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PubMed1989

[Effects of amygdaloid stimulation on efferent activities of the vesical branch of the pelvic nerve and the urethral branch of the pudendal nerve in dogs].

Experiments were performed to elucidate the effects of amygdaloid stimulation on the urinary bladder and external sphincter in 38 dogs anesthetized with ketamine and alpha-chloralose and immobilized with gallamine. The hypogastric nerves were severed in all dogs. The bladder was filled with Tyrode's solution under intravesical pressure maintained within a range of 15-20 cmH2O. The outflows of the pelvic vesical branch (PV) and pudendal urethral branch (PU) were recorded simultaneously with isotonic vesical contractions. Stimulation was applied through a unipolar platinum electrode (50 microns, in diameter) inserted into the amygdala from the ventral surface of the exposed pyriform lobe. When bladder contraction was elicited by amygdaloid stimulation, PV excitation and PU inhibition occurred simultaneously, but when the bladder was relaxed, PV inhibition and PU excitation appeared concomitantly. The PV excitation (bladder contraction) was elicited from medial parts of the intermediate and medial principal nuclei and parts of the cortical and pericortical nuclei. Inhibition of PV (bladder relaxation) was induced from the medial nucleus, the central nucleus, lateral parts of the medial principal nucleus and parts of the pericortical nucleus. Electrical stimulation was applied to the excitatory points at varied frequencies (2-100 Hz). PV excitation and bladder contraction were produced at 10, 20 and 50 Hz, but not at 2 Hz. At 5 and 100 Hz, the effects varied with the stimulating points. At the inhibitory points, PV inhibition and bladder relaxation were elicited at 10, 20 and 50 Hz, but not at 2 Hz. (ABSTRACT TRUNCATED AT 250 WORDS)

Amygdala↗
PubMed1991

[Effects of olfactory tubercle stimulation on efferent activities in the vesical branch of the pelvic nerve and in the urethral branch of the pudendal nerve in dogs].

Experiments were performed to elucidate the effects of stimulation of the olfactory tubercle on the urinary bladder and external urethral sphincter in 31 dogs anesthetized with ketamine and alpha-chloralose and immobilized with gallamine. The hypogastric nerve was severed in all dogs, and the bladder was filled with Tyrode's solution under constant pressure (15-20 cmH2O). The outflows of the pelvic vesical branch (PV) and the pudendal urethral branch (PU) and isotonic vesical contractions were recorded simultaneously. Stimulation (5-100 Hz, 3 msec, 0.2 mA) was applied through a unipolar platinum electrode (50 microns, in diameter) inserted into the olfactory tubercle from the ventral surface. Olfactory tubercle stimulation elicited PV excitation (bladder contraction) and concomitant PU inhibition (urethral relaxation), but no reverse effect. Electrical stimulation was applied to the excitatory points at varied frequencies (5-100 Hz). PV excitation and bladder contraction were produced at 10, 20, 50 and 100 Hz, but not at 5 Hz. In another group, the vesicopressor pathway from the tubercle was investigated by partial sectioning of the brain stem in dogs from which the left fore- and mid-brain had been previously removed. The vesicopressor response induced by tubercle stimulations was not abolished by sectioning of the medial preoptic area, medial hypothalamus or periaqueductal grey, but was abolished by sectioning of the lateral preoptic area, lateral hypothalamus or ventral mesencephalic tegmentum, respectively. At the rostral pontine level, the response was abolished by partial sectioning of the lateral part of the pontine reticular formation ipsilateral to the stimulation.

Animals↗
PubMed1999

Short-arm (1.9 m) +2.2 Gz acceleration: isotonic exercise load-O2 uptake relationship.

