bluuebunny/crossref_metadata_2025 huggingface dataset:
The flow and lipoid composition of thoracic duct lymph in the grazing cow
Authors: Hartmann P. E. , Lascelles A. K.
Published: December 2014

1. A technique is described for the collection of thoracic duct lymph from the grazing cow.

2. The effects of continuing drainage of lymph were overcome by establishing an exteriorized lymphatico‐venous shunt from which lymph and blood samples were obtained when required. The shunt functioned satisfactorily for periods of 10, 14 and 28 days in the three cows.

3. The rate of lymph flow and concentration of lipids in the lymph were low during and immediately after the operation. Higher sustained levels of flow of 1·37 ± 0·43 (
S.D.), 1·88 ± 0·40 (
S.D.) and 1·90 ± 0·45 (
S.D.) 1./hr, for the dry and two lactating cows respectively, were observed during the period 3‐9 days after the operation.

4. More than 200% of the volume and 100% of the protein of the blood plasma compartment passed through the thoracic duct each day.

5. Chlyomicron triglyceride comprised 50‐70% and phospholipid 20% of the total lipid in lymph.

6. The results indicated that at least 200 and 400 g of esterified fatty acid were transported daily in the lymph of the dry and lactating cows respectively.
The local training effect of secretory activity on the response of eccrine sweat glands
Authors: Collins K. J. , Crockford G. W. , Weiner J. S.
Published: December 2014

1. The influence of repeatedly raising the body temperature by radiant heat to a level at which acclimatization to heat is normally acquired was investigated in two series of experiments, the first without the subjects sweating, the second with sweating.

2. In a second investigation local sweat‐gland activity was induced by drug injections on successive days without raising the body temperature.

3. These experiments show that the increased sweating capacity characteristic of acclimatization to heat is a result of sweat‐gland activity and does not appear to be induced by or to depend on an elevated body temperature.

4. Secretory activity results in a loss of glycogen from sweat‐gland cells on the first day of heat exposure but not after the glands have been ‘trained’ by acclimatization to heat.

5. The state of acclimatization has no influence on the threshold concentration of acetylcholine required to elicit sweating when injected intradermally.
The placental transfer of hexoses and polyols in the guinea‐pig, as shown by umbilical perfusion of the placenta
Authors: Ely Pauline A.
Published: December 2014

1. Experiments involving polyol and sugar transfer across the guineapig placenta have been described.

2. Regarding the former, sorbitol, dulcitol and mannitol are all transferred at approximately the same rate and more slowly than meso‐inositol. Erythritol is not transferred.

3. Concerning the hexose transfers, glucose and galactose are transferred at approximately the same rate and more rapidly than fructose.

4. With regard to glucose transfer, there appears to be a mechanism with the following properties: (a) It tends towards saturation under certain conditions. (b) It favours saturation rather than diffusion kinetics for forward flows. (c) It exhibits competition with fructose and with galactose. Glucose/galactose competition has been used to demonstrate uphill transport by counterflow. (d) Competitive inhibition by phlorrhizin or phloretin could not be demonstrated.
Circulatory control in hypoxia by the sympathetic nerves and adrenal medulla
Authors: Korner P. I. , White S. W.
Published: December 2014

1. The effects of severe arterial and primary tissue (carbon monoxide) hypoxia on cardiac output, arterial and right atrial pressures, heart rate and ventilation, have been studied in unanaesthetized normal rabbits, and in animals subjected to adrenalectomy, ‘sympathectomy’ (guanethidine), adrenalectomy + ‘sympathectomy’, and section of the carotid sinus and aortic nerves.

2. In both arterial and primary tissue hypoxia the sympathetic nerves play a more important part in the normal circulatory response than the adrenal medullary hormones.

3. Provided one adrenergic effector pathway remains intact, animals with intact chemoreceptors and baroreceptors tolerate both types of hypoxia well. Circulatory control during both types of hypoxia by means of sympathetic nerves alone produces relatively more peripheral vasoconstriction than is observed during reflex control through increased adrenal catecholamine secretion.

4. The occurrence of tonic sympathetic activity in animals with section of carotid sinus and aortic nerves permits maintenance of a high cardiac output during hypoxia but the arterial pressure is low and there is probably less selective distribution of blood flow to the periphery than in animals with normal reflex control.

5. Absence of any adrenergic activity in adrenalectomized and ‘sympathectomized’ animals results in a gradual fall in cardiac output during prolonged hypoxia, after an initial small rise.

6. The results in guanethidine‐treated animals suggest that the sympathetic discharge to the arterial chemoreceptors is a factor sustaining chemoreceptor discharge during prolonged arterial hypoxia.
The dual effect of calcium on the action potential of the frog's heart
Authors: Niedergerke R. , Orkand R. K.
Published: December 2014

1. Using ventricle strips of the frog's heart stimulated at the low rate of about 1 shock/min intracellular action potentials were recorded under conditions of varying calcium concentrations.

2. Overshoots of action potentials were increased by about 18·3 mV as a result of a 10‐fold increase, within the range of 0·1‐5 m
M, of the calcium concentration.

3. A similar effect was obtained by strontium, but magnesium was ineffective.

4. The increase of the overshoot by high calcium was associated with an increased rate of rise of the potential during the later part of its ascending phase. The initial fast upstroke remained unaltered.

