Effect of dexamethasone on voltage-gated Ca2+ channels and cytosolic Ca2+ in rat chromaffin cells.
The present study examined whether the synthetic glucocorticoid dexamethasone (DEX) can modulate voltage-gated Ca2+ channel (VGCC) activity, and as a consequence agonist-induced increases in cytosolic Ca2+, in cultured rat adrenal medullary chromaffin (RAMC) cells. Exposure to 1 microM DEX for 48 h significantly increased peak VGCC current (delta +140%). DEX treatment also significantly potentiated the increases in cytosolic Ca2+ in response to submaximal stimulatory concentrations of KCl (delta +64%) and nicotine (delta +32%). The Ca2+ channel agonist BAY K-8644 increased both VGCC current (delta +109%) and potentiated the KCl-stimulated increase in cytosolic Ca2+ (delta +35%) to a comparable extent to that seen with DEX. These data suggest that DEX treatment increases VGCC activity, and that this increased Ca2+ influx leads to potentiation of agonist-induced increases in cytosolic Ca2+ in RAMC cells.
Fuller
L
L
Department of Physiology, University of Kentucky, College of Medicine, Lexington 40536-0084, USA.
Lu
C
C
McMahon
D
D
Alaudin
E
E
Jorgensen
M
M
Rau
S
S
Sisken
J
J
Jackson
B
B
D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester / Q000494:pharmacology; D000818:Animals; D002120:Calcium Channel Agonists / Q000494:pharmacology; D015220:Calcium Channels / Q000187:drug effects*; D002478:Cells, Cultured; D019439:Chromaffin Cells / Q000187:drug effects* / Q000378:metabolism; D003600:Cytosol / Q000187:drug effects* / Q000378:metabolism; D003907:Dexamethasone / Q000494:pharmacology*; D005938:Glucocorticoids; D015640:Ion Channel Gating / Q000187:drug effects*; D008297:Male; D018408:Patch-Clamp Techniques; D051381:Rats; D017207:Rats, Sprague-Dawley
D002120:Calcium Channel Agonists; D015220:Calcium Channels; D005938:Glucocorticoids; D001498:3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester; D003907:Dexamethasone