bluuebunny/crossref_metadata_2025_split huggingface dataset:
Permeation and distribution of deuterated and triated water in smooth and striated muscle
Authors: Elford B. C. 
Published: December 2014

1. The diffusion of deuterated water (HDO) into and out of isolated guinea‐pig taenia coli and frog sartorius was followed by means of a recording electronic microbalance.2. A comparison was made of the rates of efflux of deuterated and tritiated (HTO) water using the microbalance and a standard tracer technique.3. The time course of the exchange of HDO in both smooth and striated muscle was fitted to the sum of two exponential functions; however, it was not possible to correlate sizes of the intra‐ and extracellular spaces in the muscles with the sizes of the two compartments in model systems based on compartmental theory of tracer kinetics.4. The efflux of HDO, which was measured by means of the microbalance under stagnant conditions, occurred at a rate approximately 3 times slower than the efflux of HTO which took place while muscles were agitated vigorously in their bathing media.5. There was a marked deviation at short times from a double exponential time course during the efflux of HTO.6. Values of the tracer water permeability, Pd, of smooth and striated muscle fibres, and the extracellular space, E, of the muscles were obtained using a computer to numerically evaluate the series solutions of the equations describing the permeation of labelled water in the muscles.7. It was necessary to assume a value for the diffusion coefficient of the tracer in extracellular fluid in order to compute a unique fit to an exchange curve.8. Values of Pd and E given by the analysis depended upon the method used for monitoring the exchange, and an interpretation of this dependence was made difficult by the variation in the thickness of unstirred layers on the surface of the muscles under the different experimental conditions.
Selective reinnervation of two cell populations in the adult pigeon ciliary ganglion
Authors: Landmesser Lynn , Pilar G. 
Published: December 2014

1. Presynaptic fibres innervating the adult pigeon ciliary ganglion were cut 2 mm proximal to the ganglion. The modification of transmission in the ciliary and choroid cell populations was studied after periods of 6 hr—100 days.2. Transmission failed after 2 days and for the next 10 days there was no transmission through the ganglion. Long latency responses in both ciliary and choroid nerves were first observed at 13–15 days, and the latency decreased toward control values in 40 days. Electrical transmission reappeared in the ciliary population in about 26 days.3. Presynaptic fibres innervating the ciliary population have higher conduction velocities and lower electrical thresholds than those innervating the choroid group. This relation was maintained throughout the reinnervation process. Fibres innervating the extraocular muscles also regenerated and achieved conduction velocities similar to their control values.4. In two experiments out of seventeen, a few fast conducting, low threshold fibres, presumably stray ciliary fibres, innervated choroid cells and induced electrical transmission.5. It is concluded that each group of cells, ciliary and choroid, was reinnervated in a highly selective manner by its original class of presynaptic fibres, and that the presynaptic ciliary elements cause the specializations necessary for electrical transmission.
Voltage clamp of the Aplysia giant neurone: early sodium and calcium currents
Authors: Geduldig D. , Gruener R. 
Published: December 2014

1. The membrane properties of the Aplysia giant neurone were studied under controlled voltage conditions. Emphasis was placed on the early transient currents resulting from step polarizations applied while the ganglion was immersed in different test solutions.2. Early inward‐going currents were observed when the neurone was bathed in normal saline (containing both Na and Ca), in Ca‐free (Na‐containing) saline, in Na‐free (Ca‐containing) saline, and in the normal saline to which tetrodotoxin 10−5 g/ml. was added. When both Na and Ca are absent from the bathing solution no evidence for early inward‐going current could be found.3. When tetrodotoxin is added to the normal saline, the maximum inward‐going current is reduced, and no further reduction of this current is observed when the external Na‐concentration is subsequently halved in the presence of the drug. When the external Ca‐concentration is increased fivefold in the presence of the drug, the maximum transient current increases significantly.4. Hyperpolarizing prepulses result in a membrane inactivation in the presence of tetrodotoxin or in the absence of Na. In the presence of Na (and absence of tetrodotoxin) no such voltage‐dependent inactivation occurs, and for this case, inactivation results only from depolarizing prepulses.
The effect of carotid body denervation upon the respiratory response to hypoxia and hypercapnia in the duck
Authors: Jones D. R. , Purves M. J. 
Published: December 2014

