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PubMedDate not supplied

Myocardial catecholamine responsiveness of spontaneously hypertensive rats as influenced by swimming training.

Alterations of myocardial mechanical catecholamine responsiveness by swimming training (2 X 90 min/day, 4 weeks) were examined in 13-week-old spontaneously hypertensive males rats (SHR). The relationships between myocardial mechanical catecholamine responsiveness and ventricular beta-adrenoceptors as well as myosin isoenzyme pattern were also examined. Compared with sedentary controls, trained rats showed a greater responsiveness to isoproterenol (10(-6) mol/l) on isometric tension (T) and its first derivative (dT/dt) (delta T: 0.45 +/- 0.55 vs. -0.15 +/- 0.11 10(-2) N/mm2, p less than 0.01, delta dT/dt: 17.1 +/- 10.1 vs. 8.3 +/- 3.6 10(-2) N/mm2 X s, p less than 0.05). In sedentary SHR, dT/dtmax increased significantly, whereas developed tension decreased slightly, coupled with a decrease of time to peak tension by high dose (10(-6) mol/l) isoproterenol. Therefore, it can be stated that dT/dt is a better indicator for catecholamine sensitivity than isometric tension. beta-adrenoceptor density [( 3H]-dihydroalprenolol binding) decreased significantly in trained rats (68.7 +/- 7.62 vs. 102.4 +/- 4.37 fmol/mg protein, p less than 0.01) with no significant difference in KD values (4.61 +/- 2.26 vs. 6.11 +/- 1.94 nM, ns). In addition, myosin isoenzyme pattern revealed by pyrophosphate gel electrophoresis shifted towards VM-1 after swimming training. The increased catecholamine sensitivity of fast contracting myocardium is, in principle, compatible with the assumption of cAMP-dependent regulation of myofibrillar ATPase activity (21) or cross bridge kinetics (9), although other postreceptor processes should also be taken into consideration for the increased catecholamine sensitivity.

Adenosine Triphosphatases↗
PubMed1982

Effects of L-aspartic acid, L-asparagine and/or L-asparaginase on forced swimming-induced immobility, analgesia, and decrease in rectal temperature in rats.

The effect of L-aspartic acid, L-asparagine and/or L-asparaginase were compared with those of imipramine on immobility, number of defecations, increase of nociceptive threshold, and hypothermia, induced by forced swimming in rats. L-Aspartic acid was found to be as effective as imipramine in reducing the effects of forced swimming, presumable by normalizing the decreased level of endogenous L-aspartic acid, due to the inhibition of L-asparaginase activity and/or by stimulating the inhibited enzyme. The other treatments antagonized the immobility, but not the increased number of defecations. All compounds abolished the elevation of nociceptive threshold and hypothermia.

Analgesia↗
PubMed1986

Inbreeding considerations in a REM sleep model for rat swimming activity.

Over the past few years, our laboratory group has elaborated a repeated measures rat swimming test. It provides an animal base for showing that the REM sleep mechanism is important to both emotional responsiveness and environmental adaptations. All of that work has been done with Sprague-Dawley rats obtained from a local supplier. Work done with two European rat stocks (by researchers in France and The Netherlands) shows general agreement with our own. In this presentation, we directly compare rats derived from an English vendor's Sprague-Dawley stock with the U.S. based Sprague-Dawley stock which we have been using. We also make strain comparisons via the F344 and the Long Evans strains. Although the literature has numerous examples of swimming test differences between inbred and wild rat stocks, strain difference effects have not been reported. We report that there are significant differences attributable to inbred strain but not to vendor on this measure.

Animals↗
PubMed1990

Antidepressant-like activity of 5-HT1A agonists measured with the forced swim test.

This study examined the abilities of 5-hydroxytryptamine (5-HT) agonists with varying selectivity for different subtypes of 5-HT receptors to produce antidepressant-like behavioral effects in the forced swim test in rats. The 5-HT1A agonists 8-OH-DPAT (0.125-1.0 mg/kg, SC) and tandospirone (SM-3997) (5-20 mg/kg, SC) both produced dose-related decreases in immobility time following subchronic treatment in rats. These effects were similar to those of the tricyclic antidepressants imipramine (5-15 mg/kg) and desipramine (5-15 mg/kg). In addition, the 5-HT1A agonists, buspirone (20 mg/kg), gepirone (20 mg/kg) and ipsapirone (10 and 20 mg/kg) demonstrated antidepressant-like effects. Other groups of rats treated subchronically with each of the 5-HT1A agonists or antidepressants showed no increase in locomotor activity, so that general changes in activity could not account for the reduction of immobility time in the forced swim test. 5-HT agonists selective for other receptor subtypes, such as the 5-HT1B/1C agonist m-CPP (5 mg/kg) and the 5-HT2/1C agonist DOB (1 mg/kg), were not effective in this behavioral test. The benzodiazepine diazepam (5 mg/kg) also failed to reduce immobility time, suggesting that anxiolytic properties of 5-HT1A agonists did not mediate this behavioral effect. A common metabolite of some of the 5-HT1A agonists, 1-PP, was ineffective in reducing immobility time. The stimulant d-amphetamine (2 mg/kg) significantly reduced immobility time but also significantly increased locomotor activity.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Antidepressant-like effect of neurotensin administered in the ventral tegmental area in the forced swimming test.

