bluuebunny/crossref_metadata_2025_split huggingface dataset:
Secretory behaviour and histamine formation in the rat Heidenhain pouch following antrectomy
Authors: Svensson S. E. 
Published: December 2014

1. In conscious rats provided with a Heidenhain pouch, the changes in the secretion of acid and pepsin following antrectomy were investigated in the interdigestive state and in response to graded doses of intravenous hog gastrin II and methacholine. The change in mucosal histamine formation (histamine‐forming capacity, HFC, i.e. histidine decarboxylase activity) was determined in the fasting state in the Heidenhain pouch following antrectomy.2. Antrectomy was followed by a substantial reduction in the interdigestive secretion of acid.3. Methacholine infusion when the antrum was intact evoked a maximal acid secretory response that exceeded twice the response obtained with gastrin.4. After resection of the antrum the acid response to graded doses of methacholine and to gastrin at maximal but not at submaximal dose levels was significantly reduced.5. After antrectomy, threshold or submaximal infusion of gastrin accentuated the acid secretory responses to methacholine, but did not restore the maximal secretory response to methacholine obtained before antrectomy.6. The changes in pepsin secretion following antrectomy were similar to those in acid secretion but smaller.7. Mucosal HFC of the pouch was significantly lowered following antrectomy.8. After antrectomy gastrin failed to accelerate histamine formation in the mucosa in the usual way.
Early facilitation at corticomotoneuronal synapses
Authors: Porter R. 
Published: December 2014

1. Corticomotoneuronal EPSPs have been generated in lumbar motoneurones of the monkey by single and paired corticospinal volleys. The facilitation of the second of a pair of EPSPs with respect to the size of the first has been measured.2. The relationship between the degree of facilitation of the second response and the interval between the two volleys has been studied. Average facilitation of minimal EPSPs was found to be maximal about 2 msec after the arrival of the corticospinal volley and to decay roughly exponentially thereafter with a time constant of about 10 msec.3. The degree of facilitation varied from one minimal corticomotoneuronal EPSP to another but this facilitation was not statistically correlated with the time course of the individual EPSPs.4. Significant facilitation (0·4) was still present 10 msec after a corticospinal volley so that this phenomenon could play a part in the initiation of motoneuronal discharge by corticospinal activity at natural frequencies of the order of 100 impulses/sec.
Electron microscopic and electrophysiological studies on the carotid body following intracranial section of the glossopharyngeal nerve
Authors: Biscoe T. J. , Lall A. , Sampson S. R. 
Published: December 2014

1. The innervation of carotid body Type I cells has been investigated in seventeen cats. At a sterile operation the glossopharyngeal and vagus nerve roots were cut intracranially on one side.2. From 1½ to 378 days after the operation the carotid bodies were fixed in situ and prepared for electron microscopy. Nerve endings on Type I cells were found to degenerate with a prolonged time course. In each cat there was a decrease in the number of nerve endings on the operated side as compared with the non‐operated side.3. Before the carotid bodies were fixed, recordings were made from chemoreceptor, and baroreceptor, afferent fibres in the sinus nerve on the operated side. The chemoreceptors responded in the usual way to changes in arterial O2, CO2 and pH; the injection of cyanide evoked a brisk response.4. It is concluded that the nerve endings on Type I cells are efferent rather than afferent and the cell bodies of their axons are probably in the brain stem.
Activity patterns in respiratory muscles and in respiratory neurones of the rostral medulla of the cat
Authors: Waldron Ingrid 
Published: December 2014

1. In the rostral medulla the activity patterns of respiratory neurones are of two main types: inspiratory and expiratory (Fig. 1). Some expiratory neurones begin activity early enough to fit Cohen & Wang's (1959) category of ‘inspiratory—expiratory’. However, in the rostral medulla, ‘inspiratory—expiratory’ neurones do not constitute a distinct category within the expiratory group, since all intermediate activity patterns are observed. Similarly, no distinct categories of activity patterns can be distinguished within the inspiratory group.2. Expiratory neurones are rare in the extreme medial and lateral portions of the respiratory regions on each side of the rostral medulla (Fig. 3). Respiratory neurones are not bunched in anatomical clusters within each region, though a medio‐dorsal group of neurones on each side is somewhat anatomically separated from the rest.3. At any one time there are at the very least 1000 respiratory neurones on each side of the rostral medulla.4. Many of the patterns of single unit activity recorded in respiratory muscles of the nose, throat and pharynx are different from the patterns of activity typical of respiratory neurones in the medulla near the cranial motor nuclei (Figs. 1 and 4). This suggests that many of the medullary recordings are from cells other than the motor neurones innervating these muscles.
Some factors influencing stimulation‐induced release of potassium from the cat submandibular gland to fluid perfused through the gland
Authors: Petersen O. H. 
Published: December 2014

