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Biomedical subjects

R Flandrois

Publications and source records attributed to R Flandrois.

At least 37 records · Page 2Linked to original sources
PubMed1982

Effects of chronic lung denervation on breathing pattern and respiratory gas exchanges during hypoxia, hypercapnia and exercise.

The influence of vagal fibres from the lung on ventilatory responses to hypercapnia, hypoxia and exercise was studied in two intact dogs (C) and two chronically lung denervated dogs (C.L.D.). In intact dogs, inspiration duration did not change as tidal volume increased in response to increased chemical drives. Chronic lung denervation did not affect the hypercapnia- or hypoxia-induced elevations in V, despite significant changes in breathing pattern. During exercise, oxygen consumption was similar for C and C.L.D. animals. V for a given oxygen uptake was the same in C and C.L.D. dogs, but VT was higher in C.L.D. animals at all levels of exercise. It is concluded that vagal fibres from the lung play a role in determining the breathing pattern, but are not required for a normal ventilatory response to hypercapnia, hypoxia and exercise. Interaction between vagal sensory input and specific structures sensitive to chemical or physical stimuli is discussed.

Animals↗
PubMed1982

[Maximal oxygen uptake in French children in relation to age, sex and physical training].

1. Maximal oxygen uptake (VO2 max) was determined in 451 boys and girls ranging from 11 to 16 years and divided in two groups. Group I (n = 287) was considered as an untrained reference group. Group II (n = 174) was regularly trained. This group concerned school-children affiliated to a swimming club and trained 5 to 10 h per week. Body growth is nearly the same in the two groups until puberty but, at 15-16 years in the boys, 14-16 years in the girls, height and weight are higher in group II. 2. In group I, between 11 and 16 years, VO2 max increases by 50% in boys against only 25% in girls. For the same age, VO2 max remained smaller in girls, even before puberty although there is no difference in body growth. At 11 years, specific VO2 max averaged 47 ml . min-1 . kg-1 in boys and 40 ml . min-1 . kg-1 in girls and decreases with age only in sedentary girls down to 37 ml . min-1 . kg-1. From the results presented here it appears that maximal oxygen uptake in the average french schoolchild is similar to those of subjects from different countries with same cultural and socio-economical level. 3. In group II, VO2 max is similar in both sexes at 11-12 years old, and then up to 16 years of age increases more rapidly in boys (+100%) than in girls (+50%). Specific VO2 max ranges between 57 and 62 m. min-1 . kg-1 in boy swimmers and averages 53 ml . min-1 . kg-1 in girl swimmers. The influence of physical training on aptitude development is discussed and compared with previously published data.

Adolescent↗
PubMed1981

Carotid chemoreceptor function in ventilatory and circulatory O2 convection of exercising dogs at low and high altitude.

Awake dogs were studied before (control) and after chronic bilateral carotid denervation (denervated) at rest and running for 3 min on a treadmill at 8 km . h-1 and at various grades, in an altitude chamber operated either at 140 m or at 4000 m for 3 h. Steady-state pulmonary ventilation (Vg) and breathing pattern (VT, fR), oxygen consumption (MO2), O2 concentrations (C) and pressures (P) in the arterial (a) and mixed venous blood (v), hematocrit (Ht) and acid-base status in arterial blood, and heart frequency (fH) were measured. From these data cardiac output (Vb) and stroke volume (Vs), ventilatory and circulatory requirements (Vg/Mo2, Vb/MO2), extraction of O2 from inspired gas (EairO2) and blood (EbO2), and capacitance coefficient of blood for oxygen (beta bO2) were calculated. Ventilatory responses to transient O2-inhalation were also studied and the aortic (AP) and pulmonary (PP) blood pressures measured in resting conditions. 1. After chronic carotid denervation the hypoxic chemoreflex drive of ventilation was reduced by about half, maximal MO2 remained unaffected at 140 m, but at 4000 m decreased 50% compared to 30% in controls. 2. In all experimental conditions, Vg/MO2, PaO2 and CaO2 were less in denervated animals than in controls, and EairO2, PaCO2 and H+ ion concentration were higher. 3. At 140 m, circulatory O2 convective transport was identical in the two groups of dogs. At 4000 m, beta bO2 increased similarly in both groups, but Vb and Vb/MO2 were higher in denervated dogs than in controls, in relation with reduced CaO2-CVO2 difference which contributed to restore PVO2 towards higher values. 4. At 140 m, mean resting AP and PP were similar in both groups of dogs. At 4000 m, AP increased not significantly in controls, and decreased in denervated animals; PP increased in controls, but not in denervated dogs. It is concluded that integrity of the arterial chemoreceptor drive is essential in determining the eupneic level of ventilation and normal acid-base status of the blood in both resting and exercising dogs, at low and at high altitude, and in reducing the O2 circulatory requirement at high altitude. At 4000 m, the lack of carotid chemosensitivity is accompanied by severe hypoxemia, in association with hypercapnia and acidosis, and by increased cardiac blood flow, most presumably due to decreased peripheral resistance and increased venous return; despite these compensatory changes in circulatory O2 convective transport, denervated animals reach a maximum O2 uptake at lower work load than controls.

