We have studied the effects of La 3+ on UTP-induced rises in intracellular calcium levels ([Ca 2+ ] i ) measured by fura-2 fluorimetry in Madin Darby canine kidney (MDCK) cells. UTP induced [Ca 2+ ] i rises dose-dependently with an EC 50 of 1 mM. The Ca 2+ signal was triggered by a Ca 2+ release from the inositol 1,4,5-trisphosphate (IP 3 )-sensitive pool because the signal was completely blocked by pretreatment of the endoplasmic reticulum (ER) Ca 2+ pump inhibitor thapsigargin (TG) or the phospholipase C (PLC) inhibitor U73122. Both the peak height and under-curve area of 10 μM UTP-induced Ca 2+ signal was reduced by approximately 40% by extracellular Ca 2+ removal, suggesting that UTP induced capacitative Ca 2+ entry. La 3+ inhibited the UTP-induced Ca 2+ signal dose-dependently when added before or after UTP. Pretreatment of 0.1 mM La 3+ inhibited the UTP response more than Ca 2+ removal did. The mechanisms underlying the La 3+ inhibition appear to involve not only block of capacitative Ca 2+ entry.
|Number of pages||6|
|Journal||Chinese Journal of Physiology|
|Publication status||Published - 1998 Mar 31|
All Science Journal Classification (ASJC) codes
- Physiology (medical)