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PubMed1994

UNDULATORY SWIMMING: HOW TRAVELING WAVES ARE PRODUCED AND MODULATED IN SUNFISH (LEPOMIS GIBBOSUS)

We have developed an experimental procedure in which the in situ locomotor muscles of dead fishes can be electrically stimulated to generate swimming motions. This procedure gives the experimenter control of muscle activation and the mechanical properties of the body. Using pumpkinseed sunfish, Lepomis gibbosus, we investigated the mechanics of undulatory swimming by comparing the swimming kinematics of live sunfish with the kinematics of dead sunfish made to swim using electrical stimulation. In electrically stimulated sunfish, undulatory waves can be produced by alternating left­right contractions of either all the axial muscle or just the precaudal axial muscle. As judged by changes in swimming speed, most of the locomotor power is generated precaudally and transmitted to the caudal fin by way of the skin and axial skeleton. The form of the traveling undulatory wave ­ as measured by tail-beat amplitude, propulsive wavelength and maximal caudal curvature ­ can be modulated by experimental control of the body's passive stiffness, which is a property of the skin, connective tissue and axial skeleton.

Journal Article↗
PubMed1994

SPONTANEOUS SWIMMING ACTIVITY OF ATLANTIC COD GADUS MORHUA EXPOSED TO GRADED HYPOXIA AT THREE TEMPERATURES

The spontaneous swimming activity of Atlantic cod Gadus morhua was investigated at graded levels of hypoxia at three temperatures (5, 10 and 15 °C) by using a computerized system monitoring animal activity. The fish were tested individually, and swimming distance was used as a measure of activity. No significant effect of temperature on swimming distance in normoxic water was found. At all temperatures, activity level decreased with decreasing oxygen saturation. Swimming behaviour at normoxia and 50 % and 25 % oxygen saturation is described. No apparent avoidance of hypoxic water was found based on the distribution of swimming speeds and turning angles. The possible benefits of a decreased activity level in a hypoxic environment are discussed.

Journal Article↗
PubMed1995

Red muscle motor patterns during steady swimming in largemouth bass: effects of speed and correlations with axial kinematics

We analyzed midline kinematics and obtained electromyograms (EMGs) from the superficial red muscle at seven longitudinal positions in four largemouth bass swimming steadily at standardized speeds of 0.7, 1.2, 1.6, 2.0 and 2.4 lengths s-1. Analysis of variance was used to test for significant variation attributable to both speed and longitudinal position. EMGs propagated posteriorly were unilateral and alternated between the left and right sides. Despite the propagation of EMGs, all the red muscle along an entire side of the fish was simultaneously active for as much as one-quarter of the locomotor cycle. When expressed as a proportion of the locomotor cycle, EMG durations at a given site did not vary significantly with speed but did vary longitudinally, ranging from values of 0.45 cycles anteriorly to 0.35 cycles posteriorly. The amplitudes of lateral displacement and bending depended on longitudinal position and also increased by a maximum of approximately 50 % with increased swimming speed, whereas for all longitudinal positions the intensity of EMGs increased approximately fourfold with increased swimming speed. Electrical activity of red muscle did not correspond simply to the time of muscle shortening. Instead, the timing of EMG onset and offset relative to both lateral bending and displacement changed significantly with both longitudinal position and increased speed, such that the phase shifts between the EMGs and kinematic values were generally greatest for posterior sites at the fastest speeds. At a single longitudinal position, the phase shift between the EMG and maximal lateral bending could change by more than one-tenth of a cycle from the slowest to the fastest swimming speed. Phase lags per body segment of EMG onset and EMG offset did not vary significantly with either swimming speed or longitudinal position. EMG offset was propagated posteriorly faster than EMG onset, and both EMG onset and EMG offset were generally propagated faster than both lateral bending and displacement. Largemouth bass have a similar number of vertebrae to carp, and these two species also have a very similar pattern of muscle activation that differs substantially from that of the trout, which has nearly twice as many vertebrae.

