bluuebunny/crossref_metadata_2025_split huggingface dataset:
Neuromuscular Physiology of the Longitudinal Muscle of the Earthworm, Lumbricus Terrestris
Authors: Drewes C. D. , Pax R. A. 
Published: April 2021

ABSTRACT
An earthworm saline commonly used in previous investigations of earthworm neuromuscular physiology has been shown to be inappropriate for such studies because the ionic composition of the saline does not correspond to that of earthworm body fluids. Problems encountered when using this saline include: increased excitability of motor axons innervating the longitudinal muscle, a decrease in the amplitude of external electrical responses of the muscle, an increased susceptibility of longitudinal muscle fibres to injury spiking, and a decrease in resting potentials of longitudinal muscle fibres (to a mean of – 36·1 mV). Such problems have been overcome by the development of a new physiological saline whose composition closely corresponds to the ionic composition of earthworm body fluids. In the new saline responses of the nerve-muscle preparation remain stable for more than 1 h. Resting potentials of longitudinal muscle fibres are also stable with time, the mean resting potential being – 47·9 mV.
Coupling of Transmural Flows of NaCl and Water in the Intestine of the EEL (Anguilla Anguilla)
Authors: Skadhauge Erik 
Published: April 2021

ABSTRACT
An in vivo perfusion of the intestine of the yellow European eel (Anguilla anguilla) was used to measure the net absorption of NaCl and water, the osmotic permeability coefficient, the solute-linked water flow, and the osmolality difference against which the intestine could transport water as functions of the salinity of the surrounding water. The eels were adapted to fresh water, to sea water, and to strength sea water. The osmolality difference against which the intestine could transport water was observed to be linearly related to the net transmural flow of NaCl ; the solute-linked water flow had a constant hypertonicity in spite of differing net flows of NaCl. The findings are in agreement with the hypothesis of uphill water movement being caused by local osmosis due to the salt flow and with a shunt leak proportional to the transmural osmotic difference. An important part of adaptation to waters of higher salinity is a pronounced increase in the intestinal absorption of NaCl. The osmotic permeability coefficient varied from experiment to experiment without relation to the state of adaptation. An explanation for this finding may be that the osmotic permeability of the intestinal epithelium is of little importance for the total intestinal transfer of water.
Drinking Rate and Oxygen Consumption in the Euryhaline Teleost Aphanius Dispar in Waters of High Salinity
Authors: Skadhauge E. , Lotan R. 
Published: April 2021

ABSTRACT
The drinking rate and the oxygen consumption were measured in Aphanius in sea water (SW) at 17, 20 and 24·5 °C and at 20 °C in 2-fold and -fold SW. Both untrained (shocked) and trained fish were used. In this species shock was observed to reduce the drinking rate. In trained fish the drinking rate was 11·0±1·0μl/g.h (mean μ S.E.) in SW at 20 °C. The oxygen comsumption was 346± 16 μl O2/g.h. These parameters were not significantly changed in 2 SW and SW. At 17 °C both drinking rate and oxygen consumption were reduced, and at 24·5 °C were increased. The results suggest that adaptation to waters of high salinity primarily involves a reduced effective osmotic permeability of the integument (the gills) and an increase in the transport rate of NaCl by the intestine, roughly proportional to the salinity.
Flow along the Gut and Intestinal Absorption of Salt and Water in Euryhaline Teleosts: A Theoretical Analysis
Authors: Kristensen K. , Skadhauge E. 
Published: April 2021

ABSTRACT
In euryhaline teleosts the transmural salt and water flow and the flow and concentration changes along the gut were simulated by analogue computation. The purpose was to elucidate the interaction of and sensitivity to the parameters of the system particularly with respect to intestinal water absorption. The simulations were based on data obtained from the yellow European eel, the rainbow trout and the cyprinodont Aphanius dispar. When the experimental values for drinking rate, maximal NaCl absorption rate and concentration at half-maximal absorption rate, osmotic permeability coefficient, solute-linked water flow, and concentrations in the gut were used in the model, good consistency was achieved, and predictions could be made. The simulations demonstrated a close linkage between drinking rate and maximal NaCl absorption rate. A large water absorption was only possible close to an optimal drinking rate for each value of maximal NaCl transport rate. The water absorption was little sensitive to the osmotic permeability coefficient of the intestinal wall. As a means of adaptation to waters of high salinity an increase in maximal NaCl absorption rate was shown to be very costly for energetic reasons. This supports indirectly the concept that the osmotic permeability of the gills must go down. The increase in plasma osmolality was a useful part of the adaptation.
Gas Exchange and its Effect on Blood Gas Concentrations in the Amphibian, Xenopus Laevis
Authors: Emilio M. G. , Shelton G. 
Published: April 2021

