| First Author | Zhang Q | Year | 2013 |
| Journal | Cell Metab | Volume | 18 |
| Issue | 6 | Pages | 871-82 |
| PubMed ID | 24315372 | Mgi Jnum | J:206136 |
| Mgi Id | MGI:5547999 | Doi | 10.1016/j.cmet.2013.10.014 |
| Citation | Zhang Q, et al. (2013) Role of KATP channels in glucose-regulated glucagon secretion and impaired counterregulation in type 2 diabetes. Cell Metab 18(6):871-82 |
| abstractText | Glucagon, secreted by pancreatic islet alpha cells, is the principal hyperglycemic hormone. In diabetes, glucagon secretion is not suppressed at high glucose, exacerbating the consequences of insufficient insulin secretion, and is inadequate at low glucose, potentially leading to fatal hypoglycemia. The causal mechanisms remain unknown. Here we show that alpha cell KATP-channel activity is very low under hypoglycemic conditions and that hyperglycemia, via elevated intracellular ATP/ADP, leads to complete inhibition. This produces membrane depolarization and voltage-dependent inactivation of the Na(+) channels involved in action potential firing that, via reduced action potential height and Ca(2+) entry, suppresses glucagon secretion. Maneuvers that increase KATP channel activity, such as metabolic inhibition, mimic the glucagon secretory defects associated with diabetes. Low concentrations of the KATP channel blocker tolbutamide partially restore glucose-regulated glucagon secretion in islets from type 2 diabetic organ donors. These data suggest that impaired metabolic control of the KATP channels underlies the defective glucose regulation of glucagon secretion in type 2 diabetes. |