BACKGROUND: The deconditioning syndrome from prolonged bed rest (BR) or spaceflight includes decreases in maximal oxygen uptake (VO2max), muscular strength and endurance, and orthostatic tolerance. In addition to exercise training as a countermeasure, +Gz (head-to-foot) acceleration training on 1.8-2.0 m centrifuges can ameliorate the orthostatic and acceleration intolerances induced by BR and immersion deconditioning. PURPOSE: Study A was designed to determine the magnitude and linearity of the heart rate (HR) response to human-powered centrifuge (HPC) acceleration with supine exercise vs. passive (no exercise) acceleration. Study B was designed to test the hypothesis that moderate +Gz acceleration during exercise will not affect the respective normal linear relationships between exercise load and VO2max, HR, and pulmonary ventilation (VEBTPS). Study C: To determine if these physiological responses from the HPC runs (exercise + on-platform acceleration) will be similar to those from the exercise + off-platform acceleration responses. METHODS: In Study A, four men and two women (31-62 yr) were tested supine during exercise + acceleration and only passive acceleration at 100% [maximal acceleration (rpm) = Amax] and at 25%, 50%, and 75% of Amax. In Studies B and C, seven men (33+/-SD 7 yr) exercised supine on the HPC that has two opposing on-platform exercise stations. A VO2max test and submaximal exercise runs occurred under three conditions: (EX) exercise (on-platform cycle at 42%, 61%, 89% and 100% VO2max) with no acceleration; (HPC) exercise + acceleration via the chain drive at 25%,50%, and 100% Gzmax (35%, 72% and 100% VO2max); and (EXA) exercise (on-platform cycle at 42%, 61%, 89%, and 100% VO2max) with acceleration performed via the off-platform cycle operator at +2.2+/-0.2 Gz [50% of max (rpm) G]. RESULTS: Study A: Mean (+/-SE) Amax was 43.7+/-1.3 rpm (mean = +3.9+/-0.2, range = 3.3 to 4.9 Gz). Amax run time for exercise +acceleration was 50-70 s, and 40-70 s for passive acceleration. Regression of X HR on Gz levels indicated explained variances (r2) of 0.88 (exercise) and 0.96 (passive). The mean exercise HR of 107+/-4 (25%), to 189+/-13 (100%) bpm were 43-50 bpm higher (p < 0.05) than comparable passive HR of 64+/-2 to 142+/-22 bpm, respectively. Study B: There were no significant differences in VO2, HR or VEBTPS at the submaximal or maximal levels between the EX and EXA runs. Mean (+/-SE) VO2max for EX was 2.86+/-0.12 L x min(-1)(35+/-2 ml x min(-1) x kg(-1)) and for EXA was 3.09+/-0.14 L x min(-1) (37+/-2 ml-min(-1) x kg(-1)). Study C: There were no significant differences in the essentially linear relationships between the HPC and EXA data for VO2 (p = 0.45), HR (p < 0.08), VEBTPS (p = 0.28), or the RE (p = 0.15) when the exercise load was % VO2max. CONCLUSION: Addition of + 2.2 Gz acceleration does not significantly influence levels of oxygen uptake, heart rate, or pulmonary ventilation during submaximal or maximal cycle ergometer leg exercise on a short-arm centrifuge.

Acceleration↗
PubMed2000

Study of the explosive strength of the rectus femoris muscle using electromyography.

The rectus femoris muscle was electromyographically studied in eleven individuals of the masculine sex. The objective was to study the action potential and the explosive strength of this particular muscle in the movement utilized to kick the field soccer ball and in other exercises of the orthostatic position. The following movements were analyzed: flexibility of the hip with the knee bent, flexibility and extension of the knee (completely crouched), flexibility of the hip with the knee extended, movement of the kick without contact with the ball and movement of the kick in contact with the ball. The results were: the rectus femoris muscle showed much stronger action potential in flexing the hip with the knee flexed more than 90 degrees; with the knee extended 60 to 90 degrees; in the movement extending the knee from a complete crouch and at the moment of the kick in contact with the ball. The action potential was strong in the movements flexing the knee (crouch) and in the initial movement of the kick.

Action Potentials↗
PubMed1999

Relatively shorter but intensive isotonic exercise in legs prevented the decrease in maximal aerobic power after 20 days of head down tilt bed rest in man.

As a countermeasures for the decrease in maximal oxygen uptake (VO2max) during prolong simulated weightlessness, it has been suggested that intensive isotonic legs exercise was useful. The reason is possibly that a dynamic and intensive resistance exercise training makes to maintain not only the volume of exercising muscles but also cardiac output. For the reason, it has been studied the effects of 3 different exercise training on VO2max during simulated weightlessness.

Bed Rest↗
PubMed2001

Viscoelastic properties and flexibility of the human muscle-tendon unit in benign joint hypermobility syndrome.

