AJP - Endocrinology and Metabolism, Vol 241, Issue 1 28-E34, Copyright © 1981 by American Physiological Society
Norepinephrine-stimulated lipolysis in acute and chronic hypoxemia
D. Baum and P. Oyer
The effects of acute and chronic hypoxemia on norepinephrine-stimulated
lipolysis were studied in dogs. Right-to-left shunts were created in
experimental dogs to render them chronically hypoxemic (PaO2 37-55 torr).
Control animals received sham operations (PaO2 greater than 70 torr).
During air ventilation, there was no significant difference in
norepinephrine-induced glycerol and free fatty acid (FFA) rises in the
control and experimental groups. In control dogs, glycerol and FFA
responses to norepinephrine were unaffected by acutely lowering oxygen
tensions (PaO2 46-48 torr) to levels found in air-breathing experimental
dogs. However, greater acute reductions in oxygen tensions (PaO2 less than
30 torr) in both control and experimental animals resulted in pronounced
glycerol and FFA falls from the elevated levels produced by norepinephrine
infusions during air ventilation. PaO2 levels less than 30 torr similarly
decreased the glycerol and FFA elevations in control animals given
phenoxybenzamine and norepinephrine. As with severe hypoxemia, propranolol
suppressed glycerol and FFA increases stimulated by norepinephrine.
Theophylline did not influence the hypoxemic-induced glycerol and FFA
falls. These observations suggest that severity was important in the
hypoxemic inhibition of norepinephrine-stimulated lipolysis; the effects of
low oxygen breathing were not ameliorated by chronic hypoxemia. A
beta-adrenergic receptor abnormality appears to contribute to this
inhibition.