5. Another effect, a depression of the overshoot, developed during periods of repetitive stimulation, at the rate of 20/min, and this was followed by a gradual recovery during subsequent periods of rest.

6. The depression of the overshoot increased with increasing calcium concentrations reaching values of over 40 mV.

7. High concentrations of strontium and low concentrations of sodium also induced depression of the overshoot, but high magnesium was ineffective.

8. A tentative hypothesis has been proposed attributing these two effects: (a) to an entry of calcium through the excitable membrane thus contributing to the ionic inward current, and (b) to a resulting accumulation of calcium in some cellular store.
The preparation and properties of porcine neurophysin and the influence of calcium on the hormone‐neurophysin complex
Authors: Ginsburg M. , Jayasena K. , Thomas P. J.
Published: December 2014

1. The preparation of a hormone‐binding protein fraction (neurophysin) from porcine neurohypophyses is described.

2. It was shown by gel‐filtration that the protein (which sedimented as a single component on analytical ultracentrifugation) forms complexes with oxytocin and lysine vasopressin. The maximum capacity of porcine neurophysin to bind oxytocin and lysine vasopressin was estimated from the results of dialysis experiments as 232 u. oxytocin and 48 u. lysine vasopressin/mg protein.

3. Binding of oxytocin and lysine vasopressin by neurophysin was completely inhibited in the presence of calcium in concentrations greater than 10−6
M but is unaffected at less than 10−7
M‐Ca. The concentration of calcium required to inhibit binding did not appear to be dependent on hormone or protein concentrations.

4. No evidence was obtained that calcium was bound by neurophysin or by the peptide hormones either alone or in combination.

5. These results are discussed in the light of the hypothesis that release of the hormone from the neurohypophysis is mediated by calcium.
Contraction kinetics of striated muscle fibres following quick changes in load
Authors: Civan M. M. , Podolsky R. J.
Published: December 2014

1. The contraction kinetics of single striated muscle fibres and small fibre bundles from the frog and the toad were measured when the load was changed from P0 to L < P0. Simultaneous recordings were made of displacement at one end and force at the other end of the preparation.

2. After the load was changed, the contractile force generally reached a steady value before the contraction velocity became steady. The amount of time required for isotonic contraction to become steady depended on the change in fractional load and on the temperature; it did not depend on sarcomere length in the range 2·2‐3·0 μ or on the number of fibres in the preparation. The characteristics of the non‐steady state are described in terms of the displacement deviation (the difference between the actual displacement at a given time and the back extrapolation of the steady phase of the displacement record) and the null times (the times at which the displacement deviation became zero, measured relative to the time at which the contractile force first reached the value of the load).

3. The time average of the transient velocity was approximately equal to the final steady velocity.

4. The product of the null time following a given relative force step and Vmax, the steady velocity of unloaded contraction, was found to be independent of temperature. This is taken as evidence that the isotonic velocity transients originate in the contractile mechanism.

5. The non‐steady state following step changes in load is identified with the motion of cyclic contraction mechanisms. The motion of the specific model formulated by A. F. Huxley (1957) was compared with that of frog muscle fibres and, although the transients in the two systems differ in detail, the characteristic dimensions are of the same order.
The effects of cyclopropane, halothane and ether on central baroreceptor pathways
Authors: Biscoe T. J. , Millar R. A.
Published: December 2014

1. The reductions in arterial pressure and preganglionic sympathetic activity evoked by aortic nerve stimulation in the rabbit were studied before and during administration of constant inspired concentrations of the inhalation anaesthetics cyclopropane, halothane, and ether. The background anaesthetic was pentobarbitone, gallamine triethiodide was given, and pulmonary ventilation was with 100% oxygen.

2. During light pentobarbitone anaesthesia, aortic nerve stimulation usually induced similar reductions in arterial pressure and preganglionic discharge, expressed as the maximum percentage reduction from prestimulation levels. There were two components in the sympathetic responses, attributable to A and C fibre excitation in the aortic nerve, which was also shown to contain a third fibre group with properties similar to those of B fibres.

3. The arterial pressure, heart rate, and preganglionic sympathetic responses to aortic nerve stimulation were rapidly and profoundly inhibited by 50% cyclopropane, which also produced arterial hypertension.

4. Halothane (3%) significantly inhibited the depressor responses, but even in the presence of severe hypotension the arterial pressure could usually be further reduced by aortic nerve stimulation. The inhibitory effects of 2% halothane were slow in onset and not pronounced. In the concentrations used, these actions of halothane were significantly less than those of cyclopropane.

5. The inhibitory effects of ether on the depressor responses were roughly intermediate between those of cyclopropane and halothane; complete suppression of the responses occurred with high ether concentrations, which were also liable to cause circulatory collapse.

6. It is concluded that the three anaesthetics significantly inhibit impulse transmission through central baroreceptor pathways; the implications of the findings are discussed in relation to the different circulatory actions of these anaesthetics.
In vitro absorption of γ‐globulin by neonatal intestinal epithelium of the pig
Authors: Lecce James G.
Published: December 2014

1. An in vitro method, using fluorescent γ‐globulin and everted neonatal pig's intestinal slices, for the study of the active transport of large molecules is described.