1. The release of K from the cat submandibular gland to the extracellular fluid (ECF) after stimulation with acetylcholine (ACh) and the subsequent uptake of K from the ECF was studied in glands perfused artificially with Locke solutions.2. The first injection of ACh after shift of the perfusion fluid from control to K‐free Locke solution evoked a normal loss of K and a normal secretion of saliva. The second injection only evoked a small release of K and a reduced secretion.3. Perfusion with dinitrophenol (DNP) (10−4
M) containing solutions, Na‐free Li Locke solutions and chloride‐free nitrate Locke solutions inhibited salivary secretion and the uptake of K. The first injection of ACh after shift of the perfusion fluid from control to test solution gave a normal K loss, but thereafter the ACh‐induced K‐loss declined.4. Perfusion with g‐strophanthin (10−5‐10−4
M) always inhibited K uptake whereas K release was not affected primarily. The sensitivity of the secretory mechanism of different glands to strophanthin varied considerably.5. Perfusion with tetraethylammonium Locke solution inhibited secretion, K uptake and release of K.6. It is suggested that the release of K from salivary glands to the ECF after stimulation with ACh can be explained by diffusion as a consequence of an enhanced permeability of the cell membranes to K. Concomitantly with the release of K, Na is taken up. It is suggested that the subsequent uptake of K and extrusion of Na is due to active transport processes probably involving a Na—K activated ATP‐ase.
The metabolism of [3H]noradrenaline released by electrical stimulation from the isolated nictitating membrane of the cat and from the vas deferens of the rat
Authors: Langer S. Z. 
Published: December 2014

1. The noradrenaline (NA) stores of the isolated medial muscle of the cat's nictitating membrane were labelled with [3H]NA and the tissue was set up in an isolated organ bath for field stimulation. The tritiated NA and its metabolites released spontaneously and by field stimulation were determined by scintillation counting following chromatographic separation.2. NA represented 11·8 ± 1·0% of the total radioactivity of the spontaneously released tritiated compounds. The rest was accounted for by NA metabolites: (a) normetanephrine (NMN), 35%; (b) 4‐hydroxy‐3‐methoxymandelic acid (VMA), 20%; (c) 3,4‐dihydroxyphenylglycol (DOPEG), 10%; (d) 3,4‐dihydroxymandelic acid (DOMA), 10%; (e) 4‐hydroxy‐3‐methoxyphenylglycol (MOPEG), 14%.3. Field stimulation at 25 shocks/sec with supramaximal stimuli of 1 msec duration increased the outflow of NA six to eightfold and that of NMN, DOPEG and VMA two to threefold. The increase in outflow of DOMA and MOPEG was small. NA represented 35·8 ± 4·1% of the total increase in radioactivity.4. After pargyline pretreatment field stimulation increased the outflow of NA and NMN. Stimulation in the presence of pyrogallol raised the release of NA, DOMA and DOPEG. Neither pargyline nor pyrogallol affected the total release induced by stimulation.5. Cocaine 0·3 μg/ml. increased the release due to stimulation at 4 shocks/sec but not at 25 shocks/sec. Cocaine did not affect the metabolism of the released transmitter.6. Phenoxybenzamine (10 μg/ml.) increased release by stimulation at 4 and 25 shocks/sec. Metabolism of the released transmitter was prevented in the presence of phenoxybenzamine.7. Phentolamine (3 μg/ml.), like phenoxybenzamine, blocked responses to field stimulation, but failed to modify release and subsequent metabolism of NA liberated by field stimulation.8. The main NA metabolites in the rat vas deferens were DOPEG, DOMA and MOPEG. Stimulation at 4 shocks/sec resulted in an increased outflow of NA and of DOPEG. Fifty per cent of the total increase of radioactive compounds was accounted for by NA metabolites.9. These experiments show that for the calculation of the actual output of transmitter it is important to include the metabolites and not to rely on the determination of [3H]NA alone.
Rigor contraction and the effect of various phosphate compounds on glycerinated insect flight and vertebrate muscle
Authors: White D. C. S. 
Published: December 2014

