bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of Catecholamines on Gas Exchange and Ventilation in Rainbow Trout (Salmo Gairdneri)
Authors: Playle Richard C. , Munger R. Stephen , Wood Chris M. 
Published: April 2021

ABSTRACTA transient inhibitory effect of catecholamines on relative CO2 excretion, mediated by an inhibition of HCO3− dehydration through the red blood cell (RBC), has been proposed to cause the increase in routinely observed after strenuous exercise in fish (‘CO2 retention hypothesis’, Wood and Perry, 1985). To evaluate this idea, trout fitted with arterial cannulae, oral membranes and opercular catheters were placed in ventilation chambers. , RBC intracellular pH (pHi) and other blood acid-base parameters were monitored from the arterial cannulae. The ventilation chamber system allowed continuous, almost instantaneous, measurements of water ΔO2 and ΔCO2 across the gills, and therefore of respiratory exchange ratio (RE), as well as Δammonia, mean expired pH and ventilation volume . Physiological doses of adrenaline and noradrenaline (3.2 nmol kg−1), designed to duplicate typical post-exercise concentrations, together with appropriate saline controls, were injected into resting fish. Adrenaline caused an immediate hypoventilation, while the response to noradrenaline was biphasic: hyperventilation followed by hypoventilation. With both drugs, ΔO2 and ΔCO2 increased, but RE remained constant (adrenaline) or increased (noradrenaline). There was no evidence of a specific inhibition of CO2 excretion, nor was there any increase in ; changes in RBC pHi were small (noradrenaline) or non-existent (adrenaline). These results confirm those of Steffensen el al. (1987) and do not support the CO2 retention hypothesis. However, the RBCs of resting trout may be relatively insensitive to catecholamines at normal arterial blood pH (pHa).
Transient behavior of sea urchin sperm flagella following an abrupt change in beat frequency
Authors: Eshel Dan , Shingyoji Chikako , Yoshimura Kenjiro , Gibbons Barbara H. , Gibbons Ian R. , Takahashi Keiichi 
Published: April 2021

ABSTRACT
Within the approximate range of 30–80 Hz, the flagellar beat frequency of a sea urchin sperm held by its head in the tip of a micropipet is governed by the vibration frequency of the micropipet. We have imposed abrupt changes in flagellar beat frequency by changing the vibration frequency of the micropipet within this range and used a high-speed video system to analyze the flagellar wave parameters during the first few cycles following the change. Our results demonstrate that the various flagellar beat parameters differ in the time they take to adjust to the new conditions. The initiation rate of new bends at the base is directly governed by the frequency of the vibration and changes immediately to the new frequency. The length and the propagation velocity of the developed bends become adjusted to the new conditions within approximately 1 beat cycle, whereas the bend angles take more than 4 beat cycles to attain their new steady-state value. Bends initiated shortly before the change in frequency occurs attain a final length and angle that depends on the relative durations of growth at the old and new frequencies. Our results suggest that the flagellar wavelength and bend angle are regulated by different mechanisms with the second not being directly dependent on bend initiation.
Na+ and Cl− Uptake Kinetics, Diffusive Effluxes and Acidic Equivalent Fluxes Across the Gills of Rainbow Trout II. Responses to Bicarbonate Infusion
Authors: Goss Greg G. , Wood Chris M. 
Published: April 2021

ABSTRACT
Adult rainbow trout fitted with arterial and bladder catheters were chronically infused with either bicarbonate (as NaHCO3) or NaCl for 19 h at approximately 410μequivkg−1h−1. NaHCO3 infusion produced a pure exogenous metabolic alkalosis of approximately 0.35 pH units accompanied by a decrease in plasma [Cl−] but no change in plasma [Na+]. Alkalosis stimulated Cl− influx and inhibited Na+ influx (measured at 10-16h infusion), resulting in a negative Na+ balance, a positive Cl− balance and a large net basic equivalent excretion (=acidic equivalent uptake) across the gills. The latter was approximately equal to the rate of HCO3−loading. The kidney accounted for approximately 13 % of the acid-base compensation.
Kinetic analysis revealed that reductions in were accomplished by increases in (463μuquivl−1; NaHCO3-infused vs 276μequivl−1; NaCl-infused) and large decreases in (262μequivkg−1h−1 vs 689μequivkg−1 h−1) while stimulation of was accomplished by large increases in only (674 μequiv kg−1 h−1 vs 360μequivkg−1 h−1). Thus, Jmax can be increased or decreased in response to acid-base disturbance, but Km can only be increased; the Na+ and Cl− carriers operate close to maximum affinity under control conditions. Basic equivalent excretion was described by a virtually identical kinetic curve to that of the Cl− uptake. NaHCO3 infusion also induced a differential diffusive efflux of Na+ over Cl− which could account for up to 35 % of the acid-base compensation during alkalosis.
Urine Production in Octopus Vulgaris
Authors: Wells M. J. , Wells J. 
Published: April 2021