1. Respiratory responses to altered Pa, O2 at constant Pa, CO2 and altered Pa, CO2 at constant Pa, O2 were measured in fourteen unanaesthetized ducks 5‐9 weeks old.2. All the ducks responded to the inhalation of a few breaths of 100% O2 with a fall in V̇E of between 11 and 17% of control, and to the reduction in Pa, O2 from control levels (93–101 mm Hg) to 38–47 mm Hg with an average increase in V̇E of 190% of control which was potentiated by raising the level of CO2.3. Ventilation approximately doubled when Pa, CO2 was raised to 55 mm Hg, the greatest sensitivity to changes in Pa, CO2 being over the range 40–45 mm Hg.4. Carotid body denervation was carried out in nine ducks and the respiratory responses were modified. The fall in V̇E with inhalation of 100% O2 was abolished in all ducks and the rise in V̇E with hypoxia was abolished in six. The increase in V̇E as Pa, CO2 was altered in steps was unaffected but the rate at which V̇E increased in response to 4% CO2 was markedly reduced.5. It is concluded that the chemoreceptor regulation of respiration in ducks is similar to that observed in non‐diving animals.
The effect of ions on the photoresponses of pigeon cones
Authors: Arden G. B. , Ernst W. 
Published: December 2014

1. Pigeon cone receptor potentials have been identified in a preparation of isolated, incubated retina.2. There is an approximately linear relationship between response amplitude and sodium concentration of the bathing medium.3. A decrease of chloride ions produces results equivalent to a decrease of sodium ions. The response amplitude is a power function of the product of the sodium and chloride concentrations. For most experiments, the exponent is ca. 1.4. After treatment of the retina with ouabain, responses vanish, but can be temporarily restored, in normal, or inverted polarity, by appropriate changes in sodium or chloride concentration.5. Ammonium and potassium ions can substitute quantitatively for sodium ions. Lithium ions initially carry response currents, but later block all responses. Bromide, nitrate and thiocyanate can substitute for chloride ions.6. The response wave form, and the amplitude/light intensity relationship are independent of ions.7. Models of the photoreceptor are discussed. It is concluded that the membrane potential of the cone in light is chiefly determined by the distribution of anions across the membrane, and in darkness there is an increase in outer limb cation permeability.
Effects of tetraethylammonium chloride on the membrane activity of guinea‐pig stomach smooth muscle
Authors: Ito Y. , Kuriyama H. , Sakamoto Y. 
Published: December 2014

1. The effects of tetraethylammonium (TEA) on the membrane activity of the antral circular muscle of the guinea‐pig stomach were investigated with micro‐electrode and double sucrose gap methods.2. In a concentration of 1‐1·5 × 10−3 g/ml. (3‒5 m
M), the membrane potential was not influenced; the membrane resistance measured by inward current pulses remained the same but the rectifying property of the membrane was suppressed.3. TEA (1–1·5 × 10−3 g/ml.) enhanced the spike amplitude markedly even from fibres which generated graded responses.4. TEA (1–1·5 × 10−3 g/ml.) did not increase the maximum rate of rise of the spike but decreased the maximum rate of fall of the spike markedly.5. In Na‐free (Tris or sucrose) solution, in K‐deficient and excess‐K solutions, TEA (1–1·5 × 10−3 g/ml.) suppressed the rectifying property of the membrane and enhanced the spike amplitude.6. Atropine (10−6 g/ml.) had no effect on the enhancement of the spike amplitude produced by TEA.7. The minimum concentration of Ca ions required for the effect of TEA on the spike amplitude was one fifth of the normal concentration. TEA also enhanced the spike amplitude in Sr—Krebs.8. The possible role of TEA on the membrane activity is considered to be due to suppression of the K conductance when the membrane is depolarized. Alternative possible roles of TEA on the spike amplitude are also discussed.
The relation between L‐methionine uptake and sodium in rat small intestine in vitro
Authors: Newey H. , Rampone A. J. , Smyth D. H. 
Published: December 2014