2. Uptake of γ‐globulin occurred within 15 min and required no exogenous substrates.

3. In vitro absorption of γ‐globulin by intestinal epithelium was limited to the neonatal pig and 5‐day‐old mouse. No uptake was seen in intestines from a mature mouse, a pig with diarrhoea, a normal pig, a mature rabbit, a guinea‐pig, a chick, and a chick embryo. Chick embryo yolk sac readily took up γ‐globulin.

4. Rings of everted intestinal epithelium remained active (still absorbed γ‐globulin) after incubating for 4‐6 hr in balanced salt solution (BSS).

5. Uptake of γ‐globulin required oxygen and sodium and was reversibly inhibited by metabolic antagonists such as iodoacetate, arsenate, fluoride, 4,6‐dinitro‐ϕ‐cresol, phlorrhizin, anaerobiosis and cold. Under the conditions of the test, large colloidal molecules did not inhibit uptake of γ‐globulin.

6. Similar results (although not as clear‐cut) with metabolic inhibitors were obtained with preparations of chick embryo yolk sacs.

7. Injuring mature pig's intestinal epithelium with surface‐active agents did not produce non‐specific absorption artifacts that resembled the specific absorption found in immature pig's intestinal epithelium.
The importance of peripheral changes in determining the sensitivity of striated muscle to depolarizing drugs
Authors: Maclagan Jennifer , Vrbová Gerta
Published: December 2014

1. The sensitivity of the flexor digitorum longus and soleus muscles to depolarizing drugs was tested after cross‐union of their respective motor nerves.

2. The alien innervation did not affect the sensitivity of either the flexor digitorum longus (FDL) or soleus muscles, which retained their normal characteristic responses to decamethonium and suxamethonium. The time course of muscle contractions was, however, altered by the cross‐union operation.

3. A considerable increase in sensitivity to depolarizing drugs was shown after de‐afferentation and after tenotomy of the soleus muscles. Both these conditions are associated with muscle atrophy.

4. It is suggested that hypersensitivity to depolarizing drugs can be expected in any situation where the muscle is undergoing atrophy.
The subcellular localization of kallikrein, amylase and acetylcholine in the submaxillary gland of the guinea‐pig
Authors: Bhoola K. D. , Ogle C. W.
Published: December 2014

1. The subcellular distribution pattern of kallikrein was compared with that of amylase and acetylcholine in submaxillary gland homogenates of the guinea‐pig.

2. Kallikrein was located in particles which sedimented in the nuclear (46%) and mitochondrial (17%) fractions. These particles were probably similar if not identical to zymogen granules.

3. The above observations would support a digestive role for salivary kallikrein.
Amino acid transport in the goldfish intestine
Authors: Mepham T. B. , Smith M. W.
Published: December 2014

1. The serosal transfer of the following eight amino acids: threonine, alanine, serine, histidine, valine, methionine, phenylalanine and leucine, was measured using everted sacs of anterior intestine taken from goldfish acclimatized to 8° C and incubated at 25° C.

2. All eight amino acids were actively transported and the serosal transfer correlated with the steady potential (P < 0·001) and with the amino acid‐evoked potential (P < 0·05) measured on the same preparations.

3. The goldfish rectum actively transported alanine and the steady potential was raised when alanine bathed the mucosa of the everted preparation.

4.
L‐aspartic acid was partly transaminated to alanine by the goldfish anterior intestine; the rectum transaminated alanine to an unidentified amino acid which might have been serine, asparagine or glutamine or some mixture of these three.

5. It is suggested that
L‐amino acids increase the ease by which sodium enters the mucosal cell but that it is the rate at which this sodium is transported across the basal membrane which determines the net serosal transfer of amino acids.
The influence of diameter of medullated nerve fibres of cats on the rising and falling phases of the spike and its recovery
Authors: Paintal A. S.
Published: December 2014

1. The relation of conduction velocity, i.e. fibre diameter (Hursh, 1939a) to certain temporal dimensions of the nerve impulse recorded monophasically was studied in medullated fibres of cats in vivo at temperatures mostly ranging between 21 and 37° C.

2. Contrary to existing belief, it was demonstrated unequivocally that spike duration varies inversely with the conduction velocities of the fibres; so also the durations of the rising and the falling phases (rise‐time and fall‐time) of the impulse. The fall‐time is linearly related to conduction velocity at all recorded temperatures. The rise‐time varies steeply with conduction velocity at the lower levels of conduction rate, and very gradually at the higher conduction rates.

3. The spike duration of preganglionic sympathetic fibres is identical with that of somatic medullated fibres with similar conduction velocities. There is therefore little justification for classifying them separately as so‐called B fibres.

4. The rate of recovery of spike amplitude following a preceding impulse also varies inversely with conduction velocity, and in the same manner as the absolute refractory period (ARP). In fact the relation of time for 40% recovery of spike amplitude to conduction velocity is identical with the relation of conduction velocity to ARP. The Q10 for 40% recovery of spike amplitude is 4·7 between 13 and 29° C.

5. Rise‐time increases exponentially with fall in temperature in all medullated fibres, fast (say 64 m/sec) and slow (say 16 m/sec), the Q10 being 2·5. Fall‐time varies exponentially with temperature in slow fibres (Q10 = 3·5); in fast fibres it varies linearly. The Q10 for spike duration is the same in all fibres between 27 and 37° C only, its value being about 3·4. Below 27° C the Q10 depends on the conduction velocity of the fibres. Only in slow fibres does spike duration tend to vary exponentially with temperature.

