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At least 1,711 records · Page 95Linked to original sources
PubMed1997

Perseveration on place reversals in spatial swimming pool tasks: further evidence for place learning in hippocampal rats.

Animals with damage to the fimbria-fornix (FF) or cells of the hippocampus (HIP) can learn a place problem but cannot learn matching-to-place problems, which feature a series of place "reversals." The two experiments described in the present report were designed to examine the causes of impairment on reversal learning. In experiment 1, control, HIP, and FF groups were trained to asymptote on a place problem, and then the location of the platform was moved. Control rats learned the reversal response more quickly than the initial response; the HIP rats learned both problems at the same rate. Swim analysis showed that the impairment in the lesion group on the reversal response was aggravated by perseverative returns to the first learned place. In experiment 2, control and FF groups were trained on a task in which the platform was visible on three daily trials and hidden on one daily trial. After 10 days, the platforms were moved. In the reversal response, the FF group showed enhanced performance on the cue trials and severely impaired performance on the place trials relative to initial learning and control performance. Swim analysis showed that FF rats perseverated on the initial place response in place trials. These experiments provide further evidence for place learning in hippocampal rats and show that perseverative responses contribute to impairments in new learning. The results are discussed in relation to the idea that the hippocampus mediates spatial mapping and/or uses self-movement cues to solve spatial problems.

Animals↗
PubMed2000

Effect of Ocimum sanctum roots extract on swimming performance in mice.

The effect of a methanol extract, obtained from the roots of Ocimum sanctum, on mouse swimming performance were studied using three different doses. On the basis of our findings, a high dose (400 mg/kg, i.p.) of the extracts of Ocimum sanctum increased the swimming time suggesting a central nervous system stimulant and/or antistress activity. The effect produced by the extract was comparable to that of desipramine, an antidepressant drug.

Animals↗
PubMed2002

Orientation of paramecium swimming in a DC magnetic field.

We found that a ciliated protozoan, Paramecium, swam perpendicular to a static (DC) magnetic field (0.68 T). The swimming orientation was similar even when the ionic current through the cell membrane disappeared after saponin treatment. To determine the diamagnetic anisotropy of intracellular organs, macronuclei, cilia, and secretory vesicles, trichocysts, were selectively isolated. Both cilia and trichocysts tended to align their long axis parallel to the magnetic field (0.78 T). Paramecium mutants that lack trichocysts also swam perpendicular to the magnetic field, although the proportion fraction was smaller than the normal population. Since large numbers of cilia and trichocysts are arranged at right angles to the long axis of the cell, the diamagnetic anisotropies of cilia and trichocysts cause the long axis of the cell to align perpendicular to the magnetic field. In contrast to the DC magnetic field, an alternative (AC) magnetic field (60 Hz, 0.65 T) had almost no effect on the swimming orientation of Paramecium.

Animals↗
PubMed1993

Hippocampal synaptic enhancement and spatial learning in the Morris swim task.

The authors attempted to replicate the study of Castro, Silbert, McNaughton, and Barnes (1989) in which it was concluded that bilateral saturation of hippocampal synaptic enhancement produced a deficit in acquisition of a spatial navigation problem in the Morris swim task. The original protocol was followed as closely as possible, but no effect of long-term enhancement (LTE) saturation on spatial performance in this task was found. This negative result suggests either that the previous finding using the swim task reflected statistical error or that some as yet undetermined variable is of critical importance in this phenomenon. The present negative finding also raises a question concerning the reproducibility of the earlier results of McNaughton, Barnes, Rao, Baldwin, and Rasmussen (1986) in which LTE saturation apparently led to a prolonged deficit on a different spatial task. Although negative results in such experiments do not constitute grounds for rejecting the underlying hypothesis, the present lack of a positive effect renders uncertain, for the time being, one of the lines of experimental support for the theory that LTE at hippocampal synapses reflects a mechanism for the associative, distributed storage of new spatial information.

Animals↗
PubMed2005

Tail loss, body condition and swimming performances in tiger snakes, Notechis ater occidentalis.

