland to 76·2 ± 5·7 μg/g (P < 0·01). Although there was little change in content when TSH was given alone, a significant increase in tyrosine levels was observed when TSH plus PTU were administered (P < 0·01). In hypophysectomized rats thyroid tyrosine decreased and was further lowered (to 46·0 ± 3·1 μg/g; P < 0·05) by T 4 treatment. When tyrosine concentrations were expressed in relation to ribonucleic acid (RNA) or protein content of the assayed gland, all differences in tyrosine content became greater.
The action of chlormadinone acetate (6‐chloro‐Δ6‐dehydro‐17α‐acetoxyprogesterone) upon experimentally induced ovulation in the rabbit
Authors: Harris G. W. , Sherratt R. M.
Published: December 2014

1. The ovulation response to electrical stimulation of the median eminence, or to the intrapituitary infusion of median eminence extract, was observed in control rabbits and animals pre‐treated with chlormadinone acetate.

2. Chlormadinone acetate pre‐treatment did not significantly reduce the proportion of rabbits ovulating in response to electrical stimulation. However, there was a significant reduction in the average number of ruptured follicles when compared with the animals in the control group.

3. Chlormadinone acetate pre‐treatment significantly reduced the proportion of animals ovulating in response to the intrapituitary infusion of median eminence extract as compared with the control series. However, there was no significant reduction in the average number of ruptured follicles (in those rabbits that ovulated) when compared with the control groups.

4. Chlormadinone acetate pre‐treatment produced no significant effect upon either the proportion of animals ovulating, or the average number of ruptured follicles, following
I.V. injection of 50 μg LH.

5. The conclusion drawn is that chlormadinone acetate blocks copulattion‐induced ovulation in the rabbit by action at a site in the central nervous system located above the median eminence. The possible effects of chlormadinone acetate upon the secretion of FSH, the pituitary sensitivity to releasing factors and the ovarian sensitivity to LH are discussed.
Early changes in the forearm circulation following transient increase of local external pressure*
Authors: Foley T. H. , Greenberg J. L.
Published: December 2014

1. The pressure at the surface of a segment of forearm enclosed in a plethysmograph was abruptly raised from atmospheric level to +40 mm Hg, held at the new level for 4 sec, and abruptly dropped to atmospheric level.

2. Forearm circumference (Vf) equivalent to the volume of a small segment of forearm, was monitored with a mercury‐in‐rubber strain gauge. Pressure was measured in the cylinder (Pp) in veins exposed to external compression (Pv, e), and in the radial artery exposed to compression (Pra).

3. Forearm blood flow was measured by venous occlusion plethysmography before, and after, release of external compression. There was, on average, over the 3rd and 4th second after release of pressure, a 2·4‐fold increase of inflow, as compared with resting level.

4. By the 15th second after release of compression, forearm blood flow had returned to its previous resting level.

5. The increase in blood flow after compression appears to be due to active reduction in vascular resistance, for refilling of the arteries and arterioles would be completed before the increased flow was recorded; venous backflow can be excluded, and the pressure difference for flow (arterial minus venous) is virtually unchanged.
Post‐tetanic potentiation at the neuromuscular junction of the frog
Authors: Rosenthal Jean
Published: December 2014

1. Post‐tetanic potentiation (PTP) was studied at the neuromuscular junction of the frog. The magnitude and time course of PTP was dependent on the number of stimuli in the tetanus, rather than on the frequency or duration of the tetanus. At low temperature the maximum amplitude of PTP was unchanged, but the time course was prolonged.

2. The magnitude and time course of PTP was accounted for quantitatively by estimated changes in the fraction of transmitter released per stimulus.

3. As external [Ca] was reduced, the time for decay of PTP was decreased. The maximum amplitude of PTP, measured with respect to control amplitude at the same [Ca], was unchanged, but occurred at earlier times. The time course of PTP was dependent only on the [Ca] present during the tetanus.

4. It is concluded that PTP is associated with an intracellular accumulation of Ca during the tetanus.
The yellow colour of the lens of man and other primates
Authors: Cooper G. F. , Robson J. G.
Published: December 2014

1. Measurements have been made of the absorption spectra of the lenses of human, baboon (Papio), rhesus monkey (Macaca), squirrel monkey (Saimiri sciureus) and bush baby (Galago crassicaudatus).

2. In all these species an absorption maximum was found between 365 and 368 nm.

3. The pigment responsible for this absorption was water‐soluble and aqueous extracts were examined. Protein‐free aqueous extracts showed an additional maximum at 260 nm which could be only partially accounted for by the presence of ascorbic acid.

