bluuebunny/crossref_metadata_2025_split huggingface dataset:
Effects of Substance P and Vasoactive Intestinal Polypeptide on Gastrointestinal Blood Flow in the Atlantic Cod Gadus Morhua
Authors: Jensen Jörgen , Axelsson Michael , Holmgren Susanne 
Published: April 2021

ABSTRACT
The cardiovascular effects of vasoactive intestinal polypeptide (VIP) and substance P (SP) in vivo were studied in the Atlantic cod Gadus morhua. Special interest was focused on the distribution of blood to the gastrointestinal circulation.
VIP increased the blood flow to the gut by increasing cardiac output and by decreasing resistance in the vascular bed supplied by the coeliac artery. In addition, VIP had an inhibitory effect on spontaneous stomach motility.
SP induced a triphasic response in the coeliac artery blood flow. An initial increase was followed by a rapid decrease, to the control level or below, and a second increase in flow. The triphasic response was not changed after vagotomy, while atropine blocked the second phase, the decrease, indicating that a local cholinergic mechanism is involved. The significance of this temporary decrease in flow remains to be elucidated. SP also caused an increase in cardiac output and in mesenteric artery blood flow. In addition to the increase in cardiac output, the increase in gastrointestinal blood flow produced by SP is accomplished by a decreased resistance in the coeliac and mesenteric vascular beds.
Ontogeny of Heart Function in the Little SkateRaja Erinacea
Authors: Pelster Bernd , Bemis William E. 
Published: April 2021

ABSTRACTThe development of the cardiovascular system has been analysed in embryos of the little skate, Raja erinacea, ranging in age from 27 to 144 days after spawning. Circulation starts at the end of the first month. At that time, the heart is S-shaped, there is no differentiation between ventricle and conus arteriosus and no valve formation is detectable. Complete differentiation of the central circulatory system and its valves was observed at about 40 days after spawning, although there are changes in proportion that occur before hatching.In the smallest embryos used for physiological studies, 27 days post-spawning (0.01–0.03g body mass), circulation of blood was observed and heart rate was 35–40 beats min−1. Heart rate increased with development, reaching a maximum of 65–68 beats min−1 at a body mass of 0.2 g (60 days post-spawning) and then slowly decreased until just prior to hatching.Ventricular diastolic pressure remained below 0.1 kPa throughout development whereas ventricular systolic pressure increased significantly with increasing body mass. In small embryos (&lt;0.05 g) the conus arteriosus collapsed at the end of each heart beat, completely occluding its lumen and separating the ventral aorta from the diastolic heart. In larger animals (&gt;0.1g) serial flap valves in the conus separated the ventral aorta from the diastolic ventricle, and the conus supported ventral arterial blood pressure because of its elastic properties.
Effect of Pregnancy and Temperature on Red Cell Oxygen-Affinity in the Viviparous Snake Thamnophis Elegans
Authors: Ingermann Rolf L. , Berner Nancy J. , Ragsdale Frances R. 
Published: April 2021

ABSTRACT
The oxygen affinity of red cell suspensions from fetal garter snakes was higher than that of cell suspensions from their mothers. This difference appeared to be due to different concentrations of nucleoside triphosphate (NTP, primarily adenosine triphosphate). NTP concentrations were significantly higher, and oxygen affinities were significantly lower, in red cell suspensions from pregnant females compared with those from nonpregnant females or males; there is no precedent for such a pronounced effect of pregnancy on the oxygen affinity of maternal blood. These data indicate that pregnancy may result in an enhanced ability of adult blood to deliver oxygen to the fetus. Since the binding of organic phosphates and oxygen to hemoglobin is sensitive to temperature, and since these animals experience diurnal changes in temperature, we examined the influence of relatively low (20°C) and high (34 °C) temperatures on red cell oxy gen-affinity. The temperature increase of 14 °C resulted in a lowered oxygen-affinity of all red cell suspensions examined. However, this increase in temperature lowered the affinity of maternal red cells to a greater extent than it did the affinity of fetal red cells. This suggests that daytime temperatures may further enhance the ability of maternal blood to deliver oxygen to the fetus at times when fetal oxygen demand is probably greatest.
Transintestinal Acetate Transport in a herbivorous Teleost: Anion Exchange at the Basolateral Membrane
Authors: Titus E. , Ahearn G. A. 
Published: April 2021