ABSTRACT
Unrestrained Xenopus with access to air had an oxygen consumption, as measured at 20 °C by manometric and electrode techniques, of approximately 4·5 ml O2 100 g−1 h−1 of which 1·1 ml was taken in through the skin. Measurements of body volume showed that the rate of oxygen uptake from the lungs was high when the animal was at the surface but fell rapidly during the first few minutes of a dive. Oxygen tensions in systemic (80 mmHg) and pulmocutaneous (60 mmHg) vessels provided evidence for separation of blood flows in the ventricle of the animal when breathing air. The tensions fell in all parts of the circulation throughout a dive. The above data, together with a conventionally determined oxygen dissociation curve, show that both blood and lungs are used to a limited extent as oxygen stores during a dive, the blood being more important. The stores do not permit tissue consumption to go on at a uniform rate throughout a normal breathing - diving cycle.
On the Mechanical Properties of the Vitelline Membrane of the Frog Egg
Authors: Mild Kjell Hansson , Løvtrup Søren , Bergfors Tommy 
Published: April 2021

ABSTRACT
Cole’s method is employed to measure the internal pressure in body cavity eggs of Rana temporaria. In the interpretation of the results the effect of bending resistance is considered.
The internal pressure in the undeformed egg in isotonic solution, at 25 °C, is 30 dyn/ cm2, corresponding to a stress resultant, or tension, in the vitelline membrane of 1-5 dyn/cm. In hypotonic solutions substantial increases in the pressure have been recorded.
When the pressure is studied as a function of temperature an anomalous high pressure is found at 16 °C for all the different incubation media employed.
A new method is applied to determine Young’s modulus of the membrane. The result obtained is 3·7 x 105 dyn/cm2 at 23° C.
Ventricular Outflow Dynamics in the Lizard, Varanus Niloticus: Responses to Hypoxia, Hypercarbia and Diving
Authors: Millard R. W. , Johansen K. 
Published: April 2021

ABSTRACT
Blood flow and blood pressure have been measured in the right aorta and left pulmonary artery of the semi-aquatic lizard, Varanus niloticus, during normal breathing, during hypercarbic and hypoxic breathing and during voluntary diving. Mean pulmonary blood pressure during normal breathing was 19 · 5 ± 2 · 0 cmH2O while right aortic pressure was 118 · 0± 3·0 cmH2O. The high systemic blood pressure and high ratio of systemic to pulmonary vascular resistance (4·0−6·0) stand out among reptiles and approach values in homeotherm vertebrates. Pulmonary pressure rise preceded right aortic pressure rise by 120 msec at a heart rate of 25/min. Pulmonary ejection lasted 50% of the cardiac cycle compared to 25 % for aortic ejection during normal breathing. CO2 breathing increased right aortic vascular resistance by 120% while pulmonary resistance increased moderately by 30%. Carotid vascular resistance decreased during CO2 breathing. The pulmonary blood pressure increase was however much higher than the systemic, but at no time did systemic and pulmonary blood pressures overlap. Hypoxic breathing increased pulmonary blood pressure to 36·0 ± 4·0 cmH2O while right aortic pressure fell to 100·0± 10·0 cmH2O. Ejection time remained unchanged in the right aorta while pulmonary flow became continuous. Overall pulmonary vascular resistance increased markedly while systemic resistance changed little. Voluntary diving increased pulmonary blood pressure while the systemic blood pressure fell markedly. The results obtained are discussed in the light of ventricular outflow distribution in reptiles. Directional shunting of blood inside the heart of V. niloticus during cardiac systole must be reduced or absent. Intracardiac shunting during cardiac filling or by systolic residual volumes is small, placing varanid lacertilians haemodynamically closer to homoetherm vertebrates than other reptiles studied.
Directional Sensitivity of Microphonic Potentials Form the Perch Ear
Authors: Sand Olav 
Published: April 2021

