bluuebunny/crossref_metadata_2025_split huggingface dataset:
The respiration of the anterior byssus refractor muscle of Mytilus edulis (ABRM) after a phasic contraction
Authors: Baguet F. , Gillis J. M. 
Published: December 2014

1. The oxygen consumption of isolated anterior byssus retractor muscle of Mytilus edulis (ABRM) has been measured at rest and after phasic contractions induced by a.c. stimulation.2. The respiration was measured with a Clark oxygen electrode in successive periods of 5 or 15 min, at 20° C.3. The resting respiration is 71·8 ± 2·4 n‐moles O2/g wet weight.min (mean ±
S.E., n = 70). It is increased by a release and decreased by a passive stretch.4. After phasic stimulation of up to 30 sec the respiration is increased and returns to a slightly higher level than the resting level in an exponential fashion with a time constant of about 10 min.5. The duration of stimulation does not change the time course of the excess respiration but it affects its magnitude. The amount of extra oxygen consumed, in n‐moles O2/g, is made up of a constant amount, 449 ± 102, and an amount that depends on the duration of stimulation (t, sec), which is given by t × 13·2 ± 4·3. When due account is taken for the tension developed, these parameters become 83·1 ± 20·7 and t × 1·24 ± 0·66 n‐moles O2/g muscle and kg/cm2 of tension. This regression analysis is based on forty‐eight data, with a residual error based on 5 degrees of freedom.6. Release of the tension after the last stimulus of a 30 sec tetanus reduces by half the extra oxygen consumed during the recovery whereas the same release applied 5 min later has a much smaller effect. This suggests that relaxation is an active process.7. From these measurements of the recovery metabolism the energy cost of the contraction was estimated and compared with this cost in vertebrate striated muscle. The constant item has about the same magnitude, but the item related to the duration of stimulation is about 250 times smaller.
The central release of acetylcholine during consciousness and after brain lesions
Authors: Collier B. , Mitchell J. F. 
Published: December 2014

1. Acetylcholine (ACh) has been collected from the visual cortex of anaesthetized rabbits during stimulation of the lateral geniculate body and after cutting central nervous pathways. ACh has also been collected from the visual cortex of conscious, free‐moving rabbits.2. After a unilateral ‘vertical’ lesion separating the geniculate body from more centrally situated nuclei, ACh release evoked from the contralateral cortex by geniculate body stimulation was abolished but evoked release from the ipsilateral cortex was only reduced.3. After a bilateral, ‘horizontal’ lesion separating the thalamic nuclei from the reticular formation, unilateral geniculate stimulation gave an increased ACh release from the ipsilateral but not from the contralateral visual cortex.4. The ‘vertical’ and ‘horizontal’ lesions had no permanent effect on the spontaneous release of ACh from the visual cortex.5. Unilateral destruction of the geniculate body reduced the spontaneous release of ACh from the ipsilateral cortex but did not affect the contralateral release.6. The spontaneous and directly evoked ACh release from chronically undercut areas of cortex was found to be considerably lower than from intact areas of cortex.7. A high output of ACh was obtained from the visual cortex of conscious, free‐moving rabbits. The rate of ACh release was closely related to the activity and state of arousal of the animals.8. These results support an earlier suggestion that two major ascending cholinergic systems exist in the rabbit brain. One pathway is the non‐specific reticulo‐cortical tract responsible for cortical arousal and the other is the more specific thalamo‐cortical pathway associated with augmenting and repetitive after‐discharge responses. The functional significance of these two cholinergic pathways and their role in the conscious animal are discussed.
The effects of cross‐innervation on the myoglobin concentration of tonic and phasic muscles
Authors: McPherson Angus , Tokunaga J. 
Published: December 2014

1. The myoglobin concentrations of m. soleus and m. flexor digitorum longus (
F.D.L.) were estimated spectrophotometrically in normal cats.2. In another group of cats the nerves to m. soleus and
F.D.L. were self‐united in one limb and cross‐united in the opposite limb and the myoglobin concentrations of m. soleus and
F.D.L. in both limbs were estimated 6 months later.3. After self‐union of the nerves the
F.D.L./soleus myoglobin ratio was not significantly different from that of normal cats.4. After cross‐union of the nerves the
F.D.L./soleus myoglobin ratio was significantly greater than that of both normal cats and cats after self‐union of their nerves.
Variations in small and large vessel volumes caused by cations, adrenaline and histamine*
Authors: Chacalos Elias H. 
Published: December 2014