4. Chromatography of the protein‐free solution from human lenses yielded a fast‐moving yellow component with a blue fluorescence. Its absorption spectrum was very similar to that of the original protein‐free solution. A fast‐moving yellow component from the baboon lens had a yellow fluorescence.

5. The human lenses appeared to contain more of the yellow, water‐soluble pigment at birth than in adult life. The concentration remains constant during adult life.

6. There is evidence for the appearance of another pigment in the human lens in later adult life. It is not water‐soluble and has an absorption maximum at about 330 nm.
Termination and functional organization of the dorsolateral spino‐olivocerebellar path
Authors: Larson B. , Miller S. , Oscarsson O.
Published: December 2014

1. Pathways ascending in the lateral funiculus of the spinal cord and terminating as climbing fibres in the anterior lobe of the cerebellum have been investigated in decerebrate cats with the cord partially transected in the third cervical segment, sparing only part of the left lateral funiculus. The climbing fibre responses evoked in Purkinje cells by electrical stimulation of peripheral nerves were studied by recording from single cells and by recording the mass activity at the cerebellar surface.

2. Two pathways have been distinguished. One ascends through the dorsal part of the lateral funiculus and relays in the inferior olive. It is denoted the dorsolateral spino‐olivocerebellar path (DLF—SOCP) and forms the subject of this paper. The other path occupies in part a more ventral position in the lateral funiculus and it is not known if it relays in the inferior olive. It is denoted the LF—CF—SCP (lateral funiculus—climbing fibre—spinocerebellar path).

3. The DLF—SOCP is activated predominantly by cutaneous afferents from restricted areas in the ipsilateral paws. The relay in the spinal cord is almost certainly monosynaptic, but a long delay in the brain stem suggests that the path is interrupted by several synapses at this level. The pathway terminates in the pars intermedia in sagittal zones with a somatotopical organization (Fig. 12).

4. Components of the DLF—SOCP and the dorsal spino‐olivocerebellar path converge onto the same olivary neurones which project to the pars intermedia and it is concluded on this evidence that the DLF—SOCP also relays in the inferior olive.

5. The DLF—SOCP is compared with the other known spinocerebellar paths terminating as climbing fibres in the anterior lobe. The functional role of these paths and the general significance of the sagittal projection patterns are discussed.
The catecholamine content of hypothalamic nerve cells after acute exposure to cold and thyroxine administration
Authors: Lichtensteiger Walter
Published: December 2014

1. In female rats, the intensity of the catecholamine fluorescence was determined in nerve cells of the arcuate and periventricular hypothalamic nuclei by means of a microfluorimetrical technique which is based on the fluorescence method of Falck & Hillarp. Frequency distributions were established by grouping the nerve cells according to their fluorescence intensity which was referred to that of a noradrenaline standard.

2. When rats were exposed to a cold environment (4° C) on dioestrous day 1, the frequency distribution of relative fluorescence intensity was shifted towards classes of higher fluorescence intensity within 10 min. The mean relative fluorescence intensity and the symmetry of the distribution did not change further during the next 20 min.

3. The change in the frequency distribution was almost completely prevented by
L‐thyroxine (50 μg/kg) administered 3 hr before exposure to cold.

4. The direction of the cold‐induced change in the frequency distribution is interpreted as reflecting an increase in neuronal activity. Since it was observed in nerve cells which belong to catecholamine‐containing tubero‐infundibular neurones, it might be related to the release of thyrotropin. Differences in the frequency distributions of the anterior and posterior tuberal regions are discussed with regard to possible functional implications.
The use of [125I]polyvinyl pyrrolidone K. 60 in the quantitative assessment of the uptake of macromolecular substances by the intestine of the young rat
Authors: Clarke Rufus M. , Hardy R. N.
Published: December 2014

1. A method has been developed which allows the quantitative estimation of the uptake of labelled polyvinyl pyrrolidone (PVP) of mean mol. wt. 160,000 (K. 60) by the wall of the small intestine of young rats.

2. Four hours after feeding a standard dose of [125I]PVP by stomach tube, the small intestine was thoroughly washed out, and the radioactivity of the intestinal wall measured. Under these conditions, the small intestine of animals less than 18 days old took up more than 50% of the radioactivity which had left the stomach. There was no increase in PVP uptake if the duration of absorption exceeded 4 hr. The PVP was taken up by the epithelial cells of the villus, and its intracellular localization has been demonstrated by fluorescence microscopy and can be related to vacuolation in the cells.

3. In animals between 18 and 20 days old the uptake of PVP declined progressively, until, in animals more than 20 days old, less than 5% of the radioactivity was taken up by the intestinal wall.

