Quinine-induced modifications of insulin release and glucose metabolism by isolated pancreatic islets

Regulation of 86Rb+ outflow from pancreatic islets. I. Reciprocal changes in the response to glucose, tetraethylammonium and quinine

Glucose (16.7 mM), tetraethylammonium (TEA; 10.0 mM) and quinine (0.1 mM) all decreased 86Rb fractional outflow rate from isolated pancreatic islets. At the concentration here used, the effect of glucose was not augmented by TEA, suggesting that glucose affected the TEA-sensitive modality of Rb extrusion. The effects of TEA and quinine were not additive. In the presence of quinine which was as potent as glucose in decreasing 86Rb efflux, an early inhibition of 86Rb outlow was still observed in response to glucose administration. However, the latter inhibition was followed by a glucose-induced secondary rise in 86Rb fractional outflow rate. It is proposed that quinine unmasks a dual or discontinuous effect of glucose upon 86Rb+ handling by the islet cells.

Chloroquine, quinine, procaine, quinidine, tricyclic antidepressants, and methylxanthines as prostaglandin agonists and antagonists

Chloroquine, quanine, procaine, quinidine, clomipramine, theophylline, and caffeine have been shown to be strong prostaglandin antagonists and weak agonists. The antagonist effect is clearly demonstrable at concentrations reached in human plasma when the drugs are used therapeutically. This suggests that prostaglandins are important in several situations in which their role has hitherto been unsuspected. New approaches to the development of prostaglandin antagonists and new uses for established drugs are indicated. In a preliminary study chloroquine has been successfully used to close patent ductus arteriosus in three infants.