title: Blockade of Na+ channels in pancreatic α-cells has antidiabetic effects.
abstract: Pancreatic α-cells express voltage-gated Na(+) channels (NaChs), which support the generation of electrical activity leading to an increase in intracellular calcium, and cause exocytosis of glucagon. Ranolazine, a NaCh blocker, is approved for treatment of angina. In addition to its antianginal effects, ranolazine has been shown to reduce HbA1c levels in patients with type 2 diabetes mellitus and coronary artery disease; however, the mechanism behind its antidiabetic effect has been unclear. We tested the hypothesis that ranolazine exerts its antidiabetic effects by inhibiting glucagon release via blockade of NaChs in the pancreatic α-cells. Our data show that ranolazine, via blockade of NaChs in pancreatic α-cells, inhibits their electrical activity and reduces glucagon release. We found that glucagon release in human pancreatic islets is mediated by the Nav1.3 isoform. In animal models of diabetes, ranolazine and a more selective NaCh blocker (GS-458967) lowered postprandial and basal glucagon levels, which were associated with a reduction in hyperglycemia, confirming that glucose-lowering effects of ranolazine are due to the blockade of NaChs. This mechanism of action is unique in that no other approved antidiabetic drugs act via this mechanism, and raises the prospect that selective Nav1.3 blockers may constitute a novel approach for the treatment of diabetes.
authors.affiliation: Department of Biology, Cardiovascular Therapeutic Area, Gilead Sciences, Inc., Fremont, CA arvinder.dhalla@gilead.com.
authors.forename: Arvinder K
authors.initials: AK
authors.lastname: Dhalla
authors.affiliation: Department of Biology, Cardiovascular Therapeutic Area, Gilead Sciences, Inc., Fremont, CA.
authors.forename: Ming
authors.initials: M
authors.lastname: Yang
authors.affiliation: Department of Biology, Cardiovascular Therapeutic Area, Gilead Sciences, Inc., Fremont, CA.
authors.forename: Yun
authors.initials: Y
authors.lastname: Ning
authors.affiliation: Department of Biology, Cardiovascular Therapeutic Area, Gilead Sciences, Inc., Fremont, CA.
authors.forename: Kristopher M
authors.initials: KM
authors.lastname: Kahlig
authors.affiliation: Department of Biology, Cardiovascular Therapeutic Area, Gilead Sciences, Inc., Fremont, CA.
authors.forename: Michael
authors.initials: M
authors.lastname: Krause
authors.affiliation: Department of Biology, Cardiovascular Therapeutic Area, Gilead Sciences, Inc., Fremont, CA.
authors.forename: Sridharan
authors.initials: S
authors.lastname: Rajamani
authors.affiliation: Department of Biology, Cardiovascular Therapeutic Area, Gilead Sciences, Inc., Fremont, CA.
authors.forename: Luiz
authors.initials: L
authors.lastname: Belardinelli
mesh_terms: D000083:Acetanilides / Q000494:pharmacology / Q000627:therapeutic use*; D000818:Animals; D003921:Diabetes Mellitus, Experimental / Q000188:drug therapy* / Q000378:metabolism; D005089:Exocytosis / Q000187:drug effects; D005934:Glucagon / Q000378:metabolism; D050416:Glucagon-Secreting Cells / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D007004:Hypoglycemic Agents / Q000494:pharmacology / Q000627:therapeutic use*; D007515:Islets of Langerhans / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D062552:NAV1.3 Voltage-Gated Sodium Channel / Q000378:metabolism*; D010879:Piperazines / Q000494:pharmacology / Q000627:therapeutic use*; D000069458:Ranolazine; D051381:Rats; D017207:Rats, Sprague-Dawley; D026941:Sodium Channel Blockers / Q000494:pharmacology*
chemical_list: D000083:Acetanilides; D007004:Hypoglycemic Agents; D062552:NAV1.3 Voltage-Gated Sodium Channel; D010879:Piperazines; D026941:Sodium Channel Blockers; D005934:Glucagon; D000069458:Ranolazine