The adenylyl cyclase inhibitor MDL-12,330A potentiates insulin secretion via blockade of voltage-dependent K(+) channels in pancreatic beta cells

• Published in: PloS one 2013, Vol.8 (10), p.e77934-e77934
• Main Authors: Li, Xiaodong, Guo, Qing, Gao, Jingying, Yang, Jing, Zhang, Wan, Liang, Yueqin, Wu, Dongmei, Liu, Yunfeng, Weng, Jianping, Li, Qingshan, Zhang, Yi
• Format: Article
• Language: English
• Subjects: Adenylyl Cyclase Inhibitors; Animals; Beta cells; Calcium (intracellular); Calcium - metabolism; Calcium imaging; Cell adhesion & migration; Cell growth; Cell survival; Cells, Cultured; Channels; Cyclic AMP; Cyclic AMP - metabolism; Diabetes; Electric potential; Electrophysiology; Endocrinology; Experiments; Fluorescence; Glucose; Glucose - metabolism; Imines - pharmacology; Inhibition; Inhibitors; Insulin; Insulin - metabolism; Insulin Secretion; Insulin-Secreting Cells - drug effects; Insulin-Secreting Cells - metabolism; Insulin-Secreting Cells - pathology; Kinases; Male; Pancreas; Pharmacology; Potassium; Potassium channels (voltage-gated); Potassium Channels, Voltage-Gated - antagonists & inhibitors; Potassium currents; Protein kinase A; Proteins; Radioimmunoassay; Rats; Rats, Sprague-Dawley; Rodents; Secretion; Signal Transduction - drug effects; Signaling
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0077934

Adenylyl cyclases (ACs) play important role in regulating pancreatic beta cell growth, survival and secretion through the synthesis of cyclic AMP (cAMP). MDL-12,330A and SQ 22536 are two AC inhibitors used widely to establish the role of ACs. The goal of this study was to examine the effects of MDL-12,330A and SQ 22536 on insulin secretion and underlying mechanisms. Patch-clamp recording, Ca(2+) fluorescence imaging and radioimmunoassay were used to measure outward K(+) currents, action potentials (APs), intracellular Ca(2+) ([Ca(2+)]i) and insulin secretion from rat pancreatic beta cells. MDL-12,330A (10 µmol/l) potentiated insulin secretion to 1.7 times of control in the presence of 8.3 mmol/l glucose, while SQ 22536 did not show significant effect on insulin secretion. MDL-12,330A prolonged AP durations (APDs) by inhibiting voltage-dependent K(+) (KV) channels, leading to an increase in [Ca(2+)]i levels. It appeared that these effects induced by MDL-12,330A did not result from AC inhibition, since SQ 22536 did not show such effects. Furthermore, inhibition of the downstream effectors of AC/cAMP signaling by PKA inhibitor H89 and Epac inhibitor ESI-09, did not affect KV channels and insulin secretion. The putative AC inhibitor MDL-12,330A enhances [Ca(2+)]i and insulin secretion via inhibition of KV channels rather than AC antagonism in beta cells, suggesting that the non-specific effects is needed to be considered for the right interpretation of the experimental results using this agent in the analyses of the role of AC in cell function.