OBJECTIVE: To examine the passive energy absorption of the hamstring muscle-tendon unit in 9 women with benign joint hypermobility syndrome (BJHS) and 9 age and sex matched controls. METHODS: Resistance to stretch was measured as knee flexion moment (N.m) with an isokinetic dynamometer during passive knee extension. The angle that induced a stretch sensation without pain was the maximal stretch angle. Force, angle, angular velocity (0.09 rad/s), and electromyograph were simultaneously and continuously recorded during the stretch. Hamstring cross sectional area was obtained with magnetic resonance imaging. RESULTS: Forearm skin extensibility was greater for BJHS (3.6+/-0.5 cm) than for controls (1.3+/-0.2 cm) (p < 0.01). Similarly, the Beighton score was greater for BJHS (6.6+/-0.8) than for controls (0.4+/-0.2) (p < 0.001). Maximal stretch angle was greater for BJHS (delta1.35+/-0.07 rad) compared to controls (delta0.98+/-0.05 rad) (p < 0.001), and the corresponding peak moment was also greater for BJHS (1.3+/-0.4 Nm/cm2) than for controls (0.6+/-0.1 Nm/cm2) (p < 0.01). For a given mutual angle the passive energy absorption was the same for both groups, but at the maximal stretch angle the total area-normalized energy was greater for BJHS (0.36+/-0.04 J/cm2) than for controls (0.18+/-0.28 J/cm2) (p < 0.001). CONCLUSION: The lack of difference in passive energy absorption for a given mutual stretch angle suggests that passive properties of the muscle-tendon unit of BJHS are similar to those of controls. However, the greater maximal stretch angle and corresponding peak moment in BJHS suggests a greater subjective tolerance to passive stretch. That is, increased flexibility in BJHS is not a function of altered passive properties of the muscle-tendon complex. It remains unknown if the enhanced tolerance to passive tension plays a role in the development of musculoskeletal ailment.

Adult↗
PubMed1992

A simple and rapid in vitro test system for the screening of histamine H3 ligands.

A simple and rapid functional test system for the screening of histamine H3 ligands is described. It is based on the inhibitory effect of histamine H3 agonists on electrically-evoked contractile response of isolated guinea pig intestine. Whole jejunum segments are continuously stimulated maximally (15 V) by electrical pulses with a frequency of 0.1 Hz and a duration of 0.5 msec. The resulting twitches are recorded isotonically (1.0 g) and can be completely abolished by atropine (0.1 mcM).

Acetylcholine↗
PubMedDate not supplied

Vascular action of natural vasopressin-like peptides in isolated rat tail artery.

The literature data regarding the vasoconstriction potency of natural vasopressin-like peptides are contradictory. The cumulative concentration-response curve for arginine-vasopressin (AVP), lysine-vasopressin (LVP), arginine-vasotocin (AVT), lysine-vasotocin (LVT) and phenypressin (PHP) on the isolated rat tail artery was determined. The potency rank of these peptides on the vascular smooth muscle of the rat tail artery was the following: AVP greater than LVP greater than AVT = LVT greater than PHP. The results are discussed in comparison to the data in the literature.

Animals↗
PubMed2004

[Molecular probes].

Explore the source record for details and available documents.

Electron Transport↗
PubMedDate not supplied

Effects of a task failure exercise on the peroneus longus and brevis during perturbed gait.

Ankle inversion injuries represent the most common trauma sustained by athletes. Muscle fatigue from activity may contribute to a delay in the response of the ankle proprioceptors and dynamic restraints during unexpected inversion. The purpose of this investigation was to determine changes in peroneal average EMG, peak EMG, and time to peak EMG following a task failure exercise. Thirty-two subjects (age 20+/-1.43 yrs; 21 male, 11 female) with no lower extremity injuries reported for data collection. Data were collected from each subject's dominant leg using surface electromyography (EMG). EMG electrodes were applied over the peroneus longus (PL) and brevis (PB) using a standard protocol Subjects walked at a fixed pace on a 6.1 m runway with one section that could be unexpectedly dropped into 30 degrees of inversion upon foot contact. Trials with perturbed and unperturbed gait were randomized to reduce prediction of the unexpected inversion. Once 3 trials of perturbed gait were recorded, subjects completed an isotonic activity that isolated the peroneals. The task was completed to failure. Immediately following the task failure exercise, subjects walked on the perturbation runway once again until 3 trials of perturbed gait were recorded. Analysis revealed no significant differences with regard to average muscle activity between pre- and post-task failure exercise for the PL (F1,31 = 0.133; p = 0.718) or for the PB (F1,31 = 0.795; p = 0.380). There was also no significant difference in peak muscle activity pre- to post-task failure for the PL (F1,31 = 0.032; p = 0.859) or the PB (F1,31 = 0.156; p = 0.695). Finally, there was no significant difference in time-to-peak muscle activity pre- to post-task failure for the PL (F1,31 = 0.830; p = 0.369) or the PB (F1,31 = 1.037; p = 0.316). We concluded that the task failure exercise did not contribute to changes in peroneal activity during perturbed gait. These results indicate that peroneal fatigue does not play a significant role in the incidence of inversion ankle sprains.

Adult↗
PubMed2005

Can progressive resistance training reverse cachexia in patients with rheumatoid arthritis? Results of a pilot study.