Journal Article↗
PubMed1996

Functions of fish skin: flexural stiffness and steady swimming of longnose gar, Lepisosteus osseus

The functions of fish skin during swimming remain enigmatic. Does skin stiffen the body and alter the propagation of the axial undulatory wave? To address this question, we measured the skin's in situ flexural stiffness and in vivo mechanical role in the longnose gar Lepisosteus osseus. To measure flexural stiffness, dead gar were gripped and bent in a device that measured applied bending moment (N m) and the resulting midline curvature (m-1). From these values, the flexural stiffness of the body (EI in N m2) was calculated before and after sequential alterations of skin structure. Cutting of the dermis between two caudal scale rows significantly reduced the flexural stiffness of the body and increased the neutral zone of curvature, a region of bending without detectable stiffness. Neither bending property was significantly altered by the removal of a caudal scale row. These alterations in skin structure were also made in live gar and the kinematics of steady swimming was measured before and after each treatment. Cutting of the dermis between two caudal scale rows, performed under anesthesia, changed the swimming kinematics of the fish: tailbeat frequency (Hz) and propulsive wave speed (body lengths per second, L s-1) decreased, while the depth (in L) of the trailing edge of the tail increased. The decreases in tailbeat frequency and wave speed are consistent with predictions of the theory of forced, harmonic vibrations; wave speed, if equated with resonance frequency, is proportional to the square root of a structure's stiffness. While it did not significantly reduce the body's flexural stiffness, surgical removal of a caudal scale row resulted in increased tailbeat amplitude and the relative total hydrodynamic power. In an attempt to understand the specific function of the scale row, we propose a model in which a scale row resists medio-lateral force applied by a single myomere, thus functioning to enhance mechanical advantage for bending. Finally, surgical removal of a precaudal scale row did not significantly alter any of the kinematic variables. This lack of effect is associated with a lower midline curvature of the precaudal region during swimming compared with that of the caudal region. Overall, these results demonstrate a causal relationship between skin, the passive flexural stiffness it imparts to the body and the influence of body stiffness on the undulatory wave speed and cycle frequency at which gar choose to swim.

Journal Article↗
PubMed1998

A note on interactions between temperature, viscosity, body size and swimming energetics in fish larvae

In a previous study, it was shown that at a given speed the larvae of a species of freshwater fish, the Danube bleak Chalcalburnus chalcoides, expended considerably more metabolic energy at 15 degreesC than at 20 degreesC. We applied hydromechanical arguments to our previous data in order to determine whether the higher cost of swimming at the lower temperature might be due to the effects of viscous forces. However, even under the unrealistic assumption of the larvae swimming in the viscous regime at Reynolds numbers as high as 2000, we show here that hydromechanical forces cannot explain the high energy cost of swimming at 15 degreesC. Instead, we offer a new hypothesis that the 'two-gear system' of the swimming muscles operating in juvenile and adult fish is not yet functional in the larvae, with the consequence that, when these fish are swimming at high speeds in cold water, the muscle fibres have to operate over an increasingly inefficient range of shortening velocities.

Journal Article↗
PubMed1999

Locomotor forces on a swimming fish: three-dimensional vortex wake dynamics quantified using digital particle image velocimetry.