Locomotor activity and behaviour in the forced swimming test were examined in rats which had received neurotensin (0.5-5.0 micrograms) in the ventral tegmental area. Doses of 5 micrograms neurotensin but not lower increased the locomotor activity for at least 2 h. At 0.5 and 1.0 microgram neurotensin significantly increased the time the animals spent in struggling with no changes in general motor activity (swimming). The effect of 1.0 microgram neurotensin on struggling was completely antagonized by 0.5 microgram (-)-sulpiride administered in the posterior nucleus accumbens. The results suggest that activation of the mesolimbic dopamine system through administration of neurotensin in the ventral tegmental area produces antidepressant-like effects. The significance of these findings for a role of endogenous neurotensin in depression remains to be clarified.

Analysis of Variance↗
PubMed1996

Effect of the underwater torque on the energy cost, drag and efficiency of front crawl swimming.

Underwater torque (T') is defined as the product of the force with which the swimmer's feet tend to sink times the distance between the feet and the centre of volume of the lungs. It has previously been shown that experimental changes of T', obtained by securing around the swimmer's waist a plastic tube filled, on different occasions, with air, water or 2-kg lead, were accompanied by changes in the energy cost of swimming per unit of distance (Cs) at any given speed. The aim of this study was to investigate whether the observed increases of Cs with T' during front crawl swimming were due to an increase of active body drag (Db), a decrease of drag efficiency (eta /d) or both. The effect of experimental changes of T' on Cs, Db and eta /d were therefore studied on a group of eight male elite swimmers at two submaximal speeds (1.00 and 1.23 m.s-1). To compare different subjects and different speeds, the individual data for Cs, Db, eta /d and T' were normalized dividing them by the corresponding individual averages. These were calculated from all individual data (of Cs, Db, eta /d and T') obtained from that subject at that speed. It was found that, between the two extremes of this study (tube filled with air and with 2-kg lead), T' increased by 73% and that Cs, Db and eta /d increased linearly with T'. The increase of Cs between the two extremes was intermediate (approximately 20%) between that of Db (approximately 35%) and of eta /d (approximately 16%). Thus, the actual strategy implemented by the swimmers to counteract T', was to tolerate a large increase of Db. This led also to a substantial (albeit smaller) increase of r/d, the effect of which was to reduce the increase of Cs that would otherwise have occurred.

Adult↗
PubMed1990

The effect of swimming on bone modeling and composition in young adult rats.

The purpose of this study was to investigate the adaptability of long bones of young adult rats to the stress of chronic aquatic exercise. Twenty-eight female Sabra rats (12 weeks old) were randomly assigned to two groups and treatments: exercise (14 rats) and sedentary control (14 rats) matched for age and weight. Exercised animals were trained to swim in a water bath (35 degrees +/- 1 degree C, 1 hour daily 5 times a week) for 12 weeks loaded with lead weights on their tails (2% of their body weight) (BW). At the end of the training period following blood sampling for alkaline phosphatase, all rats were sacrificed and the humeri and tibiae bones were removed for the following measurements: bone morphometry, bone water compartmentalization, bone density (BD), bone mineral content (BMC), and bone ions content (Ca, Pi, Mg, Zn). The results indicate that exercise did not significantly affect the animals' body weight, bone volume, or length and diameters. However, bone hydration properties, BD, bone mass, and mineralization revealed significant differences between swim-trained rats and controls (P less than 0.05). Longitudinal (R1) measurement was higher by 43% for both humerus and tibia, and Transverse (R2) relaxation rates of hydrogen proton were higher by 117 and 76% for humerus and tibia, respectively; fraction of bound water was higher by 36 and 46% for humerus and tibia, respectively. BD, bone weight, and ash were higher by 13%. BMC and bone ions content were higher by 10%, and alkaline phosphatase was higher by 67%.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1997

[Green hair caused by frequent swimming pool use].

