bluuebunny/crossref_metadata_2025 huggingface dataset:
Release of endogenous serotonin from two identified serotonin‐containing neurones and the physiological role of serotonin re‐uptake
Authors: Hamon M. , Gerschenfeld H. M. , Paupardin-Tritsch Daniele
Published: December 2014

1. The amounts of endogenous serotonin (5‐HT) released into the medium by the cerebro‐buccal ganglionic ring of Aplysia californica incubated in artificial sea water (ASW) were measured. The rate of spontaneous 5‐HT release varied between 0·4 and 1·2 p‐mole per hour, which is less than 1% of the total 5‐HT present in this preparation.

2. Direct stimulation of the ordinarily silent 5‐HT‐containing giant cerebral neurones resulted in a 80‐100% increase of the 5‐HT released, but only when the 5‐HT uptake was blocked by chlorimipramine (1‐10 μ
M).

3. High K+ media (50 m
M) also caused a significant increase in the amount of 5‐HT released from the preparation provided that chlorimipramine (1‐10 μ
M) was present in the incubation fluid.

4. Co2+ ions (10‐30 m
M) added to the incubating medium blocked the spontaneous leak of endogenous 5‐HT as well as the release, in the presence of chlorimipramine, evoked either by stimulation of the 5‐HT‐giant cerebral neurones or high K+‐media.

5. In the presence of chlorimipramine or desmethylimipramine, the duration and/or the amplitude of the excitatory or the inhibitory synaptic potentials evoked in the buccal neurones by the stimulation of the 5‐HT giant cerebral neurones were markedly enhanced.

6. These results strongly support the idea that 5‐HT is the synaptic transmitter released at the excitatory and inhibitory junctions established by the 5‐HT giant cerebral neurones in the ipsilateral buccal ganglia. In addition, they underline the role of amine re‐uptake in the physiological inactivation of 5‐HT as a transmitter.
Electrical properties of neurones in the olfactory cortex slice in vitro.
Authors: Scholfield C N
Published: December 2014

1. Slices of guinea‐pig olfactory cortex were maintained in vitro. Electrical properties of neurones in the prepyriform region were studied using single high resistance glass micro‐electrodes filled with potassium acetate, connected to a resistance‐compensating circuit to allow passage of current through the electrode. 2. Neurones showed a high, stable resting membrane potential (75.4 +/‐ 2.7 mV, mean +/‐ S.D.; n = 47). Input resistance measured with small depolarizing currents varied over a range of 9‐280 Momega. The time constant for decay of depolarizing potentials was 19.4 +/‐ 7.5 msec (mean +/‐ S.D.).. 4. Depolarization produced repetitive action potentials (maximum frequency of 85 Hz) having peak amplitudes of +16 to +47 mV. The action potential was followed by a depolarizing after potential of about 20 mV positive to the membrane potential. 5. In these and other respects, the prepyriform neurones appear to behave like most other neurones in the mammalian brain, after allowing for the more stable recording conditions in this preparation.
Deficient influence of peripheral stimuli on precentral neurones in monkeys with dorsal column lesions.
Authors: Brinkman J , Bush B M , Porter R
Published: December 2014

1. Four male monkeys (M. fascicularis) were trained in a movement performance task which involved pulling a horizontal lever into a target zone and then collecting, from one of a variety of positions, a small food reward. The same animals were also trained to sit quietly and accept passive manipulation and natural stimulation of the arm and hand while remaining relaxed. 2. After complete bilateral section of the cuneate fasciculi or division of a major part of these dorsal column afferents at C1‐C2 or at C5 level, the animals were still able to perform movement tasks normally. Disturbance of discrimination ability was revealed after vision was occluded it the animal was required to detect differences in texture with only a small cutaneous area in contact with the object (e.g. using only the tip of the index finger). Contactual‐placing reactions could be performed in the absence of vision and the movements the animal made in these reactions were well controlled and appropriately directed. Minimal disturbance of contact placing was noticed if the surface touched was on the hand or fingers or if the reaction involved crossed placing. 3. An examination of the natural discharges of 342 percentral neurones revealed that the patterns of activity exhibited in relation to complex movements were indistinguishable from patterns recorded in normal monkeys carrying out similar tasks. 4. Discharges of ninety‐one of 321 precentral neurones could be produced by appropriate natural stimuli delivered within the cell's afferent input zone at the periphery. The zone from which a given cell could be influenced was usually limited and its location could be on any part of the contralateral forelimb. However, all but nine of these responses were found in animals in which a small proportion of the cuneate fibres remained intact. In an animal with histologically proven complete section of the cuneate faciculi very few (nine of 171) precentral neurones were influenced by natural activation of peripheral receptors in the forelimb. The zones from which these few afferent inputs were found could all have been proximal to the level of the cuneate lesion. 5. The very small number of responding pre‐central neurones found in an animal with complete section of the cuneate fasciculi made it likely that the dorsal columns provide the major pathway for effects from circumscribed peripheral receptors in the forelimb to influence precentral neurones. However, even in an animal with complete interruption of cuneate fibres, a proportion of post‐central neurones could still be influenced by natural activation of peripheral receptors within restricted regions of the forelimb. Hence the 'sensory' cortex was still in receipt of afferent projections which could be revealted readily by the tests used. 6...
Morphology and organization of axon collaterals from afferent fibres of slowly adapting type I units in cat spinal cord.
Authors: Brown A G , Rose P K , Snow P J
Published: December 2014