1. Glycerol‐extracted flight muscle from the giant water‐bug, Lethocerus cordofanus, undergoes contraction when deprived of ATP. This rigor contraction occurs in the presence of the calcium chelating agent EGTA, under conditions in which the predicted free calcium ion concentration is less than 5 × 10−9
M. A mechanically similar contraction has been observed by depriving the muscle of Mg2+, in the presence of 5 m
M‐ATP.2. In the rigor contraction tensions of up to 120 mN/mm2 under isometric conditions, and shortenings of between 2½ and 6% under isotonic conditions, have been observed at 20° C.3. Muscles in rigor can be relaxed by the addition of ATP. The minimum concentration of ATP required to give full relaxation depends upon other ionic constituents of the solutions, and upon temperature, but is between 0·3 and 1 m
M at 20° C. Lower concentrations result in partial reduction of tension and stiffness.4. Pyrophosphate (PP) causes a reduction in the tension of muscle which has developed rigor under isometric conditions, but the stiffness, when measured at frequencies between 1 and 100 Hz, remains indistinguishable from that of rigor muscle. The stiffness when measured by applying slow length changes is comparable to that of ATP‐relaxed muscle. It is suggested that in PP‐relaxed muscle the cross‐bridges remain in close proximity to, but are not rigidly attached to, the I filaments, resulting in a high viscous interaction between the two sets of filaments.5. The addition of low concentrations of ADP (less than about 0·7 m
M) to rigor muscle in the absence of ATP causes an increase in tension. The effect is sigmoid, and is probably due to the formation of low concentrations of ATP throughout the body of the fibre by myokinase activity. Larger concentrations of ADP (about 5 m
M) added to rigor muscle cause relaxation, probably due to the formation of higher ATP concentrations.6. AMP and inorganic orthophosphate have little effect upon the mechanical properties of rigor muscle.7. There is a delay of about 1 min before the onset of rigor contraction when fibres are transferred from an ATP‐solution to one containing no ATP, due to the transfer of ATP in the body of the fibres. Both ATP hydrolysis by the fibres and diffusion of ATP into the bathing solution contribute significantly to the rate of depletion of ATP.8. Rabbit psoas muscle shows a similar rigor contraction in the presence of EGTA, and has mechanical properties similar to those described for Lethocerus flight muscle in the presence of pyrophosphate.
Voltage clamp experiments in striated muscle fibres
Authors: Adrian R. H. , Chandler W. K. , Hodgkin A. L. 
Published: December 2014

1. Membrane currents during step depolarizations were determined by a method in which three electrodes were inserted near the end of a fibre in the frog's sartorius muscle. The theoretical basis and limitations of the method are discussed.2. Measurements of the membrane capacity (CM) and resting resistance (RM) derived from the current during a step change in membrane potential are consistent with values found by other methods.3. In fibres made mechanically inactive with hypertonic solutions (Ringer solution plus 350 m
M sucrose) step depolarizations produced ionic currents which resembled those of nerve in showing (a) an early transient inward current, abolished by tetrodotoxin, which reversed when the depolarization was carried beyond an internal potential of about +20 mV, (b) a delayed outward current, with a linear instantaneous current—voltage relation, and a mean equilibrium potential with a normal potassium concentration (2·5 m
M) of −85 mV.4. The reversal potential for the early current appears to be consistent with the sodium equilibrium potential expected in hypertonic solutions.5. The variation of the equilibrium potential for the delayed current (V′K) with external potassium concentration suggests that the channel for delayed current has a ratio of potassium to sodium permeability of 30:1; this is less than the resting membrane where the ratio appears to be 100:1. V′K corresponds well with the membrane potential at the beginning of the negative after‐potential observed under similar conditions.6. The variation of V′K with the amount of current which has passed through the delayed channel suggests that potassium ions accumulate in a space of between ⅓ and ⅙ of the fibre volume. If potassium accumulates in the transverse tubular system (T system) much greater variation in V′K would be expected.7. The delayed current is not maintained but is inactivated like the early current. The inactivation is approximately exponential with a time constant of 0·5 to 1 sec at 20° C. The steady‐state inactivation of the potassium current is similar to that for the sodium current, but its voltage dependence is less steep and the potential for half inactivation is 20 mV rate more positive.8. Reconstructions of ionic currents were made in terms of the parameters (m, n, h) of the Hodgkin—Huxley model for the squid axon, using constants which showed a similar dependence on voltage.9. Propagated action potentials and conduction velocities were computed for various conditions on the assumption that the T system behaves as if it were a series resistance and capacity in parallel with surface capacity and the channels for sodium, potassium and leak current. There was reasonable agreement with observed values, the main difference being that the calculated velocities and rates of rise were somewhat less than those observed experimentally.
The afferent innervation of two infrahyoid muscles of the cat
Authors: Fernand V. S. V. 
Published: December 2014

