Figure 3.
The relaxing effects of ZD6169, levcromakalim and nifedipine on the urethral tone. (a) The effects of ZD6169 and levcromakalim on the urethral tone in the absence and presence of 1 μM Bay K8644. The dashed line indicates the increased urethral tone in the presence of Bay K8644. (b) Relationships between the relative value of the glibenclamide-sensitive ZD6169-induced relaxation and the concentration of ZD6169. The peak amplitude of the 10 μM levcromakalim-induced relaxation was taken as one. Each symbol indicates mean with s.d. shown by vertical lines (n=4 – 7). The line was drawn by eye. The curve with the broken line (ZD6169) is obtained from Figure 1(b). *Significantly different from the relative value in the absence of Bay K8644 (t-test, P<0.01). (c) When extracellular Ca2+ was removed (and 2 mM EGTA added), the resting urethral tone was reversibly reduced. The dashed line indicates the mean resting urethral tone. (d) Applying 1 μM nifedipine caused an irreversible urethral relaxation. The dashed line indicates the mean resting urethral tone.