1. The morphology of the collaterals of single axons innervating Type I slowly adapting receptors was studied by using the intra‐axonal injection of the enzyme horseradish peroxidase in anaesthetized cats. The axons were impaled near their dorsal root entrance zone in the lumbosacral cord. The morphology was revealed by subsequent histochemistry. 2. Thirteen Type I axons were stained, nine with receptors in the hairy skin and four with receptors in the glabrous foot pad skin. Twelve axons could be traced back into their dorsal roots and 11 of these divided into rostral and caudal branches shortly after entering the spinal cord. 3. One hundred and twelve collaterals were given off the thirteen axons and all well filled collaterals had a similar morphology. In the dorsal horn they gave rise to wide elliptical areas of terminal arborization (in transverse sections of cord) that were limited to laminae III, IV and the dorsal part of lamina V. The terminal arborizations of collaterals from the same axon were in line in the saggittal plane, but only rarely did the terminal arborizations of adjacent collaterals overlap; usually there was a gap between adjacent terminal arborizations. 4. Synaptic boutons of Type I units from hairy skin were mainly of the "en passant" variety whereas those of Type I units from glabrous skin were generally "boutons terminaux" with very few boutons "de passage". 5. The morphology of axon collaterals of Type I units is compared with that of hair follicle units.
The representation of facial temperature in the caudal trigeminal nucleus of the cat.
Authors: Dostrovsky J O , Hellon R F
Published: December 2014

1. In cats anaesthetized with urethane, extracellular micro‐electrode recordings were made in the marginal layer of the trigeminal nucleus caudalis between the level of the obex and the Cl rootlets. 2. Nearly 300 neurones were found whose discharge rate increased with a reduction of facial temperature and a few which were excited by an increase in temperature. Over half of the neurons in each group were specifically sensitive to temperature and the remainder had a weak input from mechanical stimulation of the face. 3. Thermal receptive fields were all ipsilateral and found most frequently on the nose, lips, lower eyelid and pinna. There was a somatotopic organization of the receptive fields according to the three divisions of the trigeminal nerve. 4. On quantitative thermal testing, the neurones showed responses which were similar to those of the skin temperature sensors. 5. The thermal neurones could be antidromically fired by a stimulating electrode in the thalamus.
The effects of nerve growth factor and its antiserum on synapses in the superior cervical ganglion of the guinea‐pig.
Authors: Njå A , Purves D
Published: December 2014

1. The effects of nerve growth factor (NGF) and its antiserum on synapses in the superior cervical ganglion of the guinea‐pig have been examined by intracellular recording and electron microscopy. 2. Exogenous NGF, supplied locally from a silicone rubber pellet implanted near ganglia for 4‐7 days, had little effect on either the function or the number of ganglionic synapses. 3. However, the depression of synaptic transmission and loss of synaptic contacts on ganglion cells which follow post‐ganglionic axotomy were diminished by about 50% in the presence of exogenous NGF. 4. Other post‐axotomy changes such as the development of subthreshold regenerative responses in neuronal processes, the appearance of ultrastructurally abnormal neuronal profiles suggesting rapid membrane turnover, and the cytoplasmic and nuclear changes characteristic of "chromatolysis", were also largely prevented by exogenous NGF. 5. Systemic treatment of neonatal and young adult guinea‐pigs with antiserum to NGF for 4‐5 days caused depression of intracellularly recorded synaptic responses within 5‐8 days of the end of antiserum administration. Synapse counts in electron microscopical sections from these ganglia showed only about half as many contacts as in control ganglia from animals receiving normal rabbit serum. 6. These findings suggest that the loss of synapses from sympathetic neurones which follows axotomy results from a reduction in the amount of NGF supplied to ganglion cells. A corollary is that, among other biological roles, NGF is required by peripheral sympathetic neurones to maintain the synapses they receive.
Axonal conduction velocity and voluntary discharge properties of individual short toe extensor motor units in man.
Authors: Borg J , Grimby L , Hannerz J
Published: December 2014

1. The axonal conduction velocity and the voluntary discharge properties of 120 short toe extensor motor units were studied in man. 2. Electromyographic techniques were used which permitted the identification of individual motor unit potentials after proximal and distal electrical nerve stimulation and during maximum voluntary effort. 3. The necessary selectivity of the e.m.g. recordings was achieved in two circumstances. In some subjects, previous motor nerve lesions distal to the point of stimulation had led to collateral sprouting with larger motor unit potentials. In other subjects an accessory deep peroneal nerve was present, so that lidocaine block of the main motor nerve left a small number of innervated motor units. 4. The axonal conduction velocities of the individual motor units ranged from 30 to 54 m/sec with most motor units between 35 and 45 m/sec. 5. Motor units which voluntarily could be driven continuously at frequencies below 10/sec had axonal conduction velocities between 30 and 45 m/sec. 6. Motor units which on voluntary drive responded only in high frequency bursts had axonal conduction velocities between 40 and 54 m/sec. 7. Motor units with intermediate voluntary discharge properties had intermediate axonal conduction velocities. 8. Thus a relationship was established between voluntary discharge properties and axonal conduction velocity.
Mechanisms of functional recovery and regeneration after spinal cord transection in larval sea lamprey.
Authors: Selzer M E
Published: December 2014