OBJECTIVE: . A Phase II trial was performed as a preliminary test of the efficacy and safety of progressive resistance training (PRT) as adjunct treatment for rheumatoid cachexia. METHODS: Ten mildly disabled patients with well-controlled rheumatoid arthritis (RA) trained, on average, 2.5 times per week for 12 weeks. Ten age and sex matched RA patients with similar disease characteristics were non-randomly assigned to a control group. Body composition, physical function, and disease activity were assessed pre and post intervention period. RESULTS: Between group comparisons at followup by ANCOVA using baseline scores as covariate showed significant increases in fat-free mass (+1253 g, p = 0.004), total body protein (+1063 g, p = 0.044), and arm (+280 g, p = 0.005) and leg (+839 g, p = 0.001) lean mass (a proxy measure of total body skeletal muscle mass) in response to PRT with no exacerbation of disease activity. There was also a trend for loss of fat mass in the trunk (-752 g, p = 0.084) and a significant reduction in percent body fat (-1.1%, p = 0.047). Changes in body composition were associated with improvements in various measures of physical function. CONCLUSION: Intense PRT with adequate volume seems to be an effective and safe intervention for stimulating muscle growth in patients with RA. Pending confirmation of these results in a larger randomized controlled trial that includes patients with more active and severe disease, a similar PRT program should be included in the management of RA as adjunct treatment for cachexia.

Arthritis, Rheumatoid↗
PubMed2006

Validity and reliability of measurements of elbow flexion strength obtained from older adults using elastic bands.

PURPOSE: This study determined the validity and reliability of measurements of elbow flexion strength obtained from older adults using elastic bands. METHODS: Forty-eight community-dwelling older adults with documented functional limitations completed 3 assessments of elbow flexion strength: a 30-second test using elastic bands to generate resistance, a similar test using dumbbells, and a test using an isokinetic dynamometer. One week later, subjects repeated the 30-second elbow flexion test using elastic bands. RESULTS: The 30-second elbow flexion test using elastic bands was significantly correlated with both the 30-second elbow flexion test using dumbbells (r = 0.62, P < 0.01 ) and the maximum isokinetic torque of the elbow flexors (r = 0.46, P < 0.01 ). The 30-second elbow flexion test using elastic bands demonstrated a high degree of test-retest reliability (intraclass correlation coefficient = 0.89, P < 0.01 ). CONCLUSION: The validity and reliability elbow flexion strength measured with elastic bands supports its use among functionally limited elders.

Aged↗
PubMedDate not supplied

[The characteristics of the action of GABA-ergic agents on the brain microcirculation during motor activity and hypodynamia].

Changes in the microcirculatory bed of the rat brain cortex during motor activity and hypodynamia under the action of piracetam, GABA and bicuculline were studied. The possibility of the development of compensatory processes due to the cerebral blood flow increase under the influence of GABA agonists at a disturbance of the cerebral hemodynamics in combination with increased locomotor activity and also due to the improvement of the microcirculation at early stages of hypodynamia induced by administration of GABA agonists opens up new perspectives in the use of GABA-positive drugs.

Animals↗
PubMed2006

Implications for using H-max/M-max ratio in H-reflex parameters for elderly subjects compared with young subjects.

The H-max/M-max ratio has long been used to understand motoneuron excitability induced by the Ia fibers. However, we contend that when comparing young and elderly subjects, this measurement can be controversial. We compared the modulation of the soleus H-max and M-max at five different muscle lengths between elderly and young subjects. The young subjects demonstrated a significant modulation of both H-max and M-max between dorsiflexion (DF) and plantarflexion (PF) positions. In contrast, the elderly subjects demonstrated no difference in H-max and M-max between DF and PF positions. However, it was more interesting to note that those elderly subjects who had similar H-max/M-max ratios to the young subjects at 0 deg showed identical modulation of H-max and M-max to that of the young In this paper, we discuss that H-reflex comparisons between young and elderly subjects may be confounded by the initial H-max/M-max ratio. This finding has implications for both the statistical analysis of this data as well as the theoretical interpretation of H-reflex measurements.

Adult↗
PubMedDate not supplied

[Exercise and nutrition].

Aerobic exercise, particularly that of long duration and/or intensity, requires careful consideration of dietary aspects. The most important energy source are carbohydrates, and they must provide the majority of daily calories. Adequate hydration before and during exercise is the key to avoid hyperthermia. The consumption of glucose solutions during exercise is debatable, and electrolyte preparations are of no proven value, except in extreme circumstances.

Dietary Carbohydrates↗