ABSTRACT
In a recent paper (Wells and Wells, 1989) evidence was presented indicating that Octopus vulgaris takes up water and salts through the digestive gland appendages, the so-called ‘pancreas’. Animals with the digestive gland ducts ligated lost weight at around 11 % of the body mass per day and died after about 48 h. Animals with the ducts exteriorised, leaving a sufficient length to perform peristalsis, did not lose weight.
Heat Dissipation, Gas Exchange and Acid-Base Status in the Land SnailOreoheuxDuring Short-Term Estivation
Authors: Rees Bernard B. , Hand Steven C. 
Published: April 2021

ABSTRACTWithin 4 days following entry into estivation, heat dissipation and oxygen consumption by the land snail Oreohelix spp. decreased by 83% compared to standard non-estivating rates. During both non-estivating and estivating conditions, the quantity of heat dissipated per mole of O2 consumed was indicative of a completely aerobic metabolism. This calorimetric-respirometric (C/R) ratio was –461 ±12 kJ mol−1O2 (S.E.M., N=5) under standard non-estivating conditions and –464±26kJmol−1O2 (N=4) during estivation. Respiratory exchange ratios reflected a primary dependence upon carbohydrate as a metabolic substrate during both states. Carbon dioxide retention occurred during the first 36h of estivation, resulting in an increase in hemolymph and a decrease in pH. The respiratory acidosis during short-term estivation was not compensated by elevation of hemolymph [HCO3−] above levels predicted from the in vitro non-bicarbonate buffer value of hemolymph. A brief period of rapid CO2 release, which caused hemolymph and pH to return to pre-estivation values, preceded the increase in O2 consumption during arousal. Exposure of nonestivating snails to 4.67 kPa (1 kPa=7.5mmHg) caused a rapid and fully reversible 50% suppression of respiration rate. The temporal nature of CO2 retention and release during entry into and arousal from estivation, and the suppression of O2 consumption by artificial hypercapnia, support the hypothesis that elevated or the resultant acidosis may contribute to metabolic suppression during estivation by land snails.
Effects of Combined Abdominal and Thoracic Airsac Occlusion on Respiration in Domestic Fowl
Authors: Brackenbury John , Amaku Jane 
Published: April 2021

ABSTRACTVentilation and respiratory and blood gas tensions were monitored at rest and during running exercise, following bilateral occlusion of the cranial and caudal thoracic and the abdominal air sacs. This represents a removal of approximately 70% of the total air-sac capacity. At rest, the birds were strongly hypoxaemic/ hypercapnaemic. Ventilation was maintained at its control value but respiratory frequency was significantly increased and tidal volume diminished. The birds were capable of sustained running at approximately three times the pre-exercise metabolic rate. Minute ventilation during exercise was the same as that of the controls, but breathing was faster and shallower. Exercise had no effect on blood gas tensions in either the control or the experimental birds. There was no evidence of a detrimental effect of air-sac occlusion on the effectiveness of inspiratory airflow valving in the lung: hypoxaemia appeared to be due to the altered respiratory pattern, which resulted in increased dead-space inhalation.
Control of ‘Pulmonary’ Pressure and Coordination with Gill Ventilation in the Shore CrabCarcinus Maenas
Authors: Rajashekhar K. P. , Wilkens J. L. 
Published: April 2021

