bluuebunny/crossref_metadata_2025_split huggingface dataset:
The role of the solitary and paramedian reticular nuclei in mediating cardiovascular reflex responses from carotid baro‐ and chemoreceptors
Authors: Miura Mitsuhiko , Reis Donald J. 
Published: December 2014

1. With dye‐filled micro‐electrodes single neurones in the medulla of anaesthetized paralysed cats were identified which: (a) fired rhythmically in synchrony with or were modulated by the cardiac cycle, and which ceased firing with occlusion of the ipsilateral common carotid artery (carotid sinus baroreceptor neurones); (b) were excited by stimulation of carotid body chemoreceptors by close intra‐arterial injection of lobeline into the thyroid artery (carotid body chemoreceptor neurones).2. Twelve carotid baroreceptor neurones were identified, in thirty‐three cats, nine of which were localized in the intermediate area of the nucleus of the solitary tract (NTS) within 1 mm ahead of or behind the obex; three units were located either in the parahypoglossal area or the dorsal portion of the paramedian reticular nucleus (PRN).3. Of the twenty‐one carotid chemoreceptor neurones which were identified, thirteen were localized in the NTS, three in the parahypoglossal area and four in the dorsal PRN.4. Bilateral lesions of the paramedian reticular area of medulla destroying the PRN, abolished or reversed the depressor response to electrical stimulation of myelinated fibres of the carotid sinus nerve (CSN), attenuated the depressor response to carotid sinus stretch and augmented the pressor response to chemoreceptor stimulation by lobeline. Such lesions did not significantly alter the reflex heart rate responses.5. Small lesions of the NTS within an area 1 mm rostral to the obex abolished all reflex blood pressure and heart rate responses to electrical stimulation of the CSN or natural stimulation of carotid baro‐ or chemoreceptors.6. Baroreceptors and chemoreceptors of the CSN project both to the intermediate zone of the NTS and to more medial areas of the medulla, particularly the dorsal PRN and parahypoglossal area.7. The PRN serves to mediate the reflex depressor, but not cardio‐vagal, response from myelinated baroreceptors and buffers the pressor responses from chemoreceptors; it may serve as an important area integrating cardiovascular activity descending from forebrain, brain stem and cerebellum with baroreceptor reflexes.8. Cardiovascular reflex responses arising from non‐myelinated baroreceptors and all chemoreceptors are mediated by neurones in the intermediate area of the NTS.
Comparison of the hyperglycaemic and glycogenolytic responses to catecholamines with those to stimulation of the hepatic sympathetic innervation in the dog
Authors: Edwards A. V. , Silver Marian 
Published: December 2014

1. The effects of stimulation of the splanchnic innervation to the adrenal medullae, in dogs with cut hepatic nerves, were compared with those obtained previously in response to splanchnic and hepatic nerve stimulation in adrenalectomized dogs.2. Maximal stimulation of both adrenal medullae via the splanchnic innervation (20 c/s for 9 min), in dogs with cut hepatic nerves, produced closely similar hyperglycaemic and glycogenolytic responses to those obtained previously in adrenalectomized dogs with intact hepatic nerves.3. The rise in plasma glucose concentration in response to maximal stimulation of the adrenal medullae in dogs with intact hepatic nerves was found to be comparable to that which occurs in response to maximal stimulation of the hepatic sympathetic innervation alone. In contrast, the rise in haematocrit during maximal stimulation of the entire splanchnic innervation was substantially greater than that observed after removal of both adrenal glands.4. The output of adrenaline and noradrenaline from the left adrenal gland was determined during maximal stimulation of the left splanchnic nerve (20 c/s for 9 min). These results were then used to compute doses of the two amines which would reproduce the output of catecholamines from both glands under such conditions. The extent of the rise in mean plasma glucose concentration in response to these infusions was similar to that produced by maximal stimulation of both adrenal glands, but the duration of hyperglycaemia and depletion of liver glycogen were significantly less.5. Stimulation of the splanchnic innervation was found to produce an initial ‘surge’ in the release of catecholamines from the adrenal medullae, followed by a rapid decline in output when stimulation was continued for longer than 30 sec. Evidence was obtained which showed that this pattern of release is well suited to produce rapid mobilization of liver glycogen.6. Comparable changes in plasma glucose concentration occurred in response to stimulation of either the adrenal medullae or the sympathetic innervation to the liver at low frequency (2·0 c/s for 5 min). Stimulation of both pathways simultaneously, at the same frequency, produced smaller responses.7. Intramesenteric infusions of noradrenaline at 1·0 μg.kg−1 min−1 for 5 min produced comparable changes in plasma glucose concentration to those observed during stimulation of either pathway alone at low frequency. The mean plasma noradrenaline concentration of portal blood was raised by between 92 and 105 ng/ml. during these infusions.8. It is concluded that stimulation of either the splanchnic innervation to the liver, or of both adrenal medullae, at high frequency (20 c/s for 9 min) represents a supramaximal stimulus for hepatic glycogenolysis. Comparison of the responses to stimulation at low frequency (2·0 c/s for 5 min) suggests that the hepatic glycogenolytic mechanism is equally sensitive to stimulation via either route in this species.
Permeability of urinary bladder of Rana cancrivora to urea in the presence of oxytocin
Authors: Chew Miow‐Miow , Elliott Annie B. , Wong H. Y. 
Published: December 2014

