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  • Erythropoiesis  (1)
  • Magnocellular and parvocellular neurons  (1)
  • 1
    ISSN: 1439-6327
    Keywords: Altitude ; Hypobaric chamber ; Physical training ; Aerobic metabolism ; Erythropoiesis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The effects of training in a hypobaric chamber on aerobic metabolism were studied in five high performance triathletes. During 3 weeks, the subjects modified their usual training schedule (approximately 30 h a week), replacing three sessions of bicycling exercise by three sessions on a cycle ergometer in a hypobaric chamber simulating an altitude of 4,000 m (462 mm Hg). Prior to and after training in the hypobaric chamber the triathletes performed maximal and submaximal exercise in normoxia and hypoxia (462 mm Hg). Respiratory and cardiac parameters were recorded during exercise. Lactacidaemia was measured during maximal exercise. Blood samples were drawn once a week to monitor blood cell parameters and erythropoetin concentrations. Training in the hypobaric chamber had no effect on erythropoiesis, the concentrations of erythropoetin always remaining unchanged, and no effect on the maximal oxygen uptake ( $$\dot V$$ O2max) and maximal aerobic capacity measured in normoxia or hypoxia. Submaximal performance increased by 34% during a submaximal exhausting exercise performed at a simulated altitude of 2,000 m. During a submaximal nonexhausting test, ventilation values tended to decrease for similar exercise intensities after training in hypoxia. The changes in these parameters and the improved performance found for submaximal exercise may have been the result of changes taking place in muscle tissue or the result of training the respiratory muscles.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0878
    Keywords: Immunocytochemistry ; Post-natal development ; Neurohypophysial peptides ; Magnocellular and parvocellular neurons
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Immunocytochemical localization of vasopressin (VP), oxytocin (OXY) and neurophysins I and II (NI and NII) in the hypothalamus of growing rats revealed several new features. Hormones and neurophysins were present in magnocellular neurons of newborn rats: VP and NII in a first neuronal population, OXY and NI in a second neuronal population. For the first three days after birth, the ratio of detected VP to detected NII increased whereas the ratio of detected OXY to detected NI appeared constant. It was obvious that maturation of the OXY/NI magnocellular system occurred later than maturation of the VP/NII magnocellular system. During the first three weeks of development, VP/NII fibres in the median eminence were separated into two distinct groups: the hypothalamo-neurohypophysial tract in the internal part of the median eminence, and pericapillary endings heavily loaded with VP and NII in the external part of median eminence. OXY/NI fibres did not show this particular distribution. Therefore, during this post-natal period, loading of infundibular VP endings was related to the increase of ACTH synthesis demonstrated by various authors. Therefore, we suppose that simultaneous participation of VP and corticotropin-releasing hormone does not only appear during experimental and chronic stimulation of ACTH synthesis (after adrenalectomy, for example) but that it also exists during physiological stimulation of corticotropic function. At birth, parvocellular suprachiasmatic neurons were devoid of VP and NIL A slight immunological reactivity appeared in 6-to 10-day-old rats and it became equivalent to the immunological staining in the adult rat during the third post-natal week. Thus, the appearance of suprachiasmatic VP preceded the differentiation of the rhythmic activity of the pituitary adrenal axis. These chronological relationships suggest the involvement of the suprachiasmatic VP-related-peptide in the circadian periodicity of the corticotropic function.
    Type of Medium: Electronic Resource
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