Studies on 3,7-dimethyl-1-(5-oxo-hexyl)-xanthine (BL 191). II. Effect of BL 191 on lipolysis in rat epididymal adipose tissue.

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Abstract
Effects of 3,7-dimethyl-1-(5-oxo-hexyl)-xanthine (BL 191) on lipolysis in rat epididymal adipose tissue were investigated by comparison with those of theophylline. BL 191 blocked the activity of phosphodiesterase in the 105,000 x g supernatant prepared from rat epididymal adipose tissue, and the type of inhibition was noncompetitive with the Ki value of 2.1 mM. BL 191 also elicited a dose-dependent lipolytic response, as did theophylline, and the response increased 1,3-fold and about 3-fold over the basal activity at 2 mM and 5 mM, respectively. BL 191 and theophylline potentiated the lipolytic action of epinephrine and increased cyclic 3'',5''-AMP levels in adipose tissue. BL 191, in a concentration producing no effects by itself (10-4 M), together with epinephrine (10-6 M) caused a 38-fold increase in cyclic 3'',5''-AMP levels and an about 5-fold increase in lipolytic effects.