4. There is good agreement between the reported age of termination of antibody absorption in young rats and the age at which PVP uptake ceased in the present experiments. It is suggested that the loss of ability of the intestine to take up substances of high mol. wt. may be the factor which limits the duration of the period of antibody absorption in this species.
Radial spread of contraction in frog muscle fibres
Authors: Adrian R. H. , Costantin L. L. , Peachey L. D.
Published: December 2014

1. The membrane potential of isolated muscle fibres in solutions containing tetrodotoxin (TTX) was controlled with a two‐electrode voltage clamp. The striation pattern in the region of the electrodes was observed microscopically.

2. With square steps of depolarization of increasing magnitude, contraction occurs first in the myofibrils just beneath the surface membrane, and then spreads inwards towards the axis of the fibre as the depolarization is increased.

3. From the depolarizations which make the superficial and axial myofibrils contract it is possible to estimate a space constant (λT) for electrotonic spread in a transverse tubular network.

4. λT was found to vary with fibre radius; for a 50 μ fibre it was about 60 μ. λT was not greatly affected by tetraethylammonium (TEA) chloride (111 m
M), or by sucrose substitution of most of the sodium chloride in the Ringer solution.

5. The ratio of the depolarization threshold for contraction of surface myofibrils and of central myofibrils was smaller for short (3 msec) than for long depolarization.

6. Action potentials, recorded from a sartorius fibre, were used as the command signal for the voltage‐clamped fibre in tetrodotoxin. The central myofibrils of this fibre did not appear to contract unless the imposed ‘action potentials’ were of normal size.

7. The passive electrical characteristics of the transverse tubular system will just allow an action potential, at room temperature, to activate the myofibrils at the centre of a frog muscle fibre. An active potential change would be required to achieve a safety factor appreciably greater than one for this process.
The mechanical properties of cat soleus muscle during controlled lengthening and shortening movements
Authors: Joyce G. C. , Rack P. M. H. , Westbury D. R.
Published: December 2014

1. By supplying pulses to different subdivisions of the ventral nerve roots in rotation, it was possible to obtain smooth contractions of cat soleus with low rates of stimulation.

2. After contracting isometrically the muscle was subjected to constant velocity lengthening or shortening movements.

3. During shortening the tension always fell below the isometric value. The fall in tension was usually greatest when low rates of stimulation were used.

4. The effect of lengthening on tension depended on the rate of stimulation. At high rates of stimulation the tension during lengthening always rose above the isometric tension. At lower rates of stimulation (5–15 pulses/sec) the tension rose at the beginning of an extension, but decreased later in the movement to a level that was often less than the isometric tension corresponding to that muscle length. At these stimulus rates the tension during isometric contraction was usually higher than during a sustained movement in either direction.

5. At low rates of stimulation longitudinal vibratory movements of more than 0·1 mm also reduced the tension far below the isometric value, whereas the reduction was quite slight when the rate of stimulation was high.

6. The isometric tension during smooth contractions at low stimulus rates was remarkable in the following respects: it developed rather slowly, it was higher than the tension during or immediately after movements, and it was only slowly regained after movement had ceased.

7. The results are discussed in relation to the sliding filament theory of muscle contraction, which, with certain assumptions, provides an explanation for many of the findings.
The clearance and antidiuretic potency of neurohypophysial hormones in man, and their plasma binding and stability
Authors: Fabian Miriam , Forsling Mary L. , Jones J. J. , Pryor J. S.
Published: December 2014

1. Bio‐assay techniques have been used to measure plasma levels of neurohypophysial hormones in man, following either a single injection or a continuous infusion.

2. The median half‐life of oxytocin after a single injection of 2 u. was 3·2 min (2·0–5·7, 95% confidence limits); this increased significantly (P < 0·01) to 4·8 min (4·4–6·1) when the hormone was infused at a rate of 500 m‐u./min. The vasopressins had appreciably longer half‐lives. After a single injection of 1 or 1·5 u. 8‐lysine vasopressin (LVP), the half‐life was 5·7 min (3·6–6·0). Continuous infusions of the hormones at a rate of 120 m‐u./min yielded half‐lives of 5·5 min (5·0–7·1) for LVP, and 5·6 min (3·9–9·5) for 8‐arginine vasopressin (AVP).

3. The apparent volumes of distribution of the hormones were all of the order of two thirds the extracellular volume.

4. In accordance with its shorter half‐life, the clearance of oxytocin was greater than that of the vasopressins (1·5 l./min, compared with 1·0 l./min).

5. The antidiuretic potencies of the hormones were studied in over‐hydrated subjects, by measuring the rate of urine excretion following an
I.V. injection. Duration of antidiuretic action increased in the order: oxytocin, LVP, AVP. A 5:1 mixture of oxytocin and AVP was not as long‐lasting as AVP alone. 8·5% (4–22) of an administered dose of AVP was excreted in the urine, and this amount was significantly correlated with urine volume (r = +0·67, P < 0·05).