Three patients presented with an acquired green discoloration of their scalp hair. History revealed that all of them swam regularly in private swimming pools. Examination of the hair by atomic emission spectroscopy showed that the green discoloration was caused by an excessively high copper content of the hair. This exogeneous discoloration is characteristically related to the uptake of copper from private swimming pools.

Adolescent↗
PubMed2001

Nociceptin receptor antagonists display antidepressant-like properties in the mouse forced swimming test.

The present study investigated the effects of nociceptin, the peptide nociceptin receptor antagonist, [Nphe(1)]-nociceptin (1-13)-NH(2), and the non-peptide antagonist, J-113397, in the mouse forced swimming test, an animal model used for the screening of potential antidepressant drugs. Additional studies were performed with naloxone to exclude effects on traditional opioid receptors. Intracerebroventricular (ICV) administration of nociceptin (0.01-1 nmole) was devoid of any activity in the mouse forced swimming test, as was intraperitoneal (i.p.) administration of naloxone (1-10 mg/kg). ICV treatment with [Nphe(1)]-nociceptin (1-13)-NH(2) (25 nmole and 50 nmole) induced significant antidepressant-like activity ( P<0.01), as did administration of J-113397 (20 mg/kg, i.p; P<0.05). Open field analysis revealed that acute treatment with these molecules did not induce significant changes in locomotor activity at the doses tested. These results suggest that nociceptin, and its receptor, may play a role in depressive disorders and that the nociceptin system could represent a novel target for the development of new antidepressant drugs.

Animals↗
PubMed1999

Evidence of the activity of lithium on 5-HT1B receptors in the mouse forced swimming test: comparison with carbamazepine and sodium valproate.

The use of lithium in combination with various antidepressant drugs (e.g., heterocyclics and monoamine oxidase inhibitors) has been reported rapidly to improve antidepressant response in otherwise treatment-resistant patients. Carbamazepine and sodium valproate have also been shown to be effective in the treatment of several forms of affective disorders, such as treatment-resistant depression and bipolar depression. The present study, using the mouse forced swimming test, was undertaken to test the hypothesis of the action of lithium, carbamazepine or sodium valproate on some 5-HT receptor subtypes. Results showed that lithium significantly potentiated the anti-immobility effects of RU 24969 (P<0.01) and anpirtoline (P<0.01). Pretreatment with lithium did not induce any significant antidepressant-like effects when tested in combination with 8-OH-DPAT, NAN-190 or (+/-) pindolol. Pretreatment with carbamazepine provoked anti-immobility effects when tested in combination with RU 24969 (P<0.01) and 8-OH-DPAT (P<0.01), whereas prior administration of sodium valproate enhanced the antidepressant-like effects of (+/-) pindolol (P<0.01), 8-OH-DPAT (P<0.01) and RU 24969 (P<0.01). In conclusion, the results of the present study suggest that lithium may be acting through 5-HT1B receptors, whereas the action of carbamazepine and sodium valproate seems to involve 5-HT1A receptors in the mouse forced swimming test. However, considering the complexity of the actions of these compounds, it is possible that other neurotransmitter systems/receptors may be involved.

Animals↗
PubMed2001

Arm to leg coordination in humans during walking, creeping and swimming activities.

In walking humans, arm to leg coordination is a well established phenomenon. The origin of this coordination, however, remains a matter for debate. It could derive from the intrinsic organisation of the human CNS, but it could also consist of a movement induced epiphenomenon. In order to establish which of these alternatives applies, we recorded arm and leg movements as well as their muscle activities during walking, creeping on all fours and swimming. The relationship between arm and leg cycle frequency observed under these various conditions was then investigated. We found that during walking, creeping on all fours or swimming, arm and leg movements remain frequency locked with a fixed relationship of 1/1, 2/1, 3/1, 4/1 or 5/1. When movements of the legs are slowed by flippers, the frequency relationship may skip to a different value, but the coordination is preserved. Furthermore, minimising the mechanical interactions between the limbs does not abolish coordination. These findings demonstrate that the arm to leg coordination observed in the walking human is also present during other human locomotor activities. The characteristics of this coordination correspond to those of a system of two coupled oscillators like that underlying quadruped locomotion.

Adult↗
PubMed2003

K+-induced Ca2+ conductance responsible for the prolonged backward swimming in K+-agitated mutant of Paramecium caudatum.

