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  • 1
    Electronic Resource
    Electronic Resource
    Propranolol and the respiratory, circulatory, and ECG responses to high altitude (1981)
    Springer
    European journal of applied physiology 46 (1981), S. 105-119 
    Details
    ISSN: 1439-6327
    Keywords: Altitude ; Aerohypoxia ; Beta-receptor blockade ; Propranolol ; Respiratory and circulatory responses ; ECG changes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary The role of the sympatho-adrenal system in the acute respiratory and cardiovascular responses to high altitude was studied in 20 volunteers during ascent to 6,000 m in a low pressure chamber, once without (control) and once with beta-adrenergic blockade. Special attention was paid to the hypoxia-induced ECG changes. Propranolol lowered the level of hypoxia-induced cardiovascular reactions, whereas it had no effect on hypoxic hyperventilation and alveolar gases. At altitude, ECG changes during myocardial depolarization occurred in both the propranolol and the control groups, probably due to the direct effects of hypoxia. During the repolarization phase, propranolol led to an almost complete abolition of S-T depression and to significant reduction of T wave flattening. The minor but still significant flattening of the T wave as well as the relative (to the heart rate) lengthening of Q-T is probably due to the direct effects of hypoxia. Propranolol abolishes or diminishes the signs of cardiac hypoxia by antagonizing the effects of catecholamine release and/or by reducing myocardial oxygen consumption, thus probably increasing the ability to withstand oxygen-want at altitude.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00428864
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    The ECG changes due to altitude and to catecholamines (1984)
    Springer
    European journal of applied physiology 53 (1984), S. 35-42 
    Details
    ISSN: 1439-6327
    Keywords: Altitude ; Aerohypoxia ; Isoprenaline ; Beta-receptor blockade ; ECG changes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary In order to distinguish the effects of beta-receptor stimulation on the ECG from other factors during short-term adjustment to hypoxic aerohypoxia, the ECG of 19 volunteers were compared during moderately acute, stepwise exposure to high altitude (6,000 m) in a low pressure chamber, once with and once without beta-receptor blockade (propranolol), and after isoprenaline inhalation at ground level. The results show that beta-receptor stimulation accounts mainly for most ECG changes during altitude exposure, i.e., for the shortening of R-R interval, the lengthening of Q-T and in particular for the ST-T flattening, the latter therefore being only an indirect sign of hypoxia. After exclusion of the catecholamines, the minor but still significant ECG changes at altitude (shortening of R-R interval, increase of P wave, prolongation of P-Q, deviation of the R vector, T wave flattening in the left precordial leads) may be attributed to other, so far undefined factors, such as cardiac hypoxia, vagal withdrawal, or increase of pulmonary resistance.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00964687
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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