Effects of exercise on several adrenergic system parameters.
Rats were exposed to acute (1 day) or chronic (3 or 7 days) swimming exercise 1 or 2 hours daily. Chronic swimming exercise produced a shift to the right in the (-)-noradrenaline dose-response curve on isolated atria and a lower pD2 when it was compared with the control value. This indicates a decrease in the cardiac-adrenergic sensitivity to the adrenergic neurotransmitter. The ventricular endogenous levels of noradrenaline were kept unchanged in the acutely and chronically exercised rats. The hydroxylation of tyrosine was augmented after acute swimming exercise in intact adrenal gland, and this could be related to the earlier regulatory mechanisms in the synthesis of the neurotransmitter. The increase observed in the hydroxylation of tyrosine in intact adrenal gland after chronic swimming exercise has been proposed to be related to an increase in the synthesis of the enzyme, since a similar elevation in the tyrosine hydroxylase activity was observed in tissue homogenates. On the other hand, while no activation of the enzyme was observed in atria after acute exercise, the chronic treatment only produced a clear increase in the homogenate tyrosine hydroxylase activity but not in the hydroxylation of tyrosine in intact atria. The monoamine oxidase activity was decreased in adrenal gland after acute swimming.
D000818:Animals; D004305:Dose-Response Relationship, Drug; D005260:Female; D006339:Heart Rate; D008995:Monoamine Oxidase / Q000378:metabolism*; D009638:Norepinephrine / Q000378:metabolism*; D005082:Physical Exertion; D051381:Rats; D013550:Swimming; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism*
D014446:Tyrosine 3-Monooxygenase; D008995:Monoamine Oxidase; D009638:Norepinephrine