1. Large sea lamprey larvae, close to metamorphosis, regained swimming coordination after several weeks following complete spinal cord transection. Recovery was much faster when animals were kept at 23 than at 12 degrees C. 2. The behavioural recovery involved a regenerative mechanism in the spinal cord, since stimulation of the head resulted in tail curling, even when all tissue other than spinal cord and notocord was stripped away for several cm above and below the transection. 3. Following complete behavioural recovery, stimulation of the rostral cord evoked electrical signals recorded from the cord dorsum for only 10 mm below the transection. 4. Dorsal cells and giant interneurones, which normally project to the brain, could not be antidromically activated across the transection zone. However, giant interneurones could be activated polysynaptically by descending volleys. 5. Twelve of eighteen large reticulospinal axons followed in serial sections regenerated across the glial‐ependymal scar, but branched abnormally and migrated away from their customary locations. They became smaller, and were finally lost within 4 mm of the centre of the transection zone. 6. These data suggest that behavioural recovery does not involve long axon tract regeneration. An alternate hypothesis, that short distance sprouting of axons across the transection zone may result in synapse formation with propriospinal interneurones which relay the necessary information, is discussed.
Dark‐adaptation in abnormal (RCS) rats studied electroretinographically.
Authors: Perlman I
Published: December 2014

1. Electroretinogram (e.r.g.) responses recorded from dark‐reared rats with inherited retinal dystrophy (RCS) showed progressive decline in b‐wave ampliture and prolongation of the time to the peak of the b‐wave with age when compared with records obtained from dark‐reared normal albino rats. 2. Dark‐adaptation was followed in RCS and normal rats by recording the light intensity needed to evoke a criterion e.r.g. response at different time intervals after bleaching and 90% of the rhodopsin. 3. In normal rats, dark‐adaptation was governed by two mechanisms. The first 25‐‐35 min of recovery was determined by cones. The second branch, determined by the recovery of rods, lasted for about 3 hr and proceeded along an exponential time course with time constant of 41.4 +/‐ 2.4 min (S.E. of mean). 4. In RCS rats, the time course of the dark‐adaptation after a 90% bleach depended on age. In 25‐‐30 day old rats the recovery curve had at least three breaks separating three different mechanisms. Rats, 35‐‐40 days old, exhibited double exponential recovery curves, while 45‐‐70 day old rats recovered along a single exponential curve similar in time course to the cone branch of dark‐adaptation found in normal rats. 5. Action spectra obtained from RCS rats at different time intervals of the recovery curve showed that in young rats, 25‐‐30 days old, small e.r.g. responses recorded before bleaching and at the end of the recovery period were determined by rhodopsin while those recorded during the first part of the recovery from 90% bleach were determined by a combination of rods and cones. In RCS rats of advanced age (45‐‐70 days old), rhodopsin was the major contributor to the e.r.g. responses recorded either before bleaching or at the end of the recovery period. 6. The gradual deterioration with age of the e.r.g. in RCS rats cannot be explained by either the decrease in quantum catch due to the decrease in rhodopsin content or by the linear relationship between log e.r.g. threshold and pigment concentration. 7. Using estimates of rhodopsin density within surviving rods obtained from retinal densitometry, it was shown that in RCS rats where more than 30% of normal levels of rhodopsin was located within the functioning rods, the log intensity needed for a criterion e.r.g. response measured at the end of the recovery period from a 90% bleach was linearly related to the fraction of 'functional' rhodopsin. 8. No simple relationship between log e.r.g. threshold and rhodopsin concentration could be found during the course of recovery in the dark from a strong bleaching exposure in RCS rats of all ages.
Asymmetry of the hexose transfer system in human erythrocytes. Comparison of the effects of cytochalasin B, phloretin and maltose as competitive inhibitors.
Authors: Basketter D A , Widdas W F
Published: December 2014

1. Cytochalasin B inhibits glucose transfer in human red cells. With glucose exit the inhibition is typically non‐competitive, but hexose exchange is competitively inhibited. 2. At 16 degrees C the inhibitory constant for inhibition of 3‐O‐methyl glucose exchange is estimated at 1.1 X 10(‐7) M while that for inhibition of glucose exit is 5.0 X 10(‐7) M. 3. Uptake of labelled Cytochalasin B includes a saturable component which when correlated with the inhibition of exchange corresponds to a maximal binding of ca. 2.4 X 10(5) molecules per cell. 4. The kinetic parameters are compared with those for maltose (a competitive inhibitor acting on the outside only) and phloretin (an inhibitor acting both inside and out). 5. Kinetic evidence suggests that Cytochalasin B reacts with the inside of the hexose transfer system and that the anomalous inhibitory characteristics are due to the chemical asymmetry of the system. Independent evidence in support of this view is discussed.
Oxygen consumption and neonatal sleep states
Authors: Stothers J. K. , Warner Ruth M.
Published: December 2014

1. In thirty full‐term infants in the first week of life, nursed in a constant volume, closed‐circuit metabolism chamber in a neutral thermal environment (31·5‐33·5 °C), measurements were made of oxygen consumption (V̇O2) during periods of rapid eye movement (REM) sleep and non‐rapid eye movement (NREM) sleep.