1. When Rana cancrivora collected from fresh water had been exposed for 3 days to saline solutions having osmolalities from 280 to 690 m‐osmole/kg, urea concentrations in plasma and urine appeared to come into equilibrium, and were from 70 to 200 m‐mole/l.2. Plasma urea level of fresh water R. cancrivora (48 m‐mole/l.) was doubled (82 m‐mole/l.) after 8 hr of exposure to 270 m‐osmolal saline. It continued the same after 24 hr of exposure.3. When isolated urinary bladders of R. cancrivora were exposed to Ringer on the serosal aspect and one‐fifth Ringer on the mucosal aspect, then in response to this osmotic difference of 190 m‐osmole/kg, the rate of fluid movement (mucosa to serosa), which was 10·3(±2) μl./cm2.hr, was not significantly altered when up to 60% of the NaCl of the Ringer solution was substituted by urea.4. Under the same circumstances, when oxytocin (50 m‐u./ml.) was present in the serosal solution, the rate of fluid movement (mucosa to serosa) was 133·2(±7·9) μl./cm2.hr in the absence of urea; it was progressively decreased by the presence of urea until, when 80% of the NaCl had been substituted by urea, the rate of fluid movement was reduced to 14·5(±4·0) μl./cm2.hr.5. The diminished rate of fluid movement under the above circumstances could not be correlated with serosal urea concentration, with serosal availability of Na+, nor with Na+ concentration difference across the bladder wall. It appeared to be directly related to the ‘non‐urea osmotic difference’ across the bladder wall provided by solutes other than urea.6. When isolated bladders were exposed to an osmotic difference of 190 m‐osmole/kg, but having 25 m
M urea present in the mucosal solution, then fluid moved from mucosa to serosa at a rate of 10·4(±1·3) μl./cm2.hr in the absence of oxytocin and 124(±9) μl./cm2.hr when oxytocin (50 m‐u./ml.) was present. In the former case no urea passed across the bladder wall, but in the latter case urea passed from mucosa to serosa at a rate of 3·16(±0·3) μmole/cm2.hr. The fluid moving from mucosa to serosa thus contained urea 25·5 m‐mole/l.7. Vasotocin (10−9
M), which is equipotent with oxytocin (50 m‐u./ml.) in affecting permeability of the isolated urinary bladder to water, was also equipotent in producing a reduced rate of water fluid movement in the presence of 40% urea (vasotocin, 63 μl./cm2.hr; oxytocin, 59 μl./cm2.hr).8. When groups of frogs were cystectomized, and other groups of frogs were sham‐operated, then after 48 hr of exposure to fresh water or to 300 m‐osmolal saline the sham‐operated frogs had plasma urea level raised from 20 m‐mole/l. (fresh water) to 42 m‐mole/l. (saline), while the cystectomized frogs had 20 m‐mole/l. (fresh water) and 26 m‐mole/l. (saline).9. The hypothesis is presented that hormone‐induced permeability of the urinary bladder to urea contributes to the immediate adjustment of plasma urea level by which R. cancrivora survives when exposed to high environmental salinity.
Reflex effects of laryngeal irritation on the pattern of breathing and total lung resistance
Authors: Boushey H. A. , Richardson P. S. , Widdicombe J. G. 
Published: December 2014

