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Results for “Altitude adaptation”

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At least 91 records · Page 5Linked to original sources
PubMed1979

Influence of adaptation to altitude hypoxia on the behavior of rats in a conflict situation.

Adaptation to altitude hypoxia under conditions of conflict between thirst and defensive motivation was studied. The subjects adapted to altitude hypoxia made three times more attempts to drink from a water bowl despite receiving an intense shock. Adaptation to altitude hypoxia increased the stability of an initiated drinking reaction over intense shock. In adapted animals that began to drink, the drinking response changed to defensive behavior with twice the shock intensity as in control animals. In the absence of conflict, there was no difference in the satisfaction of the thirst and the defensive motivation in animals adapted to hypoxia and in controls. Hence, the effect of adaptation to hypoxia consists in making the animals more capable of inhibiting the responses to defensive motivation under conditions where it is necessary to satisfy another vital motivation.

Adaptation, Physiological↗
PubMed1977

[Adrenergic regulation and adrenoreactivity of the rat heart during adaptation to altitude hypoxia].

Male albino rats were adapted to 6 km "altitude" in barocamber. Responses of their hearts in open chest and on artificial respiration to noradrenaline and propranolol were studied. Values of the heart contractory function were by 32-140% higher in experimental animals than in control those. This excess could be eliminated by propranolol which shows it to be due to exaggerated effect of the adrenergic regulatory link. Adrenaline raises the heart function almost up to the maximal limit in adapted animals. This is followed by an increased rate of disappearance of the noradrenaline inotropic effect.

Adaptation, Physiological↗
PubMed1980

[Effect of adaptation to altitude hypoxia on the nonspecific immunity indices, production of hemagglutinins and development of adjuvant arthritis in rats].

It was established in rat experiments that adaptation to altitude hypoxia leads to the enhancement of immune response to sheep red blood cells and to an increase in the serum lysozyme level. Adaptation to altitude hypoxia also suppresses adjuvant arthritis and prevents arthritis-induced inhibition of antibody production.

Acclimatization↗
PubMed2001

Muscle adaptation to altitude: tissue capillarity and capacity for aerobic metabolism.

Prolonged exposure to high altitude leads to reduced muscle mass and performance. The fall in muscle mass follows a reduction in fiber size, which at first was believed to be accompanied by increased fiber capillarization and aerobic enzymes. Subsequent studies showed that hypoxia alone does not alter capillary number and geometry in skeletal muscles of mammals at altitude. It was also found that alterations in fiber size and aerobic enzymes depend on a number of additional factors, including animal activity and the level of hypoxia (e.g., moderate vs. extreme altitude). With training at altitude, fiber capillary number and aerobic enzymes are increased, indicating that muscle potential for plasticity is conserved in hypoxia. Recent studies have also shown that capillary number and geometry are altered in muscles of several species of birds native or exposed to higher altitude; that is, that capillary growth can occur in skeletal muscle in response to chronic exposure to high altitude. In this mini review, we summarize these data and current knowledge on muscle capillary to fiber structural relationships and their implications for muscle aerobic function at altitude.

Adaptation, Physiological↗
PubMed1976

[Effect of adaptation to altitude hypoxia in early ontogeny on the indices of higher nervous activity].

Newborn male and female Wistar rats were adapted to hypoxia in a pressure chamber. Adaptation was started from the "altitude" of 1000 m, 1 hour daily, and then the time and the intensity of hypoxic actions were gradually increased: beginning from the 17th day the animals were subjected to adaptation to the "altitude" of 5000 m, for 5 hours, 5 days a week. The defence conditioned reflex of active avoidance was provoked in the animals after 2-month adaptation. A tendency to a more rapid elaboration of the reflex and a markedly enhanced degree of its retention in comparison with control was revealed in the adapted males. No significant changes in the elaboration and rentention of the reflex were found in the female animals adapted to hypoxia under analogous conditions.

Adaptation, Physiological↗
PubMed1978

Human llamas: adaptation to altitude in subjects with high hemoglobin oxygen affinity.

To assess the adaptive value of the right-shift of the oxyhemoglobin dissociation curve (decreased affinity for oxygen) observed in humans upon altitude exposure, the short-term physiologic responses to altitude-induced hypoxia were evaluated in two subjects with a high oxygen affinity hemoglobin (Hb Andrew-Minneapolis) and in two of their normal siblings. In striking contrast to normal subjects, at moderately high altitude (3,100 m) the high affinity subjects manifested: (a) lesser increments in resting heart rate; (b) minimal increases in plasma and urinary erythropoietin; (c) no decrement in maximal oxygen consumption; and (d) no thrombocytopenia. There was no difference between subject pairs in 2,3-diphosphoglycerate response to altitude exposure. These results tend to contradict the belief that a decrease in hemoglobin oxygen affinity is of adaptive value to humans at moderate altitudes. Rather, they support the hypothesis that, despite disadvantages at low altitude, a left-shifted oxyhemoglobin dissociation curve may confer a degree of preadaptation to altitude.

Adaptation, Physiological↗
PubMed1977

[Mechanism of the prophylactic effect of adaptation to altitude hypoxia on the development of hypertension].

It was shown in experiments on 200 albino rats that prolonged adaptation to the periodical effect of hypoxia in an altitude chamber always resulted in partial atrophy of the adrenal glomerular zone and decrease in the synthesis of mineralocorticoids in the adrenals and in their concentration in blood. At the same time, the size of the supraoptic hypothalamic nuclei and their cytogically determined activity diminished. These structurally fixed adaptational changes in the hormonal control caused a stable decrease in the reseves of sodium and water in the organism of the adapted animals. This complex of shifts is contrary to the changes developing in all forms of experimental hypertension and in hypertensive disease in humans. The idea is discussed that inhibition of mineralocorticoid and ACTH secretion and the stable decrease in the sodium and water reserves in the organism during adaptation play the principal role in the mechanism of the preventive effect of adaption to altitude hypoxia in hypertension.

Adaptation, Physiological↗