2. The mean V̇O2 during REM sleep was 5·97 ml. kg−1. min−1. In NREM sleep the mean V̇O2 was 5·72 ml. kg−1. min−1. This difference was significant (paired t test P < 0·05).

3. When the direction of sleep state change was taken into account the difference in V̇O2 between the two states was much less when REM sleep preceded NREM than when the change was in the opposite direction. In nineteen infants in whom the change was from REM to NREM the difference in V̇O2 (6·18 and 6·03 ml. kg−1. min−1) was not significant (P > 0·05). The mean difference when the sleep state change was from NREM to REM was significant (P < 0·01), the values being 5·54 and 5·81 ml. kg−1. min−1 respectively.

4. In the NREM state, a gradual diminution of V̇O2 with time was consistently found. This was not the case in REM sleep.

5. In twelve infants studied in a cool environment (29 ± 0·5 °C) V̇O2 during REM sleep was 7·77, and during NREM sleep it was 6·58 ml. kg−1. min−1, (P < 0·001). Thus even the maximum difference found in a neutral thermal environment of 6·6% was significantly increased to 14·9% (P < 0·01) with mild thermal stress.

6. No consistent changes in V̇O2 with time were found in either REM or NREM sleep in twelve infants studied in a cool environment, in contrast to the findings in thermal neutrality
Exogenous prostaglandins and gastric secretion in the cat.
Authors: Baker R , Jaffe B M , Reed J D , Shaw B , Venables C W
Published: December 2014

1. In the conscious gastric fistula cate PGE2 was shown to produce dose‐related inhibition of gastric acid and pepsin secreted in response to pentagastrin, histamine and insulin. 2. PGF2alpha had little effect on pentagastrin‐stimulated gastric acid and pepsin secretion. 3PGF2 delayed the tachyphylaxis of gastric acid stimulated by pentagastrin and histamine, but not that stimulated by insulin. 4. Although not delaying tachyphylaxis of insulin stimulated acid, PGE2 delayed tachyphylaxis of insulin stimulated pepsin.
Synaptic delay in the heart: an ionophoretic study.
Authors: Hill-Smith I , Purves R D
Published: December 2014

1. Neurotransmitters were applied ionophoretically to spontaneously beating clusters of ventricular muscle cells cultured from neonatal rats. 2. Acetylcholine or its analogue carbachol produced hyperpolarization and decreased the rate of spontaneous beating. These responses had minimum latencies of about 250 msec and total durations of 6‐12 sec. 3. Noradrenaline, adrenaline or isoprenaline increased the rate of spontaneous beating. The minimum latency for this effect was 3‐6 sec. Following a single brief pulse the rate remained elevated for 2 min or more. 4. Chronotropic responses of intact atria from adult rats to stimulation of the autonomic nerves were of similar time course to responses of the cultured muscle cells. 5. Calculations based on the theory of diffusion showed that access of drugs to their receptors could not be rate‐limiting for the observed responses, unless a diffusion barrier of rather special properties was postulated. A number of other explanations for the long latencies have been ruled out; these are most likely to be due to some physical or chemical process occurring in or under the cell membrane. 6. Attempts to mimic responses to catecholamines by intracellular application of cyclic AMP were unsuccessful, perhaps because the release of nucleotide from the pipettes was insufficient. A theoretical treatment suggests that ionophoretic efflux of anions might be greatly diminished by the opposing electro‐osmotic flux.
Modulation of canine antral circular smooth muscle by acetylcholine, noradrenaline and pentagastrin.
Authors: el-Sharkawy T Y , Szurszewski J H
Published: December 2014

1. The effects of acetylcholine, noradrenaline and pentagastrin on the action potential of canine antral circular muscle were determined using the intracellular micro‐electrode technique. 2. Acetylcholine increased the amplitude and duration of the plateau potential of the action potential. Since these effects were blocked by atropine but not by hexamethonium, the effects of acetylcholine were on muscarinic receptors, probably located on the smooth muscle cell. 3. Pentagastrin 2 x 10(‐10) M increased the size of the plateau potential and the frequency of the action potential; pentagastrin 1 x 10(‐9) M increased the frequency of the action potential complex and produced a marked diastolic depolarization between action potentials. The effect on the size of the plateau potential was biphasic. The amplitude and half‐time duration of the plateau potential increased in the first 3 min, but thereafter, during steady‐state conditions, they were the same as or slightly greater than those obtained in Krebs solution. 4. All the effects produced by pentagastrin were due to a direct action on the smooth muscle cell. 5. Noradrenaline decreased the size of the plateau potential but increased its frequency; high concentrations (greater than 10(‐5) M) additionally produced a diastolic depolarization between action potentials. These effects were mediated primarily by alpha‐adrenoceptors presumably located on the smooth muscle cell. 6. It was concluded that the substances studied primarily alter the size of the plateau potential in antral circular muscle. Since phasic contractions are associated with the plateau potential, it is suggested that agents which increase the size of the plateau potential increase the force of the contraction whereas agents which decrease the size of the plateau potential have the opposite effect.
Pentobarbitone pharmacology of mammalian central neurones grown in tissue culture.
Authors: Barker J L , Ransom B R
Published: December 2014