1. Plasma and blood cell volumes were measured simultaneously with [131I]albumin and [32P]erythrocytes, together with the arterial haematocrits, in acutely splenectomized dogs anaesthetized with sodium barbital. These measurements were made during control runs and after the administration of vasoactive substances.2. With these data and previously derived equations the mean composite radius of all small vessels with a radius < 150 μ, the distribution of the blood volumes between small and large vessels, and other variables could be calculated.3. Adrenaline, CaCl2 or vasopressin administration caused a reduction of the mean composite radius, a net shift of erythrocytes and plasma out of the small vessel volume, and an expansion of the large vessel volume. Histamine, KCl and MgCl2 produced opposite effects.4. Adrenaline appeared to cause the release of sequestered erythrocytes into the active circulation.5. The effects of CaCl2 and KCl persisted for several hours, while those of MgCl2 did not.6. The effects of vasopressin could be reversed by histamine, those of adrenaline by splenic plasma or KCl, and those of CaCl2 by MgCl2.7. It was suggested that the observed vasoactions are essentially the resultants of diverse combinations of direct and indirect actions on the capacitance section of the small vessel volume.
Further studies on intestinal active transport during semistarvation
Authors: Hindmarsh J. T. , Kilby D. , Ross B. , Wiseman G. 
Published: December 2014

1. The effect of semistarvation (sufficient to produce a loss of 18‐28% of initial body weight) on the active transport of
D‐glucose and
L‐histidine by the rat, the guinea‐pig and the golden hamster has been investigated by the use of sacs of everted small intestine (from upper jejunum to lower ileum).2. In the rat and the guinea‐pig the dietary restriction resulted in increased active transport in all regions of the small intestine. In contrast, it caused no alteration in active transport in the hamster.3. The response in the rat was most impressive in the middle‐to‐lower ileum during
D‐glucose uptake. Whereas normal sacs from this area appeared unable to move the sugar against its concentration gradient, sacs from semistarved rats did so quite well.4. Although there was a considerable loss (24‐29%) of intestinal dry weight in all three species when the food intake was reduced, shortening of the small intestine was not detectable in the guinea‐pig or the hamster and was present to only a minor extent in the rat.5. Evidence is presented indicating that the enhanced active transport is not merely a reflexion of the thinning of the intestinal wall and that it occurs during complete as well as in partial starvation.
Intracellular sodium concentration and resting sodium fluxes of the frog heart ventricle
Authors: Keenan Mary J. , Niedergerke R. 
Published: December 2014

1. Using 24Na to label the exchangeable sodium in the tissue and either [35S]sulphate or [14C]sucrose to label the extracellular spaces, the intracellular sodium concentration of frog heart ventricles was determined and found to be between about 5 and 10 m‐mole/kg cell water.2. The intracellular potassium concentration, obtained by flame‐photometric analysis, was approximately 163 m‐mole/kg cell water.3. Two different methods were employed to study the sodium tracer efflux of resting heart ventricles. One involved a double‐tracer technique, using 24Na to indicate the release of the exchangeable tissue sodium, and 35SO4 to indicate, approximately, the release of extra‐myocardial sodium. In the other a comparison was made of the sodium release from the tissue when it contained sodium either at the normal concentration or at a concentration enhanced by exchange with intracellular potassium.4. The magnitude of the sodium efflux from heart fibres as measured by both methods was of the order 50‐100 p‐mole/cm2 sec. Simultaneously with this cellular efflux a substantial amount of sodium was released from extra‐myocardial spaces and tissues.5. The net efflux of potassium ions from heart cells that occurred when heart ventricles were perfused with potassium‐depleted fluids was determined. The results were used to obtain an indirect estimate, of about 2‐3 p‐mole/cm2 sec, for the resting sodium influx.6. The significance of these different values of sodium efflux and influx is discussed.
Calcium activation of frog slow muscle fibres
Authors: Costantin L. L. , Podolsky R. J. , Tice Lois W. 
Published: December 2014