ABSTRACT
Microphonic potentials were recorded from the lagena and from different parts of the sacculus in the perch during horizontal and vertical vibration of the fish in air. This stimulation technique gives a good simulation of sound stimulation in water. The lagena was predominantly sensitive to vertical vibrations, whereas the anterior part of the sacculus was equally sensitive to vertical and horizontal vibrations. A gradient is seen along the sacculus, in that the more posterior positions show a tendency towards greater relative vertical sensitivity. By comparing the nervous output from the lagena and from the sacculus the fish might thus get information about the vertical direction of the sound source. The amplitude of the saccular Microphonic potentials evoked by horizontal vibrations was a function of the vibration direction. Maximal responses were obtained when this direction deviated about 20° from the long axis of the fish, which is approximately parallel to the long axis of the sacculi. The difference in response between the two ears might be utilized to give directional information about the horizontal position of the sound source. Sound-induced pulsations radiating from the swimbladder will be efficient in evoking saccular Microphonic potentials. This causes masking of the difference in response between the two ears, but directional information may still be obtained. It is proposed that the power of angle separation in the horizontal plane should be optimal for sound waves side on to the fish, and that a fish possessing a swimbladder may be able to detect the sound direction with higher accuracy in the vertical than in the horizontal plane. The relative effect in evoking Microphonic potentials of vertical compared to horizontal vibrations was frequency dependent, and it is concluded that the pattern of otolith movements during sound stimulation may also change with frequency. This phenomenon constitutes a possible basis for peripheral frequency analysis in fish.
Potassium-Induced Release of the Diuretic Hormones of Rhodnius Prolixus and Glossina Austeni: Ca Dependence, Time Course and Localization of Neurohaemal Areas
Authors: Maddrell S. H. P. , Gee J. D. 
Published: April 2021

ABSTRACT
Exposure of neurohaemal areas to solutions of elevated K concentration (above 40 mM) causes a maximal release of diuretic hormone in Rhodnius prolixus and Glossina austeni. An involvement of Ca in hormone release is indicated by the reduction caused by low concentrations of this cation (below 2 mM) or by the presence of Mn. During prolonged treatment with K-rich solutions the rate of hormone release is initially high, but then declines. This response parallels that for Ca entry into squid giant axons during maintained potassium depolarization and suggests that the rate of Ca entry controls the rate of hormone release. Tetrodotoxin did not reduce the potassium-induced release of the hormone, suggesting that K acts directly on the neurosecretory axon endings in the neurohaemal areas.
Total Body Calcium and Haemolymph Calcium Concentrations in the Crayfish Austropotamobius Pallipes (Lereboullet)
Authors: Greenaway Peter 
Published: April 2021

ABSTRACT
Variations in the concentration of calcium in the haemolymph and of total body calcium in Austropotamobius pallipes have been investigated. Haemolymph calcium concentration was independent of both body size and sex. During premoult the calcium concentration of the haemolymph rose from 11·8 mM/1 to 15·0 mM/l. After the moult the calcium concentration remained high during stages A and B but declined to the intermoult level during stage C. Total body calcium was directly proportional to fresh body weight. No difference was apparent between calcium content of male and female crayfish of similar body weight.
Respiratory Acidosis and Eggshell Resorption by the Chick Embryo
Authors: Crooks R. Jane , Simkiss K. 
Published: April 2021

ABSTRACT
Eggs of the domestic fowl were injected with 45Ca and then subjected to normal incubation or to incubation in 9% carbon dioxide in air. The embryos, yolk, albumen and shell were analysed at various times after incubation had started. The results demonstrate that there is normally a resorption of the eggshell during the latter part of incubation but that this process is depressed by hypercapnia. The results are discussed in relation to the events in normal development and in relation to possible mechanisms of shell resorption.
The Effects of Sodium-Transport Inhibitors and Cooling on Membrane Potentials in Cockroach Central Nervous Connectives
Authors: Pichon Y. , Treherne J. E. 
Published: April 2021