1. The effects of the barbiturate anaesthetic pentobarbitone on the membrane properties and amino acid pharmacology of mammalian C.N.S. neurones grown in tissue culture were studied using intracellular recording coupled with bath application, extracellular ionophoresis, or focal diffusion. 2. The addition of an anaesthetic concentration of pentobarbitone to the bathing medium abolished all spontaneous synaptic activity, but did not render individual cells electrically inexcitable nor prevent evoked synaptic acitivity. 3. Focal ionophoresis of pentobarbitone or diffusion from blunt micropipettes reversibly increased membrane conductance, effectively dampening excitability without directly affecting individual action potential characteristics. 4. Pentobarbitone‐induced membrane conductance was reversibly blocked by picrotoxin. The inversion potential of the pentobarbitone voltage response depended on Cl‐ ion gradients and was similar to that of GABA. 5. Pentobarbitone reversibly enhanced the conductance increase produced by GABA with a variable slowing of response kinetics, shifting GABA dose‐response curves to the left. Responses to glycine and beta‐alanine were not affected. 6. Higher ionophoretic currents of pentobarbitone, which measurably increased membrane conductance, attenuated and markedly slowed GABA responses. Similar effects on GABA responses were observed by superimposing GABA pulses on low level GABA currents. 7. Pentobarbitone, in the absence of an increase in membrane conductance, reversibly depressed depolarizing responses to glutamate without changing response kinetics. Slower responses to acetylcholine which were associated with an apparent decrease in membrane conductance were not affected by the drug. 8. Analysis of double‐reciprocal plot data suggested a non‐competitive type of antagonism between pentobarbitone and glutamate. Pentobarbitone depression of glutamate was not affected by picrotoxin. 9. Both GABA and glutamate responses appeared to be equally sensitive to pentobarbitone. Specific interaction of the drug with amino acid receptor‐coupled events is indicated by the requirement for pentobarbitone pipette placement close to the amino acid response site. 10. The results suggest that pentobarbitone depresses neuronal excitability by (1) directly activating post‐synaptic GABA‐receptor coupled Cl‐ conductance, (2) potentiating post‐synaptic GABA‐induced conductance events, probably at the level of the GABA receptor, and (3) depressing post‐synaptic glutamate‐induced excitation, probably at the level of the conductance mechanism.
Free water clearance curves during saline, mannitol, glucose and urea diuresis in the rat
Authors: Martinez-Maldonado Manuel , Opava-Stitzer Susan
Published: December 2014

1. Free water clearances were measured during infusion of hypotonic saline, glucose, urea, and mannitol in Brattleboro rats. For each solute the free water clearances were plotted using either V or (CH2O + CNa) as the distal tubular delivery term.

2. In all cases the use of (CH2O + CNa) as distal delivery term yielded a steeper relationship than when V was used. There were no significant differences in the CH2O to V relationship when saline, glucose and mannitol was the solute infused. Urea, however, resulted in a curve with a slope significantly less than that for the other solutes.

3. When CH2O was plotted against (CH2O + CNa) there was still no significant difference between the slopes of the curves during saline or mannitol infusion. Use of this delivery term, however, resulted in a slope during glucose infusion which was significantly greater than that during saline or mannitol infusion. The slope for urea infusion remained lower than that for any other solute.

4. Regardless of the delivery term used, there was no significant difference in the slopes of the curves for awake Wistar and awake Brattleboro rats during mannitol infusion. This indicates that the awake rat is a suitable model for free water clearance studies.

5. The results indicate that NaCl and mannitol are both adequate for free water clearance and that (CH2O + CNa) is a better index of distal delivery than V.
Role of calcium ions in transient inward currents and aftercontractions induced by strophanthidin in cardiac Purkinje fibres.
Authors: Kass R S , Lederer W J , Tsien R W , Weingart R
Published: December 2014

1. Under the influence of strophantidin, Purkinje fibres exhibit transient inward current (TI) which contributes to arrhythmogenic activity. Voltage‐clamp experiments were carried out to study the role of Ca ions in this phenomenon. 2. The amplitude of TI varied directly with the extracellular Ca concentration, CaO. Magnesium ions had an antagonistic effect. 3. TI was closely associated with a phasic increase in force ("aftercontraction"). Like TI, the aftercontraction was evoked by a preceding action potential or by the break of a strong depolarizing pulse. 4. TI and the aftercontraction displayed similar wave forms although peak current preceded peak force by 50‐‐100 msec. Both transients were enhanced by increasing the strength or duration of the preceding depolarization pulse. Both events were slowed as the potential level following the pulse was displaced in the negative direction. 5. TI and the aftercontraction could be evoked in the absence of cardiotonic steroids by strongly elevating CaO. 6. Additional experiments were carried out to test the hypothesis the TI reflects an influx of Ca2+ ions. Moninhibited TI but the developed and removal of the inbibition lagged far behind the effects on the slow inward current. 7. TI could be suppressed and eventually inverted by varying the membrane potential in the positive direction. The inversion potential averaged ‐5mV and was not consistent with a Ca‐specific pathway. The aftercontraction was more closely related to the phasic conductance change underlying the current than to thecurrent flow itself. 8. The results are consistent with the idea that an oscillatory release of Ca from an intracellular store is the primary event underlying both the aftercontraction and the conductance change which generates TI. Digitalis intoxication or very high CaO may promote such events by elevating intracellular Ca levels.
Evidence for the maintenance of motoneurone properties by msucel activity.
Authors: Czéh G , Gallego R , Kudo N , Kuno M
Published: December 2014