ABSTRACT
Purified basolateral membrane vesicles were prepared from the intestinal epithelium of the tilapia Oreochromis mossambicus, a herbivorous teleost. Characteristics of volatile fatty acid (VFA) transport were investigated using [3H]acetate as a representative anion. No significant change in [3H]acetate influx was observed in the presence of a cation gradient (K+ or Na+) compared to the influx observed in the absence of a cation gradient, indicating the lack of cation-dependent coupling for acetate transport. The time course of [3H]acetate uptake into vesicles preloaded with acetate or bicarbonate was enhanced compared to [3H]acetate uptake into vesicles preloaded with gluconate. A series of transstimulation and cis-inhibition studies involving both organic and inorganic anions indicated the presence of a highly specific anion-exchange carrier which readily exchanged [3H]acetate with the volatile fatty acids (formate, acetate, propionate and butyrate) and bicarbonate. Kinetic analysis of [3H]acetate influx as a function of external acetate concentration yielded a biphasic uptake curve which was interpreted as carrier-mediated transfer (Jmax=21,77±2.05 nmol mg−1 protein 10s−1; Km=12.70±2.95mmoll−1) plus apparent diffusion (P=0.17±0.02 nmol mg−1 protein 10s−1 mmol−1 acetate). [3H]Acetate uptake was also a hyperbolic function of internal bicarbonate concentration, displaying a relatively low HCO3−half-saturation constant (Km=0.41 mmol l−1). Intact intestinal sheets mounted in Ussing chambers demonstrated net absorptive fluxes of [3H]acetate when serosal acetate concentration was maintained at 1.0 mmol l−1 and the mucosal acetate concentration was varied from 1.32 to 10.0mmoll−1. At mucosal acetate concentrations lower than 1.32 mmol l−1, a net secretion of VFAs was observed. Transepithelial transport of [3H]acetate was significantly inhibited by the presence of acetazolamide. A transintestinal transport model for volatile fatty acids is proposed in which specific anion antiporters, located on the brush-border and basolateral poles of the cell, exchange luminal VFAs for serosal and intracellular bicarbonate, resulting in net transepithelial uptake of VFAs. This process is driven by a downhill lumen-to-blood VFA concentration gradient and the intracellular generation of bicarbonate by carbonic anhydrase.
Skeletal Muscle Deformation in the Lateral Muscle of the Intact Rainbow TroutOncorhynchus MykissDuring Fast Start Maneuvers
Authors: Covell James W. , Smith Michael , Harper David G. , Blake Robert W. 
Published: April 2021

ABSTRACTAlthough there is an extensive body of information on the kinematics of the fast start response in teleosts, there is little information on the deformation of the skeletal muscle which produces the changes in body position during a fast start. This study presents preliminary information on the determination of skeletal muscle deformation with implanted ultrasonic dimension gauges in the intact fish during startle behavior. Deformation was measured in the lateral epaxial musculature of the rainbow trout Oncorhynchus mykiss during stage one of fast starts. The results show that ultrasound transit time dimension gauges can be implanted in the skeletal muscle of rainbow trout with minimum trauma and used to record local deformation along the length of the fish. Measurements remained stable over 4–8 h of implantation. Preliminary results show that: (1) muscle at different positions along the fish reaches its minimum length (average 9.6% shortening) at approximately the same time and coincident with the end of stage one of the fast start response; (2) the onset of concave curvature of the entire fish precedes the onset of local shortening at more caudal sites; (3) muscle on the convex side of a bend lengthens while muscle on the concave side shortens, and the two deformations follow a similar time course. These results indicate an asynchronous onset of skeletal muscle contraction in fast starts and support the hypothesis that local skeletal muscle deformation is transmitted caudally through skeletal or other structures.
Perturbation of the Motor System in Freely Walking Cockroaches: II. The Timing of Motor Activity in Leg Muscles After Amputation of A Middle Leg
Authors: Delcomyn Fred 
Published: April 2021