ABSTRACT
Cooling caused axonal depolarization in desheathed and urea-treated connectives, but induced hyperpolarizing responses (measured with microelectrodes and with the sucrose-gap) in intact preparations. Hyperpolarizing responses were also recorded with extracellularly-located microelectrodes in intact connectives. Strophanthidin (0·2 mm/1) caused axonal depolarization in desheathed preparations, ethacrynic acid being without appreciable effect. Ethacrynic acid (0·2 mm/1) induced apparent hyperpolarizations in intact connectives and abolished or reduced the effects of cooling. It is concluded that the axonal sodium pump is pharmacologically separable from that associated with the perineurial and/or the glial membranes: the former being inhibited by cardiac glycosides, the latter by ethacrynic acid. The results are discussed in relation to extra-axonal sodium regulation and the possible involvement of an electrogenic sodium pump associated with the perineurial or glial membranes.
Metabolic Rates Related to Muscle Activity in Bumblebees
Authors: Kammer Ann E. , Heinrich Bernd 
Published: April 2021

ABSTRACT
Oxygen consumption, thoracic temperature, and action potentials from the fibrillar muscles were concurrently recorded in queens and workers of Bombus vosnesenskii. The oxygen consumption of ‘inactive’ bees (quiescent and/or producing fewer than 0·3 spikes/sec) was markedly temperature-sensitive, with a Q10 of 3·4 for thoracic temperatures of 25–35°C. The oxygen consumption of bees with active fibrillar muscles was directly correlated with spike frequency; a single spike was associated with the consumption of 2·3–2·6 μl O2/gth. No oxygen debt was observed. The oxygen consumption per spike during flight was similar to that during warm-up. Oxygen consumption per gram thorax was similar in queens and workers engaging in similar activity. The results are compared with those from other insects and their adaptive significance is discussed..
Renal Concentrating Ability in Selected West Australian Birds
Authors: Skadhauge Erik 
Published: April 2021

ABSTRACT
The osmotic ratio between ‘urine’ (the supernatant of the ureteral part of the droppings) and plasma has been determined in a number of dehydrated West Australian birds. The U/P ratio was 1·4 in the Emu, 1·7 in two Columbidae (Senegal Turtle Dove and Crested Pigeon), 2·4 in two Meliphagidae (Singing Honeyeater and Red Wattle Bird), 2·6 in three Psittacidae(Bourke Parrot, 28-Parrot, and Galah), 2·7 in the Laughing Kookaburra, and 2·8 in the Zebra Finch. The Na+ and Cl− concentrations in the ‘urine’ ranged from 5 to 71 m-equiv./l, the K+ concentration from 92 to 201 m-equiv./l. There seems to be a rather narrow range for tire concentrating ability within each family, but the concentrating ability of xerophilic birds differs considerably.
Calcium Balance at the Premoult Stage of the Freshwater Crayfish Austropotamobius Pallipes (Lereboullet)
Authors: Greenaway Peter 
Published: April 2021

ABSTRACT
The premoult stage in Austropotamobius pallipes is characterized by a net loss of calcium which increases from Do to a maximum of 0·83 /μmoles/g/h at D4. The concentration of ionized calcium in the haemolymph does not increase during the premoult stage although there is an increase in complexed calcium. The electrochemical gradient across the body surface is similar to that at the intermoult stage and favours calcium outflux. Possible routes for calcium net loss have been discussed and a mechanism for elimination of calcium has been proposed.
Physiology of Insect Ecdysis: Neural and Hormonal Factors Involved in Wing-Spreading Behaviour of Moths
Authors: Truman James W. , Endo Paul T. 
Published: April 2021