Adaptation, Physiological↗
PubMed1979

[Adrenergic response to intense muscular activity in sedentary subjects as a function of emotivity and training].

Seven male sedentary human subjects were studied during intense muscular work (80% of maximal oxygen uptake) performed either for 15 min or until exhaustion (mean duration: 47 +/- 2 min). Plasma catecholamines were estimated before and after the experiment by means of an original fluorimetric assay. Epinephrine or norepinephrine were individually isolated from plasma and assayed in single extracts by a highly sensitive fluorimetric method. Epinephrine and norepinephrine levels as low as 15 ng per liter were detectable by this procedure in human plasma. The adrenergic pattern was found to be greatly different from one subject to another and related to emotivity: the effect of this factor was revealed by the predominance of epinephrine in plasma at rest or under exercise (ratio NA/A less than 1). In nonemotive subjects (ratio NA/A greater than 1 at rest) plasma epinephrine and norepinephrine increased progressively during exercise. Increments after exercise were higher for norepinephrine changes; however, the fact that epinephrine concentrations correlated significantly with norepinephrine suggests a simulataneous and coordinated stimulation of adrenal glands and orthosympathetic nervous system. In emotive subjects (ratio NA/A less than 1 at rest) the apprehension of muscular work promoted a difference in catecholamine responses: norepinephrine release was not affected by subject's anxiety, while epinephrine secretion, already elevated before the test, reached a high degree of magnitude in the first minutes of muscular work, remaining nearly constant until exhaustion. Physical training of nonemotive subjects, during 2 months with two intense exercises by a week, reduced strongly norepinephrine release after exhaustive muscular work. In the same conditions, the adrenal-medullary response was not significantly modified when compared with untrained subjects. Our results suggest that the adrenergic behaviour during exercise is a function of effort intensity to be supplied; catecholamines seem to be important factors in regulating body homeostasy during muscular work in man. In addition, emotive subjects exhibit amplified adrenal-medullary response, which may be related to psychological stimuli.

Anxiety↗
PubMed1979

Metabolic adrenergic changes during submaximal exercise and in the recovery period in man.

The urinary excretion of dihydroxyphenylalanine (DOPA), catecholamines (CA) [dopamine (DA), norepinephrine (NE), and epinephrine (e)], their 3-O-methylated derivatives [3-O-methyldopamine (3-MT), normetanephrine (NMN), and metanephrine (MN)], and their deaminated metabolites [dihydroxyphenylacetic acid (DOPAC) and vanilmandelic acid (VMA)] was studied in six healthy men, at rest during short-term (15 min) or exhaustive submaximal exercise, and in the 2-h postexercise recovery period. During short-term exercise only NE and VMA excretions increased, whereas in postexercise period only DA output was enhanced. Exhaustive muscular work induced a rise in NE and E excretion during the test, and an increase in DA, NE, and NMN urinary levels during postexercise recovery, while the output of deaminated metabolites was unaltered. It is concluded that both release and synthesis of CA are stimulated by submaximal exercise, which induces, in addition to NE, a specific release of DA. A possible role of NE in lipid mobilization during recovery from exhaustive muscular work is evoked. The origin and role of released DA are also discussed.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1979

[Chemoreflexive drive of ventilation and noradrenaline stimulus in man].