6. Only abortive spikes are generated during the interval between the end of a preceding spike and the end of the ARP which is about 1½ times spike duration in fast fibres and about twice spike duration in slow fibres.
A gastric phase of pancreatic secretion
Authors: Blair E. L. , Brown J. C. , Harper A. A. , Scratcherd T.
Published: December 2014

1. Extracts of antral mucosa increase the output of pancreatic amylase. They do not stimulate the resting pancreas of the anaesthetized cat to secrete juice, but have a slight ‘secretin‐like’ effect on a pancreas already responding to endogenous or exogenous secretin.

2. In animals with the vagus and splanchnic nerves cut instillation of meat extracts or acetylcholine into the antrum stimulates gastric acid and pancreatic amylase secretion. These responses can be prevented by injection of atropine or cocainization of the antral mucosa.

3. In animals with the splanchnic nerves cut but the vagus nerves intact, distension of the body or antrum increases the output of amylase. After vagal section distension of the body has no effect on the pancreas, but the response to antral distension is still present.

4. It is concluded that there is a gastric phase of pancreatic secretion which, in the cat, is almost entirely a stimulation of enzyme output. A vago‐vagal reflex pathway is required for the pancreatic response to mechanical stimulation of the body of the stomach, and may be involved in the response to antral stimulation. Chemical and mechanical stimulation of the antrum produces a hormonally mediated increase in pancreatic enzyme secretion. The effects of atropine and cocaine on this response are consistent with the view that the release of the antral stimulant depends on a local cholinergic reflex pathway in the antrum.
Reflex and cerebellar influences on α and on ‘rhythmic’ and ‘tonic’ γ activity in the intercostal muscle
Authors: Corda M. , von Euler C. , Lennerstrand G.
Published: December 2014

1. Efferent intercostal α and γ activity and afferent intercostal muscle spindle activity were studied in decerebrate cats in response to stimulation of the anterior lobe of the cerebellum and to postural and other reflexes.

2. Low threshold intercostal responses were elicited from lobuli IV and V of the anterior lobe of the cerebellum.

3. The existence of two functionally different types of intercostal γ neurones has been confirmed. These are the ‘rhythmic’ or ‘specifically respiratory’ γ neurones, and the ‘tonic’ γ neurones.

4. In response to cerebellar stimulation, facilitatory, inhibitory and diphasic tetanic and post‐tetanic effects were obtained from α and the two types of γ fibres in both external and internal intercostal nerve branches.

5. Generally both inspiratory and expiratory α and γ activity was facilitated in response to tetanic stimulation at contralateral stimulus sites, and inhibited in response to stimulation of ipsilateral sites.

6. ‘Rhythmic’ γ activity appeared to be rather closely linked to the respiratory α activity but the balance between ‘rhythmic’ γ and α was often changed in response to cerebellar stimulation, as indicated by the responses of primary muscle spindle afferents.

7. The ‘tonic’ γ neurones were as a rule more responsive to cerebellar stimulation than were the α and ‘rhythmic’ γ neurones. Long‐lasting post‐tetanic effects were much more prominent in the ‘tonic’ γ fibres than in the α or ‘rhythmic’ γ fibres.

8. ‘Rhythmic’ γ activity was abolished after cervical transections of the cord. ‘Tonic’ γ activity remained in the spinal preparations although usually at a different discharge rate.

9. ‘Tonic’ γ neurones were more responsive than the ‘rhythmic’ γ neurones to the proprioceptive γ reflex elicited by passive movements of the chest wall as well as to other spinal and supraspinal reflexes.

10. Both ‘dynamic’ and ‘static’ γ fibres seem to be represented in the group of ‘tonic’ intercostal γ neurones.

11. The significance of the results are discussed with regard to the following two main points: (a) integration of respiratory and postural functions of the intercostal muscles; (b) cerebellar control of the α—γ balance in active contractions and passive relaxations.
Membrane potential and conductance during transport of sodium, potassium and rubidium in frog muscle
Authors: Adrian R. H. , Slayman C. L.
Published: December 2014

1. Muscles with high intracellular sodium concentrations can extrude sodium into solutions which contain 10 m‐equiv/l. of either potassium or rubidium. Potassium or rubidium replaces the extruded intracellular sodium. These cation movements take place equally well when the external anion is chloride or sulphate, though muscles deteriorate if left for long periods in sulphate solutions.

2. Measurements of intracellular potentials during extrusion of sodium into solutions containing potassium show:

(a) an internal potential more negative than the potassium equilibrium potential (EK); at 20° C the difference is nearly 20 mV.

(b) that a difference between the membrane potential and EK is dependent on temperature and is abolished by 10−5
M ouabain.

(c) an internal potential which becomes more negative in the presence of 0·1% cocaine, a concentration of cocaine which substantially increases the membrane resistance to potassium movement.

In the absence of potassium or rubidium no such hyperpolarization occurs.

3. When muscles extrude into solutions which contain rubidium they have internal potentials which are 10‐20 mV more negative than when extruding sodium into corresponding solutions containing potassium.

