Circulating catecholamines require concentrations higher than resting levels to induce significant vasomotor and lipolytic responses in canine subcutaneous adipose tissue.
Abstract The aim of the present study was to evaluate the vascular and lipolytic effects of circulating catecholamines in canine subcutaneous adipose tissue. Adrenaline, noradrenaline or isoprena‐line were added at constant rate to the arterial blood supplying subcutaneous adipose tissue in situ . Concentrations of added catecholamine ranged from 10 ‐ ‐ 3 to 10 ‐ ‐ 1 μg/ml plasma. Blooc/ flow and the net release of glycerol were determined. Adrenaline and noradrenaline were both vasoconstrictor at concentrations above 1 × 10 ‐ ‐ 2 μg/ml plasma but differed in the character of the response. Occasionally vasodilatation was observed during infusion of both noradrenaline and adrenaline. Isoprenaline caused vasodilatation at 1 × 10 ‐ ‐ 2 μg/ml. Glycerol output was enhanced concomitantly with the vascular responses. The concentration of added noradrenaline (5 × 10 ‐ ‐ 2 μg/ml) required to elicit a significant increase in the net release of glycerol exceeded plasma levels reported to be present in resting dogs. It appeared that blood‐borne catecholamines were not as effective for lipolysis as activity in sympathetic nerves to subcutaneous adipose tissue. However, during bleeding or other extreme forms of stress the plasma catecholamine levels may be high enough to induce vasomotor as well as lipolytic responses in subcutaneous adipose tissue.
Ballard et al. (Mon,) studied this question.