1. Skinned muscle fibres were prepared from the tonus bundle of the frog iliofibularis muscle and the contractile response elicited by applied calcium ions was studied. The fibre type was determined by electron microscopy.2. Fast fibres shortened many times more rapidly than slow fibres, indicating that the slow contraction of slow fibres is an inherent property of the contractile mechanism.3. The extent of spread of contraction following local calcium application was much greater in slow than in fast fibres, a difference which is consistent with the relative sparsity of the sarcoplasmic reticulum in slow fibres.4. The ability of the sarcoplasmic reticulum of slow fibres to accumulate calcium was demonstrated by the in situ immobilization of calcium when oxalate solutions were added to the skinned fibre.
The oxygen consumption of mammalian non‐myelinated nerve fibres at rest and during activity
Authors: Ritchie J. M. 
Published: December 2014

1. A study has been made of the oxygen consumption of non‐myelinated nerve fibres of rabbit desheathed cervical vagus nerves at rest and during activity.2. The average resting oxygen consumption (Qr) was 0·0924 μmole/g. min at 21° C. Stimulation for 1‐3 min at 3/sec caused an extra oxygen consumption (Qs) of 816 p‐mole/g.shock.3. When the frequency of stimulation was increased, to 10/sec and 30/sec, Qs fell. When the frequency was decreased, to 1/sec and 0·3/sec, Qs increased slightly.4. When the temperature was decreased, Qr fell; when the temperature was increased, Qs also increased. Temperature similarly affected Qs with high frequencies of stimulation, but had relatively little effect on Qs at low frequencies of stimulation.5. An isolated single shock seemed to produce an increase in oxygen consumption of about 1200 p‐mole/g, and this value was largely independent of temperature.6. When part of the sodium in the Locke solution was replaced by barium, Qr decreased (by 12%) whereas Qs increased (by 87%).7. Veratrine (1 μg/ml.) increased both Qr (by 142%) and Qs (by 361%).8. Acetylcholine (1·7 m
M) increased Qr (by 32%).9. When nerves were transferred to potassium‐free solutions there was little change in Qr, and Qs fell slightly (by 8%).10. When the potassium concentration in the Locke solution was increased 4‐fold, Qr increased (by 27%).11. Salicylate (1‐10 m
M) increased Qr (by 24%) and abolished Qs.12. When the sodium of Locke solution was replaced by lithium, Qr decreased (by 19%) and Qs was abolished.13. In sodium‐Locke solution ouabain (100 μ
M) decreased Qr (by 26%) and abolished Qs. In lithium‐Locke solution ouabain also decreased Qr (by 28%).14. All or nearly all of the oxygen consumed at rest or during activity seemed to be used to pump potassium ions into, and sodium ions out of, the axoplasm.15. The K/O2 ratio during pumping was about 5·0.
Altered temperature and taste responses from cross‐regenerated sensory nerves in the rat's tongue
Authors: Oakley B. 
Published: December 2014

1. The chorda tympani nerve, which innervates the front of the rat tongue, was found to be much less responsive to tongue cooling than the IXth nerve, which innervates the back of the tongue. The two nerves also differed in their relative responsiveness to various taste chemicals.2. Through cross‐union the IXth nerve was made to innervate the front of the tongue, and in other rats the chorda tympani nerve the back of the tongue.3. After an average of 15 post‐operative weeks, electrophysiological recordings of whole nerve action potential discharges were made from normal, control regenerated, and cross‐regenerated nerves. Cooling, and chemical and mechanical stimulation of the tongue demonstrated that the control regenerated and cross‐regenerated nerves had established functional connexions.4. Neither the response to cooling nor the relative taste responses were altered by either of two types of control chorda tympani nerve regeneration.5. In contrast, the cross‐regenerated chorda increased its responsiveness to tongue cooling and the cross‐regenerated IXthe nerve lost much of its responsiveness to cooling.6. Cross‐regeneration also caused the relative taste responses to change and appear quite similar to the responses obtained from the nerve which normally innervated that tongue region (e.g. the cross‐regenerated IXth nerve responded like a chorda tympani nerve).7. It is suggested that the sensory response evoked in the chorda tympani and IXth nerves by tongue cooling or taste stimulation is at least partially dependent upon the character of the tongue tissue in which the nerve terminates—the epithelium at the front differs from that at the back of the rat tongue.8. These results rule out the following two hypotheses: (a) that the nerve ending itself functions as a taste receptor in direct contact with applied chemicals and yet is uninfluenced by the character of the tissue in which it terminates, (b) that assuming the taste bud cells are an integral part of the receptive process, the taste nerve ending determines the chemical specificity of the taste cell which it induces, without any previous modification of the nerve by the tissue in which it terminates.
The role of α‐ and β‐adrenergic receptors in some actions of catecholamines on intestinal smooth muscle
Authors: Jenkinson D. H. , Morton I. K. M. 
Published: December 2014