1. The reflex responses to chemical and mechanical irritation of the laryngeal mucosa have been studied by applying stimuli to the open larynx of tracheostomized cats while monitoring ventilatory and circulatory variables. The responses were studied before and after vagotomy and before and after denervation of the larynx by transection of the superior and recurrent laryngeal nerves.2. The immediate response to laryngeal irritation was not consistent. The most frequent responses were coughing, and slowing and deepening of breathing without coughing. Less common were expiratory apnoea and sustained, simultaneous inspiratory and expiratory activity.3. A consistent late change in the pattern of breathing occurred. Slower, deeper breathing with increased total lung resistance (bronchoconstriction) was seen after the immediate response abated.4. The slowing of breathing was due to prolongation of both the time for inspiration and the time for expiration. The rate of increase in phrenic nerve activity was also slowed.5. Vagotomy did not alter qualitatively the reflex changes in the pattern of breathing, although bronchoconstriction no longer occurred.6. The responses were abolished by denervation of the larynx.
Three acetylcholine receptors in Aplysia neurones
Authors: Kehoe Jacsue 
Published: December 2014

1. In the pleural ganglion of Aplysia californica, groups of cells were identified that respond differently to an iontophoretic injection of ACh. The anterior neurones are excited by ACh, whereas the medial cells are inhibited. The inhibitory response is biphasic, consisting of a short‐latency, rapid component and a longer‐latency, slow component. Homologous responses (e.p.s.p.s in the anterior cells and a two‐component inhibitory response in the medial cells) are evoked in these same cell groups by stimulation of an identifiable presynaptic neurone.2. The e.p.s.p. and the corresponding ACh potential are completely eliminated by hexamethonium which has no effect on either of the inhibitory potentials. Both the e.p.s.p. and the rapid i.p.s.p. (and the corresponding ACh potentials) are blocked by tubocurarine, dihydro‐β‐erythroidine, strychnine and brucine. These drugs have no effect on the slow inhibitory potential, whether elicited synaptically or by ACh injection. The slow response can be selectively blocked by methylxylocholine, tetraethylammonium (TEA), and phenyltrimethylammonium (PTMA). Since the three types of potentials were found to be differentially affected by ACh antagonists, it was concluded that the various responses are due to activation of three different ACh receptors.3. Of the cholinomimetics tested, only carbamylcholine imitates all three actions of ACh. Nicotinic agents, which were shown to activate the two curare‐sensitive receptors, have no stimulating effect on the curare‐insensitive receptor. This latter receptor can be selectively stimulated by arecoline. The cholinomimetics were shown to have a secondary blocking effect on the receptor(s) they stimulate.4. Muscarine, even at high doses, is ineffective as either a stimulating or a blocking agent on any of the three receptor types. The muscarinelike drugs oxotremorine, methacholine, and pilocarpine have only weak and non‐specific cholinomimetic action on these receptors. Their blocking effects are likewise negligible.5. The two curare‐sensitive receptors, which are presumably the same as those described by Tauc & Gerschenfeld (1962), respond like vertebrate nicotinic receptors to both cholinomimetics and cholinolytics. The third receptor type, on the other hand, has a unique pharmacological profile. It is unaffected by both nicotine and muscarine, and is blocked neither by curare nor by atropine. Knowing that it can be stimulated by arecoline and blocked by methylxylocholine, TEA and PTMA does not facilitate its incorporation into the classical scheme of cholinergic receptors.
The physiological role of three acetylcholine receptors in synaptic transmission in Aplysia
Authors: Kehoe Jacsue 
Published: December 2014