1. Uptakes of
L‐methionine and mannitol by rat jejunum in vitro were measured over test periods from 5 to 120 sec after 30 min pre‐test periods in the presence or absence of Na.2. The initial stage in methionine uptake was dependent on the presence of Na+ and to a lesser extent on the K+ concentration. In contrast mannitol uptake was independent of Na and K.3. The initial stage in methionine uptake can be reactivated 30–60% within 5 sec by replacing an Na‐deficient intestine into an Na‐containing medium.4. Initial methionine uptake was greater with a normal intracellular and low medium Na concentration than with a high medium and low intracellular Na concentration. It is suggested that the intracellular Na concentration is a critical factor, more important than the Na gradient, in determining the rate of amino acid transfer across the luminal membrane.
Evidence for two types of sodium conductance in axons perfused with sodium fluoride solution
Authors: Chandler W. K. , Meves H. 
Published: December 2014

1. Voltage clamp experiments were carried out on squid giant axons internally perfused with 300 m
M‐NaF + sucrose. K‐free artificial sea‐water, −0·3 to 3·5° C, was used externally.2. Membrane currents were corrected for capacitative and leakage components, and the resulting Na current was converted to Na conductance, gNa. An attempt was made to fit changes in gNa according to the Hodgkin—Huxley model, namely [Formula: see text].According to the model ḡNa is a constant, m∞ and h∞ are steady‐state values which depend only on voltage, τm−1 and τh−1 are rate constants which also are functions only of voltage.3. Stepwise depolarizations from the holding potential (−67 to −83 mV) to a potential which varied from −10 to +63 mV resulted in an exponential decline of h from its initial level to a final, non‐zero level. If the test depolarization was preceded by a positive prepulse (duration, 19–105 msec; voltage, −6 to 94 mV) the rate constant for h, τh−1, was increased roughly threefold with practically no change in the final level.4. The steady‐state level of h was studied by using prepulses of varying amplitude followed by a test depolarization. In one such experiment a value of 0·34 was obtained for a 105 msec prepulse to −49 mV. The same value for the steady level of h was obtained from analysing a record taken at +52 mV. If the potential was switched from −49 to +52 mV there was a transient increase in gNa although h∞ had the same value at these two potentials.5. Recovery from depolarization was studied by repolarizing the fibre for varying lengths of time, then applying a test depolarization. If the first depolarization was strongly positive (for example, 70 mV), so that the steady level of h was large (0·39), the currents associated with the test pulse could not be fitted on the basis of an exponential increase in h during the recovery period. Rather, the results suggested that on repolarization h rapidly decreased initially, then slowly increased.6. These results can be explained by assuming that h is given by the sum of two components, h1 and h2. Changes are represented kinetically by h1 ⇌ x ⇌ h2, where x signifies the inactive state. The distribution is shifted to the left at negative potentials and to the right for positive ones. The resulting Na conductance is comprised of two types: the first type, ḡNam3h1, is similar to the Hodgkin—Huxley system and underlines the usual transient increase in gNa associated with depolarization; the second type, ḡNam3h2, is maintained with depolarization and gives rise to a steady level of gNa.
Rates of oxygen consumption and of anaerobic glycolysis in renal cortex and medulla of adult and new‐born rats and guinea‐pigs
Authors: Dicker S. E. , Shirley D. G. 
Published: December 2014

