Highly potent and stereoselective effects of the benzoic acid derivative AZ‐DF 265 on pancreatic β‐cells

Abstract

1 Mouse islets were used to define the characteristics and study the mechanisms of the stimulation of insulin release by compound 2 At a non-stimulatory concentration of glucose (3 mM), (-)-AZ-DF 265 reversibly inhibited 'Rb efflux from islet cells, depolarized the P-cell membrane, induced electrical activity, stimulated 45Ca efflux, and triggered insulin release. Maximum inhibition of 'Rb efflux occurred at 0.03 tiM (-)-AZ-DF 265, whereas the threshold concentration for stimulation of release was 0.1 M. Omission of extracellular Ca2" abolished all effects of the drug but the inhibition of 86Rb efflux. 3 At a stimulatory concentration of glucose (10mM), (-)-AZ-DF265 reversibly increased 86Rb efflux, potentiated electrical activity, augmented 45Ca efflux, and increased insulin release. Maximum stimulation of 'Rb efflux and insulin release was obtained with 0.03 pM (-)-AZ-DF 265. Omission of extracellular Ca2" abolished all effects of the drug. 4 The potency of (-)-AZ-DF 265 was similar to that of glibenclamide, whereas the (+ )-enantiomer was about 10 times less potent on 86Rb efflux and insulin release. 5 It is concluded that, like sulphonylureas, compound AZ-DF 265 decreases K+ permeability of the P-cell membrane and thereby causes depolarization. This activates voltage-dependent Ca channels, permits Ca2" influx and eventually stimulates insulin release. Its stereoselectivity may help to elucidate the mechanisms of K channel blockade and, hence, lead to the design of more potent and specific insulinotropic drugs.

Multiple effects and stimulation of insulin secretion by the tyrosine kinase inhibitor genistein in normal mouse islets

“…The concentration of Rb never exceeded 0.4 mM. After being washed, the islets were then placed in perifusion chambers permitting 86Rb efflux to be monitored in the effluent fractions (Garrino & Henquin, 1988).…”

Clonidine inhibits ATP‐sensitive K+channels in mouse pancreatic β‐cells

“…7.4 to 18.5 TBq mol 1). The Rb concentration never exceeded 0.4mm (Garrino & Henquin, 1988). 86Rb efflux was then monitored in a dynamic perifusion system (Henquin, 1978).…”

Effect of the hypoglycaemic drug (−)‐AZ‐DF‐265 on ATP‐sensitive potassium channels in rat pancreatic β‐cells

“…(-)-AZ-DF-265 was about 9 to 80 fold more potent in our electrophysiological assay (IC50;l.2 nM) than in the insulin secretory studies of Garrino & Henquin (1988). (ICso in their study estimated by us to be about 100 and 11 nM at 3 and 10 mM glucose, respectively).…”

“…We have shown previously that the non-sulphonylurea drug, linogliride, also leads to the inhibition of ATP-sensitive potassium channels (Ronner et al, 1991). Garrino & Henquin (1988) reported that another new drug, (-)-AZ-DF-265 (4-{N-(a-phenyl-2-piperidino-benzyl) carbamoyl] methyl) benzoic acid) stimulates insulin release and electrical activity, and also inhibits 86Rb-efflux from 86Rb-preloaded mouse islets in the presence of 3 mM glucose. Since the substituted carbamoyl group of (-)-AZ-DF-265 may be homologous with the sulphonylurea group, we tested the hypotheses that (-)-AZ-DF-265 inhibits ATP-sensitive K+-channels and displaces [3H]-glibenclamide from its binding site.…”