title: Effect of nortriptyline on Ca²⁺ handling in SIRC rabbit corneal epithelial cells.
abstract: To explore the effect of nortriptyline, a tricyclic antidepressant, on cytosolic free Ca²⁺ concentrations ([Ca²⁺]i) in corneal epithelial cells, [Ca²⁺]i levels in suspended SIRC rabbit corneal epithelial cells were measured by using fura-2 as a Ca²⁺-sensitive fluorescent dye. Nortriptyline at concentrations between 20-200 microM increased [Ca²⁺]i in a concentration-dependent manner. The Ca²⁺ signal was reduced partly by removing extracellular Ca²⁺. Nortriptyline-induced Ca²⁺ influx was inhibited by the store-operated Ca²⁺ channel blockers econazole and SK&F96365, the phospholipase A2 inhibitor aristolochic acid, and alteration of activity of protein kinase C. In Ca²⁺-free medium, 200 microM nortriptyline pretreatment greatly inhibited the rise of [Ca²⁺]i induced by the endoplasmic reticulum Ca²⁺ pump inhibitor thapsigargin. Conversely, pretreatment with thapsigargin or 2,5-di-tert-butylhydroquinone (BHQ; another endoplasmic reticulum Ca²⁺ pump inhibitor) nearly abolished nortriptyline-induced [Ca²⁺]i rise. Inhibition of phospholipase C with U73122 decreased nortriptyline-induced [Ca²⁺]i rise by 75%. Taken together, nortriptyline induced [Ca²⁺]i rises in SIRC cells by causing phospholipase C-dependent Ca²⁺ release from the endoplasmic reticulum and Ca²⁺ influx via store-operated Ca²⁺ channels.
authors.affiliation: Department of Psychiatry, Yung-Kang Veterans Hospital, Tainan 71051, Taiwan, ROC.
authors.forename: Kai-Hsien
authors.initials: KH
authors.lastname: Chang
authors.forename: Hung-Pin
authors.initials: HP
authors.lastname: Tan
authors.forename: Chun-Chi
authors.initials: CC
authors.lastname: Kuo
authors.forename: Daih-Huang
authors.initials: DH
authors.lastname: Kuo
authors.forename: Pochuen
authors.initials: P
authors.lastname: Shieh
authors.forename: Fu-An
authors.initials: FA
authors.lastname: Chen
authors.forename: Chung-Ren
authors.initials: CR
authors.lastname: Jan
mesh_terms: D000818:Animals; D000929:Antidepressive Agents, Tricyclic / Q000494:pharmacology*; D034341:Aristolochic Acids / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D020013:Calcium Signaling / Q000187:drug effects* / Q000502:physiology; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004721:Endoplasmic Reticulum / Q000378:metabolism; D019573:Epithelium, Corneal / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D004963:Estrenes / Q000494:pharmacology; D023421:Models, Animal; D009661:Nortriptyline / Q000494:pharmacology*; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D064801:Phospholipase A2 Inhibitors; D011760:Pyrrolidinones / Q000494:pharmacology; D011817:Rabbits; D019284:Thapsigargin / Q000494:pharmacology; D013997:Time Factors; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors / Q000378:metabolism
chemical_list: D000929:Antidepressive Agents, Tricyclic; D034341:Aristolochic Acids; D002121:Calcium Channel Blockers; D004963:Estrenes; D010726:Phosphodiesterase Inhibitors; D064801:Phospholipase A2 Inhibitors; D011760:Pyrrolidinones; C060229:1-(6-((3-methoxyestra-1,3,5(10)-trien-17-yl)amino)hexyl)-1H-pyrrole-2,5-dione; D019284:Thapsigargin; C000228:aristolochic acid I; D009661:Nortriptyline; D010738:Type C Phospholipases; D002118:Calcium