1. Rates of oxygen uptake and of anaerobic glycolysis were estimated in slices from the renal cortex and medulla (a) of adult rats and guinea‐pigs, (b) of new‐born (1−, 5‐ and 21‐day‐old) rats and of guinea‐pigs of 1, 12, 21, 24 and 120 hr age.2. In the adult rat, QO2 values for the cortex were 12·55 ± 0·20 (22) and for the medulla: 8·56 ± 0·17 (22) μl./hr.mg dry weight, while in the new‐born rat (24 hr old) they were 10·99 ± 0·46 (12) and 9·33 ± 0·18 (9) μl./hr.mg dry weight respectively.3. Values for QCO2N2 (anaerobic glycolysis) in the 14 hr old new‐born rat were in the renal cortex 9·65 ± 0·35 (5) and in the medulla 7·39 ± 0·43 (5) μl./hr.mg dry weight; while in the adult they were 2·25 ± 0·08 (16) and 5·76 ± 0·14 (16) μl./hr.mg dry weight, respectively.4. In the adult guinea‐pig values for QCO2N2 were of the same order as in the adult rat, though the rate of O2 uptake was for the cortex 8·12 ± 0·22 (12) and for the medulla 5·02 ± 0·23 (11) μl./hr.mg dry weight.5. Though the QO2 values in the renal cortex and medulla were smaller in the 1 hr old new‐born guinea‐pig, they were already increasing in the 12 hr old neonate.6. The results are discussed in the light of enzyme changes occurring during the process of maturation of the nephron as indicated by histochemical observations.
Galactose transport across the hamster small intestine; the effect of sodium electrochemical potential gradients
Authors: Smulders Anthony P. , Wright Ernest M. 
Published: December 2014

1. Measurements of galactose unidirectional fluxes across the isolated mucosa of the hamster small intestine were made under a variety of experimental conditions designed to investigate the interrelationships between galactose transport, the sodium ion and electrical potentials.2. Galactose transport was inhibited by lowering the sodium concentration in the mucosal and/or serosal solutions and by increasing the p.d. across the tissue. This inhibition of galactose transport was judged to be irreversible.3. Transport was unaffected by decreasing the p.d. across the tissue.4. These results are discussed in relation to the model proposed to explain galactose transport across the intestine.
Relation of cardiovascular changes in fighting to emotion and exercise*
Authors: Adams D. B. , Baccelli G. , Mancia G. , Zanchetti A. 
Published: December 2014

1. To obtain evidence on the relative importance of exercise and emotion in the cardiovascular changes of fighting in the cat, the changes during fighting were compared with changes during a mild non‐emotional exercise (walking on a treadmill at low speed), and during confrontation without fighting (preparation for fighting), an emotional condition accompanied by no or very little motor activity.2. The direction of change of all variables we measured, iliac and mesenteric flows and conductances, total peripheral conductance, heart rate, cardiac output and blood pressure, was similar in both fighting and exercise.3. Some of the cardiovascular manifestations of preparation for fighting were very different from those of motor activity. These were iliac vasoconstriction, a fall in cardiac output, and often a strong bradycardia, all of these changes being in the opposite direction to changes during exercise and fighting.4. It is suggested that the changes during preparation for fighting represent the cardiovascular manifestations of an emotional state, and that during fighting these manifestations are superseded and masked by changes due to motor activity.
Unit activity in rat diencephalic islands — the effect of anaesthetics
Authors: Cross B. A. , Dyer R. G. 
Published: December 2014

1. Unit activity was recorded with steel micro‐electrodes from 486 hypothalamic neurones in rat diencephalic island preparations.2. The histograms of firing frequencies for populations of hypothalamic units from unanaesthetized preparations and from those under urethane anaesthesia were not significantly different. The firing rates of both were significantly faster than those observed in intact brains under urethane.3. The mean distance between stable units in unanaesthetized island preparations did not differ significantly from that in preparations anaesthetized with urethane.4. The response of individual neurones to intravenous injections of urethane was variable, and apparently not associated with the onset or maintenance of anaesthesia. Some showed transient acceleration, some deceleration and some no change in rate or pattern of discharge.5. All neurones tested were slowed or stopped by intravenous injections of subanaesthetic doses of sodium methohexitone (Brietal). The responses were highly reproducible and dose‐dependent.6. Brietal also produced a fall in arterial pressure and depressed respiration. Inhalation of amyl nitrite evoked larger hypotensive responses but did not affect unit activity; nor did inhalation of CO2 (hypercapnia) or N2O (hypoxia).7. It is concluded that urethane anaesthesia is not associated with any direct action on hypothalamic neurones. The depression of firing rate in hypothalamic neurones induced by Brietal may represent an important forebrain mechanism in anaesthesia by this agent.
Changes in monoamine oxidase and catechol‐o‐methyl transferase activities after denervation of the nictitating membrane of the cat
Authors: Jarrott B. , Langer S. Z. 
Published: December 2014

