Fig. 3

Measurement of intracellular Ca²⁺ concentration before and after application of extracellular Ca²⁺: a RT-PCR in isolated mouse trophoblasts from placenta at 18 days post-fertilization. The strong placental lactogen II signal suggested that this included a trophoblast-rich population. TRPM6 as well as TRPM7 were expressed in these cells. Control means PCR reaction using plasmid of partial TRP channel cDNA as a template. b, c Time traces of intracellular Ca²⁺ concentration before and after extracellular EDTA (2 mM) treatment in mouse primary trophoblasts. The Ca²⁺ increase after application of 2 mM Ca²⁺ represents plasma membrane Ca²⁺ permeability. Co-application of 2-APB (2 mM) significantly increased the Ca²⁺ permeability (n = 12, c, d) but lower concentrations (50 and 100 μM, d) did not (n = 12), suggesting a contribution of the TRPM6/TRPM7 heteromers to the Ca²⁺ permeability in primary trophoblasts. e Plasma membrane Ca²⁺ permeability in mock-transfected HEK293T cells or HEK293T cells expressing TRPM6, TRPM7, or TRPM6 with TRPM7. The Ca²⁺ permeability of TRPM6 with TRPM7 was statistically higher compared to the mock-transfected cells (p < 0.001, n = 20, Student’s t test), but not in the cell transfecting TRPM6 or TRPM7 alone