bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mineral composition and rates of flow of effluent from the distal ileum of liquid‐fed calves
Authors: Smith R. H. 
Published: December 2014

1. Liquid‐fed calves (aged 1½‐4 months) examined more than five weeks after inserting a re‐entrant fistula into the distal ileum, of normal sodium and potassium status and without abnormal gut infection, showed mean emergence rates from the ileum for sodium, potassium and water of 2·3 m‐mole/hr, 0·38 m‐mole/hr and 21 g/hr respectively after 16 hr fasting.2. Sodium and potassium emergence rates changed little when the residues from a milk or glucose‐solution feed arrived at the distal ileum. When magnesium chloride was added to a glucose‐solution feed an increase sometimes occurred but only in association with decreased small‐intestine transit time.3. Widely differing sodium and potassium intakes had no appreciable direct effect on their emergence rates. Continued feeding of a diet deficient in either ion, however, altered the calf's metabolism and led to appropriate changes in the sodium/potassium ratio of ileal effluent. These changes were not simulated by injecting adrenal cortex hormones. The ratio also decreased when ileal effluent was allowed to discharge for several weeks without being returned to the colon. It was abnormally high in samples obtained less than five weeks after inserting cannulae.4. An increase in sodium and potassium emergence rates, which often occurred spontaneously at about 3 months of age, appeared to be due to infection and was usually prevented by giving aureomycin orally.5. Water emergence rate reflected changes in the emergence rates of osmotically effective constituents and isotonicity was maintained. In effluent after fasting, the cations involved were mainly sodium and potassium, and [Na] + [K] was approximately constant (mean 132 m‐mole/l.). In effluent following feeds of milk or glucose, magnesium chloride solution, [Na] + [K] was depressed and [Na] + [K] + 1·5 [Mg] was approximately constant (mean 139 m‐mole/l.). Magnesium behaved as it were mainly ionic. Calcium had no apparent osmotic effect and was probably insoluble.6. Bicarbonate was the major anion in ileal effluent after a milk feed with smaller amounts of chloride, phosphate and some other unknown anion(s).
The surface area of the intestinal mucosa in the lactating rat
Authors: Boyne R. , Fell B. F. , Robb I. 
Published: December 2014

1. The mucosal and serosal surface dimensions of the rat duodenum, jejunum and ileum were obtained by measurement of photographs of histological sections. The surface areas were calculated from these data.2. Measurements were made on the intestines from virgin rats and from rats on the sixteenth day of lactation. The mucosal area/unit length of serosa was appreciably increased in all parts of the intestine during lactation. The mucosal area/serosal area (MA/SA) ratio was also markedly increased, but to a lesser extent distally, where an important component of the intestinal hypertrophy was dilatation of the intestine.
Pharmacological properties of cholinoceptive neurones in the medulla and pons of the cat
Authors: Bradley P. B. , Dhawan B. N. , Wolstencroft J. H. 
Published: December 2014

1. Iontophoretic application of acetylcholine to neurones in the medulla and pons of the unanaesthetized decerebrate cat excited 35·5% and inhibited 22%. This was not a representative sample of lower brain stem neurones, since most penetrations were made medially. Some cholinoceptive neurones were in the medial reticular formation.2. The time course of the response to different doses has been described.3. Nicotine and nicotinic agents 1,1‐dimethyl‐4‐phenylpiperazinium iodide (DMPP) and choline phenyl ether (TM1) excited neurones excited by acetylcholine but, with one exception, did not inhibit neurones inhibited by acetylcholine.4. Muscarinic agents mimicked both the excitatory and inhibitory responses to acetylcholine. (±)‐muscarine and bethanechol (β‐methylcholine carbamate) had a prolonged and powerful inhibitory action.5. Oxotremorine [1‐(2‐oxopyrrolidino)‐4‐pyrrolidino‐butyne‐2] had a long‐lasting excitatory action on neurones excited by acetylcholine.6. Eserine and neostigmine potentiated the action of acetylcholine but in addition they had a strong excitatory effect on many brain stem neurones, independently of the action of acetylcholine.7. Excitatory and inhibitory responses to acetylcholine could be antagonized by gallamine, hexamethonium and atropine. Dihydro‐β‐erythroidine (DHβE) antagonized only excitatory responses. (+)‐Tubocurarine was a weak antagonist.8. It is concluded that the excitatory responses have both nicotinic and muscarinic properties but the inhibitory responses are only muscarinic. Since the pharmacology of these two types of response is different, it is concluded that the inhibitory action is not due to an indirect effect from excitation of a neighbouring inhibitory neurone.
Exchange of structurally bound phosphate in muscular activity
Authors: Cheesman D. F. , Hilton Elizabeth 
Published: December 2014