6. Ultrafiltration of human plasma containing exogenous hormones showed that 30% (13–50) of AVP was bound, the degree of binding being independent of concentration over the range used (50–400 μ‐u./ml.) In contrast, oxytocin was completely unbound.

7. Exogenous oxytocin was more stable than exogenous AVP in human plasma. At 4° C there was no significant loss of oxytocin until 7 days, whereas 20% of AVP was inactivated in 2 days. At 37° C a 20% loss of AVP occurred within 4 hr, and a 50% loss within 24 hr; corresponding times for oxytocin were 24 and 48 hr.
Nerve‐mediated excitation and inhibition of the smooth muscle cells of the avian gizzard
Authors: Bennett Terence
Published: December 2014

1. The electrical events evoked in smooth muscle cells of the chick and pigeon gizzards by vagal, perivascular sympathetic and transmural stimulation were recorded with intracellular micro‐electrodes.

2. Single stimulating pulses applied to the extrinsic nerves, or to intrinsic fibres, produced excitatory junction potentials (E.J.P.s) which were blocked by hyoscine. Repetitive stimulation caused facilitation of E.J.P.s and, at higher frequencies, summation. When the tissue was well oxygenated, maximal stimulation evoked action potentials and the tissue contracted. If the tissue was allowed to become anoxic, action potentials were blocked and thus junctional transmission could be observed uncomplicated by tissue contraction.

3. Cholinergic E.J.P.s appeared to be due to stimulation of both post‐ganglionic neurones and the pre‐ganglionic input to post‐ganglionic neurones, since ganglion‐blocking drugs abolished the late phase of complex E.J.P.s while leaving unaffected their initial components.

4. Repetitive perivascular sympathetic stimulation, after cholinergic E.J.P.s had been blocked by hyoscine, evoked a slow, long‐lasting depolarization of the muscle cells. This depolarization was blocked by guanethidine (5 × 10−6 g/ml.) and was mimicked by noradrenaline (10−7 g/ml.).

5. Under non‐anoxic conditions, the tissue underwent rhythmical contractions which were associated with action potential firing. When the tissue was anoxic action potentials were not seen, but spontaneous membrane depolarizations resembling E.J.P.s were observed. Spontaneous miniature excitatory junction potentials (M.E.J.P.s) were observed only infrequently whether the tissue was well oxygenated or not.

6. Single stimulating pulses applied to extrinsic or intrinsic nerves frequently evoked inhibitory junction potentials (I.J.P.s) in smooth muscle cells of the gizzards of both birds. I.J.P.s were blocked by tetrodotoxin (10−7 g/ml.). Repetitive stimulation of inhibitory nerves gave rise to a membrane hyperpolarization; when stimulation was stopped the membrane potential showed rebound depolarization.

7. These results are discussed in terms of the autonomic innervation of the avian gizzard, and possible explanations of the various types of activity observed are considered.
Fat metabolism and heat production in young rabbits
Authors: Hardman M. J. , Hey E. N. , Hull D.
Published: December 2014

1. The rates of oxygen consumption were measured in 6–8‐day‐old rabbits at 34 and 15° C after varying periods of starvation and cold exposure. At the start of the experiment the rabbits had been fasted for 24 hr. Eight rabbits were studied immediately, six after 24 and six after 48 hr in a cold environment (20° C), and twelve after a further 48 hr in a warm environment (34° C). All the animals had a similar increase in oxygen consumption during the final hour of cold exposure (15° C).

2. The rabbits kept at 20° C lost 83% of the fat stored in their brown adipose tissue within 24 hr and a further 11% in the next 24 hr. The fat content of white adipose tissue had fallen by 75% at 48 hr. In contrast rabbits kept unfed at 34° C had lost 47% of the fat in brown adipose tissue and 44% of the fat in white adipose tissue after 48 hr.

3. In six rabbits subcutaneous thermocouples demonstrated that local heat production continued in brown adipose tissue after 48 hr cold exposure.

4. In the rabbits kept at 34° C the final cold exposure caused a large increase in the serum free fatty acid and glycerol concentrations. Much lower concentrations were found in rabbits kept at 20° C.

5. The results show that the fat stored in the brown adipose tissue of young rabbits exposed to cold is preferentially used for heat production. When this store of fat is exhausted, brown adipose tissue still produces heat presumably by oxidizing fat and glucose taken from the circulation.
Calcium and potassium currents of the membrane of a barnacle muscle fibre in relation to the calcium spike
Authors: Hagiwara Susumu , Hayashi Hideo , Takahashi Kunitaro
Published: December 2014

1. The behaviour of membrane currents in a giant muscle fibre of a certain barnacle Balanus nubilus, Darwin, was studied by using voltage clamp technique after treating fibres with a Ca‐chelating internal solution.