1. The afferent innervation of the straplike muscles of the infrahyoid region were investigated in two ways. The morphology of spindles and counts of tendon organs were investigated by the gold chloride technique in ten muscles. Spindle counts were made in forty pairs of thyrohyoid and infrahyoid muscles. De‐efferenting of the nerves to these muscles was done in three cats and the calibre spectra of the afferent innervation investigated. These were compared with the total counts of fibres in intact nerves.2. In the thyrohyoid, spindles are frequently absent. No tendon organs were seen. In the large infrahyoid (combined sternohyoid and sternothyroid), spindle counts varied from 0 to 20 and the mean spindle count per gram of muscle was 3·5. A maximum of five tendon organs were seen in the muscle. Both spindle and tendon organ counts are low when compared with a limb muscle of similar weight and size.3. In the infrahyoid muscle complex spindles were about equal in number to simple spindles.4. Counts of spindles in the infrahyoid muscle in families of three or more siblings suggest that some families of kittens tend to have higher spindle counts than other families.5. The afferent innervation of the two muscles varied between 21 and 42% of the total fibre population and the fibre diameter spectrum is in keeping with the low counts of encapsulated endings.
The effect of the internal sodium concentration on calcium fluxes in isolated guinea‐pig auricles
Authors: Glitsch H. G. , Reuter H. , Scholz H. 
Published: December 2014

1. Calcium efflux from guinea‐pig auricles followed saturation kinetics when [Ca]o and [Na]o were changed while the ratio [Ca]o/[Na]o2 was kept constant. The Michaelis constant, KmCa+Na = 40 m
M, suggests that a hypothetical carrier system, responsible for sodium—calcium exchange, is far from saturation with the inside concentrations of these ions.2. [Na]i was altered in the auricles between 12·5 and 60 m
M/kg fibre water while total cellular calcium concentration ([Ca]t) at the beginning of the influx period was not significantly different in the various groups of preparations.3. 45Ca influx increased appreciably with increasing [Na]i. 45Ca influx from sodium‐poor solution corresponded to an almost equal increase in [Ca]t, while [Ca]t did not change much in preparations loaded with 45Ca in Tyrode solution. When the sodium‐activated fraction of calcium influx was plotted against [Na]i2 the resulting curve indicated saturation with KmNa = 3500 (m
M [Na]i)2 and maximal influx rate, Ji, maxCa' = 1·35 m
M/kg wet weight × 10 min.4. When the preparations were re‐equilibrated for various times in normal Tyrode solution after [Na]i had been increased, both the sodium‐activated component of calcium influx and [Na]i2 decreased with approximately the same rate constants.5. Calcium efflux from auricles with high [Na]i was increased when it was measured in Tyrode solution while the efflux in sodium‐poor solution was inhibited.6. Auricles with increased [Na]i showed a positive inotropic contractile response.7. The main conclusion reached by these experiments is that calcium influx is affected by [Na]i in a way which is compatible with a carrier‐mediated sodium—calcium exchange system.
Suprathreshold spectral properties of single optic tract fibres in cat, under mesopic adaptation; cone—rod interaction
Authors: Andrews D. P. , Hammond P. 
Published: December 2014