1. When rectus abdominis and sartorius muscles of the frog are incubated with 32P‐orthophosphate and subsequently minced, extracted with carbonate‐bicarbonate buffer and water, and converted to acetone powders, considerable radioactivity remains associated with the solid material.2. Muscles labelled with 32P and subjected to contracture at room temperature with KCl or ACh yield acetone powders which, in comparison with those of uncontracted control muscles, show a significantly decreased radioactivity. There is no evidence for a corresponding decrease in the total phosphate content.3. Relaxation of a contracted muscle restores the 32P content of its acetone powder at least to the level for a resting, control muscle.4. When two recti are incubated with 5 × 10−4
M‐DNP after labelling with 32P, subsequent depolarization of one muscle with KCl usually results in an increase in the activity of the bound phosphate fraction, with little or no contracture in addition to that already caused by the DNP.5. It is concluded that the bound phosphate fraction undergoes exchange during activation, shortening and relaxation of muscle, and may represent a source of energy for muscular activity.
The activity of post‐ganglionic sympathetic nerves to the uterus of the rabbit
Authors: Bower E. A. 
Published: December 2014

1. The spontaneous activity recorded from the central ends of the uterine nerves of the rabbit is described. The discharges resembled those reported from other post‐ganglionic sympathetic nerves; the individual units appeared to discharge remarkably regularly at frequencies between 4/sec and 1 per 3 sec.2. The resting discharge in late pregnant rabbits was usually more intense than in non‐pregnant rabbits; otherwise no clear relation existed between variations in the discharges and in the sexual state.3. The discharge was reduced by stimulation of the central end of the depressor nerve and increased by asphyxia.4. Stimulation of either the preganglionic or the post‐ganglionic nerve by a single shock evoked a long after‐discharge in the post‐ganglionic nerve. It is shown that this after‐discharge is a property of some of the post‐ganglionic neurones supplying the rabbit's uterus which does not depend on the integrity of the preganglionic nerves or of the spinal cord, or on transmission through the ganglia, and that it is not a general property of the sympathetic post‐ganglionic neurones of the rabbit.5. Repetitive stimulation of the preganglionic nerve at low frequencies augmented the after‐discharge in some cases and depressed it in others; stimulation at high frequencies invariably depressed the after‐discharge. Repetitive stimulation of the post‐ganglionic nerve at low or high frequencies depressed the after‐discharge.6. If the normal preganglionic activity was interrupted abruptly by an anode block, the post‐ganglionic discharge also stopped abruptly.7. A ganglion‐stimulating action of hexamethonium is described.8. Adrenaline inhibited the post‐ganglionic neurones with no sign of excitation. This effect was antagonized by Rogitine without affecting the resting discharge, the action of the depressor nerve or the after‐discharge in any way.
The effect of (+)‐tubocurarine chloride and of acute hypertension on electrocortical activity of the cat
Authors: Amassian V. E. , Weiner H. 
Published: December 2014