ABSTRACTThe effects of amputation of a middle leg on the motor pattern in the legs of freely walking cockroaches (Periplaneta americana L.) were studied. The general effects of amputating a middle leg are similar to those arising from amputation of a rear leg. These effects are: multiple bursting, more variable and inconsistent timing (phase) between bursts and a tendency for timing effects to appear only during relatively slow walking. The phase of bursts in the amputated stump relative to bursts in the leg in front of it was speed-dependent. However, the phase of stump bursts relative to bursts in the legs across from and behind the stump were not especially dependent on the speed of walking. In general, the phases of bursts in most leg pairs seemed relatively little affected by the amputation except for an increase in scatter. It is concluded that loss of a middle leg disrupts the motor pattern less severely than does loss of a rear leg. The implications of this and other results for the understanding of motor control are discussed.
FMRFamide-LIKE IMMUNOREACTIVITY IN THE CRAYFISH NERVOUS SYSTEM
Authors: Mercier A. Joffre , Orchard Ian , Tebrugge Victoria 
Published: April 2021

ABSTRACTFMRFamide-like immunoreactivity (FLI) was detected in the nervous system of the crayfish Procambarus clarkii using an antiserum that recognizes extended RFamide peptides. Immunocytochemistry revealed FLI in neuronal somata, axons and varicose processes within the central nervous system. In the periphery, plexuses of immunoreactive varicosities were present in the pericardial organs (POs), in thoracic roots and on the hindgut. The hindgut plexus arose from 3–5 axons leaving the sixth abdominal ganglion (A6) via the intestinal nerve. The presence of FLI in these locations was confirmed by radioimmunoassay. In contrast, no FLI was detected in motor axons innervating exoskeletal muscles of the abdomen.The POs contained by far the largest amount of FLI of all tissues examined. The immunoreactive material was partially characterized by extraction and separation on two consecutive reversed-phase high performance liquid chromatography (RP-HPLC) columns. The largest amount of immunoreactivity on the second column co-eluted with a synthetic peptide, SDRNFLRFamide (F2), previously identified as one of two or more FMRFamide-related peptides contained in lobster POs. The immunoreactive fractions and peptide F2 elicited similar effects on isolated crayfish hearts; all increased the rate and amplitude of spontaneous cardiac contractions. As with the immunoreactivity, the highest level of bioactivity was contained in the fraction that co-eluted with F2.The results suggest that FMRFamide-related peptides act as neurohormones in crayfish and are likely to play roles in controlling circulation and defecation.
5-Hydroxytryptamine: A Second Diuretic Hormone in Rhodnius Prolixus
Authors: Maddrell S. H. P. , Herman W. S. , Mooney R. L. , Overton J. A. 
Published: April 2021

ABSTRACT
Bioassays of 5-hydroxytryptamine (5-HT) in fifth-instar Rhodnius prolixus haemolymph using Calliphora salivary glands indicate that: (1) biologically active 5-HT is present, (2) in unfed animals there is not enough 5-HT to stimulate Malpighian tubule fluid secretion, and (3) there is enough 5-HT soon after the initiation of feeding to stimulate rapid tubule secretion. The 5-HT receptor antagonists ketanserin and spiperone reversibly and selectively inhibit 5-HT-induced fluid secretion, indicating the presence of specific 5-HT receptors on Rhodnius Malpighian tubules. The data provide evidence that 5-HT is a naturally occurring hormone acting with a previously described peptide hormone to regulate diuresis in this species.
Peptide Potentiation of Calcium Channel Activity can be Seasonally Variable
Authors: Bishop C. A. , Krouse M. E. , Wine J. J. 
Published: April 2021