Quantifying the locomotor forces experienced by swimming fishes represents a significant challenge because direct measurements of force applied to the aquatic medium are not feasible. However, using the technique of digital particle image velocimetry (DPIV), it is possible to quantify the effect of fish fins on water movement and hence to estimate momentum transfer from the animal to the fluid. We used DPIV to visualize water flow in the wake of the pectoral fins of bluegill sunfish (Lepomis macrochirus) swimming at speeds of 0.5-1.5 L s(-)(1), where L is total body length. Velocity fields quantified in three perpendicular planes in the wake of the fins allowed three-dimensional reconstruction of downstream vortex structures. At low swimming speed (0.5 L s(-)(1)), vorticity is shed by each fin during the downstroke and stroke reversal to generate discrete, roughly symmetrical, vortex rings of near-uniform circulation with a central jet of high-velocity flow. At and above the maximum sustainable labriform swimming speed of 1.0 L s(-)(1), additional vorticity appears on the upstroke, indicating the production of linked pairs of rings by each fin. Fluid velocity measured in the vicinity of the fin indicates that substantial spanwise flow during the downstroke may occur as vortex rings are formed. The forces exerted by the fins on the water in three dimensions were calculated from vortex ring orientation and momentum. Mean wake-derived thrust (11.1 mN) and lift (3.2 mN) forces produced by both fins per stride at 0.5 L s(-)(1) were found to match closely empirically determined counter-forces of body drag and weight. Medially directed reaction forces were unexpectedly large, averaging 125 % of the thrust force for each fin. Such large inward forces and a deep body that isolates left- and right-side vortex rings are predicted to aid maneuverability. The observed force balance indicates that DPIV can be used to measure accurately large-scale vorticity in the wake of swimming fishes and is therefore a valuable means of studying unsteady flows produced by animals moving through fluids.

Journal Article↗
PubMed1976

Energetics of swimming of a sea turtle.

Young (mean mass 735 g) green turtles (Chelonia mydas) were able to swim in a water channel at sustained speeds between 0-14 and 0-35 m.s-1. Oxygen consumption at rest was was 0-07 l.kg-1.h-1; at maximum swimming speed oxygen consumption was 3-4 times greater than at rest for a given individual. In comparison with other animals of the same body mass the cost of transport for the green turtle (0.186lO2.kg-1.km-1) is less than that for flying birds but greater than that for fish. From drag measurements it was calculated that the aerobic efficiency of swimming was between 1 and 10%; the higher efficiencies were found at the higher swimming speeds. Based upon the drag calculations for young turtles, it is estimated that adult turtles making the round-trip breeding migration between Brazil and Ascension Island (4800 km) would require the equivalent of about 21% of their body mass in fat stores to account for the energetic cost of swimming.

Aerobiosis↗
PubMed1992

[Strain differences of mice in learning of swimming behavior and effect of hemicholinium and vasopressin. Observation by a simple water maze apparatus].

In order to determine the strain differences in learning of swimming behavior and to study the influence of vasopressin or its derivatives on hemicholinium-3-induced impairment of water maze learning in mice, we designed a new apparatus using water maze which has three panels in small fish breeding water bath (L60 x W30 x H36 cm). In the first swimming, six strains of adult male mice, ICR, ddY, ddN, C3H/He, BALB/C and C57BL were subjected to learn swimming behavior twice a day for 6 d in a straight course. Only ICR, ddN, C57BL and BALB/C strain mice were chosen for the next experiment. In the second swimming, mice (ICR, ddN, C57BL, BALB/C) were swum in the water maze apparatus. Scopolamine-induced impairment of water maze learning was produced only in ICR, BALB/C mice, but not in C57BL and ddN strain, which was recovered by physostigmine. Amnesia was not obtained by intracerebroventricular injection (i.c.v.) of cycloheximide and AlCl3 in mice (ICR). Hemicholinium-induced amnesia was improved by vasopressin and desmopressin. Lysine-vasopressin and oxytocin were without affecting hemicholinium-induced amnesia. Pretreatment with a vasopressin antagonist, ([1-(beta-mercapto-beta,beta-cyclopenta-methylene propionic acid), 2-(o-methyl)tyrosine arginine]-vasopressin) resulted in a reversible effect on the improvement of hemicholinium-induced amnesia by vasopressin. Of four different strain mice, ICR mice were the most preferable to the presently used test. They were also more responsive to hemicholinium and vasopressin than the other strains. These results suggest that the simple water maze apparatus may be useful for a pre-examination of nootropics or a study of learning of swimming behavior in mice.