1. The effects of
I.V. injection of tubocurarine (3 mg/kg) and of acute hypotension upon electrocortical activity of cats under sodium pentobarbitone were analysed. Technical artifacts associated with changes in brain volume were minimized.2. Initially, the superficial cortical response was reduced by tubocurarine either insignificantly or by 34% or less. Cats bled before injection of tubocurarine showed initially a similar reduction but, occasionally, a severe delayed reduction was found. Any fall in the superficial cortical response started during the secondary rise in
B.P., many seconds after the
B.P. had reached its lowest initial level. By contrast, spontaneous electrocortical activity was reduced approximately when the peak initial fall of
B.P. occurred and it started to recover during the secondary rise in
B.P. Reduction of the superficial cortical response could still be elicited after spindling had been suppressed by deep barbiturate anaesthesia. The initial thalamocortical afferent component in somatosensory area I, which was evoked by dorsal column stimulation, was less reduced by injection of tubocurarine than were the post‐synaptic positive—negative components.3. The depressant effects of injected tubocurarine upon the superficial cortical response and spindle activity were approximated by rapid arterial bleeding.4. The superficial cortical response was reduced following virtual arrest of the cerebral circulation by acute exsanguination or by acute oil embolization. Such reduction most likely does not depend on systemic transport of inhibitory substances to the brain.5. After injection of tubocurarine the rate of outflow from the superior sagittal sinus was variably reduced during the initial fall in
B.P., and often showed a variable, secondary increase. A net deficit in cerebral blood flow was usually present during the period of 80 sec after injection.6. The variability in the effects of injected tubocurarine upon electrocortical activity is attributed to the variability of the net deficit in cerebral blood flow.
Pharmacology of cortical inhibition
Authors: Krnjević K. , Randić Mirjana , Straughan D. W. 
Published: December 2014

1. We have studied the effects of various pharmacological agents on the cortical inhibitory process described in the previous two papers (Krnjević, Randić & Straughan, 1966a, b); the drugs were mostly administered directly by iontophoresis from micropipettes and by systemic injection (
I.V.).2. Strychnine given by iontophoresis or by the application of a strong solution to the cortical surface potentiated excitatory effects, but very large iontophoretic doses also depressed neuronal firing. Subconvulsive and even convulsive systemic doses had little or no effect at the cortical level. There was no evidence, with any method of application, that strychnine directly interferes with the inhibitory process.3. Tetanus toxin, obtained from two different sources and injected into the cortex 12‐48 hr previously, also failed to block cortical inhibition selectively. As with strychnine, there was some evidence of increased responses to excitatory inputs.4. Other convulsant drugs which failed to block cortical inhibition included picrotoxin, pentamethylene tetrazole, thiosemicarbazide, longchain ω‐amino acids and morphine.5. The inhibition was not obviously affected by cholinomimetic agents or by antagonists of ACh.6. α‐ and β‐antagonists of adrenergic transmission were also ineffective.7. Cortical inhibition was fully developed in the presence of several general anaesthetics, including ether, Dial, pentobarbitone, Mg and chloralose. A temporary reduction in inhibition which is sometimes observed after systemic doses of pentobarbitone, is probably secondary to a fall in blood pressure.8. Several central excitants such as amphetamine, caffeine and lobeline also failed to show any specific antagonistic action on cortical inhibition.9. In view of the possibility that GABA is the chemical agent mediating cortical inhibition, an attempt was made to find a selective antagonist of its depressant action on cortical neurones. None of the agents listed above, nor any other of the substances tested, were able to block this action.10. It was concluded that cortical inhibition differs from spinal inhibition in its pharmacological properties; and that our observations are consistent with the possibility that GABA is the cortical inhibitory transmitter.
Composition of the secretion from the eccrine sweat glands of the cat's foot pad
Authors: Foster K. G. 
Published: December 2014