ABSTRACTUsing the single-channel patch-clamp technique we have recently shown that the peptide cotransmitter proctolin can potentiate the activity of a large (38 pS in 137 mmol l−1 Ba2+; 26 pS in 137 mmol l−1 Ca2+), depolarization-inducible Ca2+ channel in the plasma membrane of the crayfish tonic flexor muscle (Bishop et al. 1991). Parallels between the modulatory effects of the peptide on channel activity and tension generated in the muscle suggest that this channel activation is probably partly responsible for the amplification of tension by proctolin (Bishop et al. 1991). Our initial studies of this phenomenon were performed during the spring and summer of 1988, using excised, inside-out patches. During that time, we found that the addition of 5×10−9moll−1 proctolin to the bath at least 5 min prior to seal formation (this dose gives a maximal response) caused a large increase in the proportion of patches with active channels and enhanced the single-channel open probability, Po by as much as 40-fold. (Ca2+ channels remained remarkably active in these excised patches: there was usually no obvious diminution in channel activity for the duration of the recordings; Bishop et al. 1991.) Identical results were obtained during the spring of 1989. In this communication we show that, during the winter months between these two periods, proctolin had virtually no effect on channel activity, indicating a seasonal variability in the potentiating effect of the peptide.
Neural Regulation of Pupariation in Tsetse Larvae
Authors: Žďárek Jan , Denlinger David L. 
Published: April 2021

ABSTRACT
A neural mechanism coordinates pupariation behavior and tanning in the tsetse larva. At parturition, the mature larva has already received sufficient ecdysteroid to commit the epidermal cells to metamorphosis but, before sclerotization and tanning of the cuticle can begin, the larva must first select a pupariation site and then proceed through a stereotypic sequence of pupariation behavior that culminates in the formation of a smooth, ovoid puparium. Both pupariation behavior and tanning are inhibited by the central nervous system (CNS) during the wandering phase. This central inhibition is maintained by sensory input originating in the extreme posterior region of the body. At the transition from wandering to pupariation, the posterior signal that induces inhibition of pupariation behavior is removed and the larva begins the contractions associated with pupariation, but the CNS inhibition of tanning persists. At this point, separation of the body into two halves by ligation or nerve transection prevents tanning of the anterior half (containing the CNS), whereas the denervated integument of the posterior half tans completely. Transection of nerves to the midline of the body produces larvae with a tanning pattern that ends abruptly along a sagittal plane, implying that the central control of this process is uncoupled between the left and right regions of the CNS. A few minutes later, when the final shape of the puparium is completed, the CNS inhibition is lifted and the tanning process begins. At this time, separation of the body into two halves by ligation or nerve transection has no inhibitory effects on either part. Exogenous ecdysteroids fail to release the CNS inhibition, and hemolymph containing the pupariation factors from Sarcophaga bullata have no accelerating effects on tsetse pupariation. These results imply that regulation of metamorphosis in the insect integument is not the exclusive domain of blood-borne hormones.
Reversal of Interleg Coupling in Backward Locomotion Implies a Prime Role of the Direction of Locomotion
Authors: Eilam David , Shefer Gabi 
Published: April 2021

ABSTRACT
Conventional descriptions of interleg coupling relate to anatomical definitions such as fore- or hindlegs, right or left legs (i.e. the body is the frame of reference). This convention is obvious for forward walking, where forelegs (in anatomical terms) are also the leading legs (in terms of direction). In backward locomotion, however, the leading legs in terms of direction are the hindlegs in terms of anatomy. What effects do the anatomy and direction of movement have on the sequence of stepping? Our observations on the locomotion of mole rats in a transparent acrylic tunnel revealed that, as in nature, mole rats moved both forwards and backwards. They typically employed a diagonal sequence of steps in forward walking, whereas in backward walking they typically employed a lateral sequence. However, when stepping was described with movement direction as the frame of reference, both forward and backward walking were made up of the same sequence of steps. The same invariant trend was recorded during backward galloping, but to a lesser extent than during walking. We suggest that the backward sequence is simply a reversal of the forward sequence: a hindleg during backward locomotion acts like a foreleg in forward locomotion, while a foreleg acts like a hindleg in forward locomotion. Interleg coupling therefore remains invariant in relation to the direction of locomotion.
The Fatty Acid 8,11,14-Eicosatrienoic acid Induces Spawning in the Male Lugworm Arenicola Marina
Authors: Pacey A. A. , Bentley M. G. 
Published: April 2021

