title: Caffeine induced Ca2+ release and capacitative Ca2+ entry in human embryonic kidney (HEK293) cells.
abstract: The potential role of endogenous ryanodine receptor (RyR) in modulating Ca2+ handling in HEK293 cells is controversial. Using Fura2/AM, here we provide evidence that caffeine can induce Ca2+ release from inositol 1,4,5-trisphosphate receptor-sensitive stores and Ca2+ entry in early passage numbers of HEK293 cells, but not in late passage ones. Ryanodine blocks caffeine-mediated effect, whereas 4-chloro-m-cresol can mimic these effects. In contrast, an increase in cyclic AMP or activation of voltage-dependent Ca2+ channels does not induce detectable alteration in intracellular Ca2+. Importantly, immunoblotting and staining have revealed that endogenous RyR expression is more abundant in the early than in the late passage cells. Additionally, similar to carbachol, Ca2+ entry in response to caffeine is blocked by capacitative Ca2+ entry inhibitors. These results indicate that the endogenous RyR in HEK293 cells can function as Ca2+ release channels and mediate capacitative Ca2+ entry, but they may be reduced due to cell passage.
authors.affiliation: Institute of Cardiovascular Science, Health Science Center, Peking University, Beijing 100083, P.R. China. luodl@bjmu.edu.cn
authors.forename: Dali
authors.initials: D
authors.lastname: Luo
authors.forename: Hongli
authors.initials: H
authors.lastname: Sun
authors.forename: Rui Ping
authors.initials: RP
authors.lastname: Xiao
authors.forename: Qide
authors.initials: Q
authors.lastname: Han
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D015153:Blotting, Western; D001896:Boron Compounds / Q000494:pharmacology; D002110:Caffeine / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism*; D020013:Calcium Signaling / Q000187:drug effects; D002217:Carbachol / Q000494:pharmacology; D002460:Cell Line; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D005682:Gadolinium / Q000494:pharmacology; D015544:Inositol 1,4,5-Trisphosphate / Q000378:metabolism; D007668:Kidney / Q000166:cytology / Q000196:embryology / Q000378:metabolism; D032383:Myocytes, Cardiac / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D019837:Ryanodine Receptor Calcium Release Channel / Q000378:metabolism
chemical_list: D001896:Boron Compounds; D019837:Ryanodine Receptor Calcium Release Channel; D005576:Colforsin; D002110:Caffeine; D015544:Inositol 1,4,5-Trisphosphate; D002217:Carbachol; D005682:Gadolinium; D000242:Cyclic AMP; C109986:2-aminoethoxydiphenyl borate; D002118:Calcium