2. Membrane currents can be classified into an early transient current and a late outward current.

3. The early transient current can be considered a sum of an inward and an outward component of different properties.

4. A conditioning depolarization suppresses the inward component but not the outward component.

5. Procaine suppresses the outward component and Co ions suppress the inward component.

6. Changes in the external Ca ion concentration alter the inward component but not the outward component.

7. The inward component is considered to be carried by Ca ions and the outward component mainly by K ions.

8. The outward component of the early current is similar to the current expected from the resting membrane conductance.

9. It is concluded that the early conductance increase of the barnacle muscle fibre membrane occurs only to Ca ions but not to K ions, although the membrane potential at the peak of spike is determined by both ions.
The preferential release of newly synthesized transmitter by a sympathetic ganglion
Authors: Collier B.
Published: December 2014

1. The acetylcholine (ACh) store of cat's superior cervical ganglia was replaced with radioactive ACh by perfusion, during stimulation, with [3H]choline—Locke solution. Perfusion was continued with Locke containing unlabelled choline (Ch) (in physiological concentration) and the release of labelled and unlabelled ACh was measured.

2. Electrical stimulation of the preganglionic sympathetic nerve (20/sec or 5/sec), or stimulation by perfusing with raised K, released ACh that had a lower specific radioactivity than ganglionic ACh. The proportion of released ACh that was labelled was slightly higher when stimulation was at lower frequency or by K.

3. Preganglionic nerve stimulation released, in the first few minutes, ACh that had a specific activity 70–80% of ganglionic ACh, but after 5 min the proportion of label in the released ACh fell to 35–45% of that in the ganglion.

4. It is concluded that newly synthesized ACh is released before equilibration with preformed stores, and the significance of this to the mechanism of transmitter release is discussed.
The delayed pressor response to small doses of intravenous noradrenaline in conscious rabbits
Authors: de Swiet M. , Dickinson C. J.
Published: December 2014

1. Noradrenaline, infused intravenously at low rates into conscious rabbits, can sustain a moderate elevation of blood pressure of 20–40 mm Hg. The most effective dose range is 0·1–0·5 μg.kg−1.min−1.

2. Toxic manifestations and tachyphylaxis occur at higher infusion rates, but have also been seen at infusion rates within this range.

3. The highest sustained rise of blood pressure was obtained after initially low infusion rates had been gradually increased over a period of 2‐4 weeks.
A study of chemoreceptor and baroreceptor A and C‐fibres in the cat carotid nerve
Authors: Fidone S. J. , Sato A.
Published: December 2014

1. 149 A‐fibres and 52 C‐fibres from the cat carotid nerve were studied in vivo with single‐unit recording techniques. These units subserved chemoreceptor and baroreceptor modalities. In addition, half of the C‐fibres were determined to be efferent in origin. The estimated fibre diameter spectrum for chemoreceptor and baroreceptor A‐fibres is described.

2. The discharge pattern of chemoreceptor A and C‐fibres was characteristically irregular both at rest and during activation. However, about 5% of the chemoreceptor A‐fibre population exhibited a very regular discharge pattern, even at low rates of firing.

3. In comparing A and C‐fibres, it was found that chemoreceptor and baroreceptor A‐fibres had lower thresholds, shorter response latencies, more rapid acceleration of discharge and higher discharge frequencies than their C‐fibre counterparts.

4. During strong chemoreceptor or baroreceptor stimulation, interaction of the ‘spontaneous’ whole nerve activity with the evoked A and C‐fibre compound action potentials provided a method of estimating the relative proportions of chemoreceptors and baroreceptors in the A and C‐fibre populations of the carotid nerve. The A‐fibre population was found to be comprised of approximately 2/3 chemoreceptors, 1/3 baroreceptors. The reverse was true for the C‐fibre population, i.e. 2/3 baroreceptors, 1/3 chemoreceptors.

5. A stepwise C‐fibre response is described which may arise from the several C‐fibres within a single Schwann cell.
Enzymic properties of myosin in fast and slow twitch muscles of the cat following cross‐innervation
Authors: Buller A. J. , Mommaerts W. F. H. M. , Seraydarian Krikor
Published: December 2014

1. Following cross‐innervation of the cat flexor digitorum longus muscle (
F.D.L., fast‐twitch) and soleus muscle (slow‐twitch) the isometric twitch speed of the
F.D.L. muscle decreases while the contraction time of soleus increases. The tetanus—twitch ratio of soleus is also increased.

