Arylcyanoguanidines as Activators of Kir6.2/SUR1KATP Channels and Inhibitors of Insulin Release

• Published in: Journal of medicinal chemistry 2004-06, Vol.47 (12), p.3202-3211
• Main Authors: Tagmose, Tina M, Schou, Søren C, Mogensen, John P, Nielsen, Flemming E, Arkhammar, Per O. G, Wahl, Philip, Hansen, Birgit S, Worsaae, Anne, Boonen, Harrie C. M, Antoine, Marie-Hélène, Lebrun, Philippe, Hansen, John Bondo
• Format: Article
• Language: English
• Subjects: Biological and medical sciences; General and cellular metabolism. Vitamins; Medical sciences; Pharmacology. Drug treatments
• ISSN: 0022-2623; 1520-4804
• DOI: 10.1021/jm031018y

Phenylcyanoguanidines substituted with lipophilic electron-withdrawing functional groups, e.g. N-cyano-N‘-[3,5-bis-(trifluoromethyl)phenyl]-N‘ ‘-(cyclopentyl)guanidine (10) and N-cyano-N‘-(3,5-dichlorophenyl)-N‘ ‘-(3-methylbutyl)guanidine (12) were synthesized and investigated for their ability to inhibit insulin release from beta cells, to repolarize beta cell membrane potential, and to relax precontracted rat aorta rings. Structural modifications gave compounds, which selectively inhibit insulin release from βTC6 cells (e.g. compound 10:  IC50 = 5.45 ± 1.9 μM) and which repolarize βTC3 beta cells (10: IC50 = 4.7 ± 0.5 μM) without relaxation of precontracted aorta rings (10:  IC50 > 300 μM). Inhibition of insulin release from rat islets was observed in the same concentration level as for βTC6 cells (10:  IC50 = 1.24 ± 0.1 μM, 12:  IC50 = 3.8 ± 0.4 μM). Compound 10 (10 μM) inhibits calcium outflow and insulin release from perifused rat pancreatic islets. The mechanisms of action of 10 and 12 were further investigated. The compounds depolarize mitochondrial membrane from smooth muscle cells and beta cell and stimulate glucose utilization and mitochondrial respiration in isolated liver cells. Furthermore, 10 was studied in a patch clamp experiment and was found to activate Kir6.2/SUR1 and inhibit Kir6.2/SUR2B type of KATP channels. These studies indicate that the observed effects of the compounds on beta cells result from activation of KATP channels of the cell membrane in combination with a depolarization of mitochondrial membranes. It also highlights that small structural changes can dramatically shift the efficacy of the cyanoguanidine type of selective activators of Kir6.2/SUR2 potassium channels.