1. Electrophysiological properties of soleus motoneurones in adult cats were examined with intracellular electrodes following alterations of activity of the soleus muscle induced by transection of the thoracic spinal cord or by conduction block of the muscle nerve with tetrodotoxin (TTX) cuffs. Attempts were also made to maintain muscle activity by daily stimulation of the maintain muscle activity by daily stimulation of the peripheral nerve. 2. Within 8 days after transection of the thoracic cord, soleus motoneurones showed a significant decrease in the duration of afterhyperpolarization following action potentials. This change in motoneurone properties induced by cord transection was prevented by daily stimulation of the sciatic nerve. 3. Soleus motoneurones showed a significant decrease in the duration of after‐hyperpolarization within 8 days after conduction block of the soleus nerve with TTX. This change in montoneurone properties was prevented by daily stimulation of the nerve peripheral to the TTX cuff but not central to the cuff. 4. The soleus muscle showed a significant decrease in weight relative to body weight within 8 days after transection of the thoracic cord. This decrease in muscle weight following cord transection was prevented by daily stimulation of the sciatic nerve. 5. No fibrillation was detected in the soleus muscle 8 days after conduction block of the soleus nerve with TTX. The maximum twitch tension of the soleus muscle evoked by nerve stimulation showed no significant difference between the two sides treated and untreated with TTX. Fast axoplasmic transport measured with cholinesterase as a marker was not affected by TTX. Thus, there was no sign of functional although morphological abnormalities were found in some nerve fibres. 6. It is concluded that motoneurone properties in an adult depend partly upon some factors associated with activity of the innervated muscles and that such trophic signals are retrogradely carried by the motor axons.
An alpha‐adrenergic receptor mechanism controlling potassium permeability in the rat lacrimal gland acinar cell.
Authors: Parod R J , Putney J W
Published: December 2014

1. Rat lacrimal gland slices, incubated in a balanced, buffered salt solution, were found to be physiologically stable for up to 2 hr with respect to O2 consumption, extracellular space, and water and ion content. 2. The release of 86Rb serves as a good substitute for 42K in monitoring the movement of K through the cell membrane. 3. Adrenaline appears to increase membrane permeability to K as evidenced by an increase in the rate of 86Rb efflux. 4. This response to adrenaline was blocked by phentolamine but not by propranolol and was mimicked by phenylephrine but not by isoprenaline. 5. The magnitude of the 86Rb release indicates that it is being released, at least in part, from the lacrimal gland acinar cell. 6. It is concluded that the lacrimal gland acinar cell has an alpha‐adrenergic receptor, activation of which leads to an increase in membrane permeability to K.
The interactions of protons, calcium and potassium ions on cardiac Purkinje fibres.
Authors: Brown R H , Cohen I , Noble D
Published: December 2014

1. In sheep Purkinje fibres, acidosis shifts the steady‐state current‐voltage relation in an inward direction over a wide range of negative potentials. The reversal potential for iK2 is shifted in a positive direction. These changes are consistent with K+ accumulation in the extracellular spaces of the Purkinje fibre. 2. These effects of acidosis are completely prevented by increasing [K]0 from the normal range (2.7‐‐5.4 mM) to 10.8 mM. 3. Increasing [Ca]0 from 2 to 6 mM also produces an inward shift in the steady‐state current‐voltage relation and a positive shift of the iK2 reversal potential. 4. In 10.8 mM‐[K]0 these effects are absent even when [Ca]0 is increased to 20 mM. 5. One possible explanation is that K+ ions may protect the Na pump from inhibition by protons and Ca2+ ions. Alternative explanations are also discussed.
Electrophysiology of the afferent innervation of the penis of the domestic ram.
Authors: Cottrell D F , Iggo A , Kitchell R L
Published: December 2014

1. The discharge of impulses in afferent fibres dissected from the dorsal nerve of the penis of chloralose‐anaesthetized rams was recorded electrophysiologically during controlled natural stimulation of the surgically exposed penis maintained at body temperature and mechanically stabilized in a plaster of Paris mould. 2. Fifty‐eight slowly adapting mechanorecptor units were examined and their pressure, velocity and displacement thresholds were determined. Units often responded best to integumental stretch. Few had resting discharges. During a sustained perpendicularly applied displacement most units adapted to silence within 1.5 min. The units were classified into types from an analysis of their adapted impulse trains in response to a sustained mechanical stimulus. 3. Twenty‐five mechanoreceptive units had rapidly adapting responses. Most units had typical rapid adapting characteristics and discharged impulses only during the dynamic phase of the application of the displacement. A subgroup had intermediate adapting characteristics, and discharged intermittently during steady displacement of the integument. 4. The mechanical sensitivity of most receptors altered when the temperature of the receptive field was changed with a positive correlation in eleven units, a negative correlation in six. Six slowly adapting units were thermally insensitive. Twelve rapidly adapting units were tested. Six had a positive thermal correlation and four a negative correlation. 5. The conduction velocities of axons of mechanoreceptor units in the dorsal nerve of the penis were in the Aalpha range (12‐‐77 msec‐1). 6. Two specific warm and five specific cold units were found. The conduction velocities of the axons supplying warm receptors were 45.4 msec‐1 (one unit) and those for cold receptors were 7.5, 7.8, 30, 45.5, 48.7 msec‐1. 7. No correlation could be found between the receptor submodality and the profuse receptor end bulb population demonstrated histologically.
Microvascular pressures and filtration coefficients in the cat mesentery.
Authors: Fraser P A , Smaje L H , Verrinder A
Published: December 2014

