La3+ inhibits the UTP-induced Ca2+ mobilization in MDCK cells.
We have studied the effects of La3+ on UTP-induced rises in intracellular calcium levels ([Ca2+]i) measured by fura-2 fluorimetry in Madin Darby canine kidney (MDCK) cells. UTP induced [Ca2+]i rises dose-dependently with an EC50 of 1 mM. The Ca2+ signal was triggered by a Ca2+ release from the inositol 1,4,5-trisphosphate (IP3)-sensitive pool because the signal was completely blocked by pretreatment of the endoplasmic reticulum (ER) Ca2+ pump inhibitor thapsigargin (TG) or the phospholipase C (PLC) inhibitor U73,122. Both the peak height and under-curve area of 10 microM UTP-induced Ca2+ signal was reduced by approximately 40% by extracellular Ca2+ removal, suggesting that UTP induced capacitative Ca2+ entry. La3+ inhibited the UTP-induced Ca2+ signal dose-dependently when added before or after UTP. Pretreatment of 0.1 mM La3+ inhibited the UTP response more than Ca2+ removal did. The mechanisms underlying the La3+ inhibition appear to involve not only block of capacitative Ca2+ entry.
Jan
C R
CR
Department of Medical Education and Research, Veterans General Hospital-Kaohsiung, Taiwan, ROC. crjan@isca.vghks.gov.tw
Ho
C M
CM
Wu
S N
SN
Huang
J K
JK
Tseng
C J
CJ
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D005456:Fluorescent Dyes; D005470:Fluorometry; D016257:Fura-2; D007425:Intracellular Membranes / Q000187:drug effects / Q000378:metabolism; D007668:Kidney / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D007811:Lanthanum / Q000008:administration & dosage / Q000494:pharmacology*; D014544:Uridine Triphosphate / Q000037:antagonists & inhibitors / Q000494:pharmacology*
D005456:Fluorescent Dyes; C028521:lanthanum chloride; D007811:Lanthanum; D002118:Calcium; D016257:Fura-2; D014544:Uridine Triphosphate