Ceramide modulates nicotinic receptor-dependent Ca(2+) signaling in rat chromaffin cells.
Ceramide, which is an integral component of the sphingomyelin signaling pathway, can attenuate voltage-gated Ca(2+) channel (VGCC) activity in a number of cell types. The aim of the present study was to determine whether ceramide can also modulate VGCC activity, and as a consequence nicotinic receptor-dependent Ca(2+) signaling and catecholamine secretion, in rat adrenal chromaffin cells. Short-term C(6)-ceramide (CER) treatment dose-dependently inhibited nicotine (NIC)-induced peak intracellular Ca(2+) transients. Sphingomyelinase elicited similar responses, whereas the inactive ceramide analog C(2)-dihydroceramide had no effect on NIC-induced Ca(2+) transients. CER suppressed KCl- and NIC-induced Ca(2+) transients to a similar extent, suggesting that the voltage-gated Ca(2+) channel was a primary site of inhibition. In direct support of this concept, whole-cell patch-clamp analysis demonstrated that CER and sphingomyelinase significantly reduced peak Ca(2+) currents. Pretreatment with staurosporine significantly attenuated CER-dependent inhibition of both NIC-induced Ca(2+) transients and peak Ca(2+) current, suggesting that the effects of CER are mediated at least in part by protein kinase C. Consistent with suppressed Ca(2+) signaling, CER also significantly inhibited NIC-induced catecholamine secretion measured at the single-cell level by carbon fiber amperometry. This effect of CER was also significantly attenuated by pretreatment with staurosporine These data demonstrate that the sphingomyelin signaling pathway can modulate nicotinic receptor-dependent Ca(2+) signaling and catecholamine secretion in rat chromaffin cells.
Liu
J
J
Department of Physiology, University of Kentucky, College of Medicine, Lexington, Kentucky 40536-0298, USA.
Jorgensen
M S
MS
Adams
J M
JM
Titlow
W B
WB
Nikolova-Karakashian
M
M
Jackson
B A
BA
D000313:Adrenal Medulla / Q000166:cytology / Q000378:metabolism*; D000818:Animals; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology*; D002395:Catecholamines / Q000378:metabolism*; D002478:Cells, Cultured / Q000187:drug effects / Q000378:metabolism; D002518:Ceramides / Q000378:metabolism* / Q000494:pharmacology; D019439:Chromaffin Cells / Q000187:drug effects / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008297:Male; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology; D009538:Nicotine / Q000494:pharmacology; D011189:Potassium Chloride / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D011978:Receptors, Nicotinic / Q000187:drug effects / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology; D013108:Sphingomyelin Phosphodiesterase / Q000494:pharmacology; D013109:Sphingomyelins / Q000378:metabolism*; D019311:Staurosporine / Q000494:pharmacology
D015220:Calcium Channels; D002395:Catecholamines; D002518:Ceramides; D004791:Enzyme Inhibitors; D011978:Receptors, Nicotinic; D013109:Sphingomyelins; C109343:dihydroceramide; C101954:N-caproylsphingosine; D011189:Potassium Chloride; D009538:Nicotine; D011493:Protein Kinase C; D013108:Sphingomyelin Phosphodiesterase; D019311:Staurosporine