1. Filtration coefficient and hydrostatic pressure have been measured in single capillaries and venules in the cat mesentery using a modification of the Landis (1927) single vessel occlusion technique. 2. Venules were found to be filtering fluid, not absorbing it as is often supposed. 3. The mean filtration coefficient in capillaries was 0.018 micrometers . s‐1 . mmHg‐1 (1.35 X 10(‐10)m . s‐1 . Pa‐1) while that in venules, was 0.027 micrometers . s‐1 . mmHg‐1 (2.02 X 10(‐10)m . s‐1 . Pa‐1). 4. In both capillaries and venules, filtration coefficient increased with decreasing pressure. 5. The difference between directly measured venular pressure and that calculated from the occlusion data was used to determine the contribution of the interstitium to fluid exchange. In the mesentery superfused with Krebs solution the tissue pressure so determined was found to be zero or subatmospheric initially but became increasingly positive with lengthening exposure of the mesentery.
Receptive field integration and submodality convergence in the hand area of the post‐central gyrus of the alert monkey.
Authors: Hyvärinen J , Poranen A
Published: December 2014

1. An exploration of the occurrence of different functional cell types was made in the three cytoarchitectural subdivisions (areas 3, 1 and 2) of the hand area of the post‐central gyrus of the monkey. The functional properties of 632 cells were studied using the transdural micro‐electrode recording method. 2. Over half of the neurones studied (57%) belonged to the class of simple skin neurones that were related either to rapidly adapting (272 neurones) or slowly adapting (seventeen neurones) cutaneous receptors or to both (seventy‐one neurones). The simple skin neurones were particularly common in the anterior part of S I where they constituted 60% of the cells. More complicated cutaneous neurones made up 10% of the total sample. They were more common in the posterior part of the gyrus. 3. Altogether ninety‐two neurones (15%) were related to subcutaneous or deeper receptors. Another seventy‐one neurones (11%) exhibited convergence of skin input and input from deep receptors. A smaller group of forty‐seven undamaged neurones (7%) were unrelated to stimuli of the types described above. 4. In tangential electrode penetrations made along the anterior and posterior banks of the gyrus, functional columns were found to be 500 micrometers wide on the average; this width is comparable with that of ocular dominance columns and visual orientation hypercolumns. 5. Correlation of the functional types of cells with cytoarchitecture showed that the complexity of the functional properties of the neurones increased posteriorly. The receptive field size also increased toward posterior. The changes that take place in the functional properties of cells when moving across different cytoarchitectural areas suggests intracortical information processing which leads to handling of larger body regions and more complex combinations of information in the cellular elements of the posterior part of the post‐central gyrus.
Graded synaptic transmission between local interneurones and motor neurones in the metathoracic ganglion of the locust.
Authors: Burrows M , Siegler M V
Published: December 2014

1. In the metathoracic ganglion of the locust some neurones can effect changes in the membrane potential of identified post‐synaptic motor neurones without themselves spiking. 2. These 'non‐spiking' neurones have processes only within the metathoracic ganglion, and therefore are local intraganglionic interneurones. 3. The absence of spikes in the interneurones reflects their normal physiological state and is not due to the experimental conditions. 4. When the interneurones are depolarized by the injection of current pulses lasting several hundred milliseconds, post‐synaptic motor neurones are either depolarized, or hyperpolarized, for the duration of the pulse. 5. The magnitude of the change in post‐synaptic voltage is graded according to the amount of presynaptic current. 6. A number of physiological tests indicate that the graded effects upon motor neurones are mediated by chemical synaptic transmission. For example, an evoked hyperpolarization of a motor neurone can be reversed in polarity by simultaneously hyperpolarizing the motor neurone with injected current. 7. At their resting potential some interneurones tonically release sufficient transmitter to have a measurable post‐synaptic effect. The injection of depolarizing and hyperpolarizing currents into these interneurones effects opposite changes in post‐synaptic potential. 8. Other interneurones must be depolarized from resting potential before a post‐synaptic effect is observed, and hyperpolarizing currents have no post‐synaptic effect. In these interneurones it is estimated that a depolarization of only 2 mV is sufficient to effect the release of transmitter. 9. The membrane potentials of non‐spiking interneurones can fluctuate by as much as 15 mV during active movements of the hind legs and individual p.s.p.s as large as 5 mV can be recorded. Therefore, summed p.s.p.s or even single ones are expected to be the electrophysiological signals effecting transmitter release from these interneurones.
Adaptation to abrupt time shifts of the oscillator(s) controlling human circadian rhythms.
Authors: Mills J N , Minors D S , Waterhouse J M
Published: December 2014