ABSTRACTIn the shore crab, Carcinus maenas (L.), forward ventilation creates negative pulses of hydrostatic pressure while reversed ventilation causes dramatic positive pressure fluctuations in the branchial chamber. These pressures are transmitted via the gills to the haemolymph of the open circulatory system. The branchiostegal sinus, which is a compliant chamber, may function as a reservoir for displaced haemolymph and may operate as an accessory pump driven by the action of the dorsoventral (DV) muscles. A band of dorsoventral muscles controls the volume of the branchiostegal sinuses. The muscular activity is coordinated with ventilatory activity and may assist in regulating pressure fluctuations caused by ventilatory pressure pulses. During a ventilatory reversal, the haemolymph displaced from the gills is added to the volume of haemolymph in the open circulatory system and this haemolymph may be accommodated in the branchiostegal sinus by relaxation of the DV muscles. Artificially regulating the pressure either in the branchial chamber or in the branchiostegal sinus reflexively alters DV muscle activity, which suggests the occurrence of baroreceptors in this crab. The branchiostegal nerve that innervates the DV muscles contains five neurones identified by cobalt backfills. Three of them are median and two are contralateral. The dendritic field of each neurone is confined to its respective hemiganglia. The electrical activity of one of the motoneurones in the branchiostegal nerve corresponds to the activity of the DV muscles. In vitro observations of the activity of branchiostegal motoneurones in relation to ventilatory motoneurone activity indicate that both are centrally coupled and support the hypothesis that the branchiostegal motoneurones are influenced by the ventilatory central pattern generator.
Red Pigment Concentrating Hormone is A Modulator of the Crayfish Swimmeret System
Authors: Sherff Carolyn M. , Mulloney Brian 
Published: April 2021

ABSTRACTThe crustacean red pigment concentrating hormone (RPCH) has been localized in neurons of the crayfish abdominal nerve cord and modulates the crayfish swimmeret rhythm. An antibody to RPCH labels a small set of cell bodies and axons in each abdominal ganglion. Physiological experiments in which RPCH was perfused into the ganglia of isolated nerve cords showed that RPCH modulated the swimmeret rhythm. In nerve cords that were spontaneously producing the swimmeret rhythm, RPCH lengthened both the period and the duration of bursts of action potentials, but did not alter the phase relationships between bursts in different segments. RPCH did not initiate the swimmeret rhythm in preparations that showed intermittent or no bursting activity. We believe that RPCH is released as a neurotransmitter in the lateral neuropil, where it exerts its effects on the local swimmeret circuits.
The Effects of An Air/Water Surface on the Fast-Start Performance of Rainbow Trout (Oncorhynchus Mykiss)
Authors: Webb Paul W. , Sims Dominique , Schultz William W. 
Published: April 2021

ABSTRACT
Fast-start performance of rainbow trout (mass 0.187±0.022kg; mean±2s.E., N=10) was measured in water of various depths. Relative water depth was defined as z/B, where z is the water depth measured from the air/water surface to the longitudinal midline of the body and B is the span of the caudal fin, 0.062±0.004m. Relative water depths (at absolute depths) tested were; 0.31 (at 0.05m), 1.11 (at 0.1m), 1.92 (at 0.15m), 2.73 (at 0.2m) and 7.56 (at 0.5m). Performance was defined in terms of the motion of the centre of mass as measured by the turning radius and the cumulative distance travelled in a given elapsed time. Turning radius was not affected by water depth and averaged 0.018±0.003m. Distance travelled was a positive function of water depth, although paired r-tests showed no significant effect of depth at 0.15 and 0.2 m after about 70 ms. Energy dispersion due to the formation of surface waves increased with decreasing relative water depth. The largest energy dispersion in wave formation at a relative water depth of 0.31 averaged about 70 % of the useful mechanical work performed in deep water. Energy dispersion in wave generation was negligible for relative water depths larger than approximately 3. Energy dispersion is similar to that for rigid streamlined bodies moving at constant speed.
Electrolyte Transport Through a Cation-Selective ion Channel in Large Intestinal Enterocytes ofXenopus Laevis
Authors: Krattenmacher R. , Voigt Rosita , Heinz M. , Clauss W. 
Published: April 2021

