Interpretation Of Antilipolytic Effect Of Tetracycline - Inhibition Of Adenylate Cyclase In-Vitro

In order to observe whether or not the lipolytic inhibitory effect due to the injection of tetracycline to rats could be related to the decrease of enzymic reactivity in the membrane, adenylate cyclase activities were determined in adipose cell ghosts. Basal, noradrenaline and glucagon-stimulated activities were significantly depressed by added tetracycline (in vitro experiments). It appeared that tetracycline could influence both V (inhibition of catalytic subunit) and the apparent affinity for hormones, as indicated on dose-response curves. Fluoride-stimulated adenylate cyclase activity was also affected, with no change in Km. Phosphodiesterase activity was identical whatever the concentration of added tetracycline. The adenylate cyclase inhibition by added tetracycline was not related to any chelation effect on Mg2+ of this anionic-antibiotic compound.