Effects of a xanthine derivative (BL 191) on insulin secretion in normal man

A xanthine derivative, named BL-191, was administered iv in 8 healthy volunteers alone and in association with glucose (0.33 g/kg body weight iv) or glybenclamide (1 mg iv). BL-191 was infused iv at a constant rate in a dose of 200 mg during 45 minutes. Blood glucose, free fatty acids and immunoreactive insulin were measured during one hour. It was impossible to demonstrate neither a direct effect nor an enhancement of insulin secretion during drug administration; in another experiment (treatment F) a higher dosage of BL-191 (100 mg as a priming dose + 200 mg as infusion dose) was likely ineffective. It appears that some difference in insulin response may be present in the single subject (not evident in the mean), indicating a difference in the beta-cell cAMP-system sensitivity in individuals. These negative results allow some considerations on the importance of the beta-cell cAMP-system in healthy human beings.