Animals↗
PubMed2002

Helical nature of sperm swimming affects the fit of fertilization-kinetics models to empirical data.

Models of fertilization kinetics rely upon estimates of the swimming velocity of sperm to predict collision rates between egg and sperm. Most investigators measure sperm swimming velocity without accounting for the helical motion of sperm, thereby obtaining an inflated estimate of the velocity with which sperm approach eggs. In turn, models of fertilization predict inflated rates of sperm/egg collision. I observed sea urchin sperm colliding with eggs, quantified the rate of sperm/egg collision, and measured sperm velocity as a component of the helix through which they swim. I also adjusted the "target size" of eggs to reflect the diameter of the helix. My estimate of sperm swimming velocity is an order of magnitude lower than other estimates for the same species. By using helical parameters in fertilization kinetics models and accounting for dead sperm in laboratory trials, I was able to accurately predict lower rates of sperm/egg collision. Moreover, making these adjustments in the model increased the estimated proportion of sperm that initiate fertilization by 6- to 7-fold, suggesting that a better understanding of sperm swimming might lead to a more complete understanding of fertilization biology and natural selection on gamete traits.

Animals↗
PubMed2005

[Spermatic fertilization capacity after swim-up spermatozoa recovery technique].

OBJECTIVES: To investigate sperm quality before and after swim up in infertile patients, and to compare it with a fertile men population. METHODS: Semen samples from 55 patients consulting at the infertility services of the Hospitals "Centenario" in Rosario and "Eva Perón" in Gro Baigorria were collected and analyzed accordingly with the WHO guidelines. 30 sperm samples with a volume higher than 1.0 ml, and spermatozoid concentration higher than 5,000,000/ml, not presenting hyperviscosity were selected. Outcome variables including progressive mobility (PM), morphology (M), chromatin condensation (CC) and chromatin integrity (CIl, were compared in fresh semen samples, between patients without previous treatment (G2) and after swim up (G3) and 15 fertile men (G1). Sperm morphology was evaluated by brilliant green hematoxyllin stain; progressive mobility with a subjective method accordingly to WHO (1999); chromatin condensation with aniline blue test; and chromatin integrity with acridine orange as fluorocrom. Swim up technique was based on Berger et al. ( 1985) with mHTF, heatingthe samples in a Falcon tube in a 45 degree angle in a 37 degree C gas heater for one hour (5% CO2 atmosphere). Following incubation 0.5 ml of the overlay containing sperm cells that swam up from the pellet were removed to process the recovered spermatozoids. Student's t test was applied to compare PM, M, CC, and CI between the four groups. A significant difference was found between G1 vs G3 and G2 vs G3 (p < 0.001). No significant differences were found between G1 and G3 (p > 0.1). It showed that PM, M, CC and C1 parameters in the recovered spermatozoids after swim up were similar to fertile population. CONCLUSIONS: Our results indicate that through the swim up procedure gametes with fertile ability similar to normal fertile population can be recovered to be applied in low complexity in vitro fertilization techniques such as intrauterine insemination, where the natural selection is still viable.

Fertilization↗
PubMed1999

Characterization of swimming motility and identification of flagellar proteins in Salmonella pullorum isolates.