4. Measurements of electrical conductance in the potassium solution suggest that the electrochemical potential difference for potassium ions may be large enough to account for the measured inward potassium movements during sodium extrusion. The reliability of the measurements does not, however, exclude the possibility that some part of the inward potassium movement is chemically linked to outward movement.

5. Measurements of membrane conductance in solutions containing rubidium, and of net movements of rubidium in the presence and absence of ouabain, lead to the conclusion that at least 90% of the inward rubidium movement during sodium extrusion must be chemically linked to the sodium movement.

6. The hyperpolarization during extrusion of sodium could be explained on the basis of a fall of the potassium or rubidium concentration in a region of the extracellular space immediately external to the membrane. It is argued that certain characteristics of the hyperpolarization make it difficult to explain the hyperpolarization on this basis alone, though some part of it may be due to extracellular depletion of either potassium or rubidium.

The main conclusion is that the sodium pump is capable of transferring electric charge across the membrane in which it is operating, but that, in a given time, the net charge transferred is less than the charge on the sodium ions that the pump has transported, by an amount that corresponds to the charge on the potassium or rubidium ions chemically transported by the pump.
Intracellular recording from cat spinal motoneurones during acute asphyxia
Authors: Collewijn H. , Van Harreveld A.
Published: December 2014

1. Changes in membrane and action potentials of cat spinal motoneurones during acute asphyxiation and re‐oxygenation were recorded with an intracellular technique.

2. The asphyxial potential of the grey matter, which develops in the first 2‐2·5 min of asphyxiation, can be expected to interfere with the membrane potential record. After correcting for this effect a gradual depolarization of the soma at a rate of 3‐4 mV/min was found, commencing within a fraction of a minute after the start of asphyxiation.

3. The orthodromic responses of the motoneurones were the most vulnerable to O2 lack. They failed earlier than the responses to antidromic and to direct excitation of the cell through the micro‐electrode. After failure of the orthodromic spike an excitatory post‐synaptic potential remained for a short time. Failure of antidromic excitation began by the dropping out of the some dendritic potential, followed by the arrest of the initial segment response.

4. It was concluded that the early arrest of orthodromic excitation is caused by presynaptic failure.

5. All changes in membrane and action potentials were completely reversible by re‐oxygenation after periods of asphyxia lasting from 4 to 6 min. The orthodromic response recovered markedly slower than the antidromic and direct ones.
Rebound excitation of the smooth muscle cells of the guinea‐pig taenia coli after stimulation of intramural inhibitory nerves
Authors: Bennett M. R.
Published: December 2014

1. A study has been made of the increase in the rate of action potential firing in spontaneously active cells and of the initiation of action potential firing in quiescent cells of the taenia coli after stimulation of the intramural inhibitory nerves.

2. In the majority of cells which fired action potentials spontaneously at intervals of about 1 sec, stimulation of the intramural inhibitory nerves with single pulses gave an inhibitory junction potential (
I.J.P.) which was followed by action potentials which occurred at intervals as small as 0·5 sec. The increased rate of firing lasted up to 30 sec.

3. A small number of cells were either not spontaneously active or only fired action potentials at intervals greater than 5 sec. After stimulation of the intramural inhibitory nerves with either single or repetitive pulses, the quiescent cells gave
I.J.P.S which were followed by either a single action potential or a burst of action potentials.

4. The rate of firing of action potentials after an
I.J.P., and the duration of this enhanced rate of firing increased with an increase in the mean amplitude of the hyperpolarization during the
I.J.P. As the amplitude of the
I.J.P. increases with an increase in frequency of stimulation of the nerves, the rebound excitation increases with an increase in the frequency of stimulation of the inhibitory nerves.
Entry of fluorescent dyes into the sarcotubular system of the frog muscle
Authors: Endo M.
Published: December 2014

1. A fluorescence microscope was used in order to detect whether fluorescent dyes can quickly diffuse into and out of certain parts of single muscle fibres of the frog.

2. Several fluorescent dyes entered a system arranged at the centre of each I‐band without entering the main part of the fibre.

3. The dyes quickly diffused out of the fibres on washing, becoming invisible within a few minutes.

4. In a hypertonic solution the fluorescent striations were more conspicuous and faded more slowly.

5. It is concluded that the dyes have access to some component of the triads.

6. The ‘dye space’ measured with Lissamine Rhodamine B200 was 1‐2% of the fibre volume, and the implication of this value is discussed.

7. From an analysis of the time course of entry or exit of the dye it is suggested that the principal resistance to radial diffusion of the dye is distributed along the tubules rather than at the mouths of the tubules.
The effects of hypothalamic implants of ovarian steroids on oestrous behaviour in rabbits
Authors: Palka Yvonne S. , Sawyer Charles H.
Published: December 2014

1. The brains of ovariectomized female rabbits which were anoestrous in behaviour when tested with vigorous males were implanted either bilaterally or unilaterally with 10% oestradiol benzoate in cholestrol.

2. Rabbits with implants in the ventromedial‐premammillary hypothalamus ca. 1 mm lateral to the mid line became highly oestrous in behaviour within 1–2 days of implantation and mated 100% of the times tested. Implants of blank tubing, cholesterol or progesterone in this area, or oestrogen implants elsewhere in the hypothalamus had no effect on sexual behaviour.