1. Experiments were carried out to determine the type of adrenergic receptor concerned in the action of noradrenaline in increasing the rate of exchange of potassium ions in the taenia of the guinea‐pig caecum. The preparations were bathed in potassium‐rich solutions in order to depolarize the muscle fibres and so eliminate changes in potassium flux secondary to alterations in membrane potential.2. Noradrenaline was more effective than isoprenaline in increasing both the influx and efflux of 42K, suggesting that the α‐receptors were involved. This action on potassium permeability was abolished by the α‐blocking agent phentolamine (10−7 g/ml.), the β‐blocking agent pronethalol (10−7 g/ml.) being without effect.3. In contrast, isoprenaline was about 30 times more active than noradrenaline in inhibiting calcium contractures of the depolarized taenia, suggesting that here the β‐receptors were concerned. This was confirmed by showing that this action of noradrenaline was effectively antagonized by pronethalol, again at 10−7 g/ml., but not by the same concentration of phentolamine.4. Carbachol contractures in quiescent preparations bathed in Krebs solution at 17° C could be inhibited by both noradrenaline and isoprenaline. Noradrenaline was found to be more active under these conditions, and this action was antagonized by phentolamine (and piperoxane), but not by pronethalol, at the same concentrations as before.5. These findings confirm that the α‐ and β‐receptors are quite distinct in their actions. Nevertheless, under physiological conditions, both may contribute to the inhibitory actions of catecholamines on intestinal smooth muscle.
The laminar organization of dorsal horn and effects of descending impulses
Authors: Wall P. D. 
Published: December 2014

1. An examination of the physiological properties of cells in cat lumbar dorsal horn shows that there are three horizontal laminae which correspond approximately to Rexed (1952) laminae 4, 5, and 6.2. A summary diagram (Fig. 9) suggests the relation of the laminae to each other and to afferent and descending fibres. All three laminae respond to cutaneous stimulation but only lamina 6 responds to movement. By comparing responses of cells in decerebrate and spinal preparations, it is shown that the brain stem inhibits cutaneous responses and enhances movement responses. Pyramidal tract stimulation affects cells in laminae 4, 5, and 6.3. Cells in lamina 4 have small cutaneous receptive fields and respond as though many different types of specific cutaneous afferents converge on them. Cells in lamina 5 respond as though many cells of lamina 4 converge on them. In the decerebrate animal the responses of lamina 5 cells habituate to repeated light pressure stimuli but the cells remain responsive to new stimuli in other parts of their receptive field. Impulses descending from the brain stem can switch the modality of lamina 6 cells from cutaneous to proprioceptive.
The relative roles of the aortic and carotid sinus nerves in the rabbit in the control of respiration and circulation during arterial hypoxia and hypercapnia
Authors: Chalmers J. P. , Korner P. I. , White S. W. 
Published: December 2014

1. The respiratory and circulatory effects of graded arterial hypoxia, alone or with superadded hypercapnia, were studied in four groups of unanaesthetized rabbits including normal animals and those with selective section of the aortic nerves, selective section of the carotid sinus nerves and section of both sets of nerves.2. When measured 2‐4 days after selective section of the carotid sinus nerves the resting respiratory minute volume and arterial PO2 were lower and the PCO2 higher than normal. These effects were not observed after selective section of the aortic nerves. Selective aortic nerve section, and selective carotid sinus nerve section each produced a similar increase in the resting arterial pressure and heart rate, but were without effect on the resting cardiac output.3. During arterial hypoxia reflex respiratory and circulatory effects ascribable to arterial chemoreceptor stimulation (hyperventilation, bradycardia, vasoconstriction) were mediated for the most part through the carotid sinus nerve. In animals with only the aortic nerves intact the circulatory response was determined largely by the opposing effects of aortic baroreceptor reflexes and the local peripheral dilator action of hypoxia.4. The circulatory effects of hyperventilation induced by hypercapnia during arterial hypoxia, in animals with both aortic and carotid sinus nerves cut were small.5. The results suggest that relatively few chemoreceptor fibres originate from the aortic region in the rabbit, though the carotid sinus and aortic nerves both contain baroreceptor fibres.
Excitation of afferent cardiac sympathetic nerve fibres during myocardial ischaemia
Authors: Brown A. M. 
Published: December 2014