In limbless tetrapods such as snakes, propulsive forces are generated by lateral undulations of the body and of the tail. In a large population of tiger snakes from Western Australia, tail loss was extremely common (58% of the individuals) and often very severe (more than two-thirds of the tail was missing in 14% of the cases, and in some instances, the tail was totally lost). Tail loss was not however correlated with body size, mass or body condition of wild individuals, and hence did not influence their abilities to acquire resources. These large venomous snakes exhibit marked aquatic habits. Locomotor tests in controlled conditions revealed that tail loss had a significant negative influence on burst swimming performances. However, no effect was found on routine swimming speed and total distance travelled over 5 min. These results suggest that a long and slender tail, although important for maximal speed, is not necessarily relevant for the locomotor abilities required for successful hunting. Tail-damaged individuals outnumbered intact snakes, suggesting that tail loss did not severely compromise survival. Overall, in this species, a slight deterioration of maximal speed due to severe tail loss probably has a low (undetectable) ecological impact, at least for adults.

Animals↗
PubMed2005

Dorsal fin in the white shark, Carcharodon carcharias: a dynamic stabilizer for fast swimming.

Transverse sections of the skin in the dorsal fin of the white shark, Carcharodon carcharias, tiger shark, Galeocerdo cuvier, and spotted raggedtooth shark, Carcharias taurus, show large numbers of dermal fiber bundles, which extend from the body into the fin. The bundles are tightly grouped together in staggered formation (not arranged in a straight line or in rows). This arrangement of dermal fibers gives tensile strength without impeding fiber movement. Tangential sections indicate that the fibers in all three species are strained and lie at angles in excess of 60 degrees . Of the three species investigated the dermal fibers in C. carcharias are the most densely concentrated and extend furthest distally along the dorsal fin. The overall results indicate that the dorsal fin of C. carcharias functions as a dynamic stabilizer and that the dermal fibers are crucial to this role. The fibers work like riggings that stabilize a ship's mast. During fast swimming, when the problems of yaw and roll are greatest, hydrostatic pressure within the shark increases and the fibers around the body, including in the dorsal fin, become taut, thereby stiffening the fin. During slow swimming and feeding the hydrostatic pressure is reduced, the fibers are slackened, and the muscles are able to exert greater bending forces on the fin via the radials and ceratotrichia. In C. carcharias there is a trade-off for greater stiffness of the dorsal fin against flexibility.

Animal Structures↗
PubMed2000

cDNA Cloning and mRNA analysis of PGC-1 in epitrochlearis muscle in swimming-exercised rats.

Peroxisome proliferator-activated receptor gamma coactivator-1 (PGC-1), a cold-inducible coactivator of nuclear receptors, stimulates mitochondrial biogenesis and respiration in muscle cells. In the present study, we first cloned a rat PGC-1 gene from a brown adipose tissue cDNA library which encodes a predicted 796-amino-acid protein and exhibits respectively 98% and 95% identity with the mouse and human homologues. Next, we examined the effect of swimming exercise training on the level of expression of the PGC-1 gene in rat epitrochlearis (Epi) muscle. PGC-1 mRNA level in Epi muscle in rats that swam 2 h a day for 3 and 7 days increased dramatically by 154% and 163%, respectively, compared to the non-exercised control group. PGC-1 mRNA up-regulation was not observed in an immersion group treated at 35 degrees C during the training program but without swimming exercise. These results demonstrate that expression of the PGC-1 gene in Epi muscle is induced not only by cold exposure but also by prolonged low-intensity physical exercise.

Animals↗
PubMed1993

Contribution of differentiated ratings of perceived exertion to overall exertion in women while swimming.

