2007 Fiscal Year Final Research Report Summary
Lipid mediators on the extracellular Ca^<2+>-sensing in parathyroid cells
| Project/Area Number |
17570064
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
Animal physiology/Animal behavior
|
|---|
| Research Institution | Nagasaki University |
|---|
Principal Investigator |
OKADA Yukio Nagasaki University, Sch. Biomed. Sci., Associate Professor (60136687)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
TODA Kazuo Nagasaki Univ., Sch. Biomed. Sci., Professor (80134708)
FUJIYAMA Rie Nagasaki Univ., Sch. Biomed. Sci., Assistant Professor (10274664)
ZEREDO Jorge Nagasaki Univ., Sch. Biomed. Sci., Assistant Professor (10363459)
MIYAZAKI Toshihiro Nagasaki Univ., Sch. Biomed. Sci., Assistant Professor (10174161)
HOTOKEZAKA Hitoshi Nagasaki Univ., Sch. Biomed. Sri., Senior Assistant Prof. (90199513)
|
|---|
| Project Period (FY) |
2005 – 2007
|
| Keywords | Parathyroid / Arachidonic acid / Ca^<2+> / Patch-clamp / Bullfrog / Ionic channel / Signal transduction / G protein |
|---|
| Research Abstract |
Parathyroid cells directly monitor extracellular Ca^<2+> concentration using Ca receptors(CaR). In isolated frog parathyroid cells, high extracellular Ca^<2+> concentration induces a large increase in chloride conductance. In the present study, we investigated how extracellular Ca^<2+> increases parathyroid chloride conductance while recording the whole cell current. The parathyroid cells displayed a TTX-sensitive Na^+ current in response to the depolarizing voltage steps from a holding potential of -84 mV. Extracellular Win55,212-2 greatly inhibited the voltage-gated Na+ current, suggesting that the activity can be modified by the cannabinoids. High extracellular Ca^<2+> induced an increase of the inward current at -50 mV in a dose-dependent manner. The apparent EC_<50>for Ca^<2+>was about 6 mM. When either U73122(an inhibitor of PLC), tetrahydrolipstatin(an inhibitor of DAG lipase), or methyl arachidonyl fluorophosphonate(MAFP, an inhibitor of MAG lipase)was applied extracellularly, the magnitude of extracellular Ca^<2+>-induced current decreased significantly. Internal dialysis of 2-arachidonyl glycerol(2-AG)induced a Gd^<3+>-sensitive inward current, but internal 2-AG ether did not elicit any response. Internal dialysis of arachidonic acid also induced Gd^<3+>-sensitive inward current. The results suggest that the arachidonic acid metabolite is involved in the extracellular Ca^<2+>-sensing of frog parathyroid cells.
|