OBJECTIVE: To identify swimming motility in Salmonella pullorum isolates and to characterize the flagellar proteins produced by motile isolates. SAMPLE POPULATION: 30 S pullorum isolates and isolates of 7 other Salmonella sp. PROCEDURE: Salmonella pullorum isolates were inoculated into high motility medium to evaluate swimming motility. Putative flagellar proteins were purified from the organisms and analyzed by means of gel electrophoresis and western blotting procedures, using various antisera specific for flagellar proteins. Antisera shown to be reactive with putative flagellar proteins were incorporated into the growth medium to examine their effects on motility of the isolates. RESULTS: All S pullorum isolates had evidence of swimming motility. Two putative flagellar proteins were purified from 2 of the S pullorum isolates: a 60 to 62 kd protein shown to react with antiserum specific for type y flagellar protein, and a 58 to 59 kd protein shown to react with antiserum specific for type d flagellar protein and with antibody reactive to a highly conserved flagellar epitope found on various Enterobacteriaceae. Antiserum specific for type d flagellar protein inhibited swimming motility of S pullorum isolates, but antiserum specific for type y flagellar protein did not. CONCLUSIONS: Results suggest that S pullorum isolates can be induced to manifest swimming motility when grown on medium with a low agar concentration and possess a 58 to 59 kd protein of d serotype and a second protein of 60 to 62 kd that also may be a flagellar protein.

Animals↗
PubMed2000

Effect of swim taper on whole muscle and single muscle fiber contractile properties.

TRAPPE, S., D. COSTILL, and R. THOMAS. Effect of swim taper on whole muscle and single muscle fiber contractile properties. Med. Sci. Sports Exerc., Vol. 32, No. 12, 2000, pp. 48-56. Purpose: To examine the changes in whole muscle function and single cell contractile properties of Type I and II muscle fibers from the deltoid muscle of highly trained swimmers before and after a 21-d reduction in training volume (taper). Methods: Six college male swimmers (age, 20 +/- 1 yr; height, 187 +/- 2 cm, weight, 79 +/- 3 kg, fat, 7 +/- 1%) who had been, on average, swimming 6200 m.d-1 for 5 months before the taper participated in this investigation. Results: Whole muscle power increased (P < 0.05) 17% and 13% on the swim bench and swim power tests, respectively. Swim times improved by 4% (range: 3.0-4.7%; P < 0.05). There was no change in Type I fiber diameter, whereas Type IIa fibers were 11% larger (P < 0.05) after taper. Peak force (Po) of the Type I fibers was unaffected by the taper but increased (P < 0.05) from 0.63 +/- 0.02 to 0.82 +/- 0.05 mN in the IIa fibers. However, the specific force (Po/CSA) of the IIa fibers was unchanged. Shortening velocity (Vo) was 32% and 67% faster (P < 0.05) in the Type I and IIa fibers, respectively. Although Type I fiber power was unaltered, the IIa fibers increased 2.5-fold from 24.6 +/- 2.8 to 56.2 +/- 3.9 µN.FL.s-1. When power was normalized for cell size, the power was still elevated twofold. Conclusions: These data suggest that tapering induces alterations in the contractile properties of single muscle fibers. Further, it appears that the Type IIa fibers are more affected than the Type I fibers by the taper. The increased size, strength, velocity, and power of the IIa fibers may be responsible for the improvements in whole muscle strength and power after the taper.

Journal Article↗
PubMedDate not supplied

Relationship between morphology and motion characteristics of human spermatozoa in semen and in the swim-up sperm fractions.

In this study, the authors evaluated the morphology pattern and motion characteristics of human spermatozoa before and after swim-up separation. Samples were divided into two, morphologically different groups according to the percentage of normal sperm forms assessed by the strict criteria of the Norfolk laboratory: "good"(G) and "poor" (P) prognosis patterns. The percentages of normal forms, slightly abnormal forms, and severe head defects were significantly different in the two groups. Motile characteristics were analyzed by a computerized semen analyzer with constant parameter settings. Before swim-up there were no significant differences in semen volume, percentage of neck and tail defects, concentration, or percentage of motility and linearity, but the mean velocity was higher in group G. After swim-up the percentage of motility, total number of motile cells, and recovery rate were higher for group G, and the incidence of severe head defects correlated negatively with the percentage of cells with a velocity of greater than 80 microns/sec. The results suggest that patients with a high incidence of sperm head defects have impaired original velocity, and swim-up selects for velocity as well as normal forms and motility. Although motility and velocity improved substantially after swim-up, the recovery rate and percentage of motility were significantly lower in the P group.

