You are perfusing the thick ascending limb, testing whether reabsorption of fluid is active. The perfusing fluid contains 10 cpm of methoxy inulin, which is not absorbed by the nephron. Removal of oxygen causes the rate at which fluid leaves the thick ascending limb to increase from 1 to 2 nanoliters per min, and the concentration of methoxy inulin in the fluid leaving the nephron segment falls from 20 to 10. Vin = volume rate of perfusate, nanoliters/min
Cin = concentration of methoxyinulin in the perfusate, measured in counts per minute
Vout = volume rate of fluid exiting the tubule, nanoliters/min
Cout = concentration of methoxyinulin in the perfusate, counts per minute
R = volume rate of fluid reabsorbed, nanoliters/min
Vin * Cin = Vout * Cout
Vin = Vout * Cout/Cin
R = Vin - Vout
True or False: Reabsorption of fluid by this tubule is active.
A. True
B. False