1. The sweat composition from the cat's foot pad was examined at various rates of secretion. Sodium pentobarbitone or chloralose anaesthesia were used.2. Cat's pad sweat contains lactate, glucose is almost absent, and the sodium and chloride concentrations increased with increasing sweat rate. In these respects the secretion resembles human eccrine sweat.3. The sodium, chloride, and potassium concentrations are much higher than in human sweat; also the potassium level decreased with increasing rate. Consequently, whereas human sweat is hypotonic with respect to the plasma, cat's pad sweat is slightly hypertonic with respect to the plasma even at low rates of secretion. In contrast to human sweat glands, which produce a slightly acidic secretion containing ammonia, cat's pad sweat glands produce an alkaline secretion containing bicarbonate. Also in contrast to human sweat, lactate levels decreased with increasing sweat rate.
The action of ouabain on the smooth muscle cells of the guinea‐pig's taenia coli
Authors: Casteels R. 
Published: December 2014

1. The action of 10−6 g/ml. of ouabain on the membrane potential, membrane activity, tension development and the ion content of the smooth muscle of the guinea‐pig's taenia coli has been investigated.2. This ouabain concentration produced a depolarization of the membrane, accompanied by an initial increase of the spike frequency and later a depolarization block. Removal of the ouabain produced a sudden and pronounced hyperpolarization leading to a block of spike discharge.3. Reduction of the external sodium concentration, or an increase of the external calcium concentration, or exposure to 10−7 g/ml. adrenaline repolarized the cell membrane in the presence of ouabain.4. Ouabain decreased the tension development of the taenia coli.5. Ouabain decreased the intracellular potassium and chloride and increased the intracellular sodium concentration. However, the corresponding changes of the equilibrium potentials were not sufficient to explain the changes of the membrane potential.6. A possible explanation for the action of ouabain is presented suggesting that the drug may decrease the calcium binding properties of the cell membrane.
The variation in isometric tension with sarcomere length in vertebrate muscle fibres
Authors: Gordon A. M. , Huxley A. F. , Julian F. J. 
Published: December 2014

1. The variation of isometric tetanus tension with sarcomere length in single fibres from frog striated muscle has been re‐investigated with special precautions to ensure uniformity of sarcomere length within the part of the fibre being studied.2. In most respects the results of Ramsey & Street (1940) were confirmed, but (a) the peak of the curve was found to consist of a plateau between sarcomere lengths of 2·05 and 2·2 μ, (b) the decline of tension above this plateau is steeper than found by Ramsey & Street, and (c) the decline of tension below the plateau becomes suddenly steeper at a sarcomere length of about 1·67 μ.3. Many features of this length—tension relation are simply explained on the sliding‐filament theory.4. It is concluded that, in the plateau and at greater lengths, the tension on each thin filament is made up of equal contributions from each bridge which it overlaps on adjacent thick filaments.5. Internal resistance to shortening is negligible in this range but becomes progressively more important with shortening below the plateau.
The central release of acetylcholine during stimulation of the visual pathway
Authors: Collier B. , Mitchell J. F. 
Published: December 2014

1. In rabbits anaesthetized with Dial ACh has been collected from the surface of the cerebral cortex during stimulation of the visual pathways.2. The spontaneous release of ACh from the visual and non‐visual areas of the cortex was found to be similar.3. Stimulation of the retinae by diffuse light produced a large increase in ACh release from the primary visual receiving areas (4·3 times the spontaneous release) and a smaller increase (1·9 times the spontaneous release) from other parts of the cortex.4. Direct unilateral electrical stimulation of the lateral geniculate body evoked a large increase in ACh release (3·4 times the spontaneous release) from the ipsilateral visual cortex and a smaller increase (1·7 times the spontaneous release) from the contralateral visual area and other regions of the cerebral cortex. The evoked increase from the contralateral cortex was not mediated by transcallosal pathways.5. The increase in ACh release evoked from the visual cortex by stimulation of the ipsilateral lateral geniculate body was dependent on the frequency of stimulation. The evoked release was smallest at low stimulus frequencies and increased to a maximum at 20 stimuli/sec.The evoked ACh release from other areas of the cortex was independent of the frequency at which the lateral geniculate body was stimulated.6. The possible central nervous pathways associated with the spontaneous release of ACh and the release evoked by stimulation of the eyes by light and by direct stimulation of the lateral geniculate body are discussed.7. It is concluded that two ascending cholinergic systems may be involved; the non‐specific reticulo‐cortical pathways responsible for the e.e.g arousal response, and the more specific thalamo‐cortical pathways associated with augmenting and repetitive after‐discharge responses. The first system is thought to be concerned with the small but widespread increase in ACh release from the cortex following stimulation of the visual pathway while the second system could give rise to the larger increases evoked from the primary receiving areas of cortex. The spontaneous release of ACh from the surface of the brain may be the result of contributions from both systems.
The dependence of the action potential of the frog's heart on the external and intracellular sodium concentration
Authors: Niedergerke R. , Orkand R. K. 
Published: December 2014