Cell Separation↗
PubMedDate not supplied

Teratospermic and normospermic domestic cats: ejaculate traits, pituitary-gonadal hormones, and improvement of spermatozoal motility and morphology after swim-up processing.

Electroejaculate traits, testicular volume, and circulating FSH, LH, and testosterone concentrations were compared between two populations of domestic cats consistently producing either a high (greater than 60%, normospermic) or low (less than 40%, teratospermic) incidence of structurally normal spermatozoa/ejaculate. The effects of semen dilution in Biggers, Whitten and Whittingham (BWW) or modified Krebs Ringer bicarbonate (mKRB) medium and swim-up processing on sperm viability and duration of motility in vitro also were assessed. Ejaculate volume, percent sperm motility, sperm progressive motility, motile spermatozoa/ejaculate, testes volume, and mean serum FSH and LH concentrations were similar (P greater than 0.05) between normospermic and teratospermic cats. However, sperm concentration/ml of ejaculate was greater and circulating testosterone levels were lower in teratospermic males. Swim-up processing increased (P less than 0.05) percent sperm motility, progressive motility, and the number of structurally normal sperm cells recovered and also prolonged the duration of sperm motility in both cat populations. In teratospermic ejaculates, swim-up separation increased the proportion of morphologically normal spermatozoa recovered by more than two-fold. Diluting cat semen with either BWW or mKRB increased flagellar bending in both normospermic and teratospermic cats. The sperm motility characteristics of only the teratospermic ejaculates were influenced by medium type; mKRB increased percent sperm motility and progressive motility whereas BWW had no effect. Compared with undiluted raw ejaculates, the duration of sperm motility was improved 18- to 24-fold by diluting semen in either BWW or mKRB medium followed by swim-up processing. This study demonstrates that the electroejaculate characteristics of domestic cats vary markedly and that some males consistently produce high proportions of morphologically abnormal spermatozoa. Diminished serum testosterone concentrations and normal pituitary secretion of FSH and LH in teratospermic males suggest that there is an inverse relationship between gonadal androgen production and pleiomorphic spermatozoa in the domestic cat. The swim-up procedure is effective for recovering motile, structurally normal spermatozoa from teratospermic cats.

Animals↗
PubMedDate not supplied

Chloroform in alveolar air of individuals attending indoor swimming pools.

Alveolar air samples were collected from 163 subjects at indoor swimming pools and from 77 nonexposed subjects. Chloroform was present in all samples collected from exposed subjects (median = 695.02 nmol/m3). It was found at very low levels in 53% of samples from nonexposed subjects. Alveolar air chloroform levels from people attending indoor swimming pools (mean value within each sampling session) were correlated with environmental air concentration (r = 0.907, p = .002). Analysis of variance showed that levels of chloroform in alveolar air depend on environmental air concentration, age, intensity of the sport activity, and kind of swimming. Chloroform levels in samples collected from competitive swimmers versus nonswimming visitors were different (F = 10.911, p = .001). Moreover, their pattern of swimming may affect chloroform concentration in alveolar air. The analysis of chloroform in alveolar air assesses indoor exposure in healthy subjects simply and at low cost.

Adolescent↗
PubMed2006

Ecological association between childhood asthma and availability of indoor chlorinated swimming pools in Europe.

