Summary
Experiments were designed to study changes of blood levels of norepinephrine (NE)
and epinephrine (E) and their possible role in metabolic adaptation to short-lasting
physical exercise in calves. After a resting period for 5 min (I), animals walked
on a treadmill for 10 min at a speed of 60 m/min, first horizontally for 5 min (II),
then at a slope of 6° for another 5 min (III), followed by a recovery period for 5
min (IV). Levels of NE and E increased within minutes during walking and then decreased.
Changes were closely related to respiration rate, ventilation volume, O2 -uptake, heart rate and blood lactate levels. Blood triiodothyronine and protein slightly
increased only during period III, whereas glucose, non-esterified fatty acids and
the respiration quotient increased throughout the experiment. Blood insulin levels
were decreased during walking and rapidly increased afterwards. Blood glucagon did
not change significantly. Work load affected all parameters except glucagon and triiodothyronine.
There were individually significant differences for all parameters, except for NE
and the respiration quotient. The data demonstrate rapid reactions of the Cardiorespiratory
system and of blood insulin and lactate levels on submaximal work load, normally in
close association with plasma E and NE.
Key-Words
Catecholamines
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Metabolism
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Respiration
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Heart Rate
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Exercise
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Cattle