ABSTRACTElectrogenic ion transport through the colon epithelium of the African clawed toad (Xenopus laevis) was investigated with electrophysiological methods in vitro. Interest was focused on a previously described phenomenon, that removal of Ca2+ from the mucosal Ringer’s solution increases electrogenic sodium absorption. Our results clearly show that Ca2+ removal reveals an apical ion channel that is not a specific Na+ channel, but a non-selective cation channel with an ‘apparent’ ion selectivity of the order K+&gt;Na+=Rb+&gt;Cs+&gt;Li+. This Ca2+-sensitive current increased linearly with the mucosal pH, and could be inhibited by other divalent cations (Mg2+, Ba2+) and the organic ion channel blockers quinidine and verapamil. The mucosal Ca2+ concentration that induced a half-maximal inhibition of the Ca2+-sensitive current was about 1 μmoll−1 and was independent of the mucosal pH. Owing to the high Ca2+ sensitivity, a regulation of the channel conductivity by extracellular Ca2+ is ruled out. It is concluded that this channel, which is almost identical to similar channels found in amphibian skin and bladder, acts as a pathway for cation absorbing or secreting processes. Possibly the binding of extracellular Ca2+ is related to selectivity changes of the Ca2+-sensitive ion channel.
Magnetic Orientation By Hatchling Loggerhead Sea Turtles (Caretta Caretta)
Authors: Lohmann Kenneth J. 
Published: April 2021

ABSTRACTLaboratory experiments were conducted to test the ability of loggerhead sea turtle hatchlings (Caretta caretta L.) to orient using the magnetic field of the earth. Hatchlings were tethered to a rotatable lever-arm apparatus which tracked swimming orientation in complete darkness. Hatchlings tested in the earth’s magnetic field were nonrandomly oriented with a mean angle of 42°; those tested under an earth-strength field with a reversed horizontal component were also nonrandomly oriented, but with a mean angle of 196°. The distributions under the two magnetic field conditions were significantly different, indicating that loggerhead sea turtle hatchlings can detect the magnetic field of the earth and use it as a cue in orientation.
Sodium- and Calcium-Dependent Excitability of Embryonic Leech Ganglion Cells in Culture
Authors: Schirrmacher Karin , Deitmer Joachim W. 
Published: April 2021

ABSTRACTVoltage-dependent Na+ and Ca2+ inward currents underlying the action potential in cultured embryonic ganglion cells of the leech Hirudo medicinalis have been investigated using the gigaseal whole-cell current or voltage-clamp technique. Dissociated ganglion cells were isolated from 7-to 14-day-old embryos, and maintained in primary culture for up to 5 days. More than 95 % of the cultured cells had voltage-dependent K+ currents and about 75 % of the cells had voltagedependent inward currents. Action potentials of 60mV amplitude and 4 ms duration, similar to those in embryonic nerve cells in vivo, could be recorded. Three types of inward currents occurred in these cells: (1) an initial Na+ current, which activated and inactivated rapidly; (2) a second Na+ current, which activated slowly and persisted during membrane depolarization, showing very little inactivation, and (3) a Ca2+-dependent inward current. Both types of Na+ currents were resistant to tetrodotoxin (TTX, 0.2–5 μmoll-1). The Ca2+ current was also carried by Ba2+, and was blocked by cobalt and cadmium. The fast Na+ current was first expressed in cells from 8-day-old embryos, 1 day earlier than the Ca2+ current. Between days 8 and 14 the density of the fast Na+ current increased from 22±3 to 51±6μAcm-2 (±S.D., N= 11), while the Ca2+ current grew from 10μAcm-2 (N=2) to 15±4μAcm-2 (N =10) during this time.
Glycolytic and Associated Enzymes of Rainbow Trout (Oncorhynchus Mykiss) Red Cells:In VitroAndIn VivoStudies
Authors: Ferguson Ralph A. , Storey Kenneth B. 
Published: April 2021