The purpose of this study was to identify, using multiple regression analysis, the contribution of differentiated ratings of perceived exertion to overall exertion (RPEO) in women while swimming. Ten female subjects swam at submaximal and maximal intensities and the variables measured included oxygen uptake (VO2), heart rate (fc), ventilation (VE), breathing frequency, tidal volume, blood lactate concentration ([la-]b), RPEO, and four differentiated RPE. These four differentiated RPE were cardiac frequency rating (RPEC), respiratory frequency rating (RPER), arm rating (RPE(arm)), and leg rating (RPE(leg)). These variables used the following equation based on VO2 - R = a + c.(S-b)n, where R was the response to increasing exercise intensity (S) and a, b, and c were constants. The exponents (n) of fc, VE and [la-]b were approximately 1.0, 2.0 and 3.3, respectively. The estimated exponents of RPEO, RPEC, RPER, RPE(arm) and RPE(leg) were approximately 2.4, 2.3, 2.2, 2.5 and 2.5, respectively. There was a highly significant relationship between the four differentiated RPE and their associated physiological responses. The results of this study showed that these interrelationships were clearly delineated. As the percentage maximal oxygen uptake (% VO2max) increased, the major contributing factor to RPEO changed. The RPEC was found to be the main contributing factor from 20% to 45% VO2max, but ceased to contribute beyond 50% VO2max. Above 45% VO2max, RPE(arm) was the major influence, and RPER was the secondary influence from 66% to 96% VO2max. The RPE(leg) was the secondary contributing factor only from 27% to 35% VO2max. It was concluded that differentiated RPE contribution was dependent upon the intensity of exercise in women while swimming.

Adult↗
PubMed1990

Cardiac output and stroke volume in swimming harbor seals.

Cardiac output was measured by the thermodilution method in three young harbor seals, at rest and while swimming up to the maximum effort for which they could be trained. Stroke volume was determined by counting heart rate simultaneously with determination of cardiac output. Cardiac outputs varied widely between surface breathing (7.8 ml.kg-1.s-1) and breath-holding while swimming under water (1.8 ml.kg-1.s-1). Stroke volume while at the surface was almost twice the volume while submerged. Surface cardiac output was always near maximal despite work effort, whereas submerged cardiac output gradually increased at higher work efforts. The cardiovascular performance of seals at the maximum MO2 we could induce from them is equivalent to that of the domestic goat.

Animals↗
PubMed1996

Blood lactate recovery measurements, training, and performance during a 23-week period of competitive swimming.

The purpose of this study was to relate measurements of blood lactate concentration, performance during a maximal anaerobic lactic test (MANLT) and training loads during a 23-week swimming season. Six elite 200-m freestyle male swimmers [mean age 19.5 (SD 1.6) years, height 184 (SD 5) cm and body mass 77.7 (SD 9.0) kg], participated in the study. The MANLT consisted of four all-out 50-m swims interspersed with 10-s recovery periods. Blood lactate concentrations were determined at 3 and 12-min post-exercise and were performed on weeks 2,6,10,14,18 and 21. Swimmers participated in 200-m freestyle competitions on weeks 1,7,13 and 23 (national championships). During weeks 1-10, training mostly involved aerobic exercise, while during weeks, 11-23, it involved anaerobic exercise. At 3-min and 12-min post-MANLT lactate concentrations varied throughout the season [range from 14.9 (SD 1.2) to 18.7 (SD 1.0) mmol.l-1] but demonstrated non-systematic variations. In contrast, the percentage of mean blood lactate decrease (% [La-]recovery) between min 3 and min 12 of the passive recovery post-MANLT increased from week 2 to 10 with aerobic training and decreased from week 10 to 21 with anaerobic training. The MANLT performance improved continuously throughout the season, while competition performance improved during the first three competitions but declined in the final championships, coinciding with the lowest % [La-]recovery and signs of overtraining, such as bad temper and increased sleeping heart rate. The results of this study indicated that % [La-]recovery could be an efficient marker for monitoring the impact of aerobic and anaerobic training and avoiding overtraining in elite 200-m swimmers.

Adolescent↗
PubMed1996

Saliva cortisol, physical exercise and training: influences of swimming and handball on cortisol concentrations in women.