2. Myosin or myofibrils from normal or self‐reinnervated fast‐twitch muscles of the cat split adenosine triphosphate (ATP) more rapidly than myosin or myofibrils from slow twitch muscles.

3. Following cross‐innervation the myosin and myofibrillar ATPase activity of flexor digitorum longus muscle falls, to become nearly equal to that of normal or self‐reinnervated soleus muscle. The ATPase activity of cross‐innervated soleus muscle increases only slightly.
Polymerizing equilibria in neurophysin
Authors: Burford G. D. , Ginsburg M. , Thomas P. J.
Published: December 2014

1. Evidence for the occurrence of a rapidly polymerizing equilibrium system in freshly prepared aqueous solutions of porcine neurophysin has been obtained by frontal and zonal analysis of gel‐filtration elution patterns.

2. Elution volumes increased with decreasing protein concentration and derivative analysis of fronts suggested the existence of different polymerizing forms varying in relative proportion with protein concentration.

3. In the presence of lysine vasopressin, the results suggested a shift of the equilibrium in favour of higher polymerizing forms.

4. In the presence of Ca2+ elution patterns became characteristic of a monodisperse system of relatively high molecular weight. The effect of Ca2+ did not survive removal of the ion and was not reproduced by Mg2+.

5. Evidence for a slowly developing polymerization of neurophysin in aqueous solution has been obtained in experiments with solution prepared 24 hr before subjection to gel‐filtration.

6. A model is proposed for the description of the binding of lysine vasopressin to porcine neurophysin.
Transmission from vasoconstrictor and vasodilator nerves to single smooth muscle cells of the guinea‐pig uterine artery
Authors: Bell Christopher
Published: December 2014

1. Previous studies have shown that perivascular nerve stimulation of the uterine artery of the guinea‐pig evokes an adrenergic constrictor response and a dilator response with two components. The first of these, only present during pregnancy, is cholinergic. The second is non‐cholinergic and is present at all times. Intracellular recording from single smooth muscle cells in isolated arterial segments has now been used to investigate the transmission processes associated with these responses.

2. The mean resting membrane potential of the muscle cells was 60·7 mV in arteries from both virgin animals (range 50–68 mV) and from animals in late pregnancy (range 48–76 mV).

3. Low frequency perivascular stimulation evoked excitatory junction potentials (EJPs) which reached a maximum amplitude of about 5 mV, lasted about 900‐1000 msec, and showed facilitation at frequencies of stimulation of 0·1 Hz or above and summation at frequencies of stimulation of 1·2 Hz or above.

4. These EJPs were abolished by exposure of the tissue to bretylium (2 × 10−6 g/ml.). It is therefore concluded that the EJPs were due to transmission from adrenergic nerves.

5. Perivascular stimulation at frequencies above 10 Hz evoked a depolarizing response which was often surmounted by a small (5 mV) local spike potential. Such depolarizing responses were associated only with localized contractions of the arterial muscle.

6. In the presence of low extracellular K+ concentrations, perivascular stimulation at frequencies above 10 Hz gave rise to a depolarizing response topped by an action potential of up to 50 mV amplitude, and more generalized contraction of the tissue than was seen in normal K+ solution.

7. After blockade of the adrenergic vasoconstrictor fibres, no response to perivascular stimulation was observed normally. However, following moderate depolarization of the membrane with noradrenaline, stimulation evoked a hyperpolarization of up to 6 mV in amplitude.

8. This response showed no discrete junction potentials, had a latency of up to 2000 msec and was only observed with stimulation at frequencies of 2 Hz or greater. The response was obtained in both pregnant and non‐pregnant animals, and was unaffected by hyoscine, but was abolished by cinchocaine.

9. No changes in membrane potential attributable to transmission from cholinergic dilator nerves could be revealed in arteries from pregnant animals. Furthermore, high concentrations of acetylcholine had no polarizing effect on the muscle cells. It is suggested that the cholinergic dilator nerves may not act via changes in membrane potential.
A reconsideration of the Poisson hypothesis for transmitter release at the crayfish neuromuscular junction
Authors: Bittner G. D. , Harrison J.
Published: December 2014

1. Transmitter release from excitor nerve terminals in the crayfish opener muscle was studied with both intra‐ and extracellular electrodes.

2. The amplitude distribution of quanta recorded extracellularly from a single release site did not fit the compound Poisson hypothesis in two thirds of the data sets.

3. Some data appeared to be non‐Poisson because specific quantal multiples were released; the non‐Poisson nature of release for other sets could be due to variable invasion of the axonal spike into the terminal region.