O2 chemoreflex drive of ventilation was studied before and after an intravenous infusion of L-norepinephrine (9 microgram/min), inducing a plasmatic hormone concentration similar to that obtained during submaximal exercise. The ventilation increasing rapidly at the beginning of the infusion was stabilized after 30 min : the ventilation was two times the reference value. The O2 chemoreflex drive of ventilation increased during norepinephrine infusion. When man was transiently switched from hypoxia to pure O2 (O2 test) the maximal fall of ventilation was two times the reference response. This increase in the chemoreflex drive, although the physico-chemical blood state was unchanged, may be explained by a norepinephrine chemoreceptor sensitization. Such a mechanism could partly explain the increase of O2 chemoreflex drive observed during muscular exercise.

Adult↗
PubMed1978

[Effect of submaximal muscular exercise of short duration on urinary excretion of catecholamines, DOPA and their metabolites].

Thirteen human subjects were submitted to a moderate muscular work on ergometric bicycle (at intensity corresponding to 80% of maximal oxygen uptake during 10 min). No modifications were observed in the urinary amounts of the three catecholamines (A, NA, DA), DOPA, DOPAC and 3-MT. On the contrary, the excretion of metadrenaline (MN) and normetadrenaline (NMN) was slightly increased, showing a mild stimulation of adrenergic system. Our result point out the interest of urinary methoxyamines as useful index of adrenergic activity in man. For experimental and physiopathological use, the metabolic alteration induced by a short submaximal muscular work is negligible for most adrenergic compounds, except for MN and NMN, the amounts of which are slightly modified.

3,4-Dihydroxyphenylacetic Acid↗
PubMed1977

Increase in sweating sensitivity by endurance conditioning in man.

Sweating sensitivity has been evaluated at rest in 10 competitive athletes (cross-country skiers and swimmers). Three sedentary men underwent a 3-mo period of endurance training in a temperate climate, (dry bulb temperature (Tdb): 18 degrees C) and had their sweating sensitivity measured before and after the training period. Mean maximum oxygen uptake (Vo2max, ml.min(-1).kg(-1)) was: skiers: 66.5; swimmers 65.8; sedentary men, pretraining 40.9; posttraining: 48.3 (+18%). Sweat output of athletes under a given stress (passive heating) was markedly higher than that of sedentary men. Skiers exhibited a high level of heat tolerance and were better acclimatized than swimmers, although they had never experienced exposure to heat. The increase in Vo2max of sedentary men was accompanied by 1) an increase in sweating sensitivity with a decrease of body heat storage at steady state (pretraining: 5.4 kJ.kg(-1); posttraining: 3.5 kJ.kg(-1); P less than 0.05); 2) significant shift down the temperature scale with reduced rectal temperature (Tre) for sweat onset; 3) an increase of gain constants of sweating (W.m-2 degrees C(-1) (pretraining: 168; posttraining: 269; gain constant of swimmers: 222). It was suggested that endurance training in cold or temperate conditions with significant increase of Vo2max could act on the thermoregulatory function in a way similar to body heating procedures, such as work in heat, and could contribute to heat acclimatization.

Acclimatization↗
PubMed1977

[Role of aerobic metabolism in prolonged intensive exercise].

The purpose of this review is to analyze the different factors which intervene with respect to the ability to perform intense exercises of long duration. This ability implies : (a) a high level of maximal oxygen uptake (Vo 2 max) and (b) a great endurance, i.e. the capacity of maintaining for a long time a high percentage of this Vo2 max. First of all, the values Vo2 max usually recorded on normal subjects are given, as well as those of subjects specially trained for endurance events ; then the factors which condition a high level of Vo2 max are described. These factors consist on great capacity in all of the links of the oxygen transport system. These capacities appear to be essentially dependant on the genetic endowment, but their maximal size can only by attained through intensive training. Endurance can be defined as the maximal period of time during which a given percentage of the Vo2 max can be sustained. The values recorded on normal subjects and on those specially trained for endurance events are given, and then the factors conditioning a high level of endurance are studied. Endurance appears to depend on the feeding of muscular fibers with energentic substrates. Training permits the muscles to store large quantities of glycogen. It also seems to enable the organism to increase the percentage of energetic substrates made up by lipids. This latter ability in associated with an alteration of the endocrine reactions induced by exercise. Finally, endurance is accompanied by an ability of the body to store and to eliminate the heat produced during exercise.

Adolescent↗