The rapid inhibitory effect of glucocorticoid on cytosolic free Ca2+ increment induced by high extracellular K+ and its underlying mechanism in PC12 cells.
The effect of glucocorticoid(GC) on peak cytosolic free calcium net increment (delta[Ca2+]i) induced by high-K+ was detected with MiraCal Image System. The main results were as follows: (1) Corticosterone(B) could inhibit delta[Ca2+]i in a time-dependent and concentration-dependent manner. (2) The inhibitory effect of B could be mimicked by bovine-serum albumin conjugated corticosterone (B-BSA) also in a dose-dependent manner. (3) G-protein inhibitor, either PTX or GDP beta S significantly reduced the inhibitory effect of B and B-BSA on delta[Ca2+]i (4) PMA, a stimulator for protein kinase C(PKC), could inhibit delta[Ca2+]i. (5) Although the inhibitors of PKC, chelerythrine chloride and bisindolylamide I per se had no influence on delta[Ca2+]i, but they significantly antagonized the inhibitory effect of B and B-BSA on delta[Ca2+]i. It is postulated that GC inhibit delta[Ca2+]i induced by high-K+ through a membrane mechanism and by a pathway involving G-protein and PKC.
Lou
S J
SJ
Neuroscience Institute, Second Military Medical University, Shanghai, China.
Chen
Y Z
YZ
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002417:Cattle; D003345:Corticosterone / Q000008:administration & dosage / Q000494:pharmacology*; D003600:Cytosol / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D019204:GTP-Binding Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D007424:Intracellular Fluid / Q000378:metabolism; D016716:PC12 Cells; D011188:Potassium / Q000494:pharmacology*; D011493:Protein Kinase C / Q000378:metabolism; D051381:Rats; D015290:Second Messenger Systems; D012710:Serum Albumin, Bovine; D015398:Signal Transduction; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D010566:Virulence Factors, Bordetella / Q000494:pharmacology
D010566:Virulence Factors, Bordetella; D012710:Serum Albumin, Bovine; D011493:Protein Kinase C; D019204:GTP-Binding Proteins; D013755:Tetradecanoylphorbol Acetate; D011188:Potassium; D002118:Calcium; D003345:Corticosterone