4. In some muscle fibres, the number of quanta released at one ending to any given impulse in a stimulus train was correlated with the number of quanta released at other endings on the same fibre. This suggests that such endings may be supplied by nerve twigs arising from a common branch point with a very low safety factor for transmission.

5. No consistent relationship was found between the amplitudes of the intra‐ and extracellular spontaneous potentials recorded from the same muscle fibre.
The difference in sensitivity to cardiac steriods of (Na+ + K+)‐stimulated ATPase and amino acid transport in the intestinal mucosa of the rat and other species
Authors: Robinson J. W. L.
Published: December 2014

1. The effect of various cardioactive steroids on the activity of a microsomal (Na+ + K+)‐activated ATPase from rat intestinal mucosa has been studied and compared with their effects on
L‐phenylalanine and
D‐galactose transport by rings of rat intestine in vitro. A similar comparison between the sensitivities to ouabain of microsomal (Na+ + K+)‐ATPase and of phenylalanine transport in the intestines of the mouse, guinea‐pig and toad has been made.

2. The rat intestinal enzyme is 50% inhibited by a concentration of 1 × 10−4
M ouabain, 1 × 10−5
M scillaren A and 4 × 10−6
M scilliroside. At concentrations which almost completely inhibit the (Na+ + K+)‐ATPase activity, these steroids have no effect on the transport of phenylalanine or galactose by the rat intestine. Only at concentrations of 1 × 10−3
M are scillaren A and scilliroside able to reduce phenylalanine accumulation significantly, the same concentration of ouabain being effective only in the absence of external potassium ions. Digitoxin, 1 × 10−4
M, a comparatively apolar glycoside, had no action on phenylalanine transport in the rat intestine.

3. The effect of ouabain on the (Na+ + K+)‐ATPase and phenylalanine transport system in the mouse intestine is completely analogous to its effect on these parameters in the rat.

4. A half‐maximal inhibition of guinea‐pig intestinal (Na+ + K+)‐ATPase by ouabain occurs at an inhibitor concentration of 2 × 10−6
M, but phenylalanine transport by this tissue is only half‐maximally reduced at a concentration of 3 × 10−5
M. Similarly, in the rabbit intestine, there appears to be a difference of an order of magnitude between the sensitivities of the two parameters.

5. In the toad, 50% inhibition of the enzymic activity is observed at a concentration of 3 × 10−5
M ouabain, whereas a concentration of 8 × 10−4
M is required to reduce phenylalanine accumulation by one half.

6. These findings are consistent with the suggestion that an (Na+ + K+)‐stimulated ATPase is not the only enzyme in the epithelial cells of the intestinal mucosa that is responsible for sodium extrusion (the mechanism for sodium extrusion being intimately coupled with the mechanism for active amino acid transport); therefore, a second, as yet unidentified, enzyme system must be postulated to account for bulk sodium flow through the intestine.
Synthesis, storage and release of [14C]acetylcholine in isolated rat diaphragm muscles
Authors: Potter L. T.
Published: December 2014

1. Segments of rat diaphragms were kept in choline‐free media for 4 hr and were then exposed to a physiological concentration of [14C]‐choline (30 μ
M) at 37° C. The synthesis, storage and subsequent release of [14C]acetylcholine by the muscles was assessed by isotopic‐ and bio‐assays after isolation of the transmitter by paper electrophoresis.

2. Replacement of endogenous acetylcholine (0·92 μ‐mole/kg) with labelled acetylcholine proceeded slowly at rest, but rapidly during nerve stimulation. [14C]Acetylcholine accumulated most rapidly when hydrolysis of the released transmitter, and thus the re‐use of endogenous choline, was prevented by an esterase inhibitor. Fully replaced stores were maintained during nerve stimulation by synthesis rates sufficient to replenish at least 35% of the store size in 5 min.

3 In the presence of hemicholinium‐3, which inhibits choline uptake, acetylcholine stores declined rapidly during stimulation, and residual synthesis was slight, indicating little intraneural choline. Net choline uptake into nerve terminals was estimated from the highest observed synthesis rate and from previous measurements of the number and size of terminals, as 3‐6 p‐mole/cm2 sec.

4. Transmitter synthesis was localized in the region of end‐plates, and was reduced to a few per cent of normal 6 weeks after phrenic nerve section. Release experiments suggested that at least half of the acetylcholine in phrenic nerves is in their terminals; from this content and the morphology of the terminals, the average concentration of transmitter in the whole endings would appear to be about 50 m‐mole/l. Homogenization of the muscles freed choline acetyltransferase into solution, but left some [14C]acetylcholine associated with small particles, presumably synaptic vesicles.