3. The uteri of all females implanted with diluted oestrogen were atrophic and similar to those of castrate controls, indicating that the effects of hypothalamic implants on sexual behaviour were direct local effects of oestrogen on the
C.N.S.

4. Rabbits implanted bilaterally with undiluted oestradiol benzoate showed some slight systemic spread of the implanted oestrogen. Oestrous behaviour was evoked within an average of 3·4 days by implantation into a large hypothalamic area, presumably as a result of oestrogen diffusing from the site of implantation to the critical ventromedial‐premammillary region.

5. Injections of progesterone in dosages known to block oestrous behaviour in intact or oestrogen‐primed rabbits, failed to block this behaviour in females implanted with pure oestrogen in the ventromedial‐premammillary hypothalamus.

6. Implantation of progestins into the ventromedial‐premammillary area in overiectomized rabbits did not usually inhibit oestrous behaviour induced by small threshold doses of systemically administered oestrogen. The possibilities that oestrogen and progesterone (1) interact in different areas of the
C.N.S. or (2) compete for ‘steroid receptors’ in the ventromedial‐premammillary hypothalamus are discussed.
Some properties of the external activation site of the sodium pump in crab nerve
Authors: Baker P. F. , Connelly C. M.
Published: December 2014

1. Methods are described for using the changes in respiration of intact Libinia nerve to follow the rate of energy utilization by the sodium pump in this tissue.

2. Short tetani in 10 K(Na)ASW (artificial sea water in which Na is the major cation and the potassium concentration is 10 m
M) increased the oxygen uptake which then declined exponentially. From the net influx of Na during the tetanus and the associated oxygen uptake, values between 1·9 and 3·4 were calculated for the Na: ∼ P ratio. After longer tetani, the recovery curve was S‐shaped.

3. The pump was activated by potassium ions in the external medium and this activation was competitively inhibited by external sodium ions. The data are consistent with a Michaelis constant (Km) for external potassium of 1 m
M and an inhibitor constant (Ki) for external sodium of 60 m
M.

4. In activating the pump, K could be replaced by Tl+, Rb, NH4 and Cs ions; but, of the monovalent ions tested, sodium seemed to be unique in its inhibitory action.

5. In sea waters containing 460 m
M‐Na, ouabain behaved like a mixed inhibitor of the pump, reducing both the maximum velocity and the apparent affinity for external potassium. At a given ouabain concentration, reducing the sodium content of the medium was without effect on the maximum rate of pumping; but the apparent affinity for potassium increased more steeply than in a ouabain‐free solution.

6. The rate of energy utilization associated with pumping was unaffected by inclusion of quite high concentrations of sulphydryl‐blocking agents in the external medium.
Rhythmic activity in a simulated neuronal network
Authors: Andersen P. , Gillow M. , Rudjord T.
Published: December 2014

1. A digital computer has been programmed to simulate a neuronal network consisting of eighty cells with the following characteristics:

(a) All cells in the network had a set random probability of discharge when not affected by other cells. The probability of discharge was chosen as one system parameter (PD).

(b) Subsequent to the firing of any neurone in the network, a certain number of other neurones underwent a change in their probability of discharge, consisting of an inhibitory period followed by a period of increased excitability. The changes of excitability mimic the changes of the membrane potential recorded for spontaneously rhythmically active cells in the animal thalamus.

2. Starting the network, a typical transient response appeared, consisting of a burst‐like activity. The initial activity was followed, first by random fluctuations of the number of active cells, later by periods of spontaneous rhythmic activity that had several characteristics in common with the type of spontaneous activity seen in the animal thalamus.

3. The parameters which affected the rhythmic activity of the network most strongly were the degree of the post‐inhibitory increase of the probability of discharge and the degree of distribution of the inhibition to neighbouring cells.

4. The results are compatible with the inhibitory phasing theory advanced by Andersen & Sears (1964) to explain the occurrence of spontaneous rhythmic activity in the animal thalamus. However, before sufficient experimental knowledge is available, it is difficult to establish whether the rhythmic activity in the network is of the same type as that of the animal thalamus.

5. A closer study of the parameters governing the behaviour of the simulated network has given indications of some parameters to be more closely investigated in future animal experiments.
Cobalt applied to the sensorimotor area of the cortex cerebri of the rat
Authors: Dawson G. D. , Holmes O.
Published: December 2014

1. In anaesthetized rats, the area of the cerebral cortex where the electrical response to stimulation of the fore or hind paw has a minimum latency was found to bear a fairly constant relation to bony landmarks of the skull. Reasons are given for accepting the site of minimum latency as being the area most closely associated with the periphery.

2. In animals under anaesthesia, the cortical areas responding with minimum latency to fore‐ and hind paw stimulation are spatially distinct.

3. Cobalt powder has been applied to one of the two cortical areas where the electrical response to contralateral fore‐ or hind paw stimulation is a minimum. The animals have been allowed to recover and the time course of the resulting muscular jerks has been followed.

4. Jerks occur most frequently and earliest in the contralateral forelimb after the application of cobalt to the forelimb area of the cortex. When the cobalt is placed on the hind limb area, these jerks appear first and occur most frequently in the hind limb. This implies that the cortical areas most closely connected with fore and hind limbs are physiologically distinct in the absence of anaesthesia.

