Electrical resistance of renal proximal tubule perfused in vitro.

LUTZ, MICHAEL D., JEAN CARDINAL, AND MAURICE B, BURG. Electrical resishnce of renal proximal tubule perfused z’n vitro. Am. J. Physiol. 225(3) : 729-734. 1973 .-Two techniques to measure potential differences (PD) and electrical resistance in isolated renal proximal tubules of the rabbit are described. Cable analysis was used to calculate the transepithelial resistance (RT). The applicability of cable analysis to the proximal tubule was examined and confirmed. In proximal convoluted tubules, mean PD was -3.8 mv (lumen negative) and mean RT was 964 Qcm. In proximal straight tubules, mean PD was -2.0 mv and mean RT was 1,188 Wm. The low electrical resistance of the proximal tubule reflects the high permeability of this nephron segment to electrolytes. By comparing the calculated short-circuit current with the net Na flux, it is concluded that Na is transported actively in the proximal tuble. Ouabain, consistent with its inhibition of Na transport, eliminated the PD while simultaneously increasing the RT .