Fig. 6.
LPA/LPA5R (3 μM) increases intracellular Ca2+ in polarized OK/NHERF2 cells, an LPA5R- and ERK-dependent effect. A: intracellular Ca2+ concentration ([Ca2+]i) was determined with fura-2 AM using a microscopy based system with 4-Br-A23187 as a positive control. Arrow indicates 4-Br-A23187 (1 μM) addition. B: LPA caused a rapid onset increase in [Ca2+]i that returned towards baseline in ∼4 min. Arrow indicates LPA (3 μM) addition. C: LPA failed to increase [Ca2+]i in the absence of LPA5R even in the presence of NHERF2 indicating dependence on the LPA5 receptor. D: the LPA/LPA5R increase in [Ca2+]i was prevented by 30 min preincubation with the ERK inhibitor, U0126 (10 μM), which did not alter the A23187 (1 μM) induced increase (2nd arrow). Results of a single experiment are shown and was repeated 3 times with similar results.