5. The limb jerks start to appear after 24 hr, occur with increasing frequency until the 10th day and thereafter decline. The decline in jerking is attributed to the formation around the cobalt of a connective tissue capsule.
An analysis of the transmission of excitation from autonomic nerves to smooth muscle
Authors: Bennett M. R. , Merrillees N. C. R.
Published: December 2014

1. An analysis has been made of the transmission of excitation from the hypogastric nerve to the smooth muscle cells of the guinea‐pig vas deferens.

2. Depolarization of single muscle cells with current pulses from an intracellular electrode gave local depolarizations of the cell membrane which were not propagated. The total membrane resistance after 100 msec of depolarization was 15 MΩ for depolarizations between 10 and 40 mV.

3. Depolarization of some cell membranes with a current pulse during the excitatory junction potential (
E.J.P.) decreased the amplitude of the
E.J.P. from about 10 mV at 20 mV depolarization, to nearly zero at 60 mV depolarization. In some cells the
E.J.P. was unchanged during depolarizations of 50 mV.

4. The action of transmitter on the smooth muscle cell membrane continued for the duration of the
E.J.P. Action potentials which occurred at various times during the
E.J.P. failed to remove the remaining phases of the
E.J.P.

5. It was shown that the slow time course of the
E.J.P. could not be due to the instantaneous and simultaneous release of transmitter from a number of relatively distant sources.

6. It was shown that each smooth muscle cell was innervated by several axons. The serial sections examined with the electron microscope showed that a smooth muscle had either a single axon terminating within 200 Å of the muscle or no axons terminating on it at all. Therefore transmitter must be released along the length of the axons as well as at the terminations of the axons.
S‐potentials from colour units in the retina of fish (Cyprinidae)
Authors: Naka K. I. , Rushton W. A. H.
Published: December 2014

1. S‐potentials recorded from the excised tench retina left undisturbed in the optic cup show colour cells of the two types originally described by Svaetichin & MacNichol (1958).

2. One type (green/blue, G/B) is depolarized by signals from green cones and hyperpolarized by blue cones. The other type (red/green, R/G) is depolarized by deep red and hyperpolarized by green cones.

3. By superposing spectral flashes upon steady adapting lights it is possible to find a spectral range in which only one kind of cone is effective. In this range the effect of any spectral light may be matched with that of any other provided the energies are linked in a fixed ratio that defines the action spectrum of the pigment.

4. The green pigment has an action spectrum with maximum at 540 nm and corresponds well with the pigment that Marks measured in ‘green’ cones. The blue pigment has not been measured, but it probably corresponds with that found by Marks in ‘blue’ cones. However, the red pigment whose action spectrum we measured had its maximum at 680 nm, whereas the difference spectrum of Marks's red cone pigment peaked at 620 nm. The 620 nm cones excite the luminosity S‐units but not the R/G units.

5. In the range where only one type of cone is effective the relation between the light intensity, I0, and V0, the S‐potential generated (both expressed in suitable units), is given by equation (1) p. 545. It is the relation that would be found if cone signals increased the conductance through a polarized ‘S‐membrane’ in proportion to the flux of caught quanta.
An attempt to analyse colour reception by electrophysiology
Authors: Naka K. I. , Rushton W. A. H.
Published: December 2014

1. The problem of colour reception is that we do not know the action spectra of the visual pigments involved, the nature of the signals generated nor the interaction between these signals. We only know the incident light and the electric results of interaction.

2. In Part 1 we show that S‐potentials from red/green (R/G) units saturated with deep red light show this property: added green light pulls down the ceiling of depolarization, but more added red had no power to raise it again. Thus lights that depress the deep red ceiling equally stimulate the green pigment equally. From this the action spectrum of the green pigment can be obtained.

3. If we assume that only two visual pigments are involved in the R/G unit, and that lights which do not pull down the deep red ceiling are below the threshold for green cones, then in this range only the red pigment is excited and we may obtain its action spectrum. Its maximum is at 680 nm where no visual pigment so far has been found.

4. In Part 2 we consider the following mathematical problem: ‘Is it possible that two pigments of given action spectra could combine their outputs in such a way that the resultant would be identical with the output of a third pigment of given action spectrum, for every intensity of every monochromatic light?’ The solution shows that this is always mathematically possible, and the necessary interaction function is deduced.

5. It is shown further that if the log action spectra are the ‘visual parabolas’ that resemble Dartnall's nomogram, then the interaction function is simply a linear transform such as Hartline & Ratliff (1957) have found with lateral inhibition in Limulus and Donner & Rushton (1959) with silent substitution in the frog.

6. An interaction that matches a single pigment to perfection for all monochromatic lights will not match it for certain mixtures. By this criterion the 680 nm excitability is a pigment and not the resultant of two other pigments, i.e. pigments more excitable in other spectral regions.

7. In Part 3 monochromatic lights are matched by red+green mixtures that give identical responses. From this the action spectrum of the red pigment may be obtained without involving nerve organization (except as a null detector). The result, which has one arbitrary constant, is given by the curves of Fig. 10, the continuous curve R or one of the dotted curves. Of these only curve R is acceptable.