1. The overshoot of the action potential of the frog's heart was reduced when external sodium chloride was replaced by sucrose. However, the potential decrement was only 17·3 mV for a 10‐fold reduction of sodium as compared with 58 mV expected on the basis of the sodium hypothesis of excitation.2. Replacement of up to 75% of the external sodium by choline did not reduce the overshoot, provided atropine was present in sufficient concentrations to suppress any parasympathomimetic action.3. The maximum rate of rise of the action potential markedly declined in low sodium fluids whether sucrose or choline chloride was used to replace sodium chloride.4. The maximum rate of rise was reduced to only a small extent when external sodium was replaced by lithium.5. Increasing the intracellular sodium concentration in exchange for lost potassium caused overshoots to decline. The effects resembled those obtained in similar experiments with skeletal muscle fibres (Desmedt, 1953).6. Action potentials occurring under certain conditions even in the presence of very low external sodium concentrations (≤ 5% normal) also declined in height when the intracellular sodium concentration was increased.7. The behaviour of the action potential in low external sodium concentrations may be explained by an action of calcium on the excitable membrane.
Concentration of radioiodide by the uterus of the rat and the relationship to blastocyst implantation
Authors: Brown-Grant K. 
Published: December 2014

1. When pregnant rats are ovariectomized early in pregnancy and treated with progesterone a raised uterus—plasma concentration ratio (U/P ratio) for radio‐iodide is observed at the usual stage of pregnancy (days 3, 4 and 5) but is not followed by implantation. When delayed implantation is induced by the administration of oestradiol it is not preceded by a rise in the U/P ratio for 131I.2. Similar findings are obtained when implantation is delayed by concurrent lactation in rats mated at the post‐partum oestrus.3. Ovariectomy early in pregnancy without progesterone treatment prevents the rise in U/P and oviduct—plasma (O/P) ratio for 131I that normally occurs.4. Administration of progesterone to intact or ovariectomized non‐pregnant rats produces a raised U/P and O/P ratio for 131I; oestrogen may inhibit this response. The simplest explanation of these results is a direct action of progesterone on the uterus.5. By gross dissection it was possible to show that the region of high iodide concentration in the rat uterus is the endometrium.6. No evidence of a concentration of iodide in the uterus or oviduct of the pregnant rabbit was obtained.
Rod and cone interaction in dark‐adapted monkey ganglion cells
Authors: Gouras P. , Link Krista 
Published: December 2014

1. Rod—cone interaction has been studied by analysing the response latency of large ganglion cells in the perifovea of dark‐adapted Rhesus monkey retina.2. Both rod and cone signals have been found to converge on such cells. The cone system is less sensitive but much faster than that of the rods so that the cones determine latency whenever stimuli become suprathreshold for them. Responses to dimmer stimuli are determined entirely by the rods.3. The earliest signals to excite the ganglion cell leave a transitory refractoriness in their wake. Therefore when both rods and cones are stimulated simultaneously, the earlier cone signal, arriving at the ganglion cell, has a greater chance of producing excitation than the later rod signals.