EFFECTS OF ADRENERGIC BLOCKING AGENTS ON LIPID MOBILIZATION FROM CANINE SUBCUTANEOUS ADIPOSE TISSUE AFTER SYMPATHETIC NERVE STIMULATION

¹ Department of Pharmacology, Karolinska Institute, Stockholm, Sweden

Subcutaneous adipose tissue in female dogs was isolated and perfused at a constant rate with the dogs' own blood. When the sympathetic nerve to the tissue was stimulated with frequencies of 3 to 10 cps free fatty acids and glycerol were released into the venous blood. The release was inhibited by beta adrenergic blocking agents (propranolol, pronethalol and D(-)-INPEA (D(-)-N-isopropyl-p-nitrophenylethanolamine)). Of these, propranolol and pronethalol were found to be roughly equipotent, whereas D(-)-INPEA was less active. With stimulation frequencies above 5 cps the increase of free fatty acid and glycerol release rates was delayed. This latency was considerably shortened if the alpha receptor blocking agents dihydroergotamine or phentolamine were administered before the stimulation. Moreover, the amount of free fatty acids and glycerol released per stimulus was markedly potentiated. Dihydroergotamine and phentolamine were found to have no lipomobilizing effect per se.