ABSTRACT
Spawning of the lugworm Arenicola marina (L.) (Annelida: Polychaeta) occurs in both sexes following the release of a sex-specific maturation hormone from the prostomium. In males this has been termed sperm maturation factor (SMF). Chromatographic purification of SMF, using an in vitro bioassay, has led to it being putatively identified as the 20-carbon fatty acid 8,11,14-eicosatrienoic acid and this paper describes the induction of spawning in vivo by injection of 8,11,14-eicosatrienoic acid into sexually mature individuals.
It is shown that spawning in male A. marina occurs following the injection of prostomial homogenate or 8,11,14-eicosatrienoic acid into the coelomic cavity of sexually mature specimens. The injection of 8,11,14-eicosatrienoic acid into the coelomic cavity of females does not cause spawning although it can be induced by a hormone present in the prostomium. There are, therefore, clear sex-specific differences in the chemical signal that causes spawning in this species. Sex-specific differences in the behaviour of spawning animals are also described.
The study identifies a role for the fatty acid 8,11,14-eicosatrienoic acid in the spawning of male A. marina. This is the first description of a hormone in the annelids, for which both the chemical structure and the endocrine role are known.
Apneic Oxygen Uptake in the Torpid Bat, Eptesicus Fuscus
Authors: Szewczak Joseph M. , Jackson Donald C. 
Published: April 2021

ABSTRACT
Like many mammalian heterotherms, the big brown bat, Eptesicus fuscus, breathes intermittently during torpor. By exploiting this bat’s preference to roost in crevices, we could separately measure O2 uptake during ventilatory bouts and apneic periods using a flow-through metabolic chamber with a small dead space volume and short time constant. Oxygen uptake was measured during apneas ranging from 10 to 150 min duration at body temperatures of 20, 10 and 5 °C. The fraction of total O2 uptake acquired during apnea was 0.26±0.03 (9), 0.54±0.10 (5) and 0.35±0.04 (3) for body temperatures of 20, 10 and 5 °C, respectively. Cardiogenic pulsations during apnea visible on plethysmographic pressure traces and theoretical calculations of airway and cutaneous diffusion potentials support the notion that apneic O2 uptake occurs down an open airway by both diffusion and bulk convection.
Ultrasonic Vocalizations Of Flying Bats Monitored By Radiotelemetry
Authors: Lancaster Winston C. , Keating Arthur W. , Henson O. W. 
Published: April 2021

ABSTRACT
Ultrasonic vocalizations of flying bats were effectively monitored with radiotelemetry. We describe a device light enough to be carried by an 11g bat for periods of up to 1h. It transmitted signals adequate for fine frequency analysis within a range of approximately 3 m. Telemetry permitted the recording of constant-frequency pulses free from flight-induced Doppler shifts and without time delays. The difference in frequency between telemetered signals and the same signals detected by a remote microphone was used to calculate velocity and Doppler shifts.
Pulse emission behavior of Pteronotus parnellii in flight was compared with simulated flight on a pendulum. The data showed significant differences in echo bandwidths, constant-frequency pulse durations and interpulse intervals. In flight, pulses and interpulse intervals tended to be shorter and bats maintained echo frequencies within a significantly narrower band. Phases of echolocation that characterized the approach to a target were clearly evident in flight, but not during pendulum swings. Differences in pulse durations and interpulse intervals may be correlated with the integration of wingbeat, respiration and vocalization. The absence of wing motion in simulated flight changes this integration.
Functional Specialization of the Scoloparia of the Femoral Chordotonal Organ in Stick Insects
Authors: Kittmann Rolf , Schmitz Josef 
Published: April 2021

ABSTRACT
The femoral chordotonal organ (fCO), one of the largest proprioceptive sense organs in the leg of the stick insect, is important for the control of the femur-tibia joint during standing and walking. It consists of a ventral scoloparium with about 80 sensory cells and a dorsal scoloparium with about 420 sensory cells. The present study examines the function of these scoloparia in the femur-tibia control loop. Both scoloparia were stimulated independently and the responses in the extensor tibiae motoneurones were recorded extra-and intracellularly.
The ventral scoloparium, which is the smaller of the two, functions as the transducer of the femur-tibia control loop. Its sensory cells can generate the known resistance reflexes. The dorsal scoloparium serves no function in the femur-tibia control loop and its stimulation elicited no or only minor reactions in the extensor motoneurones. A comparison with other insect leg proprioceptors shows that a morphological subdivision of these organs often indicates a functional specialization.