Figure 6.

Assays for cytosolic Ca²⁺ and cAMP. (A) GLUTag cells transduced with the Ca²⁺ reporter YC3.6 were perifused with 5.6 mM of glucose standard extracellular solution at 37°C. GTS-21 (100 μM) was applied (indicated by bars) and induced an oscillatory rise of [Ca²⁺]_i. Data are plotted as mean ± SEM for 9 cells from a single experiment and are representative of 64 cells from three independent transductions. (B) Single cell [Ca²⁺]_i response to GTS-21 (100 μM) taken from the record shown in (A). The single-cell record highlights the oscillatory [Ca²⁺]_i response. (C) GLUTag cells transduced with the cAMP reporter H188 were perifused with GTS-21 (100 μM) followed by forskolin (Fsk; 5 μM) + 3-isobutyl-1-methylxanthine (IBMX; 100 μM). GTS-21 had no effect on [cAMP]_i, whereas the positive control (Fsk + IBMX) reversibly elevated [cAMP]. Data are plotted as mean ± SEM for 24 cells from three experiments and are representative of 62 cells from three independent viral transductions.