1. It is shown that a single presumably cholinergic presynaptic neurone can mediate, monosynaptically, multicomponent responses in a given cell and different responses in different cells.2. Complex responses (whether evoked synaptically or by ACh injection) are shown to be the result of the coexistence on a given post‐synaptic neurone of more than one of three cholinergic receptor types previously described. Likewise, different responses in different cells are due to the fact that different post‐synaptic neurones bear different combinations of these three receptors.3. Pharmacological analysis shows that the multicomponent nature of many of the responses is not always evident: what appears, under normal conditions, to be a single‐component excitatory potential can be shown often to be a complex response consisting of superimposed e.p.s.p.s and rapid i.p.s.p.s which are sometimes, though not always, accompanied by a slow i.p.s.p.4. Although which and how many of the three receptor types is the major factor contributing to the type of response observed, in the case of some of the synaptic potentials certain other factors were found to contribute to the final response form. First, in the large cells of the visceral ganglion, as well as in the left giant cell of the pleural ganglion, there is a marked ‘electrical separation’ between the region in which the synaptic currents are generated and the point of recording. This ‘electrical distance’ often altered the inversion potential, and sometimes the form of the responses. Secondly, in some visceral neurones, activation of the cholinergic presynaptic neurone L10 causes (either directly or indirectly) a potential change which cannot be accounted for in terms of the activation of cholinergic receptors. This ‘non‐cholinergic’ response (not imitated by an ionophoretic injection of ACh) is unmasked by the blocking of all three cholinergic receptors. It contributes differentially in different cells to the total response pattern produced by L10 under normal conditions, but its contribution is often characterized by a late hyperpolarizing phase which appears to be impossible to invert. This phase has been shown, however, to be dependent upon the potassium concentration in the extracellular space surrounding the synapse.4. It is tentatively suggested that this residual, non‐cholinergic element of the synaptic response in some visceral cells be the result of the activation of an electrical synapse.
Some quantitative observations upon the responses of neuroglial cells which follow axotomy of adjacent neurones
Authors: Watson W. E. 
Published: December 2014

1. The dry mass and nucleic acid content of freshly isolated neuroglial cells and of their nucleoli were measured by interference microscopy and ultraviolet absorption microspectrography. The incorporation of tritiated nucleosides and of an amino acid was followed autoradiographically.2. After hypoglossal axotomy in the adult rat hypertrophy of astrocytes of the hypoglossal nucleus occurred in a biphasic manner. The first phase lasted from days 1–10 and was accompanied by a small degree of astrocytic hyperplasia, and the second from days 20–80. Hypertrophy of oligodendrocytes accompanied the second phase of the astrocytic response.3. When severed axons failed to reinnervate denervated muscle, the second phase of the astrocytic response was markedly reduced and the hypertrophy of oligodendrocytes did not occur.4. If the severed axons re‐innervated denervated muscle after a controlled delay, the second phase of the astrocytic response and the oligodendroglial hypertrophy was also delayed.5. Injection of botulinum toxin into the tongue caused changes in astrocytes and oligondendrocytes closely resembling those found after axotomy.6. Transient astrocytic hypertrophy occurred in the uninjured right hypoglossal nucleus, and had a different time course to the changes occurring on the injured side.7. The results are discussed in relation to changes in the metabolism and to alterations in the dendritic fields of injured neurones, previously measured in these circumstances.
Uptake of [3H]ouabain and Na pump turnover rates in cells cultured in ouabain
Authors: Boardman Lesley J. , Lamb J. F. , McCall D. 
Published: December 2014

1. The binding of [3H]ouabain to fresh Girardi and Hela cells and to those cultured in low concentrations of ouabain for 24 hr has been measured.2. Fresh cells bind 1·6–2·2 × 106 molecules of ouabain* per cell from K‐free Krebs, but less than 0·3 × 106 molecules from 15 m
M‐[K]o Krebs. The ouabain* binds with a t½ of about 8 min from K‐free 2 × 10−7
M ouabain* and is released with a t½ of about 20 hr. Cells in a poor condition probably exchange ouabain more quickly.3. Cells incubated in ouabain* for 24 hr bind ouabain in amounts dependent on the [ouabain] and the external [K]. At the highest [ouabain] used the total amount bound exceeds that bound by fresh cells. Lowering [K]o in the medium increases the maximum ouabain which is bound.4. Cells incubated in ouabain* for 24 hr bind an additional amount of ouabain when exposed to 2 × 10−7
M ouabain* in K‐free Krebs.5. There is a close relationship between the% of the total ouabain bound in 24 hr and the% inhibition of the Na efflux suggesting that this ouabain is bound to the Na pumps.6. Radiochromatography of the counts recovered from the cells showed that it migrated to the same place as the applied [3H]ouabain. The wash‐off rate of ouabain bound to cells during incubation is similar to that from fresh cells, both tests suggesting that the ouabain exists in the same state in the cells.7. The number of Na ions extruded per pump is constant at about 60 sec−1 in fresh cells and those pre‐incubated in ouabain.8. The total ouabain bound by the cells is closely related to the [Na]i in cells pre‐incubated in ouabain but is unaffected by it in fresh cells where [Na]i is raised acutely.9. These results are compatible with the hypothesis that partial blocking of Na pumps leads to the production of more pumping sites by the cell.
Miniature end‐plate currents and potentials generated by quanta of acetylcholine in glycerol‐treated toad sartorius fibres
Authors: Gage Peter W. , McBurney Robert N. 
Published: December 2014