1. Thirty‐six subjects in an isolation unit were subjected to time shifts of 12 hr, or of 8 hr in either direction. 2. The rhythms of body temperature and excretion of eight urinary constituents were studied before and after the shift, both on a usual nychthemeral routine and during 24 hr when they remained under constant conditions, awake, engaged in light, mainly sedentary activity, and consuming identical food and fluid every hour. 3. The rhythms on nychthemeral routine were defined by fitting cosine curves. On constant routine the rhythm after the shift was cross‐correlated with the original rhythm, either with variable delay (or advance) or with an additive mixture between this variably shifted rhythm and the unshifted or a fully shifted rhythm. The process yielding the highest correlation coefficient was accepted as the best descriptor of the nature of adaptation. 4. A combination of two rhythms was observed more often for urinary sodium, chloride and phosphate than for other variables. 5. Adaptation appeared to have proceeded further after westward than eastward shifts, and this difference was particularly noticeable for urinary potassium, sodium and chloride. 6. Partial adaptation usually involved a phase delay, even after an eastward shift when a cumulative delay of 16 hr would be needed to achieve full adaptation and re‐entrainment. 7. Observations under nychthemeral conditions often gave a false idea of the degree of adaptation. In particular, after an eastward shift the phase of the rhythms appeared to shift in the appropriate direction when studied under nychthemeral conditions whereas the endogenous oscillator either showed no consistent behaviour or, in the control of urate excretion, a shift in the wrong direction. 8. The implications for people undergoing time shifts, in the course of shift work or transmeridional flights, are indicated.
Directional tuning of complex cells in area 17 of the feline visual cortex
Authors: Hammond P.
Published: December 2014

1. Directional tuning for motion of a field of static visual noise and for motion of bar stimuli against the same stationary noise field as background was compared in eighty‐four deep‐layer complex cells recorded from area 17 of cats, lightly anaesthetized with N2O/O2 supplemented with pentobarbitone. Detailed comparisons of monocular tuning for the dominant eye receptive field were made for seventy‐two cells. Interocular, and stimulus‐dependent ocular dominance differences are reported elsewhere (Hammond, 1978c, and in preparation).

2. Directional bias for preferred and opposite directions of motion was enhanced with moving noise fields, compared with moving bar stimuli. Two thirds of cells directionally biased for bars, were directionally selective for noise (33/49); ten of these showed suppression of firing to noise moving in the ‘null’ direction. An additional twenty‐three cells were directionally selective for bar stimuli and for noise, nine with suppression of firing in the null direction.

3. A majority of cells (52/62) showed significant differences in preferred directions for bar stimuli and for noise; in an exceptional case, tuning for the two classes of stimuli was orthogonal. Tuning for bar stimuli was usually sharper than for noise. In cells asymmetrically tuned for bar stimuli, tuning was broader for the flank of the tuning curve closest to the preferred direction for noise. Ten cells showed similar tuning for bars and noise; tuning for the remaining ten cells was rather variable or poorly defined.

22/62 cells showed bimodal directional tuning to noise, with depression of sensitivity over the range of directions to which the cell responded well with a moving bar stimulus.

4. Cells were frequently more responsive to noise‐field motion than to bar motion. Cells with large receptive fields showed greater sensitivity to noise than those with small fields, and were relatively more sensitive to noise than to bar stimuli.

5. The results are interpreted as evidence that the directional and orientational sensitivity of complex cells are mediated by different mechanisms.
Coding of information about tactile stimuli by neurones of the cuneate nucleus.
Authors: Douglas P R , Ferrington D G , Rowe M
Published: December 2014

1. The responses of cuneate neurones to controlled tactile stimulation of the foot pads were examined in unanaesthetized, decerebrate cats. The neurones were divided into three functional classes; one sensitive to steady tactile stimuli, and two dynamically sensitive classes which could be readily differentiated by their responsiveness to cutaneous vibration. Each class appeared to receive an exclusive input from only one of the three known groups of tactile receptors associated with the foot pads, namely the Pacinian corpuscles, the Merkel endings and the intradermal, encapsulated endings known as Krause or Meissner corpuscles. 2. Cuneate neurones responsive to steady indentation of the skin displayed approximately linear or sigmoidal stimulus‐response relations over indentation ranges up to approximately 1.5‐‐2 mm. Response variability at a fixed stimulus intensity was relatively low and showed little systematic change over the full range of the stimulus‐response curves. 3. One class of dynamically sensitive cuneate neurones responded to cutaneous vibration over a range of approximately 5‐80 Hz with maximal responsiveness around 30 Hz. The other class, the Pacinian neurones, responded over a range of approximately 80‐ greater than 600 Hz with maximal responsiveness at 200‐400 Hz. The thresholds and combined band width of vibratory sensitivity of these populations were comparable with known subjective thresholds and range of cutaneous vibratory sensibility. 4. Responses of cuneate neurones were phase‐locked to the vibratory stimulus suggesting that information about vibration frequency could be coded by the patterns of impulse activity. Quantitative measures indicated that maximal phase‐locking occurred in responses to vibration frequencies of 10‐50 Hz with a progressive decline at higher frequencies. Above 400 Hz, impulse activity occurred almost randomly throughout the vibratory stimulus cycle and therefore carried little further signal of vibratory frequency. The decline, with increasing frequency, in the ability of cuneate neurones to signal information about vibratory frequency parallels the known subjective capacities for frequency discrimination. 5. A switch‐over occurred at approximately 80 Hz in the population of cuneate neurones able to provide the more reliable signal of vibratory frequency; above 80 Hz, the Pacinian neurones; below 80 Hz, the neurones receiving intradermal, rapidly adapting receptor input from the pads. 6. The observed properties of cuneate neurones are compatible with a role in signalling information which could contribute to subjective tactile abilities.