ABSTRACTStudies were undertaken in vitro and in vivo to assess the maximal activities of 26 glycolytic and associated enzymes of rainbow trout (Oncorhynchus mykiss) red cells. The red cells possess a complete sequence of glycolytic enzymes capable of anaerobic oxidation of glucose to lactate. Red cell pyruvate kinase (PK) was inhibited by ATP (I50 ≈ 5 mmol I 1−1), but was not sensitive to alanine inhibition or fructose-1,6-bisphosphate activation. The properties of red cell PK were similar to those of the muscle-type enzyme. Lactate dehydrogenase (LDH) from the trout erythrocyte resembled LDH from trout heart in terms of pyruvate inhibition in vitro. Enzymes associated with phosphagen and amino acid metabolism as well as the pentose phosphate shunt were also present. However, enzyme indicators of glycogenolytic and gluconeogenic potential were either absent or present at very low levels. The capacity for aerobic respiration via the tricarboxylic acid (TCA) cycle was suggested by the presence of citrate synthase activity.The association of glycolytic enzymes with the particulate fraction of the red cell was assessed for six enzymes. No binding was detected for hexokinase, PK and LDH; low levels of binding by phosphofructokinase (5%), aldolase (1%) and glyceraldehyde-3-phosphate dehydrogenase (3%) were not altered by strenuous exercise. Glycolytic enzyme binding, therefore, does not appear to be an important regulator of energy metabolism in these cells. Intracellular glucose levels, in contrast, appeared to be regulated following exercise stress. An increase in intra-erythrocytic lactate levels at this time may reflect the importance of exogenously produced lactate as a substrate for ATP production. The description of trout red cell metabolism presented here provides a basis for further study of the relationships between organismic gas exchange and molecular-level adaptation of nucleated red cell function.
The Coordinated Action of Abdominal Postural and Swimmeret Motor Systems in Relation to Body Tilt in the Pitch Plane in the Norway LobsterNephrops Norvegicus
Authors: Knox Paul C. , Neil Douglas M. 
Published: April 2021

ABSTRACTThe responses of the abdominal positioning system and the swimmerets of the Norway lobster Nephrops norvegicus to tilts in pitch and in other vertical planes have been investigated in intact and semi-intact preparations. Tilt of the intact animal in the pitch plane evoked abdominal flexion with the head up and extension with the head down. The response amplitudes were largely independent of tilt angle, and the null point for switching between flexion and extension responses was at the 10° head-up position, which corresponds to the normal posture of the animal. Intersegmental joint angles in the abdomen were significantly different for head-up and head-down tilts. These pitch responses were dependent upon the integrity of the statocysts. Tilts in different vertical planes demonstrated that the abdominal flexion/ extension response was restricted to a range of tilts within ±5° of true pitch. Outside this range, tilts in both directions elicited abdominal extension, which was accompanied by asymmetrical movements of the uropods and swimmerets. In semi-intact preparations, recordings from the motor supply to the abdominal superficial flexor muscles demonstrated a modulation of activity in response to tilt in the pitch plane: several small excitatory axons increased their discharge in the head-up position, while the inhibitory axon f5 fired when the head was down. With tilts in different vertical planes this pattern of firing persisted from pitch almost to roll. The effects of tilt in the pitch and roll planes on the temporal and spatial parameters of swimmeret beating were studied in intact animals. Swimmeret beating was bilaterally symmetrical in pitch: vigorous in the head-down position, when the powerstrokes were directed about 25° to the side, and weak in the head-up position, when the powerstrokes were directed to the rear. Responses in roll were asymmetrical, with the powerstroke of the upper swimmerets directed at about 41° to the side. Recordings of the tonic returnstroke motor neurone of the swimmeret demonstrated that its activity was modulated by tilt in the pitch plane: increasing and becoming rhythmic in the head-down position in active preparations, with the activity phase-locked to the tilt stimulus. With tilts in different vertical planes this unit showed a phase shift at intermediate angles between pitch and roll. Simultaneous recordings of motor activity to the abdominal superficial flexor muscles and the swimmeret tonic returnstroke unit demonstrate closely similar, but not completely coupled, patterns of firing. These results are discussed in terms of the nature of statocyst control of postural and rhythmic abdominal motor systems, the different relationships of motor activities and behavioural responses to tilts in pitch and other vertical planes, and possible neuronal mechanisms that control the interaction of the two abdominal motor systems.
The Motor Innervation of a Triply Innervated Crustacean Muscle
Authors: Van Harreveld A. 
Published: April 2021

ABSTRACT
The crustacean muscle is extremely sensitive to mechanical injury. This is due to the fact that the muscle fibres are innervated by a feltwork of nerve fibres which surrounds them. Appare?ntly, there is a lack of a muscular conduction process in these muscles. Contractions have been observed in the same muscle fibres during stimulation of the axon for the fast contraction as well as during stimulation of the fibre for the slow contraction.