The aim of this study was to observe the influence of physical exercise and training on saliva cortisol concentrations in women. Three groups of adult women were studied: one group of sedentary controls (n = 7) and two groups of sportswomen who competed in either handball (n = 14) or swimming (n = 10) at a national level. These sportswomen gave six saliva samples during a day that included exercise which was part of their annual training programme. We noticed a significant increase in saliva cortisol concentration after exercise in the handball players (6 p.m. vs 7.30 p.m. P < 0.05) which did not appear in the swimmers or the sedentary group. There was no difference between the sedentary group and the swimmers for each sample of the day. These results showed that the type of sport played seemed to influence the concentration of saliva cortisol, the type of stress involved, the respective haemodynamic conditions of swimming and running and thermal stress also playing a part. Moreover, it seemed that the level of performance influenced the secretion of cortisol in the saliva.

Adult↗
PubMed1988

Effect of glucose polymer diet supplement on responses to prolonged successive swimming, cycling and running.

Fifteen male endurance athletes were studied to determine the effect of a glucose polymer (GP) diet supplement on physiological and perceptual responses to successive swimming, cycling and running exercise. Thirty min of swimming, cycling and running at 70% VO2max, followed by a run to exhaustion at 90% VO2max was performed after one week of training under two dietary conditions: 1) GP (230 g of GP consumed daily) and 2) placebo (P, saccharin-sweetened supplement consumed daily). During GP, daily carbohydrate (CHO) intake was higher (p less than 0.05) by 173 g or 14% of energy intake than during P, but total energy intake was not significantly different. During 90 min of exercise, CHO utilization and blood glucose were significantly higher under GP than P by an average of 20.2% and 14.5%, respectively, but heart rate, ventilation, oxygen uptake, ratings of perceived exertion, and plasma lactate were not different. Run time to exhaustion at 90% VO2max was significantly longer by 1.2 min (23%) under GP. The results suggest that a GP diet supplement may be of value during endurance exercise by increasing the availability of CHO.

Bicycling↗
PubMed1979

Rats bred for ethanol sensitivity: impairment of swimming by ethanol and pentobarbital.

Rats selectively bred for disparate degrees of ethanol-induced depression of spontaneous locomotor activity ('most affected' = MA; 'least affected' = LA) were trained on a swim task. Undrugged rats of the MA line swam significantly faster than rats of the LA line. Ethanol, 0.0--2.25 g/kg i.p., produced dose-dependent increases in swim time in rats of the 13 generation (F13). Averaged over trials, these increases were greater in LA than in MA rats and greater in males than in females, but there was no sex difference in peak impairment. Increases in swin time were uncorrelated with predrug performance. These findings were confirmed in younger F17 rats receiving 1.75 g EtOH/kg i.p. Although the lines differed in ethanol-induced impairment, F17 males of the two lines were not differentially impaired by pentobarbital (12.5--22.5 mg/kg, i.p.). The existence of task-dependent line differences in ethanol sensitivity emphasizes the nonunitary nature of ethanol-induced 'behavioral depression.'

Animals↗
PubMed1985

Attenuated response to nomifensine in rats during a swim test following lesion of the habenula complex.

Male Lister rats with bilateral lesions of the habenula nuclei were observed during two consecutive phases of a swim test. During the first phase of the test, when escape was not possible, lesioned animals demonstrated fewer changes of behaviour. Lesioned animals failed to utilise an introduced external cue and escape route in the second part of the test. Control rats treated with the antidepressant nomifensine showed few changes of behaviour during the inescapable phase of the test but an enhanced ability to escape. Nomifensine produced no improvement of escape behaviour in lesioned animals, suggesting that this behavioural effect of nomifensine in controls is dependent on the habenula relay. The data also suggest that more than one response in swim tests can serve as an index of depression.

Analysis of Variance↗
PubMed1985

Effect of short-term swimming stress and diazepam on 3,4-dihydroxyphenylacetic acid (DOPAC) and 5-hydroxyindoleacetic acid (5-HIAA) levels in the caudate nucleus: an in vivo voltammetric study.