1. Responses of 122 on‐centre or off‐centre ganglion cells in cat to suprathreshold monochromatic stimulation have been analysed under mesopic adaptation with white light, recording from their single fibres in the optic tract at a level posterior to the chiasma. Fields described are monocularly driven, located in the right half‐fields of either eye, and are all within 30° of the area centralis.2. Retinal receptors are of two types, viz. 556 nm cones and 502 nm rods. At high mesopic adaptation (1 log cd/m2) all units receive mixed cone—rod input. Under low mesopic adaptation (0 log cd/m2) the great majority receive mixed input; a few receive pure rod input. These results are in agreement with the threshold data (Andrews & Hammond, 1970).3. Peaks of spectral response curves of units, to suprathreshold monochromatic stimuli of different wave‐length but equal quantum flux, fall primarily between 550 and 560 nm for high mesopic adaptation, and between 500 and 520 nm for low mesopic adaptation. Peak position depends on the degree of rod or cone contamination, in units treated under high or low mesopic levels respectively.4. Units with cone—rod input to the field centre receive similar but antagonistic cone—rod input to the surround. In units with pure rod input to the field centre, only rods input to the surround.5. Cone and rod components of on‐centre discharges are identifiable in terms of colour sensitivity and latency. The cone component is primarily a short‐latency, high‐frequency, excitatory transient; the rod component is a longer latency, lower frequency, maintained phase of excitation.6. Less direct evidence indicates that cone and rod input to the field surround give rise to inhibitory components of comparable latency, magnitude and time course.7. The identified cone and rod components of responses are used in further experiments to show that cone and rod input have different spatial organization both in the receptive field centre and in the surround.8. The boundary between the field centre and surround for rods has a diameter on average about twice as large as that for cones. This organization is such that the field centre for rods substantially overlies the cone surround.9. Changes in receptive field organization occur within the mesopic range, associated with the changeover from cone to rod vision.10. It is suggested that the difference between cone and rod input in the mesopic range may form the basis of the cat's ability behaviourally to discriminate between colours.
The differential effects of tetraethylammonium and zinc ions on the resting conductance of frog skeletal muscle
Authors: Stanfield P. R. 
Published: December 2014

1. The effects of tetraethylammonium (TEA) and zinc ions on the resting conductance of frog muscle were examined using a method which permitted control of the membrane potential near the end of a muscle fibre and measurement of an approximation of the membrane current.2. TEA reduced the amplitude of the inactivating inward current obtained on hyperpolarizing, both when this was measured as initial current [Im(0)] less the estimated chloride current and as [Im(0) — Im(∞)]. 115 m
M‐TEA reduced the amplitude of [Im(0) — Im(∞)] by about 85%.3. TEA had little effect on the time constant with which the inward potassium currents inactivated. This finding appeared to be in conflict with the view that the inactivation is due to depletion of potassium from the T‐system, though the results in standard Ringer were in good agreement with such an hypothesis.4. In the standard chloride Ringer, the resting membrane resistance was 3530 Ω cm2. 115 m
M‐TEA increased this 1·6 times to 5580 Ω cm2.5. The effect of TEA on voltage—current relations obtained in high K2SO4 solutions was also examined. With large pulses, the voltage—current relations in TEA and control solutions tended to become linear. This linear part could be extrapolated and subtracted from the voltage—current relation.6. TEA, at a concentration of 150 m
M, reversibly reduced by 88% the amplitude of the currents obtained during both depolarizing and hyperpolarizing pulses; this figure was obtained after subtraction of the linear part of the relation, which was itself unaffected by TEA and which represented a resistance of 5600 Ω cm2.7. The reductions in the inactivating potassium current and in the current flowing through the inwardly rectifying potassium channel in high K2SO4 solutions fit, fairly closely, a concentration—effect relation for TEA with a dissociation constant of 20 × 10−3
M.8. Also investigated were the slow time‐dependent changes in membrane potential occurring when [K]o is altered from 2·5 to 10 m
M at constant chloride (120 m
M). The findings were consistent with the view that TEA reduced the potassium conductance without much effect on the chloride conductance. In particular, when muscles equilibrated for 1 hr in 10 m
M‐K Ringer were returned to 2·5 m
M‐K, the initial rate of repolarization was reduced, even though the driving force on K was slightly larger than in the control experiment.9. Zinc ions appeared to be without effect either on the amplitude of the inactivating potassium current obtained when square hyperpolarizing pulses were applied to the fibre membrane, or on its time constant.10. In standard Tris‐buffered Ringer, the membrane resistance was 3350 Ω cm2. Zinc Ringer (2·5 m
M) increased this rather more than twice to 6830 Ω cm2.11. It is concluded that the two agents, TEA+ and Zn2+, which both reduce delayed potassium currents in muscle, act in different ways on the resting conductance of frog muscle.