5. Resting transmitter release was about 0·013% of stores/sec. With 360 nerve impulses at 1‐20/sec, release increased up to 0·43% of stores/sec, and amounted to 3·5–7 × 10−18 moles per end‐plate per impulse. The release rate was unaffected by the doubling of store size which occurred with eserine, but the extra transmitter did help to maintain releasable stores during prolonged stimulation. Experiments with fractional store labelling indicated that newly synthesized acetylcholine was preferentially released.

6. Preformed [3H]acetylcholine was not taken up and retained by muscle or nerve cells in the absence of an esterase inhibitor. With eserine present, labelled acetylcholine was taken up uniformly by muscle segments; when eserine was then removed, radioactive acetylcholine remained only near neuromuscular junctions.
The dorsal nucleus of the vagus as a centre controlling gastric motility in sheep
Authors: Howard B. R.
Published: December 2014

1. A preparation is described for investigating the central nervous control of gastric motility in decerebrate decerebellate sheep.

2. The dorsal vagal nucleus has been electrically stimulated in thirty decerebrate sheep, and the effect on the mechanical responses of the different parts of the reticulo‐rumen have been determined.

3. In the absence of recurrent rhythmic gastric contractions, punctate electrical stimulation of the dorsal vagal nucleus did not elicit gastric contraction until the intensity of stimulation was sufficiently high to excite efferent vagal fibres.

4. Direct stimulation of the vagus nerve, or of motor fibres running from the nucleus to this nerve, always caused contraction of the reticulum, and dorsal and ventral ruminal sacs.

5. Electrical stimulation of certain points within the medulla oblongata, during rhythmic gastric motility, inhibited motility for one or more contraction cycles. These inhibitory points lay on a line commencing at the mid‐point of the dorsal vagal nucleus, and extending forward and ventral to this.

6. Excitatory responses were less frequent, and were seen along a line running parallel to, but about 1 mm below, the anterior half of the line of maximum inhibition. They usually followed a period of inhibition, were generally shorter in duration, and consisted of a series of small reticular contractions at a rate of about 1/10 sec.

7. The presence of a powerful inhibitory influence on the dorsal vagal nucleus, mediated from an area lying anterior to the nucleus, is argued and its probable action at the level of the gastric motor nucleus is discussed.
The development of the metabolic response to thyroxine in the new‐born pig
Authors: Kaciuba-Uscilko Hanna , Legge K. F. , Mount L. E.
Published: December 2014

1. Rectal temperature and the rate of oxygen consumption in the new‐born pig were measured following the subcutaneous injection of
L‐thyroxine.

2. Thyroxine stimulated oxygen consumption during the post‐natal period; both immediate and latent increases were observed.

3. The immediate effect occurred after thyroxine, 80 μg/kg, in suckled pigs aged 1‐11 days; it was most marked at about 1‐4 days of age with a peak increase (20%) in oxygen consumption and a rise in rectal temperature at about 4 hr following the injection.

4. The peak increase (30%) in oxygen consumption associated with the latent effect of three successive daily injections of thyroxine, 300 μg/kg, occurred at 5‐7 days of age, whether the pigs were first injected at 1 or at 4 days of age.

5. It is concluded that there is a high sensitivity to thyroxine in the pig during the first week after birth, when the hormone is not bound to plasma proteins to the same degree as in the older animal.
Reflex inhibition of monosynaptic reflexes by stimulation of type J pulmonary endings
Authors: Deshpande S. S. , Devanandan M. S.
Published: December 2014

1. Monosynaptic reflexes, evoked from flexor and extensor hind limb muscle nerves in cats anaesthetized with pentobarbitone sodium, were depressed for several seconds after right intra‐atrial injection of phenyl diguanide. Injection of the drug close to the aortic valves did not produce the same effect on the reflex. There was no obvious depression of polysynaptic reflexes on intra‐atrial injection of phenyl diguanide.

2. This depression of the monosynaptic reflex was present even after the administration of atropine, which lessened the hypotension due to phenyl diguanide. The blood gas tensions were also measured after the administration of phenyl diguanide, and were not altered to a degree where one would expect the depression to be secondary to a change in arterial gas tensions. The depression was also present in paralysed and artificially ventilated cats.

3. The afferent pathway causing this depression of the monosynaptic reflex runs in the vagus nerve, as shown by experiments done before and after vagotomy. Intercollicular decerebration also abolished this inhibition of the monosynaptic reflex.

4. Prior intravenous injection of strychnine (0·1 mg/kg) abolished the effect of intra‐atrial administration of phenyl diguanide.

5. It was concluded that stimulation of type J pulmonary endings causes a reflex inhibition of monosynaptic reflexes lasting for several seconds via regions of the brain cephalad to the intercollicular level.