FIGURE 3.

Properties of CSR-mediated signaling in SMIE cells. A, mean fluorescence traces (representative of data from 3–4 separate experiments) of fura-2-loaded SMIE cells. Cells were bathed in Ca²⁺-free medium, and then 1–5 mm Ca²⁺ was added to the external medium to activate CSR. 1 μm NPS-2143 was added where indicated (red) to block this response. B and C, individual fluorescence traces indicate the changes in response of Fluo-4-loaded SMIE cells. Cells were bathed in 0.5 mm Ca²⁺-containing medium and then applied to 10 mm l-Phe with 1.2 mm external Ca²⁺ (B) showing pattern of [Ca²⁺]_i rise in response to both l-Phe and Ca^2+. Similarly, application of neomycin (500 μm) in external Ca²⁺ free medium followed by l-Phe (10 mm) with 0.5 mm Ca²⁺ (C) resulted Ca²⁺ entry due to [Ca²⁺]_i rise. D, Gd³⁺- (200 μm) induced activation of CSR in Fluo-4-loaded SMIE cells. Mean fluorescence traces (representative of 3–4 separate experiments) show an increase of [Ca²⁺]_i in response to Gd³⁺ and a block of this response by application of PLC inhibitor, U73122 (500 μm). U73342, an inactive analog of U73122, was used as a control. Mean fluorescence traces represent data from 3–4 separate experiments.