1. Occlusion of the main left coronary artery of lightly anaesthetized cats provoked a pseudaffective reaction. The afferent pathway was in the cardiac sympathetic nerves.2. The compound action potential evoked in the inferior or middle cardiac nerves by stimulation of the thoracic sympathetic trunk contained two elevations, a small Aδ wave and a much larger sC wave. Occasionally a B wave was present.3. During coronary occlusion, the Aδ elevation was reduced by 35‐55%, indicating afferent activity in these fibres. Multifibre preparations also showed increased afferent discharge during occlusion.4. It seems probable that the afferent activity in these fibres was mainly responsible for signalling the pseudaffective response elicited by coronary occlusion.5. Myocardial ischaemia produced by coronary occlusion was probably the stimulus for the increased activity.
The innervation of sheep mesenteric veins
Authors: Holman Mollie E. , McLean A. 
Published: December 2014

1. An isolated preparation of sheep mesenteric vein is described from which contractions of the longitudinal smooth muscle of the adventitia have been recorded in response to stimulation of intramural and periarterial nerves.2. The preparation did not respond to single stimuli but the relation between amplitude of response and frequency of stimulation was characteristic of that described for other smooth muscles innervated by sympathetic nerves.3. Responses were blocked by tetrodotoxin, guanethidine, and by a number of α‐receptor blocking drugs. Responses to peri‐arterial stimulation were unaffected by hexamethonium. It was concluded that the longitudinal smooth muscle is supplied with post‐ganglionic noradrenergic motor nerves and the presence of such fibres in the adventitia was confirmed by fluorescence microscopy.4. Acetylcholine also caused contractions. Although a direct excitatory action on the smooth muscle could not be excluded, results suggest that acetylcholine may release noradrenaline from the axons of the sympathetic ground plexus.
Influence of phospholipase C on some electrical properties of the skeletal muscle membrane
Authors: Albuquerque E. X. , Thesleff S. 
Published: December 2014

1. A study was made of the effects of phospholipase C (PhC) on the resting membrane potential, input resistance, action potential and acetylcholine sensitivity of innervated and chronically denervated single muscle fibres of the rat.2. In doses higher than 1·5 μg/ml. PhC significantly increased the ionic permeability of the muscle membrane (indicated by a fall in input resistance) and reduced the resting membrane potential of innervated fibres. The ‘fast’ or ‘white’ extensor digitorum longus muscle was the most sensitive and the ‘slow’ or ‘red’ soleus the least sensitive muscle. A similar difference was observed among ‘fast’ and ‘slow’ muscles of the chicken, the posterior latissimus dorsi being far more sensitive than the ‘slow’ anterior latissimus dorsi muscle. Chronically denervated muscles were more resistant to these actions of PhC than innervated ones but even after denervation the ‘fast’ muscles remained more sensitive than the ‘slow’ muscles.3. The action‐potential generating mechanism in the ‘fast’ and ‘slow’ muscle was completely and irreversibly blocked by 1·5 μg/ml. of PhC within 1 hr. Furthermore the innervated and chronically denervated muscles were equally sensitive to this effect of PhC. The enzyme caused a gradual increase in the threshold for excitation, reduction in the rate of rise and the amplitude of the action potential. The input resistance and the resting membrane potential were not reduced by this dose of PhC.4. Acetylcholine sensitivity of chronically denervated muscles was not affected by PhC in doses that abolished the electrical excitability of the membrane. When PhC reduced the input resistance and the resting membrane potential a decrease was also observed in the response to applied acetylcholine.5. The results suggest that PhC by acting at the polar heads of membrane phospholipids interferes with the ionic carrier mechanism which generates the action potential. The differences in sensitivity between ‘fast’ and ‘slow’ muscles and between innervated and chronically denervated ones are tentatively explained on the basis of heterologous membrane phospholipids and/or variations in their stereochemical arrangement.