The effects of swimming stress on dopaminergic and serotonergic neurons were studied by an in vivo voltammetry technique. 3,4-Dihydroxyphenylacetic acid (DOPAC) and 5-hydroxyindoleacetic acid (5-HIAA) levels in rat striatum were measured by differential pulse voltammetry with an electrochemically treated carbon fiber electrode. Exposure to swimming stress for 1 to 10 min to the animal increased the DOPAC and 5-HIAA peaks, which depended on the length of stress. Pretreatment of the rats with diazepam (10 mg/kg, i.p.) prevented completely the stress-induced increase in DOPAC levels but only partially reduced the increase in 5-HIAA levels.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1986

The significance of beta-adrenoceptor down regulation in the desipramine action in the forced swimming test.

The present studies were undertaken to clarify whether central beta-adrenoceptor down regulation is responsible for the greater effect of chronic treatment with desipramine (DMI) compared with acute treatment in the forced swimming test in rats. Repetitive administration of DMI activated the rat behaviour pattern and consequently reduced the duration of immobility. The degree of activation depended on the length of treatment, i.e. no effect when given in a single dose, moderate effect when given subchronically (3 doses) and marked activation after chronic (31 doses) treatment. Chronic treatment with DMI also produced a decrease in 3H-dihydroalprenolol (3H-DHA) binding site in the cerebral cortex. Acute stimulation of brain beta-adrenoceptors by intracerebroventricular (i.c.v.) isoprenaline significantly, though partially, attenuated the behavioural effect of chronic DMI by beta 1-adrenoceptor-related mechanisms. Similarly, chronic i.c.v. co-administration of atenolol or practolol, beta 1-adrenoceptor antagonists, together with DMI attenuated both beta-adrenoceptor down regulation and the behavioural activation by chronic DMI. On the other hand, chronic i.c.v. administration of isoprenaline, supposedly leading to down regulation of beta-adrenoceptors, facilitated the activating behavioural effect of DMI, as a single dose became effective. Changes, however, in 3H-DHA binding parameters in the cerebral cortex were not observed after chronic isoprenaline. These results suggest that down regulation of beta-adrenoceptors in brain is responsible, at least in part, for the marked activatory effect of chronic DMI in the forced swimming test, possibly by reducing an inhibitory function of beta 1-adrenoceptor mediated mechanisms.

Adrenergic beta-Antagonists↗
PubMed1994

Responses of atrial natriuretic peptide and other fluid regulating hormones to long distance swimming in the sea.

The plasma hormonal response following a swimming competition in the sea (18 km) was evaluated in 12 top level male endurance swimmers. At the end of the effort, while plasma renin activity (PRA) and aldosterone concentration (ALDO) were unchanged, a significant increase in plasma atrial natriuretic peptide (ANP) and antidiuretic hormone (ADH) concentrations were recorded. These changes were associated with a decrease in haematocrit and an increase in Na+ and Cl- plasma concentrations. The individual variations of ANP (difference between the final and initial concentrations) were inversely correlated with the corresponding individual variations of PRA and ADH. The results suggest that, during prolonged swimming, ANP may exert an inhibitory effect on the PRA-ALDO axis and have a modulatory role with regard to ADH secretion.

Adolescent↗
PubMed1981

Swim-induced grooming in mice is mediated by a dopaminergic substrate.

Grooming induced in mice after a period of swimming was potently and dose-dependently blocked by neuroleptics. The order of potency of the neuroleptics was spiroperidol greater than haloperidol greater than cis-flupenthixol greater than pimozide greater than chlorpromazine greater than thioridazine. The trans isomer of flupenthixol was inactive at 40 microM/kg. The alpha-adrenergic receptor antagonists, phentolamine and phenoxybenzamine, and the catecholamine synthesis inhibitor, alpha-methyl-p-tyrosine were essentially without effect on the grooming behaviour. Amitriptyline inhibited grooming behaviour only in doses which severely affected the animals motor function. Fluoxetine was without effect. Cis-flupenthixol was less active in inhibiting grooming in animals chronically treated with haloperidol than in control animals, indicating the presence of supersensitive dopamine receptors. The data indicate that swim-induced grooming in mice is mediated via dopaminergic systems.

Adrenergic alpha-Antagonists↗