Figure 5.

PKC-dependent negative feedback is not engaged by P2Y₂R activation. a, UTP (50 μm; 10 sec) was applied as indicated (arrows) before and during application of PMA (1 μm; black bar). b, The mean amplitudes of UTP-evoked responses in the presence of PMA (n = 15 cells), PMA plus Gö6850 (1 μm; n = 13 cells), or PMA plus Bis. V (1 μm; n = 6 cells) are plotted as a percentage of control responses before the treatments. *p < 0.01; Student's t test. c, Record of fura-2 emission ratio from an astrocyte onto which UTP (50 μm, 5 sec) was applied at a rate of 1 min ^-1 in the presence of Gö6850. d, Histogram showing mean amplitudes of responses evoked by applications of UTP at a rate of 1 min ^-1 without (black bars; n = 11 cells) or with bath-applied Gö6850 (1 μm; white bars; n = 7 cells). Response amplitudes are expressed as a percentage of the amplitude of the first response. e, Record of fura-2 emission ratios from a single cell. 2-MeSADP (10 μm, 5 sec) was applied at a rate of 1 min ^-1 over 10 min, and then UTP (50 μm, 5 sec) was applied at a similar rate. Gö6850 (1 μm, 5 sec) was bath-applied 20 min before the first 2-MeSADP application (representative of 7 cells). f, On the left, the histogram shows mean amplitudes of the seventh response evoked by applications of 2-MeSADP (10 μm, 5 sec) at a rate of 1 min ^-1 without (black bars; n = 9 cells) or with preapplication of UTP (white bars; n = 6 cells). The right part of the graph shows the mean amplitudes of the seventh response evoked by applications of UTP (50 μm, 5 sec) at a rate of 1 min ^-1 without (black bars; n = 7 cells) or with preapplication of 2-MeSADP (white bars; n = 7 cells). Response amplitudes are expressed as a percentage of the amplitude of the first response.