Fig. 5.

Effect of bumetanide on wild-type and Ncc69 mutant tubules. A: secretion rate (nl/min per tubule) was measured in wild-type tubules in the absence (n = 7) or presence (n = 8) of 10 μM bumetanide. Bumetanide (10 μM) had no effect on fluid secretion. B: K⁺ flux (pmol/min per tubule) was measured in wild-type tubules in the absence (n = 7) or presence (n = 8) of 10 μM bumetanide. Bumetanide (10 μM) had no effect on K⁺ flux. C: secretion rate (nl/min per tubule) was measured in wild-type and Ncc69^r2 mutant tubules in the absence or presence of 100 μM bumetanide (n = 14–15 tubules per genotype/condition). Bumetanide (100 μM) inhibited fluid secretion in both wild-type and Ncc69^r2 mutant tubules, indicating that Ncc69 is not the only target of high-dose bumetanide. ***P < 0.001. D: K⁺ flux (pmol/min per tubule) was measured in wild-type and Ncc69^r2 mutant tubules in the absence or presence of 100 μM bumetanide (n = 14–15 tubules per genotype/condition). Bumetanide (100 μM) inhibited K⁺ flux in both wild-type and Ncc69^r2 mutant tubules, indicating that Ncc69 is not the only target of high-dose bumetanide. ***P < 0.001.