ABSTRACT
In the tobacco hornworm, wing spreading involves a stereotyped series of movements which take 74 min to complete and which include two components, wing folding and wing inflation. Moths decapitated at the moment of eclosion show neither wing inflation nor wing folding. If decapitation is delayed until 5 sec after emergence, then the full wing-spreading behaviour is displayed. Newly emerged moths which are confined show intense digging-behaviour and delay the onset of wing spreading until after their release. Decapitated moths attempt to spread their wings immediately, regardless of whether or not they are confined. Surgical experiments showed that the brain was not required in a neural capacity in order for wing spreading to occur; it was needed only as a source of the eclosion hormone. The neural influence of the suboesophageal ganglion was required until immediately after eclosion. Newly emerged moths whose abdomens had been removed showed wing-folding behaviour. No inflation occurred and the duration of wing folding was much longer than normal. It was concluded that wing-folding behaviour was centrally programmed but that the abdomen could modify the length of the programme. Injections of bursicon into abdomenless moths reduced the duration of wing-folding behaviour to almost normal levels. Therefore, in some manner, bursicon has an important role in determining when wing-folding behaviour will come to an end.
Active Ion Transport in the Larval Hindgut of Sarcophaga Bullata (Diptera: Sarcophagi Dae)
Authors: Prusch Robert D. 
Published: April 2021

ABSTRACT
The potential difference across the hindgut of Sarcophaga is 30 mV, in vivo, the lumen being negative with respect to the haemolymph. A potential difference of the same polarity exists in the isolated hindgut. The potential difference is not a simple diffusion potential, since it is maintained in the absence of any ionic concentration difference across the gut, and is dependent on energy supplies. The potential across the gut is the algebraic sum of two separate electrogenic pumping mechanisms; a cation system which moves K+ or NH4+ and an anion system which moves Cl− into the gut lumen. Since a potential exists across the gut, the rate or amount of cation and anion movement into the gut cannot be equal; alternatively, various shunt pathways may exist for one or more of the ions involved.
The Effect of External Potassium Ions On the Electrical Potential Measured Across the Gills of the Teleost, Dormitator Maculatus
Authors: Evans David H. , Carrier Jeffrey C. , Bogan Margaret B. 
Published: April 2021

ABSTRACT
A technique has been developed for the measurement of electrical potentials (TGP ‘s) across the gills of free-swimming, Dormitator maculatus. Transfer of fish to various KC1 solutions is correlated with changes in the TGP, which are not of sufficient magnitude to account for the known potassium stimulation of sodium efflux from this species. Transfer to potassium-free sea water results in little or no change in TGP while previous results have shown that such a transfer is correlated with a 22% reduction of sodium efflux. Transfer to fresh water results in a reduction of TGP from + 17 mV (inside positive) to −36 mV which is sufficient to account for the instantaneous reduction in sodium efflux previously shown for this species. It is concluded that while changes in TGP can account for the ‘Na-free effect’ in D. maculatus they cannot account for the potassium effects on sodium extrusion. This supports the previous conclusion that sodium efflux and potassium influx are chemically linked in this species.
The Effect of Acoustic Signals On the Chirp Rhythm in the Bush Cricket Pholidoptera Griseoaptera
Authors: Jones M. D. R. 
Published: April 2021

ABSTRACT
The effect of acoustic signals on the control of chirp production has been investigated using the insect ‘s own chirp to trigger artificial sound signals (100 msec, 70dB, 12 or 15 kHz) at predetermined phases of the chirp cycle. The signals appear to reset the phase of the chirp rhythm generator, and signals given late in the cycle are followed by the greatest phase shifts. The signals may also have excitatory after-effects which are usually small, but can summate to give a slow, longer lasting increase in chirp rate. This appears to happen during alternation with a natural or artificial partner.
Active Transport by Insect Malpighian Tubules of Acidic Dyes and of Acylamides
Authors: Maddrell S. H. P. , Gardiner B. O. C. , Pilcher D. E. M. , Reynolds S. E. 
Published: April 2021

ABSTRACT
Insect Malpighian tubules carry out active transport of two types of organic anion: acylamides (such as p-aminohippuric acid) and sulphonates (such as indigo carmine and amaranth). There are separate mechanisms for the transport of these two classes of compounds.
The degree to which these compounds are concentrated depends critically on the passive permeability of the tubule wall. In the permeable Malpighian tubules of Calliphora, small transported molecules readily escape from the tubule lumen. At low rates of fluid secretion the net rate of dye transport is thereby very much reduced. As a result the rate of dye transport in this insect depends on the rate of fluid secretion, although the processes are not rigidly linked. In the less permeable tubules of Rhodnius and Carausius, dye secretion is not affected by the rate of fluid secretion.
The active transport of these two types of compounds is a means of clearing from the haemolymph the conjugated compounds which are the products of detoxication of potentially toxic products of metabolism.