8. Knowing the action spectra for red and green cones we may consider what signals are generated and how they interact to give the records. Figure 11 suggests a model that will account for the size and sign of S‐potentials as function of the quantum catch by the two pigments. It does not embrace the time or space parameters which can be very complex.
S‐potentials from luminosity units in the retina of fish (Cyprinidae)
Authors: Naka K. I. , Rushton W. A. H.
Published: December 2014

1. S‐potentials were recorded in fish from units which never responded by depolarization. These hyperpolarizing units are the L‐units of Svaetichin & MacNichol (1958).

2. Figure 5 shows some sets of action spectra from a single unit. For each curve the criterion of action was hyperpolarization to a fixed level, by lights of various wave‐lengths. When these lights fell upon zero background (circles) the curves show that two kinds of cone contribute to the action spectrum, one with the 620 nm pigment of Marks and one with the 680 nm pigment of Naka & Rushton (1966a).

3. When the lights fell upon (i) a fixed green background (triangles, Fig. 5), or (ii) a fixed red one (squares), the action spectra changed in a way that indicated greater prominence of (i) the 680 nm system (ii) the 540 nm green system that was not conspicuous without adaptation to red.

4. These observations (on the tench Tinca) are contrary to the conclusions of Svaetichin & McNichol (on Gerridae) that the action spectrum is unaltered in shape by adaptation to coloured lights. The contribution of the green cones, for example, was actually absolutely greater under deep red adaptation.

5. It is concluded that L‐units receive signals from 680, 620, 540 nm and possibly also the blue cones, that the quantum catch in all these contribute to the hyperpolarization produced, but their interaction is more complicated than the simple addition of independent cone effects.
Influence of testosterone upon sexual maturation in the rat
Authors: Smith W. N. Adams , Peng M. T.
Published: December 2014

1. Testosterone injected into the neonatal female rat induces permanent sterility. This study was carried out in an endeavour to determine where this change is induced.

2. Hypophysectomized, but otherwise normal, female rats bearing anterior pituitary transplants from androgen‐sterilized female rats under the median eminence of the hypothalamus and vascularized from it, show oestrous cycles in the vaginal smear, have corpora lutea in the ovaries and are fertile.

3. Hypophysectomized androgen‐sterilized female rats bearing anterior pituitary transplants from normal female rats under the median eminence and vascularized from it show persistent oestrus in the vaginal smear, have small ovaries containing large follicles but no corpora lutea and are sterile.

4. Testosterone injected into the female rat, and leading to sterility and ovarian malfunction, does not act at the level of the anterior pituitary, which retains the ability to function normally. It is considered that it may act upon the central nervous system to cause a disturbance of the gonadotrophin‐releasing mechanism.
Handling of glycerides of acetic acid by rat small intestine in vitro
Authors: Barry R. J. C. , Jackson M. J. , Smyth D. H.
Published: December 2014

1. When mono‐, di‐ and triacetins are incubated with sacs of rat everted intestine, they enter the epithelial cells and are hydrolysed to free glycerol and acetic acid.

2. The rate‐limiting step in the process is the entry of glyceride into the epithelial cell.

3. The three acetins enter the epithelial cell at the same rate, and the mechanism of this remains unknown.

4. The acetate released appears in higher concentrations on the serosal side, and the relation of this to the mechanism for transfer of volatile fatty acids is discussed.

5. It is not necessary to postulate a special mechanism for entry of volatile fatty acids into the cell.
An electrophysiological study of 5‐hydroxytryptamine receptors of neurones in the molluscan nervous system
Authors: Gerschenfeld H. M. , Stefani E.
Published: December 2014

1. 5‐Hydroxytryptamine (5‐HT) has been iontophoretically applied to the membrane of central neurones of Cryptomphallus aspersa; CILDA neurones (cells with inhibition of long duration) (Gerschenfeld & Tauc, 1964) are the only cells sensitive to 5‐HT. The responses to 5‐HT is always a depolarization. The CILDA cells studied were also depolarized by ACh.

2. From experiments in which pulses of 5‐HT and ACh were applied from a double‐barrelled micropipette to the CILDA cell soma, it has been calculated that 5‐HT and ACh receptors were located at different distances from the injecting micropipette tip. It has also been calculated from the diffusion equation that in the same CILDA cell a 5‐HT concentration of 8·2 × 10−9
M and a ACh concentration of 1·3 × 10−8
M caused a similar peak depolarization.

3. CILDA neurones show ‘anomalous’ rectification. 5‐HT increases the membrane conductance of CILDA.

4. 5‐HT receptors of CILDA neurone are desensitized by repeated application of 5‐HT. The desensitization lasts for ca. 40 sec.

5. 5‐HT receptors are blocked by lysergic acid diethylamide and its derivatives. Morphine chlorhydrate blocks them non‐competitively.

6. Some inhibitors of monoamine oxidase (trancylpromine, isocarboxazide, iproniazide and nialamide) have been tested. They do not prolong the action of 5‐HT, but block the 5‐HT receptors.

7. No crossed desensitization between 5‐HT and ACh has been observed. Atropine blocks both ACh‐receptors and 5‐HT receptors, 5‐HT receptors appear to be blocked to a greater extent.

8. The data presented support the assumption of a excitatory transmitter role of 5‐HT to CILDA neurones, but further evidence is necessary to confirm this hypothesis.