BACKGROUND: It has been hypothesised that the rise in childhood asthma in the developed world could result at least in part from the increasing exposure of children to toxic chlorination products in the air of indoor swimming pools. OBJECTIVES: Ecological study to evaluate whether this hypothesis can explain the geographical variation in the prevalence of asthma and other atopic diseases in Europe. METHODS: The relationships between the prevalences of wheezing by written or video questionnaire, of ever asthma, hay fever, rhinitis, and atopic eczema as reported by the International Study of Asthma and Allergies in Childhood (ISAAC), and the number of indoor chlorinated swimming pools per inhabitant in the studied centres were examined. Associations with geoclimatic variables, the gross domestic product (GDP) per capita, and several other lifestyle indicators were also evaluated. RESULTS: Among children aged 13-14 years, the prevalence of wheezing by written questionnaire, of wheezing by video questionnaire, and of ever asthma across Europe increased respectively by 3.39% (95% CI 1.96 to 4.81), 0.96% (95% CI 0.28 to 1.64), and 2.73% (95% CI 1.94 to 3.52), with an increase of one indoor chlorinated pool per 100 000 inhabitants. Similar increases were found when analysing separately centres in Western or Northern Europe and for ever asthma in Southern Europe. In children aged 6-7 years (33 centres), the prevalence of ever asthma also increased with swimming pool availability (1.47%; 95% CI 0.21 to 2.74). These consistent associations were not found with other atopic diseases and were independent of the influence of altitude, climate, and GDP per capita. CONCLUSIONS: The prevalence of childhood asthma and availability of indoor swimming pools in Europe are linked through associations that are consistent with the hypothesis implicating pool chlorine in the rise of childhood asthma in industrialised countries.

Adolescent↗
PubMed2000

Hippocampal mossy fibers and swimming navigation learning in two vole species occupying different habitats.

We showed previously for mice that size differences of the infrapyramidal hippocampal mossy fiber projection (IIP-MF) correlate with spatial learning abilities. In order to clarify the role of the IIP-MF in a natural environment, we studied the bank vole (Clethrionomys glareolus), adapted to a wide range of different habitats, and the root vole (Microtus oeconomus), living in homogenous grassland habitats with small home ranges. Morphometry on Timm-stained horizontal brain sections of six C. glareolus and six M. oeconomus revealed that the size of the entire mossy fiber projection was 42% larger in C. glareolus than M. oeconomus. C. glareolus had also an IIP-MF projection about 230% larger than that of the root vole. A sample of captured animals was then transferred to the laboratory (C. glareolus, n = 23; M. oeconomus, n = 15) and underwent testing for swimming navigation according to a standardized protocol used to assess water maze learning in about 2,000 normal and transgenic mice. Both species learned faster than laboratory mice. Overall escape times showed no differences, but path length was significantly reduced in C. glareolus, which also showed superior performance in a variety of scores assessing spatial search patterns. On the other hand, M. oeconomus showed faster swimming speed, and strong thigmotaxis combined with circular swimming. M. oeconomus also scored at chance levels during the probe trial, about as poorly as mutant knockout mice considered to be deficient in spatial memory. These differences probably reflect differential styles of water maze learning rather than spatial memory deficits: C. glareolus appears to be superior in inhibiting behavior interfering with proper spatial search behavior, while M. oeconomus succeeds in escaping by using rapid circular swimming. We assume that size variations of the IIP-MF correspond to a mechanism stabilizing hippocampal processing during spatial learning or complex activities. This corresponds to the ecological lifestyle of the two species and is in line with previous observations on the role of the IIP-MF.

Animals↗
PubMed2002

Analysis of glucose and lactate in dialysate from hypothalamus of rats after exhausting swimming using microdialysis.

A microbore flow injection analysis-immobilized enzyme reactor-electrochemical detection (FIA-IMER-ECD) system for glucose and lactate detection was built up. The assays were precise, sensitive and practicable for determination of glucose and lactate levels in hypothalamic dialysate. The method had been used to detect the dynamic changes of glucose and lactate levels during rat exhausting swimming and recovery. The data showed that after exhausting swimming, the concentration of glucose in hypothalamic dialysate that reflected the concentration in the hypothalamic extracellular fluid decreased. The level fell to its nadir at day 1 after the exercise and then went back to the basal level at day 3 after the swimming. However, lactate levels increased to a maximum at day 3 and went back to the basal level at day 5 after the swimming.

Animals↗