The K+-agitated (Kag) mutant of Paramecium caudatum shows prolonged backward swimming in K+-rich solution. To understand the regulation mechanisms of the ciliary motility in P. caudatum, we examined the membrane electrical properties of the Kag mutant. The duration of the backward swimming of the Kag in K+-rich solution was about 10 times longer than that of the wild type. In response to an injection of the outward current, the wild type produced an initial action potential and a subsequent membrane depolarization due to I-R potential drop, while the Kag exhibited repetitive action potentials during the depolarization. Under voltage-clamp conditions, the depolarization-activated transient inward current exhibited by the Kag was slightly smaller than that exhibited by the wild type. In response to an application of K+-rich solution, both the wild type and the Kag exhibited a depolarizing afterpotential representing the activation of the K+-induced Ca2+ conductance. The inactivation time course of the K+-induced Ca2+ conductance of Kag was about 10 times longer than that of the wild type. This difference corresponds well with the difference in behavioral responses between Kag and wild type to K+-rich solution. We conclude that the overreaction of the Kag mutant to the K+-rich solution is caused by slowing down of the inactivation of the K+-induced Ca2+ conductance.

Action Potentials↗
PubMed2004

Role of ligand-gated ion channels in the swimming behaviour of Xenopus tadpoles: experimental data and modelling experiments.

The swimming behaviour of lower vertebrates has been used as a model to study the function of simple neuronal circuits. Good examples are the lamprey and the Xenopus tadpole. In these two cases, glutamate-activated NMDA receptors are involved, and the relative importance of the NMDA and non-NMDA receptors as well as the involvement of other ion channels has been studied using a combination of electrophysiological recordings and modelling experiments, but little attention had been paid to their evolution during development. In the present experiments, which have been performed on Xenopus embryos from stages 31 to 42, we have probed the relative importance of the two categories of receptors using selective blockers [respectively dl-2-amino-5-phosphonovaleric acid (APV) and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX)]. The sensitivity of the swimming behaviour to APV was found to increase during development and that to CNQX to decrease. Furthermore, it has been observed that the spike activity recorded from the ventral roots is more complex in late embryonic stages that in early embryos. These modifications are associated with changes of the neuronal circuit, some of which correspond to a lengthening of the axon and an increased complexity of the dendritic tree of the motoneurons. We have incorporated these modifications in a simplified model of the central pattern generator built with Neuron software. The results indicate that at least part of the observed changes can be associated with changes in the length of the dendrites and axons.

2-Amino-5-phosphonovalerate↗
PubMed2004

The ACE gene insertion/deletion polymorphism and elite endurance swimming.

Human physical performance is influenced by genetic factors. A variation in the human angiotensin I-converting enzyme (ACE) gene has been identified, in which the insertion (I) variant may be associated with elite endurance performance, and the deletion (D) variant seems overrepresented amongst elite sprinters and short-distance swimmer status. We might thus anticipate I-allele frequency to be elevated amongst swimmers competing over very much greater distances, and have examined this hypothesis. Thirty-five truly elite very-long-distance swimmers were classified as better at 1- to 10-km distances (n=19, SLD group) or those best at 25-km races (n=16, LLD group). Genotype frequencies (II versus ID versus DD) differed between the two groups: 6% versus 47% versus 47% for SLD, and 18.8% versus 75% versus 6.2% for LLD (P=0.01). I-allele frequency was 0.29 for the shorter distance swimmers, and 0.59 for the 25 km group. These data are consistent with an association of ACE I allele with longer distance swimming, and the ACE D allele with swimming shorter distances.

Adult↗
PubMed2004

Influence of different rest intervals during active or passive recovery on repeated sprint swimming performance.

The purpose of this study was to investigate the effect of active or passive recovery after two different rest intervals on performance during repeated bouts of maximal swimming exercise. Sixteen swimmers (eight males and eight females) performed four trials in a counterbalanced order. Eight repetitions of 25-m sprints (8 x 25 m), with a rest interval of 45 or 120 s, followed by a 50-m sprint test 6 min later, were performed in each trial. The 45 or 120-s interval was either active (A45 and A120) or passive (P45 and P120). The intensity of the active recovery corresponded to 60% of the individual best 100-m velocity. Performance time was recorded using an official competition timing system. The first 25-m sprint was comparable across trials (P>0.05), but performance was decreased after the second sprint during active compared to passive recovery, irrespective of the interval duration (P<0.05). The 50-m sprint time was 2.4% better in the P120 and A120 compared to the A45 and P45 trials (P<0.05). After completing the 8x25 m, blood lactate was decreased with active recovery when the interval period was 120 s (P120 vs A120, P<0.05). Blood lactate concentration at the start as well as 5 min after the 50-m sprint was lower in the A120 and A45 compared to the P120 and P45 trials respectively (P<0.05). Plasma glycerol was not different between trials (P>0.05), whereas plasma ammonia was higher in the A45 compared to the P120 trial (P<0.05). The interval period separating short-duration sprints may therefore alter performance when subsequent maximum exertion is applied. For sustained sprinting ability, passive recovery is advised during repeated swimming sprints of short duration.

