AJP - Heart and Circulatory Physiology, Vol 237, Issue 3 386-H391, Copyright © 1979 by American Physiological Society
Vascular responses in canine subcutaneous adipose tissue to hypothalamic stimulation
R. E. Parker, R. E. Hall, H. B. Marr and N. S. Skinner Jr
The present studies investigated vascular responses to electrical
stimulation of the posterior hypothalamus in isolated but perfused and
innervated subcutaneous adipose tissue in adult dogs. Three groups of dogs
were distinguished: in one, electrical stimulation elicited vasodilation;
in another, vasoconstriction, and in a third, neither significant
vasodilation nor vasoconstriction occurred. Histological examination
revealed that electrode placements were in the medial posterior
hypothalamus, the lateral posterior hypothalamus, and the medial septal
region, respectively. Hypothalamic stimulation failed to alter
concentrations of free fatty acids or glycerol in venous blood from
subcutaneous fat. Local beta-adrenergic block (propranolol) reversed the
vasodilation to vasoconstriction while local alpha-adrenergic block
(dihydroergotamine) abolished the vaso constrictor response. These results
suggest that selective stimulation of the posterior hypothalamus results in
neurogenic activation of both alpha- and beta-adrenergic mechanisms in
adipose tissue vasculature. beta-Adrenergic vasodilation appears to
predominate if the electrode is located medially, and alpha-adrenergic
vasoconstriction appears to predominate if the electrode is located in the
lateral posterior hypothalamus.
