Figure 3.

Enhancement by ATRA and Am80 of P2Y2 receptor-mediated increase in [Ca²⁺]i in NHEKs. A. Typical traces of the UTP-evoked changes in [Ca²⁺]i in NHEKs. NHEKs were incubated with 0.1 µM ATRA (middle) or Am80 (bottom) for 6 h, incubated with normal culture medium for another 18 h, and then the fura-2 based [Ca²⁺]i measurement was performed. UTP (100 µM) was applied to cells for 10 s and the increase in the ΔF340/F380 ratio was calculated (n = 110–125). After the initial UTP-application, the extracellular Ca²⁺ was removed (0 Ca²⁺), and the second UTP was applied to the cells in the absence of extracellular Ca²⁺. Effect of ATRA and Am80 on the UTP-evoked elevation in [Ca²⁺]i in NHEKs in the presence and absence of extracellular Ca²⁺ was summarized in B. Asterisks show significant difference from control (without retinoids) (^*P < 0.05; ^**P < 0.01).