1. The question of cellular localizations of monoamine oxidase and catechol‐o‐methyl transferase, enzymes involved in the metabolism of noradrenaline, has been investigated by following the changes in the enzyme activity of the smooth muscle of the cat nictitating membrane after sympathetic denervation. Any falls in enzyme activity coinciding with the time course for degeneration of the sympathetic nerve endings (2–3 days) can reasonably be ascribed to a former localization of the enzyme within the sympathetic nerve.2. Monoamine oxidase activity of the inferior and medial smooth muscle was significantly reduced 3 days after sympathectomy and remained reduced 14 days after sympathectomy.3. A correlation was found between the fall in monoamine oxidase activity and the endogenous noradrenaline concentration of the contralateral normal muscle, indicating that the higher the endogenous noradrenaline concentration, the greater the fall in monoamine oxidase activity after denervation.4. It was concluded that the fall in monoamine oxidase activity after denervation indicated a former localization of the enzyme within the sympathetic nerve endings.5. The fall in monoamine oxidase activity of the denervated muscle was significantly less measured with benzylamine as a substrate than with tyramine. This suggested that the neuronal monoamine oxidase may have different properties than the extraneuronal enzyme.6. A small fall in the catechol‐o‐methyl transferase activity of denervated smooth muscle was found and a correlation between the fall in enzyme activity and endogenous noradrenaline indicated that in this smooth muscle a proportion of the catechol‐o‐methyl transferase activity may be of presynaptic origin.
The effects of high concentrations of an electrolyte on the swelling of non‐metabolizing tissue slices
Authors: Davey K. J. , Skegg D. C. G. 
Published: December 2014

1. Rat kidney cortical slices, with metabolism suppressed by iodoacetate, were incubated anaerobically at 26° C in hyperosmotic saline media. Changes in tissue composition with time, up to 12 hr, were studied. Despite initial shrinkage, gross swelling occurred, even in saline media of more than twice the concentration of normal extracellular fluid.2. The composition of non‐metabolizing kidney slices incubated at 26° C in a balanced saline medium containing 7 g polyethylene glycol 6000 (PEG 6000)/100 ml. was determined at intervals up to 12 hr. The tissue water, sodium and chloride contents had reached constant levels by 6 hr. Potassium continued to leak slowly from the tissue, but there was no significant further loss between 10 and 12 hr.3. Non‐metabolizing kidney slices were incubated in PEG medium containing additional quantities of either a non‐electrolyte (400 m‐osmole glucose/kg H2O) or an electrolyte (400 m‐osmole NaCl/kg H2O), both of which penetrated the tissue to attain approximately uniform concentrations in cells and media. Whereas the slices in the glucose medium attained the same equilibrium water content as those incubated in PEG medium alone, the final water content of slices in the medium containing additional NaCl was significantly lower. This difference might have resulted from depression of intracellular colloid osmotic pressure by the high salt concentration.
The release of a renally active substance by perfused rat hearts
Authors: Lockett Mary F. , Retallack R. W. 
Published: December 2014

1. A substance (HS) which resembles the 18‐monoacetate of
D‐aldosterone (18‐MA) in its biological actions is released by perfused rat hearts, HS is assayed in terms of activity equivalent to synthetic 18‐MA.2. Isolated rat hearts perfused with modified Krebs bicarbonate Ringer without recirculation secrete progressively less and less HS.3. Addition of
D‐aldosterone to recirculating perfusate supplying a heart no longer secreting measurable quantities of HS causes a rapid and very marked increase in the output of HS from the heart. If radioactively labelled
D‐aldosterone is supplied the HS synthesized is radioactively labelled. No measurable amounts of HS are formed from 18‐hydroxycorticosterone.4. Chromatographic differentiation between 18‐MA and HS, initially difficult, has been achieved.5. The rate of secretion of HS from the hearts of adrenalectomized animals is markedly reduced: synthesis of HS is immediately resumed when these hearts are supplied with
D‐aldosterone, but at a subnormal rate.