Abstract
In Madin-Darby canine kidney (MDCK) cells, the effect of 2-O-methyl PAF, an inactive analogue of platelet activating factor (PAF), on intracellular Ca 2+ concentration ([Ca2+]i) was measured by using the Ca2+-sensitive fluorescent dye fura-2. 2-O-methyl PAF (≥15 μM) caused a rapid rise of [Ca2+]i in a concentration-dependent manner. 2-O-methyl PAF-induced [Ca2+] i rise was partly reduced by removal of extracellular Ca 2+. 2-O-methyl PAF-induced extracellular Ca2+ influx was also suggested by Mn2+ influx-induced fura-2 fluorescence quench. The 2-O-methyl PAF-induced Ca2+ influx was blocked by nifedipine, verapamil and diltiazem. In Ca2+-free medium, thapsigargin, an inhibitor of the endoplasmic reticulum Ca2+-ATPase, caused a monophasic [Ca2+]i rise, after which 2-O-methyl PAF failed to increase [Ca2+]i; also, pretreatment with 2-O-methyl PAF depleted thapsigargin-sensitive Ca2+ stores. U73122, an inhibitor of phospholipase C, abolished ATP (but not 2-O-methyl PAF)-induced [Ca 2+]i rise. These findings suggest that 2-O-methyl PAF evokes a rapid increase in [Ca2+]i in renal tubular cells by stimulating both extracellular Ca2+ influx and intracellular Ca2+ release.
Original language | English |
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Pages (from-to) | 336-344 |
Number of pages | 9 |
Journal | Life Sciences |
Volume | 77 |
Issue number | 3 |
DOIs | |
State | Published - 03 06 2005 |
Externally published | Yes |
Keywords
- 2-O-methyl PAF
- Ca
- Ca stores
- Fura-2
- Madin Darby canine kidney cells