Adult↗
PubMed2005

Economy and efficiency of swimming at the surface with fins of different size and stiffness.

The aim of this study was to investigate how fins with varying physical characteristics affect the energy cost and the efficiency of aquatic locomotion. Experiments were performed on ten college swimmers who were asked to swim the dolphin kick while using a monofin (MF) and to swim the front crawl kick with a small-flexible fin (SF), a large-stiff fin (LS) and without fins (BF, barefoot). The energy expended to cover one unit distance (C) was highest for BF (C=10.6+/-1.8 kJ m(-1) kg(-1) at 0.8 m s(-1)) and decreased by about 50% with LS, 55% with SF and 60% with MF, allowing for an increase in speed (for a given metabolic power) of about 0.4 m s(-1) for MF and of about 0.2 m s(-1) for SF and LS (compared with BF). At any given speed, the fins for which C was lower were those with the lowest kick frequency (KF): KF=1.6+/-0.22 Hz at 0.8 m s(-1) (for BF) and decreased by about 40% for SF, 50% for LS and 60% for MF. The decrease in KF from BF to SF-LS and MF was essentially due to the increasing surface area of the fin which, in turn, was associated with a higher Froude efficiency (eta(F)). eta(F) was calculated by computing the speed of the bending waves moving along the body in a caudal direction (as proposed for the undulating movements of slender fish): it increased from 0.62+/-0.01 in BF to 0.66+/-0.03 in SF and 0.67+/-0.04 in LS reaching the highest values (0.76+/-0.05) with MF. No single fin characteristic can predict a swimmer's performance, rather the better fin (i.e. MF) is the one that is able to reduce most KF at any given speed and hence to produce the greatest distance per kick (d=v/KF). The latter indeed increased from 0.50+/-0.01 m in BF to about 0.90+/-0.05 m in SF and LS and reached values of 1.22+/-0.01 m in MF.

Adult↗
PubMed1987

The effects of ethanol on cellular calcium content in primary myocardial cell cultures from offspring of sedentary and swim-trained pregnant rats.

Primary myocardial cell cultures obtained from offspring of swim-trained (T) and sedentary (S) Sprague-Dawley rat mothers (dams) were used to evaluate the influence of exercise training and ethanol on cellular calcium (45Ca) content. The pregnant rats swam in water maintained at 37 degrees C 6 days/week during gestation. The dams swam continuously for 30 min on the first day of gestation. The swimming time was increased by 5 min until the rats swam continuously for 1.5 hr. After the cultures had been in incubation for 4 days, the cells were treated with 600, 800, and 1000 mg% ethanol for 30 min and 1 hr. 45Ca content (nmol/mg protein) of the untreated controls and all but one of the ethanol treated groups from the T cultures (1000 mg%) were significantly elevated over the comparable groups from the S cultures for both 30 min and 1 hr of incubation (p less than or equal to 0.05). The data suggest that exercise during pregnancy induces adaptations in myocardial cell cultures from the offspring such that 45Ca content levels are elevated which may provide protection against ethanol toxicity.

Adaptation, Physiological↗
PubMed1985

Effect of swimming on protein degradation: 3-methylhistidine and creatinine excretion.

The effect of 5-km noncompetitive swimming (moderate exercise) and 2-km competitive speed swimming (intensive exercise) on protein breakdown was studied in a group of young male volunteers (16-20 years old) who followed a 3-MH-free diet throughout the study. Urinary 3-MH and creatinine were determined over a period of 24 and 48 hr as an index of protein degradation. Basal 3-MH levels in the two groups of swimmers were 2.85 and 3.07 mumole X kg-1 X day-1. Mean rates of 3-MH excretion were, respectively, 1.54 and 1.94 mumole X kg-1 X day-1 for the 48 hr after moderate exercise and the 24 hr after intensive exercise. The decrease in 3-MH urinary excretion was still evident when calculated as the urinary 3-MH-to-creatinine ratio.

Adolescent↗