1. Part of the end‐plate region of glycerol‐treated toad sartorius muscle fibres in a hypertonic solution was voltage‐clamped using two microelectrodes. The control was adequate for recording miniature end‐plate currents (m.e.p.c.s) in the vicinity of the electrodes only, at clamp potentials from — 20 to — 100 mV. At any potential, the peak amplitude of m.e.p.c.s varied widely but their mean amplitude was linearly related to clamp potential. The equilibrium potential, obtained by extrapolation, was more positive than in normal fibres.2. The growth phase of m.e.p.c.s was linear and rapid (< 0·7 msec). The decay phase was exponential. The time constant of decay of m.e.p.c.s was affected by temperature, and increased as the membrane potential was increased. At 20° C, the time constant of decay ranged from 0·8 to 3·8 msec at membrane potentials from — 20 to — 100 mV.3. The mean conductance change caused by a quantum of acetylcholine was 5·5 × 10−8 mho.4. Voltage responses to rectangular current injections through one electrode were recorded with three other electrodes in the end‐plate region of glycerol‐treated fibres. Miniature end‐plate potentials (m.e.p.p.s) were also recorded with the same four electrodes.5. The decrement of both DC voltage responses and m.e.p.p.s along a fibre was exponential but the m.e.p.p. ‘space constant’ was significantly shorter than the DC space constant.
Acetylcholine and lobster sensory neurones
Authors: Barker David L. , Herbert Edward , Hildebrand John G. , Kravitz Edward A. 
Published: December 2014

Experiments are presented in support of the hypothesis that acetylcholine functions as a sensory transmitter in the lobster nervous system.1. Several different peripheral sensory structures incorporate radioactive choline into acetylcholine. The preparation most enriched in sensory as opposed to other nervous elements (the antennular sense organs of the distal outer flagellum) does not incorporate significant amounts of glutamate, tyrosine or tryptophan into any of the other major transmitter candidates.2. There is a parallel between the distribution of the enzyme choline acetyltransferase and the proportion of sensory fibres in nervous tissue from many parts of the lobster nervous system.3. Isolated sensory axons contain at least 500 times as much choline acetyltransferase per cm of axon as do efferent excitatory and inhibitory fibres.4. Abdominal ganglia and root stumps show a decline in the rate of incorporation of choline into acetylcholine 2 to 8 weeks after severing the first and second roots bilaterally (leaving the connectives and third roots intact). Extracts of the root stumps exhibit a significantly lower level of choline acetyltransferase 2 weeks after this operation.5. Curare and atropine partially block an identified sensory synapse in the lobster abdominal ganglion.
After‐images on backgrounds of different luminance: a new phenomenon and a hypothesis
Authors: Carpenter R. H. S. 
Published: December 2014

1. After‐images may be caused to vanish suddenly and reversibly by viewing them against a background of suitable luminance Ie.2. The value of Ie at any moment is not related to any parameter (intensity, colour, duration, time) describing the stimulus that caused the after‐image.3. On the other hand, Ie is very closely related to the immediate adaptational history of the eye, so that viewing a dark background for a few seconds lowers, and a light one raises, the value of Ie.4. It is suggested that the signal conveying sensations of relative brightness in this situation is related to the rate of change of concentration of an intermediate photo‐product decaying spontaneously with a time constant of some 14 sec.
A second neural mechanism of binocular depth discrimination
Authors: Blakemore Colin , Fiorentini Adriana , Maffei Lamberto 
Published: December 2014

1. Rotation of an object about its horizontal axis, towards or away from the viewer's eyes, usually causes the images of its contours to have slightly different orientations on the two retinae.2. We recorded action potentials from binocular neurones in the cat's visual cortex and measured their orientation‐selectivity carefully in both eyes.3. The optimal orientation for a single cell is not necessarily identical on both retinae. For a large sample of cells there is a range of more than + 15° (
S.D. about 6–9°) in the difference of preferred orientation in the two eyes. These interocular differences in receptive field properties cannot be attributed to rotation of the eyes or to the errors of measurement.4. During simultaneous binocular stimulation the images must not only lie in the correct place on both retinae but also have exactly the right orientation for both receptive fields in order to elicit the maximum response from a neurone.5. Therefore certain binocular cells respond specifically to objects tilted in three‐dimensional space towards the cat, or away from it.