This chapter focuses on the flux measurements in isolated perfused tubules. Solute fluxes are measured in isolated perfused tubule segments in much the same way that they are in any epithelium. The only additional considerations occur because of the small volume of the lumenal compartment. This imposes difficulties in both measuring solute or radioactive label concentrations in the fluid samples, and ensuring that the composition of the lumenal compartment is known and that it remains relatively constant along the length of the perfused segment. Net fluxes are measured as the rate of disappearance or appearance of the solute in the tubule lumen or, in other words, as the difference in the rate at which the solute is perfused and the rate at which it is collected at the opposite end of the tubule. The unidirectional lumen-to-bath flux of a solute can be measured in the same manner as the net flux of the solute if the solute is present in the perfusate but not